debug: add print support for new ast node types

movement between lexer states is now defined (almost) exclusively
by a table of outgoing links defined for each state type.

the main lexer system uses this table to determine when, how, and to
where the state should be changed.

also add a dedicated lexer state for scanning hashtables, due to the
particularly unique rules that apply within.

bshell.vim/syntax/bshell.vim

@@ -14,8 +14,29 @@ syn keyword	bshellKeyword	func
 syn keyword	bshellTodo	contained TODO FIXME XXX NOTE HACK TBD
 syn match	bshellLineComment	/#.*$/ contains=bshellTodo
 
-syn region	bshellInterpolatedString	matchgroup=bshellString start=+"+ end=+"+ extend contains=bshellVariable
+syn region	bshellInterpolation	matchgroup=bshellInterpolationDelimiter start=+$(+ end=+)+ keepend contained contains=@bshellAll
+syn region	bshellInterpolation	matchgroup=bshellInterpolationDelimiter start="$(" end=")" contained contains=ALL
+syn region	bshellInterpolatedString	matchgroup=bshellString start=+"+ end=+"+ extend contains=bshellVariable,bshellInterpolation
 syn region	bshellLiteralString	matchgroup=bshellString start=+\'+ end=+\'+ extend contains=bshellSpecialChar,bshellSpecialError,bshellUnicodeNumber,@Spell
+syn region	bshell1NestedParentheses	start="(" skip="\\\\\|\\)" matchgroup=bshellInterpolation end=")" transparent contained
+
+syn case	ignore
+syn match	bshellInteger	"\<0b[01_]*[01]\%([lu]\|lu\|ul\)\=\>" display
+syn match	bshellInteger	"\<\d\+\%(_\+\d\+\)*\%([lu]\|lu\|ul\)\=\>" display
+syn match	bshellInteger	"\<-\d\+\%(_\+\d\+\)*\%([lu]\|lu\|ul\)\=\>" display
+syn match	bshellInteger	"\<0x[[:xdigit:]_]*\x\%([lu]\|lu\|ul\)\=\>" display
+syn match	bshellReal	"\<\d\+\%(_\+\d\+\)*\.\d\+\%(_\+\d\+\)*\%\(e[-+]\=\d\+\%(_\+\d\+\)*\)\=[fdm]\=" display
+syn match	bshellReal	"\.\d\+\%(_\+\d\+\)*\%(e[-+]\=\d\+\%(_\+\d\+\)*\)\=[fdm]\=\>" display
+syn match	bshellReal	"\<\d\+\%(_\+\d\+\)*e[-+]\=\d\+\%(_\+\d\+\)*[fdm]\=\>" display
+syn match	bshellReal	"\<\d\+\%(_\+\d\+\)*[fdm]\>" display
+syn case	match
+syn cluster     bshellNumber	contains=bshellInteger,bshellReal
+
+syn cluster	bshellLiteral	contains=@bshellNumber,@bshellString
+syn cluster	bshellAll	contains=@bshellLiteral,bshellVariable,bshellKeyword,bshellArgFlag,bshellFunctionRef,bshellSymbolOp,bshellKeywordOp
+
+syn match	bshellSymbolOp	"[+]" display
+syn keyword	bshellKeywordOp	is not understands and or
 
 hi def link	bshellKeyword	Statement
 hi def link	bshellArgFlag	Tag
@@ -25,7 +46,12 @@ hi def link	bshellFunctionRef	Function
 hi def link	bshellString	String
 hi def link	bshellInterpolatedString	String
 hi def link	bshellLiteralString	String
+hi def link	bshellInteger	Number
+hi def link	bshellReal	Float
 
+hi def link	bshellInterpolationDelimiter Delimiter
+hi def link	bshellSymbolOp Operator
+hi def link	bshellKeywordOp Operator
 
 " The default highlighting.
 " hi def link	bshellUnspecifiedStatement	Statement

bshell/ast/array.c

@@ -0,0 +1,25 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct array_ast_node *array = (struct array_ast_node *)node;
+
+	fx_queue_entry *cur = fx_queue_first(&array->n_items);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition array_ast_node = {
+	.def_id = AST_ARRAY,
+	.def_node_size = sizeof(struct array_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/ast.c

@@ -0,0 +1,196 @@
+#include "ast.h"
+
+#include "../status.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+extern struct ast_node_definition null_ast_node;
+extern struct ast_node_definition int_ast_node;
+extern struct ast_node_definition double_ast_node;
+extern struct ast_node_definition word_ast_node;
+extern struct ast_node_definition var_ast_node;
+extern struct ast_node_definition string_ast_node;
+extern struct ast_node_definition fstring_ast_node;
+extern struct ast_node_definition cmdcall_ast_node;
+extern struct ast_node_definition pipeline_ast_node;
+extern struct ast_node_definition redirection_ast_node;
+extern struct ast_node_definition block_ast_node;
+extern struct ast_node_definition stmt_list_ast_node;
+extern struct ast_node_definition func_ast_node;
+extern struct ast_node_definition array_ast_node;
+extern struct ast_node_definition hashtable_ast_node;
+extern struct ast_node_definition hashtable_item_ast_node;
+extern struct ast_node_definition if_ast_node;
+extern struct ast_node_definition if_branch_ast_node;
+extern struct ast_node_definition op_ast_node;
+
+static const struct ast_node_definition *ast_node_defintions[] = {
+	[AST_NULL] = &null_ast_node,
+	[AST_INT] = &int_ast_node,
+	[AST_DOUBLE] = &double_ast_node,
+	[AST_WORD] = &word_ast_node,
+	[AST_VAR] = &var_ast_node,
+	[AST_STRING] = &string_ast_node,
+	[AST_FSTRING] = &fstring_ast_node,
+	[AST_CMDCALL] = &cmdcall_ast_node,
+	[AST_PIPELINE] = &pipeline_ast_node,
+	[AST_REDIRECTION] = &redirection_ast_node,
+	[AST_BLOCK] = &block_ast_node,
+	[AST_STMT_LIST] = &stmt_list_ast_node,
+	[AST_FUNC] = &func_ast_node,
+	[AST_ARRAY] = &array_ast_node,
+	[AST_IF] = &if_ast_node,
+	[AST_IF_BRANCH] = &if_branch_ast_node,
+	[AST_HASHTABLE] = &hashtable_ast_node,
+	[AST_HASHTABLE_ITEM] = &hashtable_item_ast_node,
+	[AST_OP] = &op_ast_node,
+};
+static const size_t nr_ast_node_definitions
+	= sizeof ast_node_defintions / sizeof ast_node_defintions[0];
+
+struct ast_node *ast_node_create(enum ast_node_type type)
+{
+	assert(type < nr_ast_node_definitions);
+
+	const struct ast_node_definition *def = ast_node_defintions[type];
+	struct ast_node *out = malloc(def->def_node_size);
+	if (!out) {
+		return NULL;
+	}
+
+	memset(out, 0x0, def->def_node_size);
+
+	out->n_type = type;
+
+	return out;
+}
+
+void ast_node_destroy(struct ast_node *node)
+{
+	assert(node->n_type < nr_ast_node_definitions);
+
+	struct ast_iterator it = {0};
+	ast_iterator_enqueue(&it, node);
+
+	while (1) {
+		node = ast_iterator_peek(&it);
+		if (!node) {
+			break;
+		}
+
+		const struct ast_node_definition *def
+			= ast_node_defintions[node->n_type];
+
+		if (def->def_cleanup) {
+			def->def_cleanup(node);
+		}
+
+		ast_iterator_dequeue(&it);
+		free(node);
+	}
+}
+
+void ast_node_iterate(struct ast_node *node, struct ast_iterator *it)
+{
+	ast_iterator_enqueue(it, node);
+}
+
+void ast_node_to_string(const struct ast_node *node, fx_bstr *out)
+{
+	const struct ast_node_definition *def
+		= ast_node_defintions[node->n_type];
+	if (def->def_to_string) {
+		def->def_to_string(node, out);
+	}
+}
+
+#define ENUM_STR(x)                                                            \
+	case x:                                                                \
+		return #x
+
+const char *ast_node_type_to_string(enum ast_node_type type)
+{
+	switch (type) {
+		ENUM_STR(AST_NONE);
+		ENUM_STR(AST_NULL);
+		ENUM_STR(AST_STMT_LIST);
+		ENUM_STR(AST_INT);
+		ENUM_STR(AST_DOUBLE);
+		ENUM_STR(AST_WORD);
+		ENUM_STR(AST_STRING);
+		ENUM_STR(AST_FSTRING);
+		ENUM_STR(AST_VAR);
+		ENUM_STR(AST_VAR_SPLAT);
+		ENUM_STR(AST_FLAG);
+		ENUM_STR(AST_CMDCALL);
+		ENUM_STR(AST_PIPELINE);
+		ENUM_STR(AST_REDIRECTION);
+		ENUM_STR(AST_BLOCK);
+		ENUM_STR(AST_FUNC);
+		ENUM_STR(AST_IF);
+		ENUM_STR(AST_IF_BRANCH);
+		ENUM_STR(AST_OP);
+		ENUM_STR(AST_ARRAY);
+		ENUM_STR(AST_HASHTABLE);
+		ENUM_STR(AST_HASHTABLE_ITEM);
+	default:
+		return "<unknown>";
+	}
+}
+
+struct ast_node *ast_iterator_peek(struct ast_iterator *it)
+{
+	fx_queue_entry *cur = fx_queue_first(&it->it_queue);
+	if (!cur) {
+		return NULL;
+	}
+
+	return fx_unbox(struct ast_node, cur, n_it.e_entry);
+}
+
+struct ast_node *ast_iterator_dequeue(struct ast_iterator *it)
+{
+	fx_queue_entry *cur = fx_queue_first(&it->it_queue);
+	if (!cur) {
+		return NULL;
+	}
+
+	struct ast_node *node = fx_unbox(struct ast_node, cur, n_it.e_entry);
+	const struct ast_node_definition *def
+		= ast_node_defintions[node->n_type];
+
+	it->it_insert_after = cur;
+	if (def->def_collect_children) {
+		def->def_collect_children(node, it);
+	}
+
+	fx_queue_pop_front(&it->it_queue);
+	return fx_unbox(struct ast_node, cur, n_it.e_entry);
+}
+
+void ast_iterator_enqueue(struct ast_iterator *it, struct ast_node *node)
+{
+	unsigned long new_depth = 0;
+
+	fx_queue_entry *cur = fx_queue_first(&it->it_queue);
+	if (cur) {
+		struct ast_node *cur_node
+			= fx_unbox(struct ast_node, cur, n_it.e_entry);
+		new_depth = cur_node->n_it.e_depth + 1;
+	}
+
+	node->n_it.e_depth = new_depth;
+
+	if (!it->it_insert_after) {
+		fx_queue_push_back(&it->it_queue, &node->n_it.e_entry);
+		return;
+	}
+
+	fx_queue_insert_after(
+		&it->it_queue,
+		&node->n_it.e_entry,
+		it->it_insert_after);
+	it->it_insert_after = &node->n_it.e_entry;
+}

bshell/ast/ast.h

@@ -0,0 +1,196 @@
+#ifndef AST_H_
+#define AST_H_
+
+#include "../status.h"
+
+#include <fx/bstr.h>
+#include <fx/queue.h>
+
+struct lex_token;
+
+enum ast_node_type {
+	AST_NONE = 0x00u,
+	AST_NULL,
+	AST_STMT_LIST,
+	AST_INT,
+	AST_DOUBLE,
+	AST_WORD,
+	AST_STRING,
+	AST_FSTRING,
+	AST_VAR,
+	AST_VAR_SPLAT,
+	AST_FLAG,
+	AST_CMDCALL,
+	AST_FUNCALL,
+	AST_PIPELINE,
+	AST_REDIRECTION,
+	AST_BLOCK,
+	AST_FUNC,
+	AST_ARRAY,
+	AST_HASHTABLE,
+	AST_HASHTABLE_ITEM,
+	AST_OP,
+	AST_IF,
+	AST_IF_BRANCH,
+};
+
+struct ast_iterator_entry {
+	fx_queue_entry e_entry;
+	unsigned long e_depth;
+};
+
+struct ast_node {
+	enum ast_node_type n_type;
+	struct ast_node *n_parent;
+	fx_queue_entry n_entry;
+	struct ast_iterator_entry n_it;
+};
+
+struct null_ast_node {
+	struct ast_node n_base;
+};
+
+struct int_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_value;
+};
+
+struct double_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_value;
+};
+
+struct word_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_value;
+};
+
+struct string_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_value;
+};
+
+struct fstring_ast_node {
+	struct ast_node n_base;
+	fx_queue n_elements;
+};
+
+struct var_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_ident;
+};
+
+struct var_splat_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_ident;
+};
+
+struct cmdcall_ast_node {
+	struct ast_node n_base;
+	fx_queue n_args;
+	fx_queue n_redirect;
+};
+
+struct funcall_ast_node {
+	struct ast_node n_base;
+	struct ast_node *n_func;
+	fx_queue n_args;
+};
+
+struct pipeline_ast_node {
+	struct ast_node n_base;
+	fx_queue n_stages;
+};
+
+struct redirection_ast_node {
+	struct ast_node n_base;
+	bool n_append : 1;
+	bool n_out_is_fd : 1;
+	bool n_out_is_expr : 1;
+
+	unsigned int n_in, n_out;
+	struct ast_node *n_out_path_expr;
+	const char *n_out_path;
+	struct lex_token *n_out_tok;
+};
+
+struct stmt_list_ast_node {
+	struct ast_node n_base;
+	fx_queue n_statements;
+};
+
+struct block_ast_node {
+	struct ast_node n_base;
+	fx_queue n_statements;
+};
+
+struct func_ast_node {
+	struct ast_node n_base;
+	struct lex_token *n_name;
+	fx_queue n_params;
+	struct ast_node *n_body;
+};
+
+struct array_ast_node {
+	struct ast_node n_base;
+	fx_queue n_items;
+};
+
+struct hashtable_ast_node {
+	struct ast_node n_base;
+	fx_queue n_items;
+};
+
+struct hashtable_item_ast_node {
+	struct ast_node n_base;
+	struct ast_node *n_key, *n_value;
+};
+
+struct op_ast_node {
+	struct ast_node n_base;
+	const struct operator_info *n_op;
+	struct ast_node *n_left, *n_right;
+};
+
+struct if_branch_ast_node {
+	struct ast_node n_base;
+	struct ast_node *n_cond;
+	struct ast_node *n_body;
+};
+
+struct if_ast_node {
+	struct ast_node n_base;
+	fx_queue n_branches;
+};
+
+struct ast_iterator {
+	struct ast_node *it_cur;
+	fx_queue it_queue;
+	unsigned int it_depth;
+	fx_queue_entry *it_insert_after;
+};
+
+struct ast_node_definition {
+	enum ast_node_type def_id;
+	size_t def_node_size;
+	enum bshell_status (*def_collect_children)(
+		struct ast_node *,
+		struct ast_iterator *);
+	enum bshell_status (*def_cleanup)(struct ast_node *);
+	void (*def_to_string)(const struct ast_node *, fx_bstr *);
+};
+
+extern struct ast_node *ast_node_create(enum ast_node_type type);
+extern void ast_node_destroy(struct ast_node *node);
+extern void ast_node_iterate(struct ast_node *node, struct ast_iterator *it);
+extern void ast_node_to_string(const struct ast_node *node, fx_bstr *out);
+
+extern const char *ast_node_type_to_string(enum ast_node_type type);
+
+extern struct ast_node *ast_iterator_peek(struct ast_iterator *it);
+extern struct ast_node *ast_iterator_dequeue(struct ast_iterator *it);
+extern void ast_iterator_enqueue(
+	struct ast_iterator *it,
+	struct ast_node *node);
+
+#endif

bshell/ast/block.c

@@ -0,0 +1,23 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct block_ast_node *block = (struct block_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&block->n_statements);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition block_ast_node = {
+	.def_id = AST_BLOCK,
+	.def_node_size = sizeof(struct block_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/cmdcall.c

@@ -0,0 +1,31 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct cmdcall_ast_node *cmdcall = (struct cmdcall_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&cmdcall->n_args);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	cur = fx_queue_first(&cmdcall->n_redirect);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition cmdcall_ast_node = {
+	.def_id = AST_CMDCALL,
+	.def_node_size = sizeof(struct cmdcall_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/double.c

@@ -0,0 +1,6 @@
+#include "ast.h"
+
+struct ast_node_definition double_ast_node = {
+	.def_id = AST_DOUBLE,
+	.def_node_size = sizeof(struct double_ast_node),
+};

bshell/ast/fstring.c

@@ -0,0 +1,23 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct fstring_ast_node *fstring = (struct fstring_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&fstring->n_elements);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition fstring_ast_node = {
+	.def_id = AST_FSTRING,
+	.def_node_size = sizeof(struct fstring_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/func.c

@@ -0,0 +1,36 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct func_ast_node *func = (struct func_ast_node *)node;
+
+	fx_queue_entry *cur = fx_queue_first(&func->n_params);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	if (func->n_body) {
+		ast_iterator_enqueue(it, func->n_body);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	const struct func_ast_node *func = (const struct func_ast_node *)node;
+	fx_bstr_write_fmt(out, NULL, "%s", func->n_name->tok_str);
+}
+
+struct ast_node_definition func_ast_node = {
+	.def_id = AST_FUNC,
+	.def_node_size = sizeof(struct func_ast_node),
+	.def_collect_children = collect_children,
+	.def_to_string = to_string,
+};

bshell/ast/hashtable-item.c

@@ -0,0 +1,26 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct hashtable_item_ast_node *item
+		= (struct hashtable_item_ast_node *)node;
+
+	if (item->n_key) {
+		ast_iterator_enqueue(it, item->n_key);
+	}
+
+	if (item->n_value) {
+		ast_iterator_enqueue(it, item->n_value);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition hashtable_item_ast_node = {
+	.def_id = AST_HASHTABLE_ITEM,
+	.def_node_size = sizeof(struct hashtable_item_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/hashtable.c

@@ -0,0 +1,24 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct hashtable_ast_node *hashtable
+		= (struct hashtable_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&hashtable->n_items);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition hashtable_ast_node = {
+	.def_id = AST_HASHTABLE,
+	.def_node_size = sizeof(struct hashtable_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/if-branch.c

@@ -0,0 +1,24 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct if_branch_ast_node *if_branch
+		= (struct if_branch_ast_node *)node;
+	if (if_branch->n_cond) {
+		ast_iterator_enqueue(it, if_branch->n_cond);
+	}
+
+	if (if_branch->n_body) {
+		ast_iterator_enqueue(it, if_branch->n_body);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition if_branch_ast_node = {
+	.def_id = AST_IF_BRANCH,
+	.def_node_size = sizeof(struct if_branch_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/if.c

@@ -0,0 +1,23 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct if_ast_node *if_group = (struct if_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&if_group->n_branches);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition if_ast_node = {
+	.def_id = AST_IF,
+	.def_node_size = sizeof(struct if_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/int.c

@@ -0,0 +1,14 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	struct int_ast_node *i = (struct int_ast_node *)node;
+	fx_bstr_write_fmt(out, NULL, "%lld", i->n_value->tok_int);
+}
+
+struct ast_node_definition int_ast_node = {
+	.def_id = AST_INT,
+	.def_node_size = sizeof(struct int_ast_node),
+	.def_to_string = to_string,
+};

bshell/ast/null.c

@@ -0,0 +1,7 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+struct ast_node_definition null_ast_node = {
+	.def_id = AST_NULL,
+	.def_node_size = sizeof(struct null_ast_node),
+};

bshell/ast/op.c

@@ -0,0 +1,37 @@
+#include "../operator.h"
+#include "../parse/token.h"
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct op_ast_node *op = (struct op_ast_node *)node;
+
+	if (op->n_left) {
+		ast_iterator_enqueue(it, op->n_left);
+	}
+
+	if (op->n_right) {
+		ast_iterator_enqueue(it, op->n_right);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	const struct op_ast_node *op = (const struct op_ast_node *)node;
+	fx_bstr_write_fmt(
+		out,
+		NULL,
+		"%s",
+		operator_id_to_string(op->n_op->op_id));
+}
+
+struct ast_node_definition op_ast_node = {
+	.def_id = AST_OP,
+	.def_node_size = sizeof(struct op_ast_node),
+	.def_collect_children = collect_children,
+	.def_to_string = to_string,
+};

bshell/ast/pipeline.c

@@ -0,0 +1,23 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct pipeline_ast_node *pipeline = (struct pipeline_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&pipeline->n_stages);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition pipeline_ast_node = {
+	.def_id = AST_PIPELINE,
+	.def_node_size = sizeof(struct pipeline_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/redirection.c

