meta: add vim plugin for syntax highlighting

.gitignore

@@ -143,3 +143,4 @@ tags
 # End of https://www.toptal.com/developers/gitignore/api/c,vim,linux,macos,cmake
 
 build/
+.cache/

CMakeLists.txt

@@ -1,7 +1,13 @@
 cmake_minimum_required(VERSION 3.31)
 project(bshell C)
 
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
+
 find_package(Python COMPONENTS Interpreter REQUIRED)
+find_package(FX REQUIRED COMPONENTS
+	fx.runtime
+	fx.collections
+	fx.term)
 
 execute_process(
 	COMMAND ${Python_EXECUTABLE}
@@ -16,5 +22,6 @@ message(STATUS "B Shell version: ${bshell_version}")
 
 add_executable(bshell ${bshell_sources})
 
+target_link_libraries(bshell FX::Runtime FX::Collections FX::Term)
 target_compile_definitions(bshell PUBLIC
 	BSHELL_VERSION="${bshell_version}")

bshell.vim/ftdetect/bshell.vim

@@ -0,0 +1 @@
+autocmd BufNewFile,BufRead *.bshell setfiletype bshell

bshell.vim/ftplugin/bshell.vim

@@ -0,0 +1,4 @@
+setlocal tabstop=8
+setlocal softtabstop=4
+setlocal shiftwidth=4
+setlocal expandtab