@@ -0,0 +1,49 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct redirection_ast_node *redirection
+		= (struct redirection_ast_node *)node;
+
+	if (redirection->n_out_path_expr) {
+		ast_iterator_enqueue(it, redirection->n_out_path_expr);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	struct redirection_ast_node *redirection
+		= (struct redirection_ast_node *)node;
+	fx_bstr_write_fmt(out, NULL, "&%u", redirection->n_in);
+
+	if (redirection->n_append) {
+		fx_bstr_write_fmt(out, NULL, " >>");
+	} else {
+		fx_bstr_write_fmt(out, NULL, " >");
+	}
+
+	if (redirection->n_out_is_fd) {
+		fx_bstr_write_fmt(out, NULL, " &");
+	} else {
+		fx_bstr_write_fmt(out, NULL, " ");
+	}
+
+	if (redirection->n_out_is_expr) {
+		fx_bstr_write_fmt(out, NULL, "<expr>");
+	} else if (redirection->n_out_path) {
+		fx_bstr_write_fmt(out, NULL, "'%s'", redirection->n_out_path);
+	} else {
+		fx_bstr_write_fmt(out, NULL, "%u", redirection->n_out);
+	}
+}
+
+struct ast_node_definition redirection_ast_node = {
+	.def_id = AST_REDIRECTION,
+	.def_node_size = sizeof(struct redirection_ast_node),
+	.def_collect_children = collect_children,
+	.def_to_string = to_string,
+};

bshell/ast/stmt-list.c

@@ -0,0 +1,24 @@
+#include "ast.h"
+
+static enum bshell_status collect_children(
+	struct ast_node *node,
+	struct ast_iterator *it)
+{
+	struct stmt_list_ast_node *stmt_list
+		= (struct stmt_list_ast_node *)node;
+	fx_queue_entry *cur = fx_queue_first(&stmt_list->n_statements);
+	while (cur) {
+		struct ast_node *child
+			= fx_unbox(struct ast_node, cur, n_entry);
+		ast_iterator_enqueue(it, child);
+		cur = fx_queue_next(cur);
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct ast_node_definition stmt_list_ast_node = {
+	.def_id = AST_STMT_LIST,
+	.def_node_size = sizeof(struct stmt_list_ast_node),
+	.def_collect_children = collect_children,
+};

bshell/ast/string.c

@@ -0,0 +1,15 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	const struct string_ast_node *string
+		= (const struct string_ast_node *)node;
+	fx_bstr_write_fmt(out, NULL, "%s", string->n_value->tok_str);
+}
+
+struct ast_node_definition string_ast_node = {
+	.def_id = AST_STRING,
+	.def_node_size = sizeof(struct string_ast_node),
+	.def_to_string = to_string,
+};

bshell/ast/var.c

@@ -0,0 +1,14 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	const struct var_ast_node *var = (const struct var_ast_node *)node;
+	fx_bstr_write_fmt(out, NULL, "%s", var->n_ident->tok_str);
+}
+
+struct ast_node_definition var_ast_node = {
+	.def_id = AST_VAR,
+	.def_node_size = sizeof(struct var_ast_node),
+	.def_to_string = to_string,
+};

bshell/ast/word.c

@@ -0,0 +1,14 @@
+#include "../parse/token.h"
+#include "ast.h"
+
+static void to_string(const struct ast_node *node, fx_bstr *out)
+{
+	const struct word_ast_node *word = (const struct word_ast_node *)node;
+	fx_bstr_write_fmt(out, NULL, "%s", word->n_value->tok_str);
+}
+
+struct ast_node_definition word_ast_node = {
+	.def_id = AST_WORD,
+	.def_node_size = sizeof(struct word_ast_node),
+	.def_to_string = to_string,
+};

bshell/debug.c

@@ -0,0 +1,149 @@
+#include "debug.h"
+
+#include "ast/ast.h"
+#include "parse/token.h"
+
+#include <fx/string.h>
+#include <fx/term/print.h>
+#include <stdio.h>
+
+extern void print_lex_token(struct lex_token *tok)
+{
+	printf("[%lu:%lu - %lu:%lu] ",
+	       tok->tok_start.c_row,
+	       tok->tok_start.c_col,
+	       tok->tok_end.c_row,
+	       tok->tok_end.c_col);
+
+	switch (tok->tok_type) {
+	case TOK_KEYWORD:
+		fx_puts("[magenta]");
+		break;
+	case TOK_SYMBOL:
+		fx_puts("[blue]");
+		break;
+	case TOK_INT:
+	case TOK_DOUBLE:
+	case TOK_VAR:
+	case TOK_VAR_SPLAT:
+		fx_puts("[yellow]");
+		break;
+	case TOK_OPERATOR:
+		fx_puts("[red]");
+		break;
+	case TOK_WORD:
+	case TOK_WORD_START:
+	case TOK_WORD_END:
+		fx_puts("[cyan]");
+		break;
+	case TOK_STRING:
+	case TOK_STR_START:
+	case TOK_STR_END:
+		fx_puts("[green]");
+		break;
+	case TOK_LINEFEED:
+		fx_puts("[dark_grey]");
+		break;
+	default:
+		break;
+	}
+
+	fx_puts(token_type_to_string(tok->tok_type));
+
+	switch (tok->tok_type) {
+	case TOK_WORD:
+	case TOK_FLAG:
+	case TOK_STRING:
+	case TOK_VAR:
+	case TOK_VAR_SPLAT:
+		printf("(%s)", tok->tok_str);
+		break;
+	case TOK_OPERATOR:
+		printf("(%s)", token_operator_to_string(tok->tok_operator));
+		break;
+	case TOK_SYMBOL:
+		printf("(%s)", token_symbol_to_string(tok->tok_symbol));
+		break;
+	case TOK_KEYWORD:
+		printf("(%s)", token_keyword_to_string(tok->tok_keyword));
+		break;
+	case TOK_INT:
+		printf("(%lld)", tok->tok_int);
+		break;
+	case TOK_DOUBLE:
+		printf("(%lf)", tok->tok_double);
+		break;
+	default:
+		break;
+	}
+
+	fx_puts("[reset]\n");
+}
+
+void print_ast_node(struct ast_node *node)
+{
+	struct ast_iterator it = {0};
+	ast_node_iterate(node, &it);
+
+	while (1) {
+		node = ast_iterator_peek(&it);
+		if (!node) {
+			break;
+		}
+
+		for (unsigned long i = 0; i < node->n_it.e_depth; i++) {
+			fx_puts("  ");
+		}
+
+		switch (node->n_type) {
+		case AST_IF:
+		case AST_IF_BRANCH:
+		case AST_BLOCK:
+		case AST_FUNC:
+		case AST_STMT_LIST:
+			fx_puts("[magenta]");
+			break;
+		case AST_REDIRECTION:
+		case AST_PIPELINE:
+		case AST_OP:
+		case AST_ARRAY:
+		case AST_HASHTABLE:
+		case AST_HASHTABLE_ITEM:
+			fx_puts("[blue]");
+			break;
+		case AST_CMDCALL:
+		case AST_NULL:
+			fx_puts("[red]");
+			break;
+		case AST_INT:
+		case AST_DOUBLE:
+		case AST_VAR:
+			fx_puts("[yellow]");
+			break;
+		case AST_WORD:
+			fx_puts("[cyan]");
+			break;
+		case AST_STRING:
+		case AST_FSTRING:
+			fx_puts("[green]");
+			break;
+		default:
+			break;
+		}
+
+		fx_printf("%s", ast_node_type_to_string(node->n_type));
+
+		char s[128] = {0};
+		fx_bstr str;
+		fx_bstr_begin(&str, s, sizeof s);
+		ast_node_to_string(node, &str);
+
+		if (fx_bstr_get_size(&str)) {
+			fx_printf("(%s)", fx_bstr_end(&str));
+		}
+
+		fx_printf("[reset]\n");
+
+		ast_iterator_dequeue(&it);
+	}
+}

bshell/debug.h

@@ -0,0 +1,12 @@
+#ifndef DEBUG_H_
+#define DEBUG_H_
+
+#include <stdbool.h>
+
+struct ast_node;
+struct lex_token;
+
+extern void print_lex_token(struct lex_token *tok);
+extern void print_ast_node(struct ast_node *node);
+
+#endif

bshell/operator.c

@@ -0,0 +1,264 @@
+#include "operator.h"
+
+#include "parse/token.h"
+
+#define OP(id, p, a, l, u)                                                     \
+	[OP_##id] = {                                                          \
+		.op_id = (OP_##id),                                            \
+		.op_precedence = (PRECEDENCE_##p),                             \
+		.op_associativity = (ASSOCIATIVITY_##a),                       \
+		.op_location = (OPL_##l),                                      \
+		.op_arity = (OPA_##u),                                         \
+	}
+
+#define TOK_OP(id, tok) [TOK_##tok - __TOK_INDEX_BASE] = &operators[OP_##id]
+#define SYM_OP(id, sym) [SYM_##sym - __SYM_INDEX_BASE] = &operators[OP_##id]
+#define KW_OP(id, kw)   [KW_##kw - __KW_INDEX_BASE] = &operators[OP_##id]
+#define TKOP_OP(id, kw) [TKOP_##kw - __TKOP_INDEX_BASE] = &operators[OP_##id]
+
+/* clang-format off */
+static const struct operator_info operators[] = {
+	OP(SUBEXPR,			PARENTHESIS,	LEFT,	PREFIX,		UNARY),
+	OP(ARRAY_START,			PARENTHESIS,	LEFT,	PREFIX,		UNARY),
+	OP(PAREN,			PARENTHESIS,	LEFT,	PREFIX,		UNARY),
+	OP(HASHTABLE_START,		PARENTHESIS,	LEFT,	PREFIX,		UNARY),
+	OP(ACCESS,			MEMBER_ACCESS,	LEFT,	INFIX,		BINARY),
+	OP(CONDITIONAL_ACCESS,		MEMBER_ACCESS,	LEFT,	INFIX,		BINARY),
+	OP(STATIC_ACCESS,		STATIC_ACCESS,	LEFT,	INFIX,		BINARY),
+	OP(SUBSCRIPT,			SUBSCRIPT,	LEFT,	INFIX,		BINARY),
+	OP(CONDITIONAL_SUBSCRIPT,	SUBSCRIPT,	LEFT,	INFIX,		BINARY),
+	OP(CAST,			CAST,		LEFT,	PREFIX,		UNARY),
+	OP(USPLIT,			SPLIT,		LEFT,	PREFIX,		UNARY),
+	OP(UJOIN,			JOIN,		LEFT,	PREFIX,		UNARY),
+	OP(ARRAY_DELIMITER,		ARRAY,		LEFT,	INFIX,		BINARY),
+	OP(INCREMENT,			INCREMENT,	LEFT,	INFIX,		BINARY),
+	OP(LOGICAL_NOT,			NOT,		LEFT,	PREFIX,		UNARY),
+	OP(RANGE,			RANGE,		LEFT,	INFIX,		BINARY),
+	OP(FORMAT,			FORMAT,		LEFT,	INFIX,		BINARY),
+	OP(MULTIPLY,			MULTIPLICATION,	LEFT,	INFIX,		BINARY),
+	OP(DIVIDE,			MULTIPLICATION,	LEFT,	INFIX,		BINARY),
+	OP(MODULO,			MULTIPLICATION,	LEFT,	INFIX,		BINARY),
+	OP(ADD,				ADDITION,	LEFT,	INFIX,		BINARY),
+	OP(SUBTRACT,			ADDITION,	LEFT,	INFIX,		BINARY),
+
+	OP(BSPLIT,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(BJOIN,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(IS,				COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(ISNOT,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(AS,				COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(EQUAL,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(NOT_EQUAL,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(GREATER_THAN,		COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(LESS_THAN,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(GREATER_EQUAL,		COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(LESS_EQUAL,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(LIKE,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(NOTLIKE,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(MATCH,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(NOTMATCH,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(IN,				COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(NOTIN,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(CONTAINS,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(NOTCONTAINS,			COMPARISON,	LEFT,	INFIX,		BINARY),
+	OP(REPLACE,			COMPARISON,	LEFT,	INFIX,		BINARY),
+
+	OP(LOGICAL_AND,			LOGICAL,	LEFT,	INFIX,		BINARY),
+	OP(LOGICAL_OR,			LOGICAL,	LEFT,	INFIX,		BINARY),
+	OP(LOGICAL_XOR,			LOGICAL,	LEFT,	INFIX,		BINARY),
+
+	OP(BINARY_AND,			BITWISE,	LEFT,	INFIX,		BINARY),
+	OP(BINARY_OR,			BITWISE,	LEFT,	INFIX,		BINARY),
+	OP(BINARY_NOT,			BITWISE,	LEFT,	INFIX,		BINARY),
+	OP(BINARY_XOR,			BITWISE,	LEFT,	INFIX,		BINARY),
+	OP(LEFT_SHIFT,			BITWISE,	LEFT,	INFIX,		BINARY),
+	OP(RIGHT_SHIFT,			BITWISE,	LEFT,	INFIX,		BINARY),
+
+	OP(ASSIGN,			ASSIGN,		LEFT,	INFIX,		BINARY),
+	OP(ADD_ASSIGN,			ASSIGN,		LEFT,	INFIX,		BINARY),
+	OP(SUBTRACT_ASSIGN,		ASSIGN,		LEFT,	INFIX,		BINARY),
+	OP(MULTIPLY_ASSIGN,		ASSIGN,		LEFT,	INFIX,		BINARY),
+	OP(DIVIDE_ASSIGN,		ASSIGN,		LEFT,	INFIX,		BINARY),
+	OP(MODULO_ASSIGN,		ASSIGN,		LEFT,	INFIX,		BINARY),
+};
+static const size_t nr_operators = sizeof operators / sizeof operators[0];
+
+static const struct operator_info *operator_symbols[] = {
+	SYM_OP(LOGICAL_NOT,		BANG),
+	SYM_OP(ASSIGN,			EQUAL),
+	SYM_OP(ADD,			PLUS),
+	SYM_OP(SUBTRACT,		HYPHEN),
+	SYM_OP(MULTIPLY,		ASTERISK),
+	SYM_OP(DIVIDE,			FORWARD_SLASH),
+	SYM_OP(MODULO,			PERCENT),
+	SYM_OP(ADD_ASSIGN,		PLUS_EQUAL),
+	SYM_OP(SUBTRACT_ASSIGN,		HYPHEN_EQUAL),
+	SYM_OP(MULTIPLY_ASSIGN, 	ASTERISK_EQUAL),
+	SYM_OP(DIVIDE_ASSIGN,		FORWARD_SLASH_EQUAL),
+	SYM_OP(MODULO_ASSIGN,		PERCENT_EQUAL),
+	SYM_OP(RANGE,			DOT_DOT),
+	SYM_OP(SUBSCRIPT,		LEFT_BRACKET),
+	SYM_OP(CONDITIONAL_SUBSCRIPT,	QUESTION_LEFT_BRACKET),
+
+	SYM_OP(ACCESS,			DOT),
+	SYM_OP(CONDITIONAL_ACCESS,	QUESTION_DOT),
+	SYM_OP(STATIC_ACCESS,		COLON_COLON),
+
+	/* parser-internal pseudo-operators. */
+
+	/* CAST uses the same symbol as SUBSCRIPT */
+	/* SYM_OP(CAST,			LEFT_BRACKET), */
+	SYM_OP(SUBEXPR,			DOLLAR_LEFT_PAREN),
+	SYM_OP(PAREN,			LEFT_PAREN),
+	SYM_OP(ARRAY_START,		AT_LEFT_PAREN),
+	SYM_OP(HASHTABLE_START,		AT_LEFT_BRACE),
+};
+static const size_t nr_operator_symbols = sizeof operator_symbols / sizeof operator_symbols[0];
+
+static const struct operator_info *operator_token_ops[] = {
+	TKOP_OP(FORMAT,			F),
+	TKOP_OP(BINARY_AND,		BAND),
+	TKOP_OP(BINARY_OR,		BOR),
+	TKOP_OP(BINARY_XOR,		BXOR),
+	TKOP_OP(BINARY_NOT,		BNOT),
+	TKOP_OP(LEFT_SHIFT,		SHL),
+	TKOP_OP(RIGHT_SHIFT,		SHR),
+	TKOP_OP(EQUAL,			EQ),
+	TKOP_OP(NOT_EQUAL,		NE),
+	TKOP_OP(GREATER_THAN,		GT),
+	TKOP_OP(LESS_THAN,		LT),
+	TKOP_OP(GREATER_EQUAL,		GE),
+	TKOP_OP(LESS_EQUAL,		LE),
+	TKOP_OP(MATCH,			MATCH),
+	TKOP_OP(NOTMATCH,		NOTMATCH),
+	TKOP_OP(REPLACE,		REPLACE),
+	TKOP_OP(LIKE,			LIKE),
+	TKOP_OP(NOTLIKE,		NOTLIKE),
+	TKOP_OP(IN,			IN),
+	TKOP_OP(NOTIN,			NOTIN),
+	TKOP_OP(CONTAINS,		CONTAINS),
+	TKOP_OP(NOTCONTAINS,		NOTCONTAINS),
+	TKOP_OP(LOGICAL_AND,		AND),
+	TKOP_OP(LOGICAL_OR,		OR),
+	TKOP_OP(LOGICAL_XOR,		XOR),
+	TKOP_OP(LOGICAL_NOT,		NOT),
+	/* there are also unary versions of these operators */
+	TKOP_OP(BSPLIT,			SPLIT),
+	TKOP_OP(BJOIN,			JOIN),
+
+	TKOP_OP(IS,			IS),
+	TKOP_OP(ISNOT,			ISNOT),
+	TKOP_OP(AS,			AS),
+};
+static const size_t nr_operator_token_ops = sizeof operator_token_ops / sizeof operator_token_ops[0];
+
+/* clang-format on */
+
+const struct operator_info *operator_get_by_token(unsigned int token)
+{
+	const struct operator_info **op_list = NULL;
+	size_t base = 0;
+	size_t op_list_size = 0;
+
+	if (token > __TKOP_INDEX_BASE && token < __TKOP_INDEX_LIMIT) {
+		op_list = operator_token_ops;
+		base = __TKOP_INDEX_BASE;
+		op_list_size = nr_operator_token_ops;
+	} else if (token > __SYM_INDEX_BASE && token < __SYM_INDEX_LIMIT) {
+		op_list = operator_symbols;
+		base = __SYM_INDEX_BASE;
+		op_list_size = nr_operator_symbols;
+	} else {
+		return NULL;
+	}
+
+	if (token - base >= op_list_size) {
+		return NULL;
+	}
+
+	return op_list[token - base];
+}
+
+const struct operator_info *operator_get_by_id(enum operator_id id)
+{
+	if (id >= nr_operators) {
+		return NULL;
+	}
+
+	const struct operator_info *op = &operators[id];
+	if (op->op_id != id) {
+		return NULL;
+	}
+
+	return op;
+}
+
+#define ENUM_STR(x)                                                            \
+	case x:                                                                \
+		return #x
+
+const char *operator_id_to_string(enum operator_id op)
+{
+	switch (op) {
+		ENUM_STR(OP_NONE);
+		ENUM_STR(OP_ADD);
+		ENUM_STR(OP_SUBTRACT);
+		ENUM_STR(OP_MULTIPLY);
+		ENUM_STR(OP_DIVIDE);
+		ENUM_STR(OP_MODULO);
+		ENUM_STR(OP_INCREMENT);
+		ENUM_STR(OP_DECREMENT);
+		ENUM_STR(OP_LEFT_SHIFT);
+		ENUM_STR(OP_RIGHT_SHIFT);
+		ENUM_STR(OP_BINARY_AND);
+		ENUM_STR(OP_BINARY_OR);
+		ENUM_STR(OP_BINARY_XOR);
+		ENUM_STR(OP_BINARY_NOT);
+		ENUM_STR(OP_LESS_THAN);
+		ENUM_STR(OP_GREATER_THAN);
+		ENUM_STR(OP_EQUAL);
+		ENUM_STR(OP_NOT_EQUAL);
+		ENUM_STR(OP_LESS_EQUAL);
+		ENUM_STR(OP_GREATER_EQUAL);
+		ENUM_STR(OP_ASSIGN);
+		ENUM_STR(OP_ADD_ASSIGN);
+		ENUM_STR(OP_SUBTRACT_ASSIGN);
+		ENUM_STR(OP_MULTIPLY_ASSIGN);
+		ENUM_STR(OP_DIVIDE_ASSIGN);
+		ENUM_STR(OP_MODULO_ASSIGN);
+		ENUM_STR(OP_LOGICAL_AND);
+		ENUM_STR(OP_LOGICAL_OR);
+		ENUM_STR(OP_LOGICAL_XOR);
+		ENUM_STR(OP_LOGICAL_NOT);
+		ENUM_STR(OP_RANGE);
+		ENUM_STR(OP_MATCH);
+		ENUM_STR(OP_NOTMATCH);
+		ENUM_STR(OP_REPLACE);
+		ENUM_STR(OP_LIKE);
+		ENUM_STR(OP_NOTLIKE);
+		ENUM_STR(OP_IN);
+		ENUM_STR(OP_NOTIN);
+		ENUM_STR(OP_FORMAT);
+		ENUM_STR(OP_CONTAINS);
+		ENUM_STR(OP_NOTCONTAINS);
+		ENUM_STR(OP_USPLIT);
+		ENUM_STR(OP_BSPLIT);
+		ENUM_STR(OP_UJOIN);
+		ENUM_STR(OP_BJOIN);
+		ENUM_STR(OP_IS);
+		ENUM_STR(OP_ISNOT);
+		ENUM_STR(OP_AS);
+		ENUM_STR(OP_SUBSCRIPT);
+		ENUM_STR(OP_CONDITIONAL_SUBSCRIPT);
+		ENUM_STR(OP_ARRAY_DELIMITER);
+		ENUM_STR(OP_ACCESS);
+		ENUM_STR(OP_STATIC_ACCESS);
+		ENUM_STR(OP_CONDITIONAL_ACCESS);
+		ENUM_STR(OP_CAST);
+		ENUM_STR(OP_SUBEXPR);
+		ENUM_STR(OP_PAREN);
+		ENUM_STR(OP_ARRAY_START);
+		ENUM_STR(OP_HASHTABLE_START);
+	default:
+		return "";
+	}
+}

bshell/operator.h

@@ -0,0 +1,123 @@
+#ifndef OPERATOR_H_
+#define OPERATOR_H_
+
+enum operator_precedence {
+	PRECEDENCE_MINIMUM = 0,
+	PRECEDENCE_ASSIGN,
+	PRECEDENCE_PIPELINE,
+	PRECEDENCE_LOGICAL,
+	PRECEDENCE_BITWISE,
+	PRECEDENCE_COMPARISON,
+	PRECEDENCE_ADDITION,
+	PRECEDENCE_MULTIPLICATION,
+	PRECEDENCE_NEGATE,
+	PRECEDENCE_FORMAT,
+	PRECEDENCE_RANGE,
+	PRECEDENCE_NOT,
+	PRECEDENCE_INCREMENT,
+	PRECEDENCE_ARRAY,
+	PRECEDENCE_JOIN,
+	PRECEDENCE_SPLIT,
+	PRECEDENCE_CAST,
+	PRECEDENCE_SUBSCRIPT,
+	PRECEDENCE_STATIC_ACCESS,
+	PRECEDENCE_MEMBER_ACCESS,
+	PRECEDENCE_PARENTHESIS,
+};
+
+enum operator_associativity {
+	ASSOCIATIVITY_LEFT,
+	ASSOCIATIVITY_RIGHT,
+};
+
+enum operator_location {
+	OPL_PREFIX,
+	OPL_INFIX,
+	OPL_POSTFIX,
+};
+
+enum operator_arity {
+	OPA_UNARY,
+	OPA_BINARY,
+};
+
+enum operator_id {
+	OP_NONE = 0,
+	OP_ADD,
+	OP_SUBTRACT,
+	OP_MULTIPLY,
+	OP_DIVIDE,
+	OP_MODULO,
+	OP_INCREMENT,
+	OP_DECREMENT,
+	OP_LEFT_SHIFT,
+	OP_RIGHT_SHIFT,
+	OP_BINARY_AND,
+	OP_BINARY_OR,
+	OP_BINARY_XOR,
+	OP_BINARY_NOT,
+	OP_LESS_THAN,
+	OP_GREATER_THAN,
+	OP_EQUAL,
+	OP_NOT_EQUAL,
+	OP_LESS_EQUAL,
+	OP_GREATER_EQUAL,
+	OP_ASSIGN,
+	OP_ADD_ASSIGN,
+	OP_SUBTRACT_ASSIGN,
+	OP_MULTIPLY_ASSIGN,
+	OP_DIVIDE_ASSIGN,
+	OP_MODULO_ASSIGN,
+	OP_LOGICAL_AND,
+	OP_LOGICAL_OR,
+	OP_LOGICAL_XOR,
+	OP_LOGICAL_NOT,
+	OP_RANGE,
+	OP_MATCH,
+	OP_NOTMATCH,
+	OP_REPLACE,
+	OP_LIKE,
+	OP_NOTLIKE,
+	OP_IN,
+	OP_NOTIN,
+	OP_FORMAT,
+	OP_CONTAINS,
+	OP_NOTCONTAINS,
+	OP_USPLIT,
+	OP_BSPLIT,
+	OP_UJOIN,
+	OP_BJOIN,
+	OP_IS,
+	OP_ISNOT,
+	OP_AS,
+
+	OP_SUBSCRIPT,
+	OP_CONDITIONAL_SUBSCRIPT,
+
+	OP_ARRAY_DELIMITER,
+	OP_ACCESS,
+	OP_STATIC_ACCESS,
+	OP_CONDITIONAL_ACCESS,
+
+	/* these are not real operators, and are just used internally by the
+	 * parser. */
+	OP_CAST,
+	OP_SUBEXPR,
+	OP_PAREN,
+	OP_ARRAY_START,
+	OP_HASHTABLE_START,
+};
+
+struct operator_info {
+	enum operator_id op_id;
+	enum operator_precedence op_precedence;
+	enum operator_associativity op_associativity;
+	enum operator_location op_location;
+	enum operator_arity op_arity;
+};
+
+extern const struct operator_info *operator_get_by_id(enum operator_id id);
+extern const struct operator_info *operator_get_by_token(unsigned int token);
+extern const char *operator_id_to_string(enum operator_id op);
+
+#endif

bshell/parse/lex.h

@@ -0,0 +1,94 @@
+#ifndef LEX_H_
+#define LEX_H_
+
+#include "../status.h"
+#include "token.h"
+
+#include <fx/queue.h>
+#include <fx/string.h>
+#include <fx/stringstream.h>
+
+#define LEX_STATE_MAX_TERMINATORS 16
+
+struct line_source;
+
+enum lex_flags {
+	LEX_PRINT_TOKENS = 0x01u,
+};
+
+enum lex_token_flags {
+	/* a token with this flag not only interrupts the word currently being
+	 * scanned, but also stops multi-words */
+	LEX_TOKEN_TERMINATES_WORD = 0x01u,
+	/* a token with this flag can appear at the start of an arithmetic
+	 * expression. a statement that encounters this token as its first char
+	 * will switch to arithmetic mode */
+	LEX_TOKEN_UNARY_ARITHMETIC = 0x02u,
+	/* if a token has this flag defined, the lexer will
+	 * switch to command mode after encountering it. */
+	LEX_TOKEN_COMMAND_MODE = 0x08u,
+	/* if a token has this flag defined, the lexer will
+	 * switch to statement mode after encountering it. */
+	LEX_TOKEN_STATEMENT_MODE = 0x10u,
+};
+
+enum lex_state_type_id {
+	LEX_STATE_STATEMENT = 0x01u,
+	LEX_STATE_COMMAND = 0x02u,
+	LEX_STATE_ARITHMETIC = 0x04u,
+	LEX_STATE_STRING = 0x08u,
+	LEX_STATE_WORD = 0x10u,
+	LEX_STATE_HASHTABLE = 0x20u,
+};
+
+struct lex_token_def {
+	int id;
+	const char *name;
+	uint64_t name_hash;
+	enum lex_state_type_id enabled_states;
+	enum lex_token_flags flags;
+};
+
+struct lex_symbol_node {
+	char s_char;
+	struct lex_token_def *s_def;
+
+	fx_queue_entry s_entry;
+	fx_queue s_children;
+};
+
+struct lex_state {
+	const struct lex_state_type *s_type;
+	unsigned int s_terminators[LEX_STATE_MAX_TERMINATORS];
+	unsigned int s_nr_terminators;
+	unsigned int s_paren_depth;
+	fx_queue_entry s_entry;
+	fx_string *s_tempstr;
+	unsigned int s_flags;
+};
+
+struct lex_ctx {
+	enum lex_flags lex_flags;
+	fx_queue lex_tokens;
+	struct line_source *lex_src;
+	fx_stringstream *lex_buf;
+	fx_string *lex_tmp;
+	fx_wchar lex_ch;
+	fx_queue lex_state;
+	enum token_type lex_prev_token;
+	struct char_cell lex_cursor, lex_start, lex_end;
+	struct lex_symbol_node *lex_sym_tree;
+	enum bshell_status lex_status;
+};
+
+extern enum bshell_status lex_ctx_init(
+	struct lex_ctx *ctx,
+	enum lex_flags flags,
+	struct line_source *src);
+extern enum bshell_status lex_ctx_cleanup(struct lex_ctx *ctx);
+
+extern struct lex_token *lex_ctx_peek(struct lex_ctx *ctx);
+extern struct lex_token *lex_ctx_claim(struct lex_ctx *ctx);
+extern void lex_ctx_discard(struct lex_ctx *ctx);
+
+#endif

bshell/parse/lex/arithmetic.c

@@ -0,0 +1,232 @@
+#include "lex-internal.h"
+
+static enum bshell_status arithmetic_hyphen(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	if (!fx_wchar_is_alnum(c)) {
+		push_symbol(ctx, SYM_HYPHEN);
+		handle_lex_state_transition(ctx, SYM_HYPHEN);
+		return BSHELL_SUCCESS;
+	}
+
+	struct lex_token *tok = NULL;
+	enum bshell_status status = read_word(
+		ctx,
+		READ_NO_SET_TOKEN_START | READ_APPEND_HYPHEN,
+		&tok);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	unsigned int token_type = TOK_WORD;
+	if (convert_word_to_int(tok)) {
+		token_type = TOK_INT;
+
+		/* because of APPEND_HYPHEN (which is needed to ensure operator
+		 * tokens are detected properly), the resulting number will be
+		 * negative.
+		 * this token will be preceded by a HYPHEN token, so the number
+		 * must be positive */
+		tok->tok_int *= -1;
+		push_symbol(ctx, SYM_HYPHEN);
+	} else if (convert_word_to_operator(ctx, tok)) {
+		token_type = TOK_OPERATOR;
+	}
+
+	enqueue_token(ctx, tok);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status arithmetic_symbol(struct lex_ctx *ctx)
+{
+	const struct lex_token_def *sym = NULL;
+	enum bshell_status status = read_symbol(ctx, &sym);
+
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	handle_lex_state_transition(ctx, sym->id);
+
+	struct lex_token *tok = NULL;
+	switch (sym->id) {
+	case SYM_DQUOTE:
+		return BSHELL_SUCCESS;
+	case SYM_SQUOTE:
+		status = read_literal_string(ctx, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+		enqueue_token(ctx, tok);
+		return BSHELL_SUCCESS;
+	case SYM_HYPHEN:
+		return arithmetic_hyphen(ctx);
+	case SYM_HASH:
+		return read_line_comment(ctx);
+	case SYM_DOLLAR:
+		status = read_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_AT:
+		status = read_var(ctx, TOK_VAR_SPLAT, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_DOLLAR_LEFT_BRACE:
+		status = read_braced_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	default:
+		break;
+	}
+
+	push_symbol(ctx, sym->id);
+
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status arithmetic_word(struct lex_ctx *ctx)
+{
+	struct lex_token *word = NULL;
+	enum bshell_status status = read_word(ctx, 0, &word);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	unsigned int token_type = TOK_WORD;
+	bool kw = false, number = false;
+	if (convert_word_to_keyword(word)) {
+		token_type = word->tok_keyword;
+	} else if (convert_word_to_int(word)) {
+		token_type = TOK_INT;
+	}
+
+	handle_lex_state_transition(ctx, token_type);
+
+	enqueue_token(ctx, word);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status arithmetic_pump_token(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	bool newline = false;
+
+	set_token_start(ctx);
+	while (fx_wchar_is_space(c)) {
+		if (c == '\n') {
+			newline = true;
+		}
+
+		set_token_end(ctx);
+		advance_char_noread(ctx);
+		c = peek_char_noread(ctx);
+	}
+
+	if (newline) {
+		struct lex_token *tok = lex_token_create(TOK_LINEFEED);
+		enqueue_token(ctx, tok);
+		handle_lex_state_transition(ctx, TOK_LINEFEED);
+		return BSHELL_SUCCESS;
+	}
+
+	if (char_can_begin_symbol(ctx, c)) {
+		return arithmetic_symbol(ctx);
+	}
+
+	return arithmetic_word(ctx);
+}
+
+static const struct lex_state_link links[] = {
+	LINK_CHANGE(TOK_WORD, LEX_STATE_COMMAND),
+	LINK_CHANGE(SYM_EQUAL, LEX_STATE_STATEMENT),
+	LINK_PUSH(SYM_DQUOTE, LEX_STATE_STRING, 0),
+	LINK_PUSH(SYM_DOLLAR_LEFT_PAREN, LEX_STATE_STATEMENT, 0),
+	LINK_POP(SYM_RIGHT_PAREN),
+	LINK_CHANGE(SYM_SEMICOLON, LEX_STATE_STATEMENT),
+	LINK_CHANGE(TOK_LINEFEED, LEX_STATE_STATEMENT),
+	LINK_CHANGE(SYM_PIPE, LEX_STATE_STATEMENT),
+	LINK_PUSH(SYM_AT_LEFT_BRACE, LEX_STATE_HASHTABLE, 0),
+	LINK_PUSH(
+		SYM_LEFT_PAREN,
+		LEX_STATE_STATEMENT,
+		STATEMENT_F_DISABLE_KEYWORDS),
+	LINK_END,
+};
+
+static const unsigned int keywords[] = {
+	KW_IF,
+	KW_ELSEIF,
+	KW_ELSE,
+	KW_NONE,
+};
+
+static const unsigned int operators[] = {
+	TKOP_F,        TKOP_BAND,        TKOP_BOR,      TKOP_BXOR,
+	TKOP_BNOT,     TKOP_SHL,         TKOP_SHR,      TKOP_EQ,
+	TKOP_NE,       TKOP_GT,          TKOP_LT,       TKOP_GE,
+	TKOP_LE,       TKOP_MATCH,       TKOP_NOTMATCH, TKOP_REPLACE,
+	TKOP_LIKE,     TKOP_NOTLIKE,     TKOP_IN,       TKOP_NOTIN,
+	TKOP_CONTAINS, TKOP_NOTCONTAINS, TKOP_AND,      TKOP_OR,
+	TKOP_XOR,      TKOP_NOT,         TKOP_SPLIT,    TKOP_JOIN,
+	TKOP_IS,       TKOP_ISNOT,       TKOP_AS,       TKOP_NONE,
+};
+
+static const unsigned int symbols[] = {
+	SYM_BANG,
+	SYM_PLUS,
+	SYM_HYPHEN,
+	SYM_FORWARD_SLASH,
+	SYM_ASTERISK,
+	SYM_AMPERSAND,
+	SYM_PERCENT,
+	SYM_SQUOTE,
+	SYM_DQUOTE,
+	SYM_HASH,
+	SYM_DOLLAR,
+	SYM_DOLLAR_LEFT_PAREN,
+	SYM_DOLLAR_LEFT_BRACE,
+	SYM_AT,
+	SYM_AT_LEFT_BRACE,
+	SYM_PIPE,
+	SYM_COMMA,
+	SYM_SEMICOLON,
+	SYM_LEFT_PAREN,
+	SYM_RIGHT_PAREN,
+	SYM_LEFT_BRACE,
+	SYM_RIGHT_BRACE,
+	SYM_LEFT_BRACKET,
+	SYM_RIGHT_BRACKET,
+	SYM_QUESTION_DOT,
+	SYM_QUESTION_LEFT_BRACKET,
+	SYM_EQUAL,
+	SYM_PLUS_EQUAL,
+	SYM_HYPHEN_EQUAL,
+	SYM_FORWARD_SLASH_EQUAL,
+	SYM_ASTERISK_EQUAL,
+	SYM_PERCENT_EQUAL,
+	SYM_DOT,
+	SYM_DOT_DOT,
+	SYM_COLON_COLON,
+	SYM_NONE,
+};
+
+const struct lex_state_type lex_arithmetic_state = {
+	.s_id = LEX_STATE_ARITHMETIC,
+	.s_pump_token = arithmetic_pump_token,
+	.s_links = links,
+	.s_keywords = keywords,
+	.s_operators = operators,
+	.s_symbols = symbols,
+};

bshell/parse/lex/command.c

@@ -0,0 +1,226 @@
+#include "../token.h"
+#include "lex-internal.h"
+
+static bool char_can_continue_word(struct lex_ctx *ctx, fx_wchar c)
+{
+	if (fx_wchar_is_alnum(c)) {
+		return true;
+	}
+
+	if (fx_wchar_is_space(c)) {
+		return false;
+	}
+
+	if (c == '$') {
+		return true;
+	}
+
+	if (char_can_begin_symbol_in_state(ctx, c, LEX_STATE_WORD)) {
+		return false;
+	}
+
+	return true;
+}
+
+static enum bshell_status command_symbol(struct lex_ctx *ctx)
+{
+	const struct lex_token_def *sym = NULL;
+	enum bshell_status status = read_symbol(ctx, &sym);
+
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	handle_lex_state_transition(ctx, sym->id);
+
+	struct lex_token *tok = NULL;
+	switch (sym->id) {
+	case SYM_DQUOTE:
+		return BSHELL_SUCCESS;
+	case SYM_SQUOTE:
+		status = read_literal_string(ctx, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+		enqueue_token(ctx, tok);
+		return BSHELL_SUCCESS;
+
+	case SYM_HASH:
+		return read_line_comment(ctx);
+	case SYM_DOLLAR:
+		status = read_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		if (char_can_continue_word(ctx, peek_char(ctx))) {
+			lex_state_push(ctx, LEX_STATE_WORD, 0);
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_AT:
+		status = read_var(ctx, TOK_VAR_SPLAT, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_DOLLAR_LEFT_BRACE:
+		status = read_braced_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		if (char_can_continue_word(ctx, peek_char(ctx))) {
+			lex_state_push(ctx, LEX_STATE_WORD, 0);
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	default:
+		break;
+	}
+
+	push_symbol(ctx, sym->id);
+
+	return BSHELL_SUCCESS;
+}
+
+static bool string_is_redirection(const char *s)
+{
+	if (!*s) {
+		return false;
+	}
+
+	if (!strcmp(s, ">") || !strcmp(s, ">>")) {
+		return true;
+	}
+
+	long nr_angles = 0;
+	for (size_t i = 0; s[i];) {
+		fx_wchar c = fx_wchar_utf8_codepoint_decode(s);
+		if (fx_wchar_is_number(c)) {
+			if (nr_angles) {
+				return false;
+			}
+		} else if (c == '>') {
+			nr_angles++;
+
+			if (nr_angles > 2) {
+				return false;
+			}
+		} else {
+			return false;
+		}
+
+		s += fx_wchar_utf8_codepoint_stride(s);
+	}
+
+	return true;
+}
+
+static enum bshell_status command_word(struct lex_ctx *ctx)
+{
+	struct lex_token *word = NULL;
+	enum bshell_status status
+		= read_word(ctx, READ_NO_NUMBER_RECOGNITION, &word);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	bool continue_word = false;
+
+	fx_wchar c = peek_char(ctx);
+	const char *s = word->tok_str;
+	if (char_can_begin_symbol_in_state(ctx, c, LEX_STATE_WORD)) {
+		continue_word = true;
+	}
+
+	if (char_has_flags(ctx, c, LEX_TOKEN_TERMINATES_WORD)) {
+		continue_word = false;
+	}
+
+	if (string_is_redirection(s)) {
+		continue_word = false;
+	}
+
+	if (continue_word) {
+		lex_state_push(ctx, LEX_STATE_WORD, 0);
+	}
+
+	enqueue_token(ctx, word);
+	return BSHELL_SUCCESS;
+}
+
+enum bshell_status command_pump_token(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	bool newline = false;
+
+	set_token_start(ctx);
+	while (fx_wchar_is_space(c)) {
+		if (c == '\n') {
+			newline = true;
+		}
+
+		set_token_end(ctx);
+		advance_char_noread(ctx);
+		c = peek_char_noread(ctx);
+	}
+
+	if (newline) {
+		struct lex_token *tok = lex_token_create(TOK_LINEFEED);
+		enqueue_token(ctx, tok);
+		handle_lex_state_transition(ctx, TOK_LINEFEED);
+		return BSHELL_SUCCESS;
+	}
+
+	if (char_can_begin_symbol(ctx, c)) {
+		return command_symbol(ctx);
+	}
+
+	return command_word(ctx);
+}
+
+const struct lex_state_link links[] = {
+	LINK_PUSH(SYM_DQUOTE, LEX_STATE_STRING, 0),
+	LINK_PUSH(
+		SYM_LEFT_PAREN,
+		LEX_STATE_STATEMENT,
+		STATEMENT_F_DISABLE_KEYWORDS),
+	LINK_PUSH(SYM_DOLLAR_LEFT_PAREN, LEX_STATE_STATEMENT, 0),
+	LINK_POP(SYM_RIGHT_PAREN),
+	LINK_POP(SYM_RIGHT_BRACE),
+	LINK_CHANGE(SYM_SEMICOLON, LEX_STATE_STATEMENT),
+	LINK_PUSH(SYM_AT_LEFT_BRACE, LEX_STATE_HASHTABLE, 0),
+	LINK_CHANGE(TOK_LINEFEED, LEX_STATE_STATEMENT),
+	LINK_END,
+};
+
+static const unsigned int symbols[] = {
+	SYM_DQUOTE,
+	SYM_SQUOTE,
+	SYM_DOLLAR,
+	SYM_DOLLAR_LEFT_PAREN,
+	SYM_DOLLAR_LEFT_BRACE,
+	SYM_AT,
+	SYM_AT_LEFT_BRACE,
+	SYM_AT_LEFT_PAREN,
+	SYM_AMPERSAND,
+	SYM_PIPE,
+	SYM_SEMICOLON,
+	SYM_RIGHT_PAREN,
+	SYM_LEFT_PAREN,
+	SYM_LEFT_BRACE,
+	SYM_RIGHT_BRACE,
+	SYM_NONE,
+};
+
+const struct lex_state_type lex_command_state = {
+	.s_id = LEX_STATE_COMMAND,
+	.s_pump_token = command_pump_token,
+	.s_links = links,
+	.s_symbols = symbols,
+};