bshell.vim/syntax/bshell.vim

@@ -0,0 +1,126 @@
+if exists('b:current_syntax')
+  finish
+endif
+
+let s:save_cpo = &cpoptions
+set cpoptions&vim
+setlocal iskeyword+=-
+
+syn match	bshellFunctionRef	/\<[A-Za-z][A-Za-z0-9]*\(-[A-Za-z0-9][A-Za-z0-9]*\)\+\>/
+syn match	bshellVariable	/\$[A-Za-z][A-Za-z0-9_]*/
+syn match	bshellArgFlag	/\<-[A-Za-z][A-Za-z0-9]*\(-[A-Za-z0-9][A-Za-z0-9]*\)*\>/
+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	bshellLiteralString	matchgroup=bshellString start=+\'+ end=+\'+ extend contains=bshellSpecialChar,bshellSpecialError,bshellUnicodeNumber,@Spell
+
+hi def link	bshellKeyword	Statement
+hi def link	bshellArgFlag	Tag
+hi def link	bshellVariable	Identifier
+hi def link	bshellLineComment	Comment
+hi def link	bshellFunctionRef	Function
+hi def link	bshellString	String
+hi def link	bshellInterpolatedString	String
+hi def link	bshellLiteralString	String
+
+
+" The default highlighting.
+" hi def link	bshellUnspecifiedStatement	Statement
+" hi def link	bshellUnsupportedStatement	Statement
+"
+" hi def link	bshellGlobalNamespaceAlias	Include
+"
+" hi def link	bshellType	Type
+"
+" hi def link	bshellStorage	Keyword
+" hi def link	bshellIsAs 	Keyword
+" hi def link	bshellAccessor	Keyword
+" hi def link	bshellBuiltinVar	@variable.builtin
+" hi def link	bshellSelfVar	@variable.builtin
+"
+" hi def link	bshellStatement	Statement
+" hi def link	bshellRepeat	Repeat
+" hi def link	bshellConditional	Conditional
+" hi def link	bshellSelectorLabel	Tag
+" hi def link	bshellUnnamedLabel	Comment
+" hi def link	bshellUnnamedVariable	Comment
+" hi def link	bshellLambdaParameter	@variable.builtin
+" hi def link	bshellException	Exception
+"
+" hi def link	bshellParens	Delimiter
+" hi def link	bshellBraces	Structure
+" hi def link	bshellControlSymbols	Keyword
+"
+" hi def link	bshellModifier	StorageClass
+" hi def link	bshellAccessModifier	bshellModifier
+" hi def link	bshellAsyncModifier	bshellModifier
+" hi def link	bshellCheckedModifier	bshellModifier
+" hi def link	bshellManagedModifier	bshellModifier
+" hi def link	bshellUsingModifier	bshellModifier
+"
+" hi def link	bshellTodo	Todo
+" hi def link	bshellComment	Comment
+" hi def link	bshellLineComment	bshellComment
+" hi def link	bshellBlockComment	bshellComment
+" hi def link	bshellLineContinuation	bshellComment
+"
+" hi def link	bshellKeywordOperator	Keyword
+" hi def link	bshellAsyncOperator	bshellKeywordOperator
+" hi def link	bshellTypeOf	bshellKeywordOperator
+" hi def link	bshellTypeOfOperand	Typedef
+" hi def link	bshellTypeOfError	Error
+" hi def link	bshellOpSymbols	Operator
+" hi def link	bshellPackageAccessOperator	Operator
+" hi def link	bshellOtherSymbols	Structure
+" hi def link	bshellLogicSymbols	Operator
+" hi def link	bshellWordOperator	Operator
+"
+" hi def link	bshellSpecialError	Error
+" hi def link	bshellSpecialCharError	Error
+" hi def link	bshellString	String
+" hi def link	bshellQuote	String
+" hi def link	bshellInterpolatedString	String
+" hi def link	bshellVerbatimString	String
+" hi def link	bshellInterVerbString	String
+" hi def link	bshellVerbatimQuote	SpecialChar
+"
+" hi def link	bshellConstant	Constant
+" hi def link	bshellNull	Constant
+" hi def link	bshellBoolean	Boolean
+" hi def link	bshellCharacter	Character
+" hi def link	bshellSpecialChar	SpecialChar
+" hi def link	bshellInteger	Number
+" hi def link	bshellReal	Float
+" hi def link	bshellWord	Identifier
+" hi def link	bshellUnicodeNumber	SpecialChar
+" hi def link	bshellUnicodeSpecifier	SpecialChar
+" hi def link	bshellInterpolationDelimiter	Delimiter
+" hi def link	bshellInterpolationAlignDel	bshellInterpolationDelimiter
+" hi def link	bshellInterpolationFormat	bshellInterpolationDelimiter
+" hi def link	bshellInterpolationFormatDel	bshellInterpolationDelimiter
+"
+" hi def link	bshellGenericBraces	bshellBraces
+"
+" hi def link	bshellAtomName	Constant
+"
+" hi def link	bshellComplexMessageName	Function
+" hi def link	bshellUnaryMessageName	Function
+" hi def link	bshellPropertyName	@property
+" hi def link	bshellPropertySymbol	Statement
+"
+" hi def link	bshellStatementSeparator	Comment
+" hi def link	bshellMessageTerminator	@punctuation.special
+"
+" hi def link	bshellPackageStmtIdentifier	@string.special.url
+" hi def link	bshellUseStmtIdentifier	@module
+
+
+let b:current_syntax = 'bshell'
+
+let &cpoptions = s:save_cpo
+unlet s:save_cpo
+
+" vim: vts=16,28