bshell/parse/lex/hashtable.c

@@ -0,0 +1,184 @@
+#include "lex-internal.h"
+
+static enum bshell_status hashtable_hyphen(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	if (!fx_wchar_is_alnum(c)) {
+		push_symbol(ctx, SYM_HYPHEN);
+		handle_lex_state_transition(ctx, SYM_HYPHEN);
+		return BSHELL_SUCCESS;
+	}
+
+	struct lex_token *tok = NULL;
+	enum bshell_status status = read_word(
+		ctx,
+		READ_NO_SET_TOKEN_START | READ_APPEND_HYPHEN,
+		&tok);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	unsigned int token_type = TOK_WORD;
+	if (convert_word_to_int(tok)) {
+		token_type = TOK_INT;
+		/* because of APPEND_HYPHEN (which is needed to ensure operator
+		 * tokens are detected properly), the resulting number will be
+		 * negative.
+		 * this token will be preceded by a HYPHEN token, so the number
+		 * must be positive */
+		tok->tok_int *= -1;
+		push_symbol(ctx, SYM_HYPHEN);
+	} else if (convert_word_to_operator(ctx, tok)) {
+		token_type = tok->tok_operator;
+	}
+
+	handle_lex_state_transition(ctx, token_type);
+	enqueue_token(ctx, tok);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status hashtable_symbol(struct lex_ctx *ctx)
+{
+	const struct lex_token_def *sym = NULL;
+	enum bshell_status status = read_symbol(ctx, &sym);
+
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	handle_lex_state_transition(ctx, sym->id);
+
+	struct lex_token *tok = NULL;
+	switch (sym->id) {
+	case SYM_SQUOTE:
+		status = read_literal_string(ctx, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+		enqueue_token(ctx, tok);
+		return BSHELL_SUCCESS;
+	case SYM_HYPHEN:
+		return hashtable_hyphen(ctx);
+	case SYM_HASH:
+		return read_line_comment(ctx);
+	case SYM_DOLLAR:
+		status = read_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_AT:
+		status = read_var(ctx, TOK_VAR_SPLAT, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_DOLLAR_LEFT_BRACE:
+		status = read_braced_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	default:
+		break;
+	}
+
+	push_symbol(ctx, sym->id);
+
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status hashtable_word(struct lex_ctx *ctx)
+{
+	struct lex_token *word = NULL;
+	enum bshell_status status = read_word(ctx, 0, &word);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	convert_word_to_int(word);
+
+	handle_lex_state_transition(ctx, word->tok_type);
+	enqueue_token(ctx, word);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status hashtable_pump_token(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	bool newline = false;
+
+	set_token_start(ctx);
+	while (fx_wchar_is_space(c)) {
+		if (c == '\n') {
+			newline = true;
+		}
+
+		set_token_end(ctx);
+		advance_char_noread(ctx);
+		c = peek_char_noread(ctx);
+	}
+
+#if 1
+	if (newline) {
+		struct lex_token *tok = lex_token_create(TOK_LINEFEED);
+		enqueue_token(ctx, tok);
+		return BSHELL_SUCCESS;
+	}
+#endif
+
+	if (char_can_begin_symbol(ctx, c)) {
+		return hashtable_symbol(ctx);
+	}
+
+	return hashtable_word(ctx);
+}
+
+static const struct lex_state_link links[] = {
+	LINK_PUSH_WITH_TERM(
+		SYM_EQUAL,
+		LEX_STATE_STATEMENT,
+		0,
+		SYM_RIGHT_BRACE,
+		SYM_SEMICOLON,
+		TOK_LINEFEED),
+	LINK_PUSH_WITH_TERM(
+		TOK_LINEFEED,
+		LEX_STATE_STATEMENT,
+		0,
+		SYM_SEMICOLON,
+		TOK_LINEFEED),
+	LINK_PUSH(SYM_DQUOTE, LEX_STATE_STRING, 0),
+	LINK_PUSH(
+		SYM_LEFT_PAREN,
+		LEX_STATE_STATEMENT,
+		STATEMENT_F_DISABLE_KEYWORDS),
+	LINK_PUSH(SYM_DOLLAR_LEFT_PAREN, LEX_STATE_STATEMENT, 0),
+	LINK_POP2(SYM_RIGHT_BRACE, LINK_ALLOW_RECURSION),
+	LINK_END,
+};
+
+static const unsigned int symbols[] = {
+	SYM_EQUAL,
+	SYM_DQUOTE,
+	SYM_SQUOTE,
+	SYM_SEMICOLON,
+	SYM_RIGHT_BRACE,
+	SYM_DOLLAR_LEFT_PAREN,
+	SYM_LEFT_PAREN,
+	SYM_HASH,
+	SYM_NONE,
+};
+
+const struct lex_state_type lex_hashtable_state = {
+	.s_id = LEX_STATE_HASHTABLE,
+	.s_pump_token = hashtable_pump_token,
+	.s_links = links,
+	.s_symbols = symbols,
+};

bshell/parse/lex/lex-internal.h

@@ -0,0 +1,195 @@
+#ifndef PARSE_LEX_INTERNAL_H_
+#define PARSE_LEX_INTERNAL_H_
+
+#include "../../status.h"
+#include "../lex.h"
+#include "../token.h"
+
+struct lex_ctx;
+
+enum state_flags {
+	/* statement: don't convert matching words to keywords */
+	STATEMENT_F_DISABLE_KEYWORDS = 0x01u,
+	/* arithmetic: don't switch back to statement mode even when
+	 * encountering a token that would otherwise require it. */
+	ARITHMETIC_F_DISABLE_STATEMENTS = 0x01u,
+};
+
+enum read_flags {
+	READ_APPEND_HYPHEN = 0x01u,
+	READ_NO_SET_TOKEN_START = 0x02u,
+	READ_NO_NUMBER_RECOGNITION = 0x04u,
+};
+
+enum link_flags {
+	LINK_ALLOW_RECURSION = 0x01u,
+};
+
+#define LINK_PUSH(tok, target, flags)                                          \
+	((struct lex_state_link) {                                             \
+		.l_token = (tok),                                              \
+		.l_type = LEX_STATE_LINK_PUSH,                                 \
+		.l_target = (target),                                          \
+		.l_target_flags = (flags),                                     \
+	})
+#define LINK_PUSH_WITH_TERM(tok, target, flags, ...)                           \
+	((struct lex_state_link) {                                             \
+		.l_token = (tok),                                              \
+		.l_type = LEX_STATE_LINK_PUSH,                                 \
+		.l_target = (target),                                          \
+		.l_target_flags = (flags),                                     \
+		.l_terminators = {__VA_ARGS__, TOK_NONE},                      \
+	})
+#define LINK_CHANGE(tok, target)                                               \
+	((struct lex_state_link) {                                             \
+		.l_token = (tok),                                              \
+		.l_type = LEX_STATE_LINK_CHANGE,                               \
+		.l_target = (target),                                          \
+	})
+#define LINK_POP(tok)                                                          \
+	((struct lex_state_link) {                                             \
+		.l_token = (tok),                                              \
+		.l_type = LEX_STATE_LINK_POP,                                  \
+	})
+#define LINK_POP2(tok, flags)                                                  \
+	((struct lex_state_link) {                                             \
+		.l_token = (tok),                                              \
+		.l_type = LEX_STATE_LINK_POP,                                  \
+		.l_flags = (flags),                                            \
+	})
+#define LINK_NONE(tok)                                                         \
+	((struct lex_state_link) {                                             \
+		.l_token = (tok),                                              \
+		.l_type = LEX_STATE_LINK_NONE,                                 \
+	})
+#define LINK_END ((struct lex_state_link) {})
+
+struct lex_state_link {
+	unsigned int l_token;
+	enum {
+		LEX_STATE_LINK_NONE,
+		LEX_STATE_LINK_PUSH,
+		LEX_STATE_LINK_CHANGE,
+		LEX_STATE_LINK_POP,
+	} l_type;
+	enum link_flags l_flags;
+	enum lex_state_type_id l_target;
+	enum state_flags l_target_flags;
+	unsigned int l_terminators[LEX_STATE_MAX_TERMINATORS];
+};
+
+typedef enum bshell_status (*lex_state_pump_token)(struct lex_ctx *);
+typedef enum bshell_status (*lex_state_begin)(struct lex_ctx *);
+typedef enum bshell_status (*lex_state_end)(struct lex_ctx *);
+
+struct lex_state_type {
+	enum lex_state_type_id s_id;
+	lex_state_pump_token s_pump_token;
+	lex_state_begin s_begin;
+	lex_state_end s_end;
+
+	const unsigned int *s_keywords;
+	const unsigned int *s_operators;
+	const unsigned int *s_symbols;
+	const struct lex_state_link *s_links;
+};
+
+extern enum bshell_status pump_token_statement(struct lex_ctx *ctx);
+extern enum bshell_status pump_token_expression(struct lex_ctx *ctx);
+extern enum bshell_status pump_token_command(struct lex_ctx *ctx);
+extern enum bshell_status pump_token_arithmetic(struct lex_ctx *ctx);
+extern enum bshell_status pump_token_string(struct lex_ctx *ctx);
+
+extern void set_token_start(struct lex_ctx *ctx);
+extern void set_token_end(struct lex_ctx *ctx);
+
+extern struct lex_state *lex_state_push(
+	struct lex_ctx *ctx,
+	enum lex_state_type_id state_type,
+	enum state_flags flags);
+extern void lex_state_pop(struct lex_ctx *ctx);
+extern struct lex_state *lex_state_get(struct lex_ctx *ctx);
+extern void lex_state_change(struct lex_ctx *ctx, enum lex_state_type_id type);
+extern fx_string *lex_state_get_tempstr(struct lex_ctx *ctx);
+extern void lex_state_add_terminator(struct lex_state *state, unsigned int tok);
+extern bool lex_state_terminates_at_token(
+	struct lex_ctx *ctx,
+	unsigned int tok);
+
+extern fx_wchar peek_char(struct lex_ctx *ctx);
+extern fx_wchar peek_char_noread(struct lex_ctx *ctx);
+extern fx_wchar peek2_char(struct lex_ctx *ctx);
+extern fx_wchar peek2_char_noread(struct lex_ctx *ctx);
+extern void advance_char(struct lex_ctx *ctx);
+extern void advance_char_noread(struct lex_ctx *ctx);
+
+extern bool string_is_valid_number(const char *s, long long *out);
+extern bool convert_word_to_int(struct lex_token *tok);
+extern bool convert_word_to_keyword(struct lex_token *tok);
+extern bool convert_word_to_operator(
+	struct lex_ctx *ctx,
+	struct lex_token *tok);
+
+extern void enqueue_token(struct lex_ctx *ctx, struct lex_token *tok);
+extern void enqueue_token_with_coordinates(
+	struct lex_ctx *ctx,
+	struct lex_token *tok,
+	const struct char_cell *start,
+	const struct char_cell *end);
+
+extern enum bshell_status read_word(
+	struct lex_ctx *ctx,
+	enum read_flags flags,
+	struct lex_token **out);
+extern enum bshell_status read_symbol(
+	struct lex_ctx *ctx,
+	const struct lex_token_def **out);
+extern enum bshell_status read_literal_string(
+	struct lex_ctx *ctx,
+	struct lex_token **out);
+extern enum bshell_status read_line_comment(struct lex_ctx *lex);
+extern enum bshell_status read_var(
+	struct lex_ctx *ctx,
+	enum token_type type,
+	struct lex_token **out);
+extern enum bshell_status read_braced_var(
+	struct lex_ctx *ctx,
+	enum token_type type,
+	struct lex_token **out);
+
+extern enum bshell_status push_symbol(
+	struct lex_ctx *ctx,
+	enum token_symbol sym);
+
+extern bool char_can_begin_symbol(struct lex_ctx *ctx, char c);
+extern bool char_can_begin_symbol_in_state(
+	struct lex_ctx *ctx,
+	char c,
+	enum lex_state_type_id state_type);
+extern bool char_has_flags(
+	struct lex_ctx *ctx,
+	char c,
+	enum lex_token_flags flags);
+extern bool keyword_has_flags(
+	struct lex_ctx *ctx,
+	enum token_keyword kw,
+	enum lex_token_flags flags);
+extern enum lex_token_flags keyword_get_flags(
+	struct lex_ctx *ctx,
+	enum token_keyword kw);
+extern bool symbol_has_flags(
+	struct lex_ctx *ctx,
+	enum token_symbol sym,
+	enum lex_token_flags flags);
+extern enum lex_token_flags symbol_get_flags(
+	struct lex_ctx *ctx,
+	enum token_symbol sym);
+extern enum token_operator get_operator_with_string(
+	struct lex_ctx *ctx,
+	const char *s);
+
+extern void handle_lex_state_transition(
+	struct lex_ctx *ctx,
+	unsigned int token);
+
+#endif

bshell/parse/lex/statement.c

@@ -0,0 +1,236 @@
+#include "lex-internal.h"
+
+static enum bshell_status statement_hyphen(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	if (!fx_wchar_is_alnum(c)) {
+		push_symbol(ctx, SYM_HYPHEN);
+		handle_lex_state_transition(ctx, SYM_HYPHEN);
+		return BSHELL_SUCCESS;
+	}
+
+	struct lex_token *tok = NULL;
+	enum bshell_status status = read_word(
+		ctx,
+		READ_NO_SET_TOKEN_START | READ_APPEND_HYPHEN,
+		&tok);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	unsigned int token_type = TOK_WORD;
+
+	if (convert_word_to_int(tok)) {
+		token_type = TOK_INT;
+
+		/* because of APPEND_HYPHEN (which is needed to ensure operator
+		 * tokens are detected properly), the resulting number will be
+		 * negative.
+		 * this token will be preceded by a HYPHEN token, so the number
+		 * must be positive */
+		tok->tok_int *= -1;
+		push_symbol(ctx, SYM_HYPHEN);
+	} else if (convert_word_to_operator(ctx, tok)) {
+		token_type = TOK_OPERATOR;
+	}
+
+	handle_lex_state_transition(ctx, token_type);
+	enqueue_token(ctx, tok);
+
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status statement_symbol(struct lex_ctx *ctx)
+{
+	const struct lex_token_def *sym = NULL;
+	enum bshell_status status = read_symbol(ctx, &sym);
+
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	handle_lex_state_transition(ctx, sym->id);
+
+	struct lex_token *tok = NULL;
+	switch (sym->id) {
+	case SYM_DQUOTE:
+		return BSHELL_SUCCESS;
+	case SYM_HYPHEN:
+		return statement_hyphen(ctx);
+	case SYM_SQUOTE:
+		status = read_literal_string(ctx, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+		enqueue_token(ctx, tok);
+		return BSHELL_SUCCESS;
+
+	case SYM_HASH:
+		return read_line_comment(ctx);
+	case SYM_DOLLAR:
+		status = read_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_AT:
+		status = read_var(ctx, TOK_VAR_SPLAT, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_DOLLAR_LEFT_BRACE:
+		status = read_braced_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	default:
+		break;
+	}
+
+	push_symbol(ctx, sym->id);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status statement_word(struct lex_ctx *ctx)
+{
+	struct lex_token *word = NULL;
+	enum bshell_status status = read_word(ctx, 0, &word);
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	struct lex_state *state = lex_state_get(ctx);
+
+	bool enable_keywords = !(state->s_flags & STATEMENT_F_DISABLE_KEYWORDS);
+	unsigned int token = TOK_WORD;
+
+	if (enable_keywords && convert_word_to_keyword(word)) {
+		token = word->tok_keyword;
+	} else if (convert_word_to_int(word)) {
+		token = TOK_INT;
+	}
+
+	handle_lex_state_transition(ctx, token);
+
+	enqueue_token(ctx, word);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status statement_pump_token(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+	bool newline = false;
+
+	set_token_start(ctx);
+	while (fx_wchar_is_space(c)) {
+		if (c == '\n') {
+			newline = true;
+		}
+
+		set_token_end(ctx);
+		advance_char_noread(ctx);
+		c = peek_char_noread(ctx);
+	}
+
+	if (newline) {
+		struct lex_token *tok = lex_token_create(TOK_LINEFEED);
+		enqueue_token(ctx, tok);
+		handle_lex_state_transition(ctx, TOK_LINEFEED);
+		return BSHELL_SUCCESS;
+	}
+
+	if (char_can_begin_symbol(ctx, c)) {
+		return statement_symbol(ctx);
+	}
+
+	if (char_has_flags(ctx, c, LEX_TOKEN_UNARY_ARITHMETIC)) {
+		lex_state_change(ctx, LEX_STATE_ARITHMETIC);
+		return BSHELL_SUCCESS;
+	}
+
+	return statement_word(ctx);
+}
+
+static const struct lex_state_link links[] = {
+	LINK_PUSH(SYM_DQUOTE, LEX_STATE_STRING, 0),
+	/* arithmetic tokens */
+	LINK_CHANGE(TOK_KEYWORD, LEX_STATE_ARITHMETIC),
+	LINK_CHANGE(TOK_INT, LEX_STATE_ARITHMETIC),
+	LINK_PUSH(SYM_DOLLAR, LEX_STATE_ARITHMETIC, 0),
+	LINK_PUSH(SYM_DOLLAR_LEFT_BRACE, LEX_STATE_ARITHMETIC, 0),
+	LINK_CHANGE(SYM_AT_LEFT_BRACE, LEX_STATE_ARITHMETIC),
+	LINK_PUSH(SYM_AT_LEFT_BRACE, LEX_STATE_HASHTABLE, 0),
+	LINK_PUSH(SYM_AT, LEX_STATE_ARITHMETIC, 0),
+	LINK_CHANGE(SYM_LEFT_PAREN, LEX_STATE_ARITHMETIC),
+	LINK_CHANGE(SYM_BANG, LEX_STATE_ARITHMETIC),
+	LINK_PUSH_WITH_TERM(
+		SYM_LEFT_PAREN,
+		LEX_STATE_STATEMENT,
+		STATEMENT_F_DISABLE_KEYWORDS,
+		SYM_RIGHT_PAREN),
+
+	/* statement tokens */
+	LINK_PUSH(SYM_LEFT_BRACE, LEX_STATE_STATEMENT, 0),
+	LINK_PUSH_WITH_TERM(
+		SYM_DOLLAR_LEFT_PAREN,
+		LEX_STATE_STATEMENT,
+		0,
+		SYM_RIGHT_PAREN),
+
+	/* command tokens */
+	LINK_CHANGE(KW_FUNC, LEX_STATE_COMMAND),
+	LINK_CHANGE(SYM_AMPERSAND, LEX_STATE_COMMAND),
+	LINK_CHANGE(TOK_WORD, LEX_STATE_COMMAND),
+	LINK_END,
+};
+
+static const unsigned int keywords[] = {
+	KW_FUNC,
+	KW_IF,
+	KW_ELSEIF,
+	KW_ELSE,
+	KW_NONE,
+};
+
+static const unsigned int operators[] = {
+	TKOP_BNOT,
+	TKOP_NOT,
+	TKOP_NONE,
+};
+
+static const unsigned int symbols[] = {
+	SYM_AMPERSAND,
+	SYM_BANG,
+	SYM_SQUOTE,
+	SYM_DQUOTE,
+	SYM_HASH,
+	SYM_AT,
+	SYM_AT_LEFT_BRACE,
+	SYM_PIPE,
+	SYM_COMMA,
+	SYM_SEMICOLON,
+	SYM_LEFT_BRACE,
+	SYM_RIGHT_BRACE,
+	SYM_LEFT_BRACKET,
+	SYM_RIGHT_BRACKET,
+	SYM_LEFT_PAREN,
+	SYM_RIGHT_PAREN,
+	SYM_NONE,
+};
+
+const struct lex_state_type lex_statement_state = {
+	.s_id = LEX_STATE_STATEMENT,
+	.s_pump_token = statement_pump_token,
+	.s_links = links,
+	.s_keywords = keywords,
+	.s_operators = operators,
+	.s_symbols = symbols,
+};

bshell/parse/lex/string.c

@@ -0,0 +1,141 @@
+#include "lex-internal.h"
+
+static enum bshell_status string_symbol(struct lex_ctx *ctx)
+{
+	const struct lex_token_def *sym = NULL;
+	enum bshell_status status = read_symbol(ctx, &sym);
+
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	handle_lex_state_transition(ctx, sym->id);
+
+	struct lex_token *tok = NULL;
+
+	switch (sym->id) {
+	case SYM_DQUOTE:
+		return BSHELL_SUCCESS;
+	case SYM_DOLLAR_LEFT_PAREN:
+		return push_symbol(ctx, sym->id);
+	case SYM_DOLLAR:
+		status = read_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_AT:
+		status = read_var(ctx, TOK_VAR_SPLAT, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_DOLLAR_LEFT_BRACE:
+		status = read_braced_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	default:
+		break;
+	}
+
+	return BSHELL_ERR_BAD_SYNTAX;
+}
+
+static enum bshell_status string_content(struct lex_ctx *ctx)
+{
+	fx_wchar c = FX_WCHAR_INVALID;
+	fx_string *temp = lex_state_get_tempstr(ctx);
+	set_token_start(ctx);
+	fx_string_clear(temp);
+
+	while (1) {
+		c = peek_char(ctx);
+		if (c == FX_WCHAR_INVALID) {
+			/* EOF without end of string */
+			ctx->lex_status = BSHELL_ERR_BAD_SYNTAX;
+		}
+
+		if (char_can_begin_symbol(ctx, c)) {
+			break;
+		}
+
+		fx_string_append_wc(temp, c);
+		set_token_end(ctx);
+		advance_char(ctx);
+	}
+
+	if (fx_string_get_size(temp, FX_STRLEN_NORMAL) == 0) {
+		return BSHELL_SUCCESS;
+	}
+
+	struct lex_token *tok = lex_token_create_with_string(
+		TOK_STRING,
+		fx_string_get_cstr(temp));
+	enqueue_token(ctx, tok);
+
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status string_begin(struct lex_ctx *ctx)
+{
+	struct lex_token *tok = lex_token_create(TOK_STR_START);
+	if (!tok) {
+		return BSHELL_ERR_NO_MEMORY;
+	}
+
+	enqueue_token(ctx, tok);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status string_end(struct lex_ctx *ctx)
+{
+	struct lex_token *tok = lex_token_create(TOK_STR_END);
+	if (!tok) {
+		return BSHELL_ERR_NO_MEMORY;
+	}
+
+	enqueue_token(ctx, tok);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status string_pump_token(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+
+	if (char_can_begin_symbol(ctx, c)) {
+		return string_symbol(ctx);
+	}
+
+	return string_content(ctx);
+}
+
+static const struct lex_state_link links[] = {
+	LINK_PUSH(SYM_DOLLAR_LEFT_PAREN, LEX_STATE_STATEMENT, 0),
+	LINK_POP(SYM_DQUOTE),
+	LINK_END,
+};
+
+static const unsigned int symbols[] = {
+	SYM_DOLLAR,
+	SYM_DOLLAR_LEFT_PAREN,
+	SYM_DOLLAR_LEFT_BRACE,
+	SYM_DQUOTE,
+	SYM_NONE,
+};
+
+const struct lex_state_type lex_string_state = {
+	.s_id = LEX_STATE_STRING,
+	.s_begin = string_begin,
+	.s_end = string_end,
+	.s_pump_token = string_pump_token,
+	.s_links = links,
+	.s_symbols = symbols,
+};

bshell/parse/lex/word.c

@@ -0,0 +1,162 @@
+#include "lex-internal.h"
+
+static enum bshell_status word_symbol(struct lex_ctx *ctx)
+{
+	const struct lex_token_def *sym = NULL;
+	enum bshell_status status = read_symbol(ctx, &sym);
+
+	if (status != BSHELL_SUCCESS) {
+		return status;
+	}
+
+	struct lex_token *tok = NULL;
+
+	switch (sym->id) {
+	case SYM_DOLLAR_LEFT_PAREN:
+		status = push_symbol(ctx, sym->id);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		lex_state_push(ctx, LEX_STATE_STATEMENT, 0);
+		return BSHELL_SUCCESS;
+	case SYM_RIGHT_PAREN:
+		lex_state_pop(ctx);
+
+		status = push_symbol(ctx, sym->id);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+		return BSHELL_SUCCESS;
+	case SYM_DOLLAR:
+		status = read_var(ctx, TOK_VAR, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	case SYM_AT:
+		status = read_var(ctx, TOK_VAR_SPLAT, &tok);
+		if (status != BSHELL_SUCCESS) {
+			return status;
+		}
+
+		enqueue_token(ctx, tok);
+		return status;
+	default:
+		break;
+	}
+
+	return BSHELL_ERR_BAD_SYNTAX;
+}
+
+static enum bshell_status word_content(struct lex_ctx *ctx)
+{
+	fx_wchar c = FX_WCHAR_INVALID;
+	fx_string *temp = lex_state_get_tempstr(ctx);
+	set_token_start(ctx);
+	fx_string_clear(temp);
+
+	while (1) {
+		c = peek_char(ctx);
+		if (c == FX_WCHAR_INVALID) {
+			/* EOF without end of word */
+			ctx->lex_status = BSHELL_ERR_BAD_SYNTAX;
+		}
+
+		if (fx_wchar_is_space(c)) {
+			break;
+		}
+
+		if (char_can_begin_symbol(ctx, c)) {
+			break;
+		}
+
+		fx_string_append_wc(temp, c);
+		set_token_end(ctx);
+		advance_char(ctx);
+	}
+
+	if (fx_string_get_size(temp, FX_STRLEN_NORMAL) == 0) {
+		return BSHELL_SUCCESS;
+	}
+
+	struct lex_token *tok = lex_token_create_with_string(
+		TOK_WORD,
+		fx_string_get_cstr(temp));
+	enqueue_token(ctx, tok);
+
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status word_begin(struct lex_ctx *ctx)
+{
+	struct lex_token *tok = lex_token_create(TOK_WORD_START);
+	if (!tok) {
+		return BSHELL_ERR_NO_MEMORY;
+	}
+
+	enqueue_token_with_coordinates(
+		ctx,
+		tok,
+		&ctx->lex_start,
+		&ctx->lex_start);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status word_end(struct lex_ctx *ctx)
+{
+	struct lex_token *tok = lex_token_create(TOK_WORD_END);
+	if (!tok) {
+		return BSHELL_ERR_NO_MEMORY;
+	}
+
+	enqueue_token_with_coordinates(ctx, tok, &ctx->lex_end, &ctx->lex_end);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status word_pump_token(struct lex_ctx *ctx)
+{
+	fx_wchar c = peek_char(ctx);
+
+	if (fx_wchar_is_space(c)) {
+		lex_state_pop(ctx);
+		return BSHELL_SUCCESS;
+	}
+
+	if (char_has_flags(ctx, c, LEX_TOKEN_TERMINATES_WORD)) {
+		lex_state_pop(ctx);
+		return BSHELL_SUCCESS;
+	}
+
+	if (char_can_begin_symbol(ctx, c)) {
+		return word_symbol(ctx);
+	}
+
+	return word_content(ctx);
+}
+
+static const unsigned int symbols[] = {
+	SYM_AMPERSAND,
+	SYM_HASH,
+	SYM_DOLLAR,
+	SYM_DOLLAR_LEFT_PAREN,
+	SYM_DOLLAR_LEFT_BRACE,
+	SYM_PIPE,
+	SYM_COMMA,
+	SYM_SEMICOLON,
+	SYM_LEFT_BRACE,
+	SYM_RIGHT_BRACE,
+	SYM_LEFT_PAREN,
+	SYM_RIGHT_PAREN,
+	SYM_NONE,
+};
+
+const struct lex_state_type lex_word_state = {
+	.s_id = LEX_STATE_WORD,
+	.s_begin = word_begin,
+	.s_end = word_end,
+	.s_pump_token = word_pump_token,
+	.s_symbols = symbols,
+};

bshell/parse/parse.c

@@ -0,0 +1,55 @@
+#include "parse.h"
+
+#include "../ast/ast.h"
+#include "../debug.h"
+#include "lex.h"
+#include "syntax.h"
+#include "token.h"
+
+#include <stdio.h>
+#include <string.h>
+
+enum bshell_status parse_ctx_init(struct parse_ctx *ctx, struct lex_ctx *src)
+{
+	memset(ctx, 0x0, sizeof *ctx);
+
+	ctx->p_src = src;
+
+	return BSHELL_SUCCESS;
+}
+
+void parse_ctx_cleanup(struct parse_ctx *ctx)
+{
+}
+
+struct ast_node *parse_ctx_read_node(struct parse_ctx *ctx)
+{
+	parse_symbol(ctx, SYM_SEMICOLON);
+	parse_linefeed(ctx);
+
+	struct ast_node *result = NULL;
+	bool ok = parse_statement(ctx, &result);
+
+	return ok ? result : NULL;
+}
+
+void report_error(struct parse_ctx *ctx, const char *format, ...)
+{
+	ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+	fprintf(stderr, "PARSE: ");
+
+	va_list arg;
+	va_start(arg, format);
+	vfprintf(stderr, format, arg);
+	va_end(arg);
+
+	fprintf(stderr, "\n");
+
+	struct lex_token *tok = peek_token(ctx);
+	fprintf(stderr, "  peek_token = ");
+	if (tok) {
+		print_lex_token(tok);
+	} else {
+		fprintf(stderr, " EOF\n");
+	}
+}

bshell/parse/parse.h

@@ -0,0 +1,21 @@
+#ifndef PARSE_H_
+#define PARSE_H_
+
+#include "../status.h"
+
+struct lex_ctx;
+struct ast_node;
+
+struct parse_ctx {
+	struct lex_ctx *p_src;
+	enum bshell_status p_status;
+};
+
+extern enum bshell_status parse_ctx_init(
+	struct parse_ctx *ctx,
+	struct lex_ctx *src);
+extern void parse_ctx_cleanup(struct parse_ctx *ctx);
+
+extern struct ast_node *parse_ctx_read_node(struct parse_ctx *ctx);
+
+#endif

bshell/parse/syntax.h

@@ -0,0 +1,66 @@
+#ifndef PARSE_SYNTAX_H_
+#define PARSE_SYNTAX_H_
+
+#include "../ast/ast.h"
+#include "../operator.h"
+#include "lex.h"
+#include "parse.h"
+#include "token.h"
+
+#include <stdbool.h>
+#include <stdio.h>
+
+extern void report_error(struct parse_ctx *ctx, const char *format, ...);
+
+extern struct lex_token *peek_token(struct parse_ctx *ctx);
+extern enum token_type peek_token_type(struct parse_ctx *ctx);
+extern enum token_keyword peek_unknown_keyword(struct parse_ctx *ctx);
+extern enum token_symbol peek_unknown_symbol(struct parse_ctx *ctx);
+
+extern struct lex_token *claim_token(struct parse_ctx *ctx);
+extern void discard_token(struct parse_ctx *ctx);
+
+extern bool peek_linefeed(struct parse_ctx *ctx);
+extern bool peek_symbol(struct parse_ctx *ctx, enum token_symbol sym);
+extern bool peek_word(struct parse_ctx *ctx, struct lex_token **out);
+extern bool peek_int(struct parse_ctx *ctx);
+
+extern bool parse_linefeed(struct parse_ctx *ctx);
+extern bool parse_symbol(struct parse_ctx *ctx, enum token_symbol sym);
+extern bool parse_keyword(struct parse_ctx *ctx, enum token_keyword kw);
+extern bool parse_word(struct parse_ctx *ctx, struct lex_token **out);
+extern bool parse_var(struct parse_ctx *ctx, struct lex_token **out);
+extern bool parse_flag(struct parse_ctx *ctx, struct lex_token **out);
+
+extern bool peek_arith_expr(struct parse_ctx *ctx);
+extern bool parse_arith_value(struct parse_ctx *ctx, struct ast_node **out);
+extern bool parse_arith_expr(
+	struct parse_ctx *ctx,
+	enum operator_precedence minimum_precedence,
+	struct ast_node **out);
+
+extern bool peek_keyword_expr(struct parse_ctx *ctx);
+extern bool parse_keyword_expr(struct parse_ctx *ctx, struct ast_node **out);
+
+extern bool parse_if(struct parse_ctx *ctx, struct ast_node **out);
+extern bool parse_func(struct parse_ctx *ctx, struct ast_node **out);
+
+extern bool parse_fstring(struct parse_ctx *ctx, struct ast_node **out);
+
+extern bool parse_block(struct parse_ctx *ctx, struct ast_node **out);
+
+extern bool peek_command(struct parse_ctx *ctx);
+extern bool parse_pipeline(
+	struct parse_ctx *ctx,
+	struct ast_node *first_item,
+	struct ast_node **out);
+extern bool parse_command(struct parse_ctx *ctx, struct ast_node **out);
+extern bool parse_cmdcall(struct parse_ctx *ctx, struct ast_node **out);
+extern bool parse_redirect(struct parse_ctx *ctx, struct ast_node **out);
+
+extern bool parse_expr(struct parse_ctx *ctx, struct ast_node **out);
+extern bool peek_statement(struct parse_ctx *ctx);
+extern bool parse_statement(struct parse_ctx *ctx, struct ast_node **out);
+extern bool parse_statement_list(struct parse_ctx *ctx, struct ast_node **out);
+
+#endif