bshell/file.c

@@ -0,0 +1,116 @@
+#include "file.h"
+
+#include "line-source.h"
+
+#include <errno.h>
+#include <fx/collections/array.h>
+#include <fx/string.h>
+#include <stdlib.h>
+#include <string.h>
+
+static enum bshell_status get_name(
+	struct line_source *src,
+	char *buf,
+	size_t count,
+	size_t *nr_read)
+{
+	struct file *f = (struct file *)src;
+	*nr_read = snprintf(buf, count, "%s", f->f_path);
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status get_row(
+	struct line_source *src,
+	size_t row,
+	char *buf,
+	size_t count,
+	size_t *nr_read)
+{
+	struct file *f = (struct file *)src;
+	size_t nr_rows = fx_array_size(f->f_lines);
+
+	if (row > nr_rows) {
+		return BSHELL_ERR_EOF;
+	}
+
+	fx_string *line = fx_array_at(f->f_lines, row - 1);
+
+	const char *line_str = fx_string_get_cstr(line);
+	size_t line_len = fx_string_get_size(line, FX_STRLEN_NORMAL);
+	size_t copy_len = fx_min(ulong, count, line_len);
+
+	memcpy(buf, line_str, copy_len);
+	buf[copy_len] = 0;
+	buf[strcspn(buf, "\n")] = 0;
+	*nr_read = copy_len;
+
+	return BSHELL_SUCCESS;
+}
+
+static enum bshell_status readline(
+	struct line_source *src,
+	fx_stringstream *out)
+{
+	struct file *f = (struct file *)src;
+	fx_wchar c = FX_WCHAR_INVALID;
+	size_t nr_read = 0;
+
+	while (1) {
+		fx_status status = fx_stream_read_char(f->f_strp, &c);
+		if (!FX_OK(status)) {
+			break;
+		}
+
+		fx_stream_write_char(out, c);
+		nr_read++;
+
+		if (c == '\n') {
+			break;
+		}
+	}
+
+	if (nr_read == 0) {
+		return BSHELL_ERR_EOF;
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+enum bshell_status file_open(const char *path, struct file **out)
+{
+	FILE *fp = fopen(path, "r");
+	if (!fp) {
+		return bshell_status_from_errno(errno);
+	}
+
+	fx_stream *strp = fx_stream_open_fp(fp);
+
+	struct file *file = malloc(sizeof *file);
+	if (!file) {
+		fclose(fp);
+		return BSHELL_ERR_NO_MEMORY;
+	}
+
+	memset(file, 0x0, sizeof *file);
+
+	file->f_base.s_get_name = get_name;
+	file->f_base.s_get_row = get_row;
+	file->f_base.s_readline = readline;
+	file->f_fp = fp;
+	file->f_strp = strp;
+	file->f_path = fx_strdup(path);
+	file->f_lines = fx_array_create();
+
+	*out = file;
+
+	return BSHELL_SUCCESS;
+}
+
+void file_close(struct file *file)
+{
+	fx_stream_unref(file->f_strp);
+	fx_array_unref(file->f_lines);
+	free(file->f_path);
+	fclose(file->f_fp);
+	free(file);
+}

bshell/file.h

@@ -0,0 +1,20 @@
+#ifndef FILE_H_
+#define FILE_H_
+
+#include "line-source.h"
+
+#include <fx/collections/array.h>
+#include <stdio.h>
+
+struct file {
+	struct line_source f_base;
+	fx_array *f_lines;
+	char *f_path;
+	fx_stream *f_strp;
+	FILE *f_fp;
+};
+
+extern enum bshell_status file_open(const char *path, struct file **out);
+extern void file_close(struct file *file);
+
+#endif

bshell/lex.c

@@ -0,0 +1,61 @@
+#include "lex.h"
+
+#include "token.h"
+
+#define LEX_TOKEN_DEF(i, n) {.id = (i), .name = (n)}
+
+static struct lex_token_def keywords[] = {
+	LEX_TOKEN_DEF(KW_FUNC, "func"),
+};
+static const size_t nr_keywords = sizeof keywords / sizeof keywords[0];
+
+static struct lex_token_def symbols[] = {
+	LEX_TOKEN_DEF(SYM_SQUOTE, "'"),
+	LEX_TOKEN_DEF(SYM_DQUOTE, "\""),
+	LEX_TOKEN_DEF(SYM_LEFT_BRACE, "{"),
+	LEX_TOKEN_DEF(SYM_RIGHT_BRACE, "}"),
+	LEX_TOKEN_DEF(SYM_LEFT_BRACKET, "["),
+	LEX_TOKEN_DEF(SYM_RIGHT_BRACKET, "]"),
+	LEX_TOKEN_DEF(SYM_LEFT_PAREN, "("),
+	LEX_TOKEN_DEF(SYM_RIGHT_PAREN, ")"),
+};
+static const size_t nr_symbols = sizeof symbols / sizeof symbols[0];
+
+enum bshell_status lex_ctx_init(struct lex_ctx *ctx, struct line_source *src)
+{
+	memset(ctx, 0x0, sizeof *ctx);
+
+	ctx->lex_status = BSHELL_SUCCESS;
+	ctx->lex_src = src;
+
+	return BSHELL_SUCCESS;
+}
+
+enum bshell_status lex_ctx_cleanup(struct lex_ctx *ctx)
+{
+	return BSHELL_SUCCESS;
+}
+
+static struct lex_token *dequeue_token(struct lex_ctx *ctx)
+{
+	fx_queue_entry *entry = fx_queue_first(&ctx->lex_tokens);
+	return fx_unbox(struct lex_token, entry, tok_entry);
+}
+
+static enum bshell_status pump_tokens(struct lex_ctx *ctx)
+{
+	return BSHELL_SUCCESS;
+}
+
+struct lex_token *lex_ctx_peek(struct lex_ctx *ctx)
+{
+	return NULL;
+}
+
+void lex_ctx_advance(struct lex_ctx *ctx)
+{
+	struct lex_token *tok = dequeue_token(ctx);
+	if (tok) {
+		lex_token_destroy(tok);
+	}
+}