bshell/parse/syntax/arith.c

@@ -0,0 +1,902 @@
+#include "../../debug.h"
+#include "../../operator.h"
+#include "../syntax.h"
+
+#include <fx/queue.h>
+
+enum expr_component {
+	EXPR_C_NONE = 0,
+	EXPR_C_OPERAND,
+	EXPR_C_BINARY_OP,
+	EXPR_C_UNARY_OP,
+};
+
+struct expr_parse_ctx {
+	fx_queue expr_operator_stack, expr_out_queue;
+	enum expr_component expr_prev;
+	unsigned int expr_prev_symbol;
+	enum operator_precedence expr_minimum_precedence;
+	bool expr_done, expr_fail;
+};
+
+static bool op_node_is_complete(struct op_ast_node *node)
+{
+	if (!node->n_op) {
+		return false;
+	}
+
+	switch (node->n_op->op_arity) {
+	case OPA_UNARY:
+		return node->n_right != NULL;
+	case OPA_BINARY:
+		return (node->n_left != NULL && node->n_right != NULL);
+	default:
+		return false;
+	}
+}
+
+static bool finalise_expr(
+	struct expr_parse_ctx *ctx,
+	struct ast_node **out,
+	enum operator_precedence minimum_precedence)
+{
+	fx_queue_entry *entry = NULL;
+	while (true) {
+		entry = fx_queue_pop_back(&ctx->expr_operator_stack);
+		if (!entry) {
+			break;
+		}
+
+		struct op_ast_node *node
+			= fx_unbox(struct op_ast_node, entry, n_base.n_entry);
+		if (!node) {
+			/* this should never happen */
+			return false;
+		}
+
+		const struct operator_info *op = node->n_op;
+
+		/* if we aren't processing operators below a certain precedence
+		 * then leave them on the stack and stop here. */
+		if (op->op_precedence < minimum_precedence) {
+			fx_queue_push_back(&ctx->expr_operator_stack, entry);
+			break;
+		}
+
+		fx_queue_push_back(&ctx->expr_out_queue, entry);
+	}
+
+	fx_queue q = FX_QUEUE_INIT;
+	fx_queue_entry *tmp = NULL;
+	entry = fx_queue_first(&ctx->expr_out_queue);
+	int i = 0;
+
+	while (entry) {
+		struct ast_node *item
+			= fx_unbox(struct ast_node, entry, n_entry);
+		fx_queue_entry *next = fx_queue_next(entry);
+		fx_queue_delete(&ctx->expr_out_queue, entry);
+
+		/* if the node is an operand, just push it to a
+		 * temporary queue and come back to it later. */
+		if (item->n_type != AST_OP) {
+			/* operand */
+			fx_queue_push_back(&q, &item->n_entry);
+			goto next;
+		}
+
+		const struct operator_info *op = NULL;
+
+		struct op_ast_node *op_node = (struct op_ast_node *)item;
+
+		/* if an operator node is already complete (i.e. it
+		 * already has all the operands it needs, it can be
+		 * pushed to the operand queue as-is */
+		if (op_node_is_complete(op_node)) {
+			fx_queue_push_back(&q, &item->n_entry);
+			goto next;
+		}
+
+		/* otherwise, pop the relevant operands from the operand
+		 * queue... */
+		op = op_node->n_op;
+		tmp = fx_queue_pop_back(&q);
+		op_node->n_right = fx_unbox(struct ast_node, tmp, n_entry);
+
+		if (op_node->n_right) {
+			op_node->n_right->n_parent = (struct ast_node *)op_node;
+
+#if 0
+			ast_node_extend_bounds_recursive(
+				(struct ivy_ast_node *)op_node,
+				(struct ivy_ast_node *)tmp);
+#endif
+		}
+
+		if (op->op_arity == OPA_BINARY) {
+			tmp = fx_queue_pop_back(&q);
+			op_node->n_left
+				= fx_unbox(struct ast_node, tmp, n_entry);
+
+			if (op_node->n_left) {
+				op_node->n_left->n_parent
+					= (struct ast_node *)op_node;
+
+#if 0
+				ast_node_extend_bounds_recursive(
+					(struct ivy_ast_node *)op_node,
+					(struct ivy_ast_node *)tmp);
+#endif
+			}
+		}
+
+		/* ...and push the newly-completed operator node to the
+		 * operand queue */
+		fx_queue_push_back(&q, &op_node->n_base.n_entry);
+	next:
+		entry = next;
+	}
+
+#if 0
+	debug_printf("** after hierarchisation:\n");
+	print_expr_queues(state);
+#endif
+
+	/* if we are not processing operators below a certain precedence,
+	 * i.e. when determining the recipient of a keyword-message), these
+	 * operators will still be on the parser state's operator stack, but
+	 * their operands have just been moved to the temporary operand stack
+	 * used above. move them back to the parser state's output queue here
+	 * so they can be used later. */
+	entry = fx_queue_first(&ctx->expr_operator_stack);
+	while (entry) {
+		fx_queue_entry *entry2 = fx_queue_pop_front(&q);
+		if (!entry2) {
+			return false;
+		}
+
+		fx_queue_push_back(&ctx->expr_out_queue, entry2);
+		entry = fx_queue_next(entry);
+	}
+
+#if 0
+	debug_printf("** after de-linearisation:\n");
+	print_expr_queues(state);
+	ivy_ast_node_print(*expr_tree);
+	debug_printf("------\n");
+#endif
+
+	/* the final node remaining on the temp operand stack is the
+	 * root node of the new expression tree */
+	tmp = fx_queue_pop_back(&q);
+	*out = fx_unbox(struct ast_node, tmp, n_entry);
+
+	return true;
+}
+
+bool peek_arith_expr(struct parse_ctx *ctx)
+{
+	switch (peek_token_type(ctx)) {
+	case TOK_SYMBOL:
+		return operator_get_by_token(peek_unknown_symbol(ctx));
+	case TOK_INT:
+	case TOK_DOUBLE:
+	case TOK_STRING:
+	case TOK_VAR:
+	case TOK_STR_START:
+	case TOK_OPERATOR:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool parse_subexpr(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_symbol(ctx, SYM_LEFT_PAREN)) {
+		report_error(ctx, "expected `(`");
+	}
+
+	struct ast_node *v = NULL;
+	if (!parse_expr(ctx, &v)) {
+		report_error(ctx, "error while parsing parenthesis expression");
+		return false;
+	}
+
+	if (!parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+		report_error(ctx, "expected `)` after parenthesis expression");
+		return false;
+	}
+
+	*out = v;
+	return true;
+}
+
+static bool parse_stmt_block(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_symbol(ctx, SYM_DOLLAR_LEFT_PAREN)) {
+		report_error(ctx, "expected `$(`");
+		return false;
+	}
+
+	if (parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+		*out = ast_node_create(AST_NULL);
+		return true;
+	}
+
+	struct ast_node *v = NULL;
+	if (!parse_statement_list(ctx, &v)) {
+		return false;
+	}
+
+	if (!parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+		report_error(ctx, "expected ')' after subexpression");
+		ast_node_destroy(v);
+		return false;
+	}
+
+	*out = v;
+	return true;
+}
+
+static bool parse_hashtable(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_symbol(ctx, SYM_AT_LEFT_BRACE)) {
+		report_error(ctx, "expected `@{`");
+		return false;
+	}
+
+	parse_linefeed(ctx);
+
+	struct hashtable_ast_node *table
+		= (struct hashtable_ast_node *)ast_node_create(AST_HASHTABLE);
+	if (!table) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		return false;
+	}
+
+	size_t nr_items = 0;
+	bool ok = true;
+	while (ok) {
+		if (parse_symbol(ctx, SYM_RIGHT_BRACE)) {
+			break;
+		}
+
+		parse_linefeed(ctx);
+
+		struct hashtable_item_ast_node *item
+			= (struct hashtable_item_ast_node *)ast_node_create(
+				AST_HASHTABLE_ITEM);
+		struct lex_token *tok = NULL;
+		if (parse_word(ctx, &tok)) {
+			struct string_ast_node *v
+				= (struct string_ast_node *)ast_node_create(
+					AST_STRING);
+			v->n_value = tok;
+			item->n_key = (struct ast_node *)v;
+		} else if (!parse_arith_value(ctx, &item->n_key)) {
+			report_error(ctx, "failed to parse hashtable key");
+			ast_node_destroy((struct ast_node *)item);
+			ok = false;
+			break;
+		}
+
+		if (!parse_symbol(ctx, SYM_EQUAL)) {
+			report_error(ctx, "expected `=` after hashtable key");
+			ast_node_destroy((struct ast_node *)item);
+			ok = false;
+			break;
+		}
+
+		if (!parse_expr(ctx, &item->n_value)) {
+			report_error(ctx, "failed to parse hashtable value");
+			ast_node_destroy((struct ast_node *)item);
+			ok = false;
+			break;
+		}
+
+		fx_queue_push_back(&table->n_items, &item->n_base.n_entry);
+		nr_items++;
+
+		if (parse_symbol(ctx, SYM_RIGHT_BRACE)) {
+			break;
+		}
+
+		if (!parse_linefeed(ctx) && !parse_symbol(ctx, SYM_SEMICOLON)) {
+			report_error(
+				ctx,
+				"expected `;`, `}`, or linefeed after "
+				"hashtable value");
+			ok = false;
+			break;
+		}
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)table);
+		return false;
+	}
+
+	*out = (struct ast_node *)table;
+	return true;
+}
+
+static bool parse_array(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_symbol(ctx, SYM_AT_LEFT_PAREN)) {
+		report_error(ctx, "expected `@(`");
+		return false;
+	}
+
+	struct array_ast_node *array
+		= (struct array_ast_node *)ast_node_create(AST_ARRAY);
+	if (!array) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		return false;
+	}
+
+	size_t nr_items = 0;
+	bool ok = true;
+	while (ok) {
+		if (parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+			break;
+		}
+
+		if (nr_items && !parse_symbol(ctx, SYM_COMMA)) {
+			report_error(
+				ctx,
+				"expected `,` or `)` after array value");
+			ok = false;
+		}
+
+		struct ast_node *item = NULL;
+		if (!parse_arith_value(ctx, &item)) {
+			report_error(ctx, "failed to parse array item");
+			ok = false;
+			break;
+		}
+
+		fx_queue_push_back(&array->n_items, &item->n_entry);
+		nr_items++;
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)array);
+		return false;
+	}
+
+	*out = (struct ast_node *)array;
+	return true;
+}
+
+bool parse_fstring(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (peek_token_type(ctx) != TOK_STR_START) {
+		return false;
+	}
+
+	discard_token(ctx);
+
+	struct fstring_ast_node *fstring
+		= (struct fstring_ast_node *)ast_node_create(AST_FSTRING);
+	if (!fstring) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		return false;
+	}
+
+	bool ok = true;
+	while (ok) {
+		if (peek_token_type(ctx) == TOK_STR_END) {
+			discard_token(ctx);
+			break;
+		}
+
+		struct ast_node *item = NULL;
+		if (!parse_arith_value(ctx, &item)) {
+			ok = false;
+			break;
+		}
+
+		fx_queue_push_back(&fstring->n_elements, &item->n_entry);
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)fstring);
+		fstring = NULL;
+	}
+
+	*out = (struct ast_node *)fstring;
+	return ok;
+}
+
+bool parse_arith_value(struct parse_ctx *ctx, struct ast_node **out)
+{
+	struct lex_token *tok = peek_token(ctx);
+	switch (tok->tok_type) {
+	case TOK_INT: {
+		struct int_ast_node *v
+			= (struct int_ast_node *)ast_node_create(AST_INT);
+		v->n_value = claim_token(ctx);
+		*out = (struct ast_node *)v;
+		return true;
+	}
+	case TOK_DOUBLE: {
+		struct double_ast_node *v
+			= (struct double_ast_node *)ast_node_create(AST_DOUBLE);
+		v->n_value = claim_token(ctx);
+		*out = (struct ast_node *)v;
+		return true;
+	}
+	case TOK_STRING: {
+		struct string_ast_node *v
+			= (struct string_ast_node *)ast_node_create(AST_STRING);
+		v->n_value = claim_token(ctx);
+		*out = (struct ast_node *)v;
+		return true;
+	}
+	case TOK_VAR: {
+		struct var_ast_node *v
+			= (struct var_ast_node *)ast_node_create(AST_VAR);
+		v->n_ident = claim_token(ctx);
+		*out = (struct ast_node *)v;
+		return true;
+	}
+	case TOK_STR_START:
+		return parse_fstring(ctx, out);
+	case TOK_SYMBOL:
+		switch (tok->tok_symbol) {
+		case SYM_LEFT_PAREN:
+			return parse_subexpr(ctx, out);
+		case SYM_DOLLAR_LEFT_PAREN:
+			return parse_stmt_block(ctx, out);
+		case SYM_AT_LEFT_BRACE:
+			return parse_hashtable(ctx, out);
+		case SYM_AT_LEFT_PAREN:
+			return parse_array(ctx, out);
+		case SYM_LEFT_BRACE:
+			return parse_block(ctx, out);
+		default:
+			report_error(ctx, "token is not a valid operand");
+			return false;
+		}
+		break;
+	default:
+		report_error(ctx, "token is not a valid operand");
+		return false;
+	}
+}
+
+static bool parse_operand(struct parse_ctx *ctx, struct expr_parse_ctx *expr)
+{
+	if (expr->expr_prev == EXPR_C_OPERAND) {
+		report_error(ctx, "encountered two operands in a row");
+		return false;
+	}
+
+	expr->expr_prev = EXPR_C_OPERAND;
+
+	struct ast_node *v = NULL;
+	if (!parse_arith_value(ctx, &v)) {
+		return false;
+	}
+
+	fx_queue_push_back(&expr->expr_out_queue, &v->n_entry);
+	return true;
+}
+
+void arith_push_operator(struct expr_parse_ctx *state, struct op_ast_node *node)
+{
+	const struct operator_info *op = node->n_op;
+	if (!op) {
+		return;
+	}
+
+	while (true) {
+		fx_queue_entry *top
+			= fx_queue_last(&state->expr_operator_stack);
+		if (!top) {
+			break;
+		}
+
+		struct ast_node *top_node
+			= fx_unbox(struct ast_node, top, n_entry);
+		const struct operator_info *top_op = NULL;
+
+		switch (top_node->n_type) {
+		case AST_OP: {
+			struct op_ast_node *op_node
+				= (struct op_ast_node *)top_node;
+			top_op = op_node->n_op;
+			break;
+		}
+		default:
+			return;
+		}
+
+		if (top_op->op_precedence < op->op_precedence
+		    || (top_op->op_precedence == op->op_precedence
+		        && op->op_associativity != ASSOCIATIVITY_LEFT)) {
+			break;
+		}
+
+		fx_queue_delete(&state->expr_operator_stack, top);
+		fx_queue_push_back(&state->expr_out_queue, top);
+	}
+
+	fx_queue_push_back(&state->expr_operator_stack, &node->n_base.n_entry);
+}
+
+static bool parse_unary_operator(
+	struct parse_ctx *ctx,
+	struct expr_parse_ctx *expr)
+{
+	struct lex_token *tok = peek_token(ctx);
+
+	const struct operator_info *op = NULL;
+	switch (tok->tok_type) {
+	case TOK_SYMBOL:
+		op = operator_get_by_token(tok->tok_symbol);
+		break;
+	case TOK_OPERATOR:
+		switch (tok->tok_operator) {
+		case TKOP_SPLIT:
+			op = operator_get_by_id(OP_USPLIT);
+			break;
+		case TKOP_JOIN:
+			op = operator_get_by_id(OP_USPLIT);
+			break;
+		default:
+			op = operator_get_by_token(tok->tok_operator);
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	if (expr->expr_prev == EXPR_C_OPERAND
+	    && op->op_location == OPL_PREFIX) {
+		report_error(
+			ctx,
+			"unexpected operand before unary "
+			"operator");
+		return false;
+	}
+
+	if (!op) {
+		report_error(ctx, "unknown unary operator");
+		return false;
+	}
+
+	if (op->op_precedence < expr->expr_minimum_precedence) {
+		expr->expr_done = true;
+		return true;
+	}
+
+	expr->expr_prev = EXPR_C_BINARY_OP;
+
+	struct op_ast_node *op_node
+		= (struct op_ast_node *)ast_node_create(AST_OP);
+	if (!op_node) {
+		return false;
+	}
+
+	op_node->n_op = op;
+	discard_token(ctx);
+	arith_push_operator(expr, op_node);
+	return true;
+}
+
+static bool parse_binary_operator(
+	struct parse_ctx *ctx,
+	struct expr_parse_ctx *expr)
+{
+	struct lex_token *tok = peek_token(ctx);
+
+	const struct operator_info *op = NULL;
+	switch (tok->tok_type) {
+	case TOK_SYMBOL:
+		op = operator_get_by_token(tok->tok_symbol);
+		break;
+	case TOK_OPERATOR:
+		switch (tok->tok_operator) {
+		case TKOP_SPLIT:
+			op = operator_get_by_id(OP_BSPLIT);
+			break;
+		case TKOP_JOIN:
+			op = operator_get_by_id(OP_BJOIN);
+			break;
+		default:
+			op = operator_get_by_token(tok->tok_operator);
+			break;
+		}
+	default:
+		break;
+	}
+
+	if (!op) {
+		report_error(ctx, "unknown binary operator");
+		return false;
+	}
+
+	if (op->op_precedence < expr->expr_minimum_precedence) {
+		expr->expr_done = true;
+		return true;
+	}
+
+	if (expr->expr_prev != EXPR_C_OPERAND) {
+		switch (op->op_id) {
+		case OP_PAREN:
+			break;
+		default:
+			report_error(
+				ctx,
+				"expected operand before binary "
+				"operator");
+			return false;
+		}
+	}
+
+	expr->expr_prev = EXPR_C_BINARY_OP;
+
+	struct op_ast_node *op_node
+		= (struct op_ast_node *)ast_node_create(AST_OP);
+	if (!op_node) {
+		return false;
+	}
+
+	op_node->n_op = op;
+	discard_token(ctx);
+	arith_push_operator(expr, op_node);
+	return true;
+}
+
+static bool parse_call(struct parse_ctx *ctx, struct expr_parse_ctx *expr)
+{
+	return false;
+}
+
+static bool parse_comma(struct parse_ctx *ctx, struct expr_parse_ctx *expr)
+{
+	if (PRECEDENCE_ARRAY < expr->expr_minimum_precedence) {
+		expr->expr_done = true;
+		return true;
+	}
+
+	struct ast_node *item = NULL;
+	if (!finalise_expr(expr, &item, PRECEDENCE_ARRAY)) {
+		report_error(ctx, "failed to collect first array item.");
+		return false;
+	}
+
+	struct array_ast_node *array
+		= (struct array_ast_node *)ast_node_create(AST_ARRAY);
+	if (!array) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		ast_node_destroy(item);
+		return false;
+	}
+
+	if (item) {
+		fx_queue_push_back(&array->n_items, &item->n_entry);
+	}
+
+	while (1) {
+		if (!parse_symbol(ctx, SYM_COMMA)) {
+			break;
+		}
+
+		if (!parse_arith_expr(ctx, PRECEDENCE_ARRAY + 1, &item)) {
+			report_error(ctx, "failed to parse array item.");
+			ast_node_destroy((struct ast_node *)array);
+			return false;
+		}
+
+		fx_queue_push_back(&array->n_items, &item->n_entry);
+	}
+
+	fx_queue_push_back(&expr->expr_out_queue, &array->n_base.n_entry);
+	expr->expr_prev = EXPR_C_OPERAND;
+
+	return true;
+}
+
+static void dump_expr_ctx(struct expr_parse_ctx *expr)
+{
+	printf("op stack:\n");
+	fx_queue_entry *entry = fx_queue_first(&expr->expr_operator_stack);
+	while (entry) {
+		struct ast_node *node
+			= fx_unbox(struct ast_node, entry, n_entry);
+		print_ast_node(node);
+		entry = fx_queue_next(entry);
+	}
+
+	printf("out queue:\n");
+	entry = fx_queue_first(&expr->expr_out_queue);
+	while (entry) {
+		struct ast_node *node
+			= fx_unbox(struct ast_node, entry, n_entry);
+		print_ast_node(node);
+		entry = fx_queue_next(entry);
+	}
+}
+
+static bool can_use_command(struct expr_parse_ctx *ctx)
+{
+	switch (ctx->expr_prev_symbol) {
+	case TOK_NONE:
+	case SYM_EQUAL:
+	case SYM_PLUS_EQUAL:
+	case SYM_HYPHEN_EQUAL:
+	case SYM_ASTERISK_EQUAL:
+	case SYM_FORWARD_SLASH_EQUAL:
+	case SYM_PERCENT_EQUAL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+bool parse_arith_expr(
+	struct parse_ctx *ctx,
+	enum operator_precedence minimum_precedence,
+	struct ast_node **out)
+{
+	struct expr_parse_ctx expr = {
+		.expr_minimum_precedence = minimum_precedence,
+	};
+
+	while (!expr.expr_fail && !expr.expr_done) {
+		struct lex_token *tok = peek_token(ctx);
+		if (!tok) {
+			break;
+		}
+
+		switch (tok->tok_type) {
+		case TOK_LINEFEED:
+			expr.expr_done = true;
+			break;
+		case TOK_WORD: {
+			if (!can_use_command(&expr)) {
+				report_error(
+					ctx,
+					"expected a value expression");
+				expr.expr_fail = true;
+				break;
+			}
+
+			struct ast_node *value = NULL;
+			if (!parse_command(ctx, &value)) {
+				expr.expr_fail = true;
+				break;
+			}
+
+			fx_queue_push_back(
+				&expr.expr_out_queue,
+				&value->n_entry);
+			break;
+		}
+
+		case TOK_VAR:
+		case TOK_INT:
+		case TOK_DOUBLE:
+		case TOK_STRING:
+		case TOK_STR_START:
+			expr.expr_fail = !parse_operand(ctx, &expr);
+			expr.expr_prev_symbol = tok->tok_type;
+			break;
+		case TOK_OPERATOR:
+			switch (tok->tok_operator) {
+			/* these two are special cases, as they are both
+			 * unary AND binary operators */
+			case TKOP_SPLIT:
+			case TKOP_JOIN:
+				if (expr.expr_prev == EXPR_C_OPERAND) {
+					expr.expr_fail = !parse_binary_operator(
+						ctx,
+						&expr);
+				} else {
+					expr.expr_fail = !parse_unary_operator(
+						ctx,
+						&expr);
+				}
+
+				break;
+			case TKOP_BNOT:
+			case TKOP_NOT:
+				expr.expr_fail
+					= !parse_unary_operator(ctx, &expr);
+				break;
+			default:
+				expr.expr_fail
+					= !parse_binary_operator(ctx, &expr);
+				break;
+			}
+			expr.expr_prev_symbol = tok->tok_operator;
+			break;
+		case TOK_SYMBOL:
+			switch (tok->tok_symbol) {
+			case SYM_SEMICOLON:
+			case SYM_AMPERSAND:
+			case SYM_PIPE:
+			case SYM_RIGHT_PAREN:
+			case SYM_RIGHT_BRACE:
+			case SYM_RIGHT_BRACKET:
+				expr.expr_done = true;
+				break;
+			case SYM_COMMA:
+				expr.expr_fail = !parse_comma(ctx, &expr);
+				break;
+			case SYM_LEFT_PAREN: {
+				if (expr.expr_prev == EXPR_C_OPERAND) {
+					return parse_call(ctx, &expr);
+				}
+
+				struct ast_node *v = NULL;
+				expr.expr_fail = !parse_subexpr(ctx, &v);
+				if (expr.expr_fail) {
+					break;
+				}
+
+				fx_queue_push_back(
+					&expr.expr_out_queue,
+					&v->n_entry);
+				expr.expr_prev = EXPR_C_OPERAND;
+				break;
+			}
+			case SYM_DOLLAR_LEFT_PAREN:
+			case SYM_AT_LEFT_PAREN:
+			case SYM_AT_LEFT_BRACE:
+				expr.expr_fail = !parse_operand(ctx, &expr);
+				break;
+			default: {
+				const struct operator_info *op
+					= operator_get_by_token(
+						tok->tok_symbol);
+				if (op->op_arity == OPA_BINARY) {
+					expr.expr_fail = !parse_binary_operator(
+						ctx,
+						&expr);
+				} else {
+					expr.expr_fail = !parse_unary_operator(
+						ctx,
+						&expr);
+				}
+				break;
+			}
+			}
+
+			expr.expr_prev_symbol = tok->tok_symbol;
+			break;
+		default:
+			report_error(
+				ctx,
+				"unexpected token in arithmetic "
+				"expression");
+			expr.expr_fail = true;
+			break;
+		}
+	}
+
+	if (expr.expr_fail) {
+		/* TODO cleanup */
+		return false;
+	}
+
+	struct ast_node *value = NULL;
+	if (!finalise_expr(&expr, &value, PRECEDENCE_ASSIGN)) {
+		report_error(ctx, "failed to convert expression to AST");
+		/* TODO cleanup */
+		return false;
+	}
+
+	if (PRECEDENCE_PIPELINE >= expr.expr_minimum_precedence) {
+		if (peek_symbol(ctx, SYM_PIPE)) {
+			return parse_pipeline(ctx, value, out);
+		}
+	}
+
+	*out = value;
+	return true;
+}

bshell/parse/syntax/block.c

@@ -0,0 +1,30 @@
+#include "../syntax.h"
+
+bool parse_block(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_symbol(ctx, SYM_LEFT_BRACE)) {
+		return false;
+	}
+
+	struct block_ast_node *block
+		= (struct block_ast_node *)ast_node_create(AST_BLOCK);
+
+	while (1) {
+		parse_linefeed(ctx);
+
+		if (parse_symbol(ctx, SYM_RIGHT_BRACE)) {
+			break;
+		}
+
+		struct ast_node *stmt = NULL;
+		if (!parse_statement(ctx, &stmt)) {
+			ast_node_destroy((struct ast_node *)block);
+			return false;
+		}
+
+		fx_queue_push_back(&block->n_statements, &stmt->n_entry);
+	}
+
+	*out = (struct ast_node *)block;
+	return true;
+}

bshell/parse/syntax/command.c

@@ -0,0 +1,515 @@
+#include "../../debug.h"
+#include "../syntax.h"
+
+#include <fx/encoding.h>
+
+static bool parse_fword(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (peek_token_type(ctx) != TOK_WORD_START) {
+		return false;
+	}
+
+	discard_token(ctx);
+
+	struct fstring_ast_node *fstring
+		= (struct fstring_ast_node *)ast_node_create(AST_FSTRING);
+	if (!fstring) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		return false;
+	}
+
+	bool ok = true;
+	while (ok) {
+		if (peek_token_type(ctx) == TOK_WORD_END) {
+			discard_token(ctx);
+			break;
+		}
+
+		struct ast_node *item = NULL;
+		if (peek_token_type(ctx) == TOK_WORD) {
+			struct word_ast_node *n
+				= (struct word_ast_node *)ast_node_create(
+					AST_WORD);
+			if (!n) {
+				ctx->p_status = BSHELL_ERR_NO_MEMORY;
+				ok = false;
+				break;
+			}
+
+			n->n_value = claim_token(ctx);
+			item = (struct ast_node *)n;
+		} else {
+			if (!parse_arith_value(ctx, &item)) {
+				ok = false;
+				break;
+			}
+		}
+
+		fx_queue_push_back(&fstring->n_elements, &item->n_entry);
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)fstring);
+		fstring = NULL;
+	}
+
+	*out = (struct ast_node *)fstring;
+	return ok;
+	return false;
+}
+
+static bool parse_cmdcall_arg(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (ctx->p_status != BSHELL_SUCCESS) {
+		return false;
+	}
+
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	struct ast_node *arg = NULL;
+
+	switch (tok->tok_type) {
+	case TOK_WORD_START:
+		return parse_fword(ctx, out);
+	case TOK_STR_START:
+		return parse_fstring(ctx, out);
+	case TOK_WORD: {
+		struct word_ast_node *n
+			= (struct word_ast_node *)ast_node_create(AST_WORD);
+		if (!n) {
+			ctx->p_status = BSHELL_ERR_NO_MEMORY;
+			return false;
+		}
+
+		n->n_value = claim_token(ctx);
+		*out = (struct ast_node *)n;
+		return true;
+	}
+
+	case TOK_VAR: {
+		struct var_ast_node *n
+			= (struct var_ast_node *)ast_node_create(AST_VAR);
+		if (!n) {
+			ctx->p_status = BSHELL_ERR_NO_MEMORY;
+			return false;
+		}
+
+		n->n_ident = claim_token(ctx);
+		*out = (struct ast_node *)n;
+		return true;
+	}
+
+	case TOK_VAR_SPLAT: {
+		struct var_splat_ast_node *n
+			= (struct var_splat_ast_node *)ast_node_create(
+				AST_VAR_SPLAT);
+		if (!n) {
+			ctx->p_status = BSHELL_ERR_NO_MEMORY;
+			return false;
+		}
+
+		n->n_ident = claim_token(ctx);
+		*out = (struct ast_node *)n;
+		return true;
+	}
+
+	case TOK_STRING: {
+		struct string_ast_node *n
+			= (struct string_ast_node *)ast_node_create(AST_STRING);
+		if (!n) {
+			ctx->p_status = BSHELL_ERR_NO_MEMORY;
+			return false;
+		}
+
+		n->n_value = claim_token(ctx);
+		*out = (struct ast_node *)n;
+		return true;
+	}
+
+	case TOK_SYMBOL:
+		switch (tok->tok_symbol) {
+		case SYM_LEFT_PAREN:
+		case SYM_LEFT_BRACE:
+		case SYM_DOLLAR_LEFT_PAREN:
+		case SYM_AT_LEFT_BRACE:
+		case SYM_AT_LEFT_PAREN:
+			return parse_arith_value(ctx, out);
+		default:
+			report_error(
+				ctx,
+				"encountered unsupported command arg");
+			return false;
+		}
+		break;
+	default:
+		report_error(ctx, "encountered unsupported command arg");
+		return false;
+	}
+
+	return true;
+}
+
+static bool parse_redirect_to_fd(
+	struct parse_ctx *ctx,
+	unsigned int in_fd,
+	bool append,
+	struct ast_node **out)
+{
+	if (ctx->p_status != BSHELL_SUCCESS) {
+		return false;
+	}
+
+	struct redirection_ast_node *redirect
+		= (struct redirection_ast_node *)ast_node_create(
+			AST_REDIRECTION);
+
+	redirect->n_in = in_fd;
+	redirect->n_append = append;
+
+	if (!parse_symbol(ctx, SYM_AMPERSAND)) {
+		ast_node_destroy((struct ast_node *)redirect);
+		return false;
+	}
+
+	struct lex_token *out_tok = NULL;
+	struct ast_node *out_expr = NULL;
+	long long out_fd = -1;
+
+	if (peek_word(ctx, &out_tok)) {
+		const char *s = out_tok->tok_str;
+		char *ep;
+		out_fd = strtoll(s, &ep, 10);
+		if (*ep == '\0') {
+			discard_token(ctx);
+			out_tok = NULL;
+		} else {
+			out_fd = -1;
+		}
+	} else if (!parse_cmdcall_arg(ctx, &out_expr)) {
+		return false;
+	}
+
+	redirect->n_out_is_fd = (out_fd >= 0) || out_expr;
+	redirect->n_out_is_expr = out_expr != NULL;
+	redirect->n_out = (unsigned int)out_fd;
+	redirect->n_out_path_expr = out_expr;
+	if (out_tok) {
+		redirect->n_out_tok = claim_token(ctx);
+		redirect->n_out_path = out_tok->tok_str;
+	}
+
+	*out = (struct ast_node *)redirect;
+	return true;
+}
+
+static bool parse_redirect_to_file_squashed(
+	struct parse_ctx *ctx,
+	unsigned int in_fd,
+	bool append,
+	const char *str,
+	struct ast_node **out)
+{
+	if (ctx->p_status != BSHELL_SUCCESS) {
+		return false;
+	}
+
+	struct lex_token *tok = peek_token(ctx);
+	if (*str == '\0') {
+		return false;
+	}
+
+	struct redirection_ast_node *redirect
+		= (struct redirection_ast_node *)ast_node_create(
+			AST_REDIRECTION);
+
+	redirect->n_in = in_fd;
+	redirect->n_append = append;
+	redirect->n_out_is_fd = false;
+	redirect->n_out_is_expr = false;
+	redirect->n_out_path = str;
+
+	redirect->n_out_tok = claim_token(ctx);
+
+	*out = (struct ast_node *)redirect;
+	return true;
+}
+
+static bool parse_redirect_to_file_separate(
+	struct parse_ctx *ctx,
+	unsigned int in_fd,
+	bool append,
+	struct ast_node **out)
+{
+	if (ctx->p_status != BSHELL_SUCCESS) {
+		return false;
+	}
+
+	struct ast_node *out_path = NULL;
+	if (!parse_cmdcall_arg(ctx, &out_path)) {
+		ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+		return false;
+	}
+
+	struct redirection_ast_node *redirect
+		= (struct redirection_ast_node *)ast_node_create(
+			AST_REDIRECTION);
+
+	redirect->n_in = in_fd;
+	redirect->n_append = append;
+	redirect->n_out_is_fd = false;
+	redirect->n_out_is_expr = true;
+	redirect->n_out_path_expr = out_path;
+
+	*out = (struct ast_node *)redirect;
+	return true;
+}
+
+bool parse_redirect(struct parse_ctx *ctx, struct ast_node **out)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok || tok->tok_type != TOK_WORD) {
+		return false;
+	}
+
+	unsigned int in_fd = 1;
+	const char *str = tok->tok_str;
+	bool append = false;
+
+	if (fx_wchar_is_number(*str)) {
+		in_fd = 0;
+		while (fx_wchar_is_number(*str)) {
+			in_fd *= 10;
+			in_fd += *str - '0';
+			str++;
+		}
+	}
+
+	if (*str != '>') {
+		return false;
+	}
+
+	str++;
+	if (*str == '>') {
+		append = true;
+		str++;
+	}
+
+	if (*str != '\0') {
+		return parse_redirect_to_file_squashed(
+			ctx,
+			in_fd,
+			append,
+			str,
+			out);
+	}
+
+	discard_token(ctx);
+
+	if (parse_redirect_to_fd(ctx, in_fd, append, out)) {
+		return true;
+	}
+
+	if (parse_redirect_to_file_separate(ctx, in_fd, append, out)) {
+		return true;
+	}
+
+	return false;
+}
+
+static bool peek_cmdcall_item(struct parse_ctx *ctx, bool unrestricted)
+{
+	/* each token type falls into one of three categories:
+	 * - cmdcall item: the token can be used as part of a command call. the
+	 *   token indicates the start of a command call.
+	 * - NOT a cmdcall item: the token cannot be used as part of a command
+	 *   call, usually because it as a cmdcall operator like | or &.
+	 *   encountering one of these tokens ends the cmdcall currently being
+	 *   parsed.
+	 * - RESTRICTED cmdcall item: the token can be used as part of a
+	 *   command, but will not be considered the start of a cmdcall. to run
+	 *   a command with this token as its name, the call operator must be
+	 *   used.
+	 */
+	switch (peek_token_type(ctx)) {
+	case TOK_KEYWORD:
+	case TOK_INT:
+	case TOK_DOUBLE:
+	case TOK_VAR:
+	case TOK_VAR_SPLAT:
+	case TOK_STRING:
+	case TOK_WORD_START:
+		return unrestricted;
+	case TOK_SYMBOL:
+		switch (peek_unknown_symbol(ctx)) {
+		case SYM_PLUS:
+		case SYM_HYPHEN:
+			return unrestricted;
+		case SYM_PIPE:
+		case SYM_AMPERSAND:
+		case SYM_SEMICOLON:
+		case SYM_RIGHT_PAREN:
+		case SYM_RIGHT_BRACE:
+		case SYM_RIGHT_BRACKET:
+			return false;
+		default:
+			return true;
+		}
+	case TOK_NONE:
+	case TOK_LINEFEED:
+		return false;
+	default:
+		return true;
+	}
+}
+
+bool parse_cmdcall(struct parse_ctx *ctx, struct ast_node **out)
+{
+	struct cmdcall_ast_node *node
+		= (struct cmdcall_ast_node *)ast_node_create(AST_CMDCALL);
+	if (!node) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		return false;
+	}
+
+	struct ast_node *child = NULL;
+	bool unrestricted = false;
+	bool ok = true;
+	bool stop = false;
+
+	if (parse_symbol(ctx, SYM_AMPERSAND)) {
+		unrestricted = true;
+	}
+
+	if (!peek_cmdcall_item(ctx, unrestricted)) {
+		return false;
+	}
+
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (!parse_cmdcall_arg(ctx, &child)) {
+		return false;
+	}
+
+	fx_queue_push_back(&node->n_args, &child->n_entry);
+
+	while (ok && !stop) {
+		if (!peek_cmdcall_item(ctx, true)) {
+			break;
+		}
+
+		struct lex_token *tok = peek_token(ctx);
+		if (!tok) {
+			break;
+		}
+
+		if (parse_redirect(ctx, &child)) {
+			fx_queue_push_back(&node->n_redirect, &child->n_entry);
+		} else if (parse_cmdcall_arg(ctx, &child)) {
+			fx_queue_push_back(&node->n_args, &child->n_entry);
+		} else {
+			ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+			ok = false;
+			break;
+		}
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)node);
+		node = NULL;
+	}
+
+	*out = (struct ast_node *)node;
+	return ok;
+}
+
+bool peek_command(struct parse_ctx *ctx)
+{
+	if (peek_symbol(ctx, SYM_AMPERSAND)) {
+		return true;
+	}
+
+	return peek_cmdcall_item(ctx, false);
+}
+
+bool parse_command(struct parse_ctx *ctx, struct ast_node **out)
+{
+	struct ast_node *cmdcall = NULL;
+	if (!parse_cmdcall(ctx, &cmdcall)) {
+		return false;
+	}
+
+	struct pipeline_ast_node *pipeline = NULL;
+
+	while (1) {
+		if (peek_symbol(ctx, SYM_SEMICOLON) || peek_linefeed(ctx)) {
+			break;
+		}
+
+		if (!parse_symbol(ctx, SYM_PIPE)) {
+			break;
+		}
+
+		if (!pipeline) {
+			pipeline = (struct pipeline_ast_node *)ast_node_create(
+				AST_PIPELINE);
+			if (!pipeline) {
+				ctx->p_status = BSHELL_ERR_NO_MEMORY;
+				ast_node_destroy(cmdcall);
+				return false;
+			}
+
+			fx_queue_push_back(
+				&pipeline->n_stages,
+				&cmdcall->n_entry);
+		}
+
+		if (!parse_cmdcall(ctx, &cmdcall)) {
+			ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+			return false;
+		}
+
+		fx_queue_push_back(&pipeline->n_stages, &cmdcall->n_entry);
+	}
+
+	if (pipeline) {
+		*out = (struct ast_node *)pipeline;
+	} else {
+		*out = cmdcall;
+	}
+
+	return true;
+}
+
+bool parse_pipeline(
+	struct parse_ctx *ctx,
+	struct ast_node *first_item,
+	struct ast_node **out)
+{
+	struct pipeline_ast_node *pipeline
+		= (struct pipeline_ast_node *)ast_node_create(AST_PIPELINE);
+
+	fx_queue_push_back(&pipeline->n_stages, &first_item->n_entry);
+
+	while (1) {
+		if (!parse_symbol(ctx, SYM_PIPE)) {
+			break;
+		}
+
+		struct ast_node *cmdcall = NULL;
+		if (!parse_cmdcall(ctx, &cmdcall)) {
+			ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+			return false;
+		}
+
+		fx_queue_push_back(&pipeline->n_stages, &cmdcall->n_entry);
+	}
+
+	*out = (struct ast_node *)pipeline;
+	return true;
+}

bshell/parse/syntax/expr.c

@@ -0,0 +1,15 @@
+#include "../syntax.h"
+
+bool parse_expr(struct parse_ctx *ctx, struct ast_node **out)
+{
+	bool ok = false;
+	if (!ok && peek_arith_expr(ctx)) {
+		ok = parse_arith_expr(ctx, PRECEDENCE_MINIMUM, out);
+	}
+
+	if (!ok && peek_command(ctx)) {
+		ok = parse_command(ctx, out);
+	}
+
+	return ok;
+}

bshell/parse/syntax/func.c

@@ -0,0 +1,85 @@
+#include "../syntax.h"
+
+bool parse_func(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_keyword(ctx, KW_FUNC)) {
+		return false;
+	}
+
+	struct lex_token *name = NULL;
+	if (!parse_word(ctx, &name)) {
+		report_error(ctx, "expected function identifier");
+		return false;
+	}
+
+	struct func_ast_node *func
+		= (struct func_ast_node *)ast_node_create(AST_FUNC);
+	if (!func) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		lex_token_destroy(name);
+		return false;
+	}
+
+	func->n_name = name;
+
+	if (!parse_symbol(ctx, SYM_LEFT_PAREN)) {
+		report_error(ctx, "expected `(` after function identifier");
+		ast_node_destroy((struct ast_node *)func);
+		return false;
+	}
+
+	size_t nr_args = 0;
+	bool ok = true;
+	while (1) {
+		if (parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+			break;
+		}
+
+		if (nr_args > 0 && !parse_symbol(ctx, SYM_COMMA)) {
+			report_error(
+				ctx,
+				"expected `,` or `)` after parameter name");
+			ok = false;
+			break;
+		}
+
+		struct lex_token *param_token = NULL;
+		struct var_ast_node *param_node = NULL;
+		if (!parse_var(ctx, &param_token)) {
+			report_error(ctx, "expected parameter variable");
+			ok = false;
+			break;
+		}
+
+		param_node = (struct var_ast_node *)ast_node_create(AST_VAR);
+		if (!param_node) {
+			ok = false;
+			ctx->p_status = BSHELL_ERR_NO_MEMORY;
+			lex_token_destroy(param_token);
+			break;
+		}
+
+		param_node->n_ident = param_token;
+		fx_queue_push_back(
+			&func->n_params,
+			&param_node->n_base.n_entry);
+	}
+
+	if (!ok) {
+		if (ctx->p_status == BSHELL_SUCCESS) {
+			ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+		}
+
+		ast_node_destroy((struct ast_node *)func);
+		return false;
+	}
+
+	if (!parse_block(ctx, &func->n_body)) {
+		report_error(ctx, "failed to parse function body");
+		ast_node_destroy((struct ast_node *)func);
+		return false;
+	}
+
+	*out = (struct ast_node *)func;
+	return true;
+}

bshell/parse/syntax/generic.c

@@ -0,0 +1,173 @@
+#include "../lex.h"
+#include "../parse.h"
+#include "../syntax.h"
+#include "../token.h"
+
+struct lex_token *claim_token(struct parse_ctx *ctx)
+{
+	return lex_ctx_claim(ctx->p_src);
+}
+
+void discard_token(struct parse_ctx *ctx)
+{
+	return lex_ctx_discard(ctx->p_src);
+}
+
+struct lex_token *peek_token(struct parse_ctx *ctx)
+{
+	return lex_ctx_peek(ctx->p_src);
+}
+
+enum token_type peek_token_type(struct parse_ctx *ctx)
+{
+	struct lex_token *tok = peek_token(ctx);
+	return tok ? tok->tok_type : TOK_NONE;
+}
+
+enum token_symbol peek_unknown_symbol(struct parse_ctx *ctx)
+{
+	struct lex_token *tok = peek_token(ctx);
+	return (tok && tok->tok_type == TOK_SYMBOL) ? tok->tok_symbol
+	                                            : SYM_NONE;
+}
+
+enum token_keyword peek_unknown_keyword(struct parse_ctx *ctx)
+{
+	struct lex_token *tok = peek_token(ctx);
+	return (tok && tok->tok_type == TOK_KEYWORD) ? tok->tok_keyword
+	                                             : KW_NONE;
+}
+
+bool peek_word(struct parse_ctx *ctx, struct lex_token **out)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (tok && tok->tok_type == TOK_WORD) {
+		*out = tok;
+		return true;
+	}
+
+	return false;
+}
+
+bool peek_linefeed(struct parse_ctx *ctx)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (tok && tok->tok_type == TOK_LINEFEED) {
+		return true;
+	}
+
+	return false;
+}
+
+bool peek_symbol(struct parse_ctx *ctx, enum token_symbol sym)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (tok->tok_type != TOK_SYMBOL) {
+		return false;
+	}
+
+	if (tok->tok_symbol != sym) {
+		return false;
+	}
+
+	return true;
+}
+
+bool parse_linefeed(struct parse_ctx *ctx)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (tok && tok->tok_type == TOK_LINEFEED) {
+		discard_token(ctx);
+		return true;
+	}
+
+	return false;
+}
+
+bool parse_symbol(struct parse_ctx *ctx, enum token_symbol sym)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (tok->tok_type != TOK_SYMBOL) {
+		return false;
+	}
+
+	if (tok->tok_symbol != sym) {
+		return false;
+	}
+
+	discard_token(ctx);
+	return true;
+}
+
+bool parse_keyword(struct parse_ctx *ctx, enum token_keyword kw)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (tok->tok_type != TOK_KEYWORD) {
+		return false;
+	}
+
+	if (tok->tok_keyword != kw) {
+		return false;
+	}
+
+	discard_token(ctx);
+	return true;
+}
+
+bool parse_word(struct parse_ctx *ctx, struct lex_token **out)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (tok->tok_type != TOK_WORD) {
+		return false;
+	}
+
+	*out = claim_token(ctx);
+	return true;
+}
+
+bool parse_var(struct parse_ctx *ctx, struct lex_token **out)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (tok->tok_type != TOK_VAR) {
+		return false;
+	}
+
+	*out = claim_token(ctx);
+	return true;
+}
+
+bool parse_int(struct parse_ctx *ctx, long long *out)
+{
+	struct lex_token *tok = peek_token(ctx);
+	if (!tok) {
+		return false;
+	}
+
+	if (tok->tok_type != TOK_INT) {
+		return false;
+	}
+
+	*out = tok->tok_int;
+	discard_token(ctx);
+	return true;
+}

bshell/parse/syntax/if-else.c

@@ -0,0 +1,110 @@
+#include "../syntax.h"
+
+static bool add_branch(
+	struct if_ast_node *group,
+	struct ast_node *cond,
+	struct ast_node *body)
+{
+	struct if_branch_ast_node *branch
+		= (struct if_branch_ast_node *)ast_node_create(AST_IF_BRANCH);
+	if (!branch) {
+		return false;
+	}
+
+	branch->n_cond = cond;
+	branch->n_body = body;
+	fx_queue_push_back(&group->n_branches, &branch->n_base.n_entry);
+
+	return true;
+}
+
+bool parse_if(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!parse_keyword(ctx, KW_IF)) {
+		return false;
+	}
+
+	if (!parse_symbol(ctx, SYM_LEFT_PAREN)) {
+		report_error(ctx, "expected `(` after `if`");
+		return false;
+	}
+
+	struct ast_node *if_cond = NULL, *if_body = NULL;
+	if (!parse_expr(ctx, &if_cond)) {
+		report_error(ctx, "invalid if condition");
+		return false;
+	}
+
+	if (!parse_symbol(ctx, SYM_RIGHT_PAREN)) {
+		report_error(ctx, "expected `)` after if-condition");
+		ast_node_destroy(if_cond);
+		return false;
+	}
+
+	if (!parse_block(ctx, &if_body)) {
+		report_error(ctx, "invalid if body");
+		ast_node_destroy(if_cond);
+		return false;
+	}
+
+	struct if_ast_node *if_group
+		= (struct if_ast_node *)ast_node_create(AST_IF);
+	if (!if_group) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		ast_node_destroy(if_cond);
+		ast_node_destroy(if_body);
+		return false;
+	}
+
+	if (!add_branch(if_group, if_cond, if_body)) {
+		ctx->p_status = BSHELL_ERR_NO_MEMORY;
+		ast_node_destroy(if_cond);
+		ast_node_destroy(if_body);
+		ast_node_destroy((struct ast_node *)if_group);
+		return false;
+	}
+
+	bool done = false;
+	while (!done) {
+		struct ast_node *cond = NULL, *body = NULL;
+		if (parse_keyword(ctx, KW_ELSE)) {
+			done = true;
+		} else if (parse_keyword(ctx, KW_ELSEIF)) {
+			if (!parse_expr(ctx, &cond)) {
+				report_error(
+					ctx,
+					"invalid conditional expression");
+				ast_node_destroy((struct ast_node *)if_group);
+				return false;
+			}
+		} else {
+			done = true;
+			break;
+		}
+
+		if (!parse_block(ctx, &body)) {
+			report_error(ctx, "invalid conditional body");
+			if (cond) {
+				ast_node_destroy(cond);
+			}
+
+			ast_node_destroy((struct ast_node *)if_group);
+			return false;
+		}
+
+		if (!add_branch(if_group, cond, body)) {
+			report_error(ctx, "failed to add branch to if-group");
+			if (cond) {
+				ast_node_destroy(cond);
+			}
+
+			ast_node_destroy(body);
+			ast_node_destroy((struct ast_node *)if_group);
+			return false;
+		}
+	}
+
+	*out = (struct ast_node *)if_group;
+
+	return true;
+}

bshell/parse/syntax/keyword.c

@@ -0,0 +1,21 @@
+#include "../syntax.h"
+
+bool peek_keyword_expr(struct parse_ctx *ctx)
+{
+	return peek_unknown_keyword(ctx) != KW_NONE;
+}
+
+bool parse_keyword_expr(struct parse_ctx *ctx, struct ast_node **out)
+{
+	switch (peek_unknown_keyword(ctx)) {
+	case KW_NONE:
+		return false;
+	case KW_IF:
+		return parse_if(ctx, out);
+	case KW_FUNC:
+		return parse_func(ctx, out);
+	default:
+		ctx->p_status = BSHELL_ERR_BAD_SYNTAX;
+		return false;
+	}
+}

bshell/parse/syntax/statement.c

@@ -0,0 +1,99 @@
+#include "../syntax.h"
+
+bool peek_statement(struct parse_ctx *ctx)
+{
+	if (peek_keyword_expr(ctx)) {
+		return true;
+	}
+
+	if (peek_arith_expr(ctx)) {
+		return true;
+	}
+
+	if (peek_command(ctx)) {
+		return true;
+	}
+
+	return false;
+}
+
+bool parse_statement(struct parse_ctx *ctx, struct ast_node **out)
+{
+	if (!peek_token(ctx)) {
+		/* error, or EOF */
+		return false;
+	}
+
+	bool unknown = true;
+	bool ok = false;
+	if (peek_keyword_expr(ctx)) {
+		unknown = false;
+		ok = parse_keyword_expr(ctx, out);
+	}
+
+	if (!ok && peek_arith_expr(ctx)) {
+		unknown = false;
+		ok = parse_arith_expr(ctx, PRECEDENCE_MINIMUM, out);
+	}
+
+	if (!ok && peek_command(ctx)) {
+		unknown = false;
+		ok = parse_command(ctx, out);
+	}
+
+	if (!ok && unknown) {
+		report_error(
+			ctx,
+			"encountered unknown token while parsing statement");
+		return false;
+	}
+
+	return ok;
+}
+
+static struct ast_node *convert_single_statement(
+	struct stmt_list_ast_node *list)
+{
+	fx_queue_entry *first_entry = fx_queue_first(&list->n_statements);
+	if (!first_entry || fx_queue_next(first_entry)) {
+		return (struct ast_node *)list;
+	}
+
+	fx_queue_delete(&list->n_statements, first_entry);
+	struct ast_node *first
+		= fx_unbox(struct ast_node, first_entry, n_entry);
+	ast_node_destroy((struct ast_node *)list);
+
+	return first;
+}
+
+bool parse_statement_list(struct parse_ctx *ctx, struct ast_node **out)
+{
+	struct stmt_list_ast_node *stmt_list
+		= (struct stmt_list_ast_node *)ast_node_create(AST_STMT_LIST);
+
+	bool ok = true;
+	while (ok) {
+		parse_linefeed(ctx);
+
+		struct ast_node *stmt = NULL;
+		if (!parse_statement(ctx, &stmt)) {
+			ok = false;
+			break;
+		}
+
+		fx_queue_push_back(&stmt_list->n_statements, &stmt->n_entry);
+
+		if (!parse_symbol(ctx, SYM_SEMICOLON)) {
+			break;
+		}
+	}
+
+	if (!ok) {
+		ast_node_destroy((struct ast_node *)stmt_list);
+		return false;
+	}
+
+	*out = convert_single_statement(stmt_list);
+	return true;
+}

bshell/parse/token.c

@@ -0,0 +1,213 @@
+#include "token.h"
+
+#include <fx/string.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct lex_token *lex_token_create(enum token_type type)
+{
+	struct lex_token *out = malloc(sizeof *out);
+	if (!out) {
+		return NULL;
+	}
+
+	memset(out, 0x0, sizeof *out);
+
+	out->tok_type = type;
+
+	return out;
+}
+
+struct lex_token *lex_token_create_with_string(
+	enum token_type type,
+	const char *s)
+{
+	struct lex_token *tok = lex_token_create(type);
+	if (!tok) {
+		return NULL;
+	}
+
+	tok->tok_str = fx_strdup(s);
+	if (!tok->tok_str) {
+		free(tok);
+		return NULL;
+	}
+
+	return tok;
+}
+
+void lex_token_destroy(struct lex_token *tok)
+{
+	switch (tok->tok_type) {
+	case TOK_WORD:
+	case TOK_FLAG:
+	case TOK_STRING:
+		if (tok->tok_str) {
+			free(tok->tok_str);
+		}
+
+		break;
+	default:
+		break;
+	}
+
+	free(tok);
+}
+
+struct lex_token *lex_token_change_type(
+	struct lex_token *tok,
+	enum token_type new_type)
+{
+	switch (tok->tok_type) {
+	case TOK_WORD:
+	case TOK_FLAG:
+	case TOK_STRING:
+		if (tok->tok_str) {
+			free(tok->tok_str);
+			tok->tok_str = NULL;
+		}
+		break;
+	default:
+		break;
+	}
+
+	tok->tok_type = new_type;
+	return tok;
+}
+
+void lex_token_change_string(struct lex_token *tok, const char *s)
+{
+	if (!lex_token_has_string_value(tok)) {
+		return;
+	}
+
+	if (tok->tok_str) {
+		free(tok->tok_str);
+	}
+
+	tok->tok_str = fx_strdup(s);
+}
+
+#define ENUM_STR(x)                                                            \
+	case x:                                                                \
+		return #x
+
+const char *token_type_to_string(enum token_type type)
+{
+	switch (type) {
+		ENUM_STR(TOK_NONE);
+		ENUM_STR(TOK_KEYWORD);
+		ENUM_STR(TOK_SYMBOL);
+		ENUM_STR(TOK_INT);
+		ENUM_STR(TOK_DOUBLE);
+		ENUM_STR(TOK_WORD);
+		ENUM_STR(TOK_WORD_START);
+		ENUM_STR(TOK_WORD_END);
+		ENUM_STR(TOK_OPERATOR);
+		ENUM_STR(TOK_VAR);
+		ENUM_STR(TOK_VAR_SPLAT);
+		ENUM_STR(TOK_FLAG);
+		ENUM_STR(TOK_STRING);
+		ENUM_STR(TOK_STR_START);
+		ENUM_STR(TOK_STR_END);
+		ENUM_STR(TOK_LINEFEED);
+	default:
+		return "<unknown>";
+	}
+}
+
+const char *token_keyword_to_string(enum token_keyword keyword)
+{
+	switch (keyword) {
+		ENUM_STR(KW_NONE);
+		ENUM_STR(KW_FUNC);
+		ENUM_STR(KW_IF);
+		ENUM_STR(KW_ELSEIF);
+		ENUM_STR(KW_ELSE);
+	default:
+		return "<unknown>";
+	}
+}
+
+const char *token_symbol_to_string(enum token_symbol sym)
+{
+	switch (sym) {
+		ENUM_STR(SYM_NONE);
+		ENUM_STR(SYM_PLUS);
+		ENUM_STR(SYM_HYPHEN);
+		ENUM_STR(SYM_FORWARD_SLASH);
+		ENUM_STR(SYM_ASTERISK);
+		ENUM_STR(SYM_AMPERSAND);
+		ENUM_STR(SYM_PERCENT);
+		ENUM_STR(SYM_SQUOTE);
+		ENUM_STR(SYM_DQUOTE);
+		ENUM_STR(SYM_HASH);
+		ENUM_STR(SYM_COLON_COLON);
+		ENUM_STR(SYM_SEMICOLON);
+		ENUM_STR(SYM_COMMA);
+		ENUM_STR(SYM_DOLLAR);
+		ENUM_STR(SYM_DOLLAR_LEFT_PAREN);
+		ENUM_STR(SYM_DOLLAR_LEFT_BRACE);
+		ENUM_STR(SYM_DOT);
+		ENUM_STR(SYM_DOT_DOT);
+		ENUM_STR(SYM_PIPE);
+		ENUM_STR(SYM_AT);
+		ENUM_STR(SYM_AT_LEFT_PAREN);
+		ENUM_STR(SYM_AT_LEFT_BRACE);
+		ENUM_STR(SYM_LEFT_BRACE);
+		ENUM_STR(SYM_RIGHT_BRACE);
+		ENUM_STR(SYM_LEFT_BRACKET);
+		ENUM_STR(SYM_RIGHT_BRACKET);
+		ENUM_STR(SYM_LEFT_PAREN);
+		ENUM_STR(SYM_RIGHT_PAREN);
+		ENUM_STR(SYM_EQUAL);
+		ENUM_STR(SYM_PLUS_EQUAL);
+		ENUM_STR(SYM_HYPHEN_EQUAL);
+		ENUM_STR(SYM_ASTERISK_EQUAL);
+		ENUM_STR(SYM_FORWARD_SLASH_EQUAL);
+		ENUM_STR(SYM_PERCENT_EQUAL);
+		ENUM_STR(SYM_QUESTION_DOT);
+		ENUM_STR(SYM_QUESTION_LEFT_BRACKET);
+	default:
+		return "<unknown>";
+	}
+}
+
+const char *token_operator_to_string(enum token_operator op)
+{
+	switch (op) {
+		ENUM_STR(TKOP_BAND);
+		ENUM_STR(TKOP_BOR);
+		ENUM_STR(TKOP_BXOR);
+		ENUM_STR(TKOP_BNOT);
+		ENUM_STR(TKOP_SHL);
+		ENUM_STR(TKOP_SHR);
+		ENUM_STR(TKOP_EQ);
+		ENUM_STR(TKOP_NE);
+		ENUM_STR(TKOP_GT);
+		ENUM_STR(TKOP_LT);
+		ENUM_STR(TKOP_GE);
+		ENUM_STR(TKOP_LE);
+		ENUM_STR(TKOP_MATCH);
+		ENUM_STR(TKOP_NOTMATCH);
+		ENUM_STR(TKOP_REPLACE);
+		ENUM_STR(TKOP_LIKE);
+		ENUM_STR(TKOP_NOTLIKE);
+		ENUM_STR(TKOP_IN);
+		ENUM_STR(TKOP_F);
+		ENUM_STR(TKOP_NOTIN);
+		ENUM_STR(TKOP_CONTAINS);
+		ENUM_STR(TKOP_NOTCONTAINS);
+		ENUM_STR(TKOP_AND);
+		ENUM_STR(TKOP_OR);
+		ENUM_STR(TKOP_XOR);
+		ENUM_STR(TKOP_NOT);
+		ENUM_STR(TKOP_SPLIT);
+		ENUM_STR(TKOP_JOIN);
+		ENUM_STR(TKOP_IS);
+		ENUM_STR(TKOP_ISNOT);
+		ENUM_STR(TKOP_AS);
+	default:
+		return "<unknown>";
+	}
+}

bshell/parse/token.h

@@ -0,0 +1,184 @@
+#ifndef IVY_LANG_LEX_H_
+#define IVY_LANG_LEX_H_
+
+#include <fx/queue.h>
+#include <stdbool.h>
+
+struct char_cell {
+	unsigned long c_row, c_col;
+};
+
+enum token_type {
+	TOK_NONE = 0,
+	__TOK_INDEX_BASE = 100,
+	TOK_KEYWORD,
+	TOK_SYMBOL,
+	TOK_INT,
+	TOK_DOUBLE,
+	TOK_WORD,
+	TOK_WORD_START,
+	TOK_WORD_END,
+	TOK_FLAG,
+	TOK_OPERATOR,
+	TOK_VAR,
+	TOK_VAR_SPLAT,
+	TOK_STRING,
+	TOK_STR_START,
+	TOK_STR_END,
+	TOK_LINEFEED,
+	__TOK_INDEX_LIMIT,
+};
+
+enum token_keyword {
+	KW_NONE = 0,
+	__KW_INDEX_BASE = 200,
+	KW_FUNC,
+	KW_IF,
+	KW_ELSEIF,
+	KW_ELSE,
+	__KW_INDEX_LIMIT,
+};
+
+enum token_operator {
+	TKOP_NONE = 0,
+	__TKOP_INDEX_BASE = 300,
+	TKOP_F,
+	TKOP_BAND,
+	TKOP_BOR,
+	TKOP_BXOR,
+	TKOP_BNOT,
+	TKOP_SHL,
+	TKOP_SHR,
+	TKOP_EQ,
+	TKOP_NE,
+	TKOP_GT,
+	TKOP_LT,
+	TKOP_GE,
+	TKOP_LE,
+	TKOP_MATCH,
+	TKOP_NOTMATCH,
+	TKOP_REPLACE,
+	TKOP_LIKE,
+	TKOP_NOTLIKE,
+	TKOP_IN,
+	TKOP_NOTIN,
+	TKOP_CONTAINS,
+	TKOP_NOTCONTAINS,
+	TKOP_AND,
+	TKOP_OR,
+	TKOP_XOR,
+	TKOP_NOT,
+	TKOP_SPLIT,
+	TKOP_JOIN,
+	TKOP_IS,
+	TKOP_ISNOT,
+	TKOP_AS,
+	__TKOP_INDEX_LIMIT,
+};
+
+enum token_symbol {
+	SYM_NONE = 0,
+	__SYM_INDEX_BASE = 400,
+	SYM_BANG,
+	SYM_PLUS,
+	SYM_HYPHEN,
+	SYM_FORWARD_SLASH,
+	SYM_ASTERISK,
+	SYM_AMPERSAND,
+	SYM_PERCENT,
+	SYM_SQUOTE,
+	SYM_DQUOTE,
+	SYM_HASH,
+	SYM_COLON_COLON,
+	SYM_SEMICOLON,
+	SYM_COMMA,
+	SYM_DOLLAR,
+	SYM_DOLLAR_LEFT_PAREN,
+	SYM_DOLLAR_LEFT_BRACE,
+	SYM_DOT,
+	SYM_DOT_DOT,
+	SYM_PIPE,
+	SYM_AT,
+	SYM_AT_LEFT_PAREN,
+	SYM_AT_LEFT_BRACE,
+	SYM_LEFT_BRACE,
+	SYM_RIGHT_BRACE,
+	SYM_LEFT_BRACKET,
+	SYM_RIGHT_BRACKET,
+	SYM_LEFT_PAREN,
+	SYM_RIGHT_PAREN,
+	SYM_EQUAL,
+	SYM_PLUS_EQUAL,
+	SYM_HYPHEN_EQUAL,
+	SYM_ASTERISK_EQUAL,
+	SYM_FORWARD_SLASH_EQUAL,
+	SYM_PERCENT_EQUAL,
+	SYM_QUESTION_DOT,
+	SYM_QUESTION_LEFT_BRACKET,
+	__SYM_INDEX_LIMIT,
+};
+
+struct lex_token {
+	enum token_type tok_type;
+
+	struct char_cell tok_start, tok_end;
+
+	fx_queue_entry tok_entry;
+
+	union {
+		enum token_keyword tok_keyword;
+		enum token_symbol tok_symbol;
+		enum token_operator tok_operator;
+		long long tok_int;
+		double tok_double;
+		char *tok_str;
+	};
+};
+
+extern struct lex_token *lex_token_create(enum token_type type);
+extern struct lex_token *lex_token_create_with_string(
+	enum token_type type,
+	const char *s);
+extern void lex_token_destroy(struct lex_token *tok);
+
+extern struct lex_token *lex_token_change_type(
+	struct lex_token *tok,
+	enum token_type new_type);
+extern void lex_token_change_string(struct lex_token *tok, const char *s);
+
+static inline bool lex_token_is_symbol(
+	struct lex_token *tok,
+	enum token_symbol sym)
+{
+	return (tok->tok_type == TOK_SYMBOL && tok->tok_symbol == sym);
+}
+static inline bool lex_token_is_keyword(
+	struct lex_token *tok,
+	enum token_keyword kw)
+{
+	return (tok->tok_type == TOK_KEYWORD && tok->tok_keyword == kw);
+}
+static inline bool lex_token_type_has_string_value(enum token_type type)
+{
+	switch (type) {
+	case TOK_WORD:
+	case TOK_STRING:
+	case TOK_FLAG:
+	case TOK_VAR:
+	case TOK_VAR_SPLAT:
+		return true;
+	default:
+		return false;
+	}
+}
+static inline bool lex_token_has_string_value(const struct lex_token *tok)
+{
+	return lex_token_type_has_string_value(tok->tok_type);
+}
+
+extern const char *token_type_to_string(enum token_type type);
+extern const char *token_keyword_to_string(enum token_keyword keyword);
+extern const char *token_symbol_to_string(enum token_symbol sym);
+extern const char *token_operator_to_string(enum token_operator op);
+
+#endif

doc/sample/redirection.bshell

@@ -0,0 +1 @@
+echo hello 2> error.txt | ls -la | echo done; exit -1

doc/sample/simple.bshell

@@ -1,8 +1,14 @@
 func test-function($name) {
-	echo "Hello, $name!"
+	echo "Hello, $name! $(2 + 4 + 2) wow"
 }
 
 # Example of instantiating an FX runtime object.
 $obj = new-object -type-name fx.string -arguments "John Doe"
 
+$hash = @{
+    1       = 'one'
+    2       = 'two'
+    'three' = 3
+}
+
 test-function -name $obj

doc/sample/syntax.bshell

@@ -0,0 +1,173 @@
+# The lexer has three modes: ARITHMETIC, COMMAND, and STRING
+# ARITHMETIC mode is operand-based, all symbols, keywords, and constant parsing
+# is enabled.
+# COMMAND mode is word-based, only a subset of symbols are enabled, no keyword
+# or constant parsing is performed, and more liberal word formations and
+# substitutions are allowed
+# STRING mode is used to read string literals (i.e. those strings that DON'T
+# support variable substitutions). All chars read are appended to the resulting
+# string, with no further parsing performed.
+
+# Initially, the lexer mode is unspecified, until:
+#  a) The lexer reads a character, from which the correct mode is deduced.
+#  b) The parser manually switches the lexer's mode
+# Lexer state supports nesting.
+
+# ARITHMETIC
+# both of these are equivalant
+$a = 2
+# VAR(a)
+# SYMBOL(=)
+# INT(2)
+
+$b=4
+# VAR(b)
+# SYMBOL(=)
+# INT(4)
+
+# ARITHMETIC
+# this is a syntax error (there should be an operator between the two vars)
+$a$b
+# VAR(a)
+# VAR(b)
+
+# When the parser encounters SYMBOL(%) it should switch the lexer to COMMAND
+# mode, which will allow the following word construction to be used.
+# this executes the command whose name is equal to concatenating the values
+# of $a and $b (in this case, '24')
+% $a$b
+# SYMBOL(%)
+# WORD_START
+# VAR(a)
+# VAR(b)
+# WORD_END
+
+# executes the command with the name 'a+2b'. because the first char encountered
+# by the lexer is alphabetic, it reads a regular word in COMMAND mode.
+a+2b
+# WORD(a+2b)
+
+# executes the command with the name '-no$a' ($a is not substituted).
+# the first char encountered is a symbol, which is read as a word in COMMAND
+# mode
+-no$a
+# WORD(-no)
+
+# returns the result of applying the NOT operator to the value of $a.
+# the first char encountered is a symbol, which is read as a word in COMMAND
+# mode. as characters are read, they are compared against registered operators.
+# if a match is found, the operator is emitted, and the parser will switch
+# the lexer to ARITHMETIC mode
+-not$a
+# OP(not)
+# VAR(a)
+
+# executes the command with the name '-not$a' ($a is NOT substituted)
+# because of the preceding hyphen, variable substitution is not performed.
+% -not$a
+# SYMBOL(%)
+# WORD(-not$a)
+
+# executes the command with the name '-not2' ($a IS substituted)
+# variable substitution IS performed in dquote strings regardless of the hyphen.
+% "-not$a"
+# SYMBOL(%)
+# STR_START
+# STRING(-not)
+# VAR(a)
+# STR_END
+
+# interpreted as a command with args ['a', '+b', '/c']
+# the first char encountered is alpbabetic, so the expression is parsed in
+# COMMAND mode
+a +b /c
+# WORD(a)
+# WORD(+b)
+# WORD(/c)
+
+# interpreted as an arithmetic expression (but not a well-formed one)
++b /c
+# SYM(+)
+# WORD(b)
+# SYM(/)
+# WORD(c)
+
+# interpreted as a command with name '%+'
+%+
+# WORD(%+)
+
+# interpreted as a command with args ['%', '+']
+% +
+# WORD(%)
+# WORD(+)
+
+# interpreted as a command with name '%'
+%;
+# WORD(%)
+# SYMBOL(;)
+
+# interpreted as a command with name '+'
+&+
+# SYMBOL(&)
+# WORD(+)
+
+# interpreted as a string, which triggers the parser to enter ARITHMETIC mode
+'hello world'
+# STRING(hello world)
+
+# interpreted as a command with args ['echo', 'hello world']
+echo 'hello world'
+# WORD(echo)
+# STRING(hello world)
+
+# interpreted as an interpolated string
+"Hello $(if ($x -lt 5) { echo 'yes' } else {echo 'no'})"
+
+
+###############################################################################
+# The lexer operates as a state machine, moving between different states as
+# different characters are encountered
+# The states are stored in a stack, to allow recursive parsing.
+# The lexer has the following states:
+# STATEMENT: A generic statement, could be a command, keyword, arithmetic
+#       expression, etc. The next char or symbol encountered will cause the
+#       lexer to switch to the appropriate state type:
+#           letters, word-symbols -> COMMAND
+#           squote -> ARITHMETIC
+#           dquote -> ARITHMETIC, FSTRING
+#           Digits, vars, var-splats, keywords, all other symbols -> ARITHMETIC
+# EXPRESSION: Similar to STATEMENT, but only allows a single command or
+#       arithmetic expression. CANNOT use keywords or statement terminators.
+#           Letters, word-symbols -> COMMAND
+#           squote -> ARITHMETIC
+#           dquote -> ARITHMETIC, FSTRING
+#           Digits, vars, var-splats, keywords, all other symbols -> ARITHMETIC
+# COMMAND: Only words, (f)strings, vars, var-splats, and a subset of symbols are
+#       parsed.
+# ARITHMETIC: Words, strings, vars, var-splats, all symbols, keywords are parsed.
+# STRING: Only a subset of symbols are parsed, all other characters are appended
+#       to the resulting string.
+#
+# Once a state has changed from EXPRESSION to one of the other three state
+# types, certain characters will result in the current state either changing
+# type or being popped from the stack:
+#   STATEMENT: semicolon -> STATEMENT
+#            left-paren, left-brace -> POP
+#   EXPRESSION: semicolon -> POP
+#            left-paren, left-brace -> POP
+#   COMMAND: semicolon -> STATEMENT
+#            left-paren, left-brace -> POP
+#   ARITHMETIC: semicolon -> STATEMENT
+#            left-paren, left-brace -> POP
+#
+# Certain symbols require recursive parsing:
+# - dquote strings allow string interpolation, so expressions withing the string
+#   may be parsed in a different state. Once the expression is complete, the
+#   lexer returns to the previous state.
+# - in most cases, $(...) can be used to delimit sub-expressions (including in
+#   strings. When '$(' is encountered, a new state entry of type EXPRESSION is
+#   pushed onto the stack. When the corresponding ')' is encountered, that state
+#   entry is popped from the stack.
+# - similarly to $(...), (...) can be used to group expressions, just like in
+#   mathematical expressions.
+