bshell/lex.h

@@ -0,0 +1,31 @@
+#ifndef LEX_H_
+#define LEX_H_
+
+#include "status.h"
+
+#include <fx/queue.h>
+
+struct lex_token;
+struct line_source;
+
+struct lex_token_def {
+	int id;
+	const char *name;
+	uint64_t name_hash;
+};
+
+struct lex_ctx {
+	fx_queue lex_tokens;
+	struct line_source *lex_src;
+	enum bshell_status lex_status;
+};
+
+extern enum bshell_status lex_ctx_init(
+	struct lex_ctx *ctx,
+	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 void lex_ctx_advance(struct lex_ctx *ctx);
+
+#endif

bshell/line-ed/buffer.c

@@ -0,0 +1,40 @@
+#include "buffer.h"
+#include "line-ed.h"
+
+const char *line_start(struct line_ed *ed, size_t y)
+{
+	const char *line = ed->l_buf;
+
+	for (size_t i = 0; i < y; i++) {
+		line += strcspn(line, "\n");
+
+		if (*line == '\n') {
+			line++;
+		}
+	}
+
+	return line;
+}
+
+size_t line_length(struct line_ed *ed, size_t y)
+{
+	const char *line = ed->l_buf;
+
+	for (size_t i = 0; i < y; i++) {
+		line += strcspn(line, "\n");
+		if (*line == '\n') {
+			line++;
+		}
+	}
+
+	if (*line == '\0') {
+		return 0;
+	}
+
+	size_t len = strcspn(line, "\n");
+	if (line[len] == '\n') {
+		len++;
+	}
+
+	return len;
+}

bshell/line-ed/buffer.h

@@ -0,0 +1,16 @@
+#ifndef LINE_ED_BUFFER_H_
+#define LINE_ED_BUFFER_H_
+
+#include <stddef.h>
+
+struct line_ed;
+
+/* returns a pointer to the start of the line based on the given `y`
+ * coordinate */
+extern const char *line_start(struct line_ed *ed, size_t y);
+/* returns the length of the line based on the given `y` coordinate.
+ * for any line other than the last line in the buffer, this length
+ * INCLUDES the trailing linefeed. */
+extern size_t line_length(struct line_ed *ed, size_t y);
+
+#endif

bshell/line-ed/cursor.c

@@ -0,0 +1,26 @@
+#include "line-ed.h"
+#include "cursor.h"
+#include "prompt.h"
+
+void line_ed_coords_to_physical_coords(
+	struct line_ed *ed, size_t x, size_t y, size_t *out_x, size_t *out_y)
+{
+	size_t prompt_len = 0;
+	if (ed->l_cursor_y == 0) {
+		prompt_len = prompt_length(ed, PROMPT_MAIN);
+	} else if (ed->l_cursor_y <= ed->l_continuations) {
+		prompt_len = prompt_length(ed, PROMPT_CONT);
+	}
+
+	if (y == 0) {
+		x += prompt_len;
+	}
+
+	if (out_x) {
+		*out_x = x;
+	}
+
+	if (out_y) {
+		*out_y = y;
+	}
+}

bshell/line-ed/cursor.h

@@ -0,0 +1,9 @@
+#ifndef LINE_ED_CURSOR_H_
+#define LINE_ED_CURSOR_H_
+
+struct line_ed;
+
+extern void line_ed_coords_to_physical_coords(
+	struct line_ed *ed, size_t x, size_t y, size_t *out_x, size_t *out_y);
+
+#endif

bshell/line-ed/history.c

@@ -0,0 +1,72 @@
+#include "../misc.h"
+#include "line-ed.h"
+
+#include <fx/collections/array.h>
+#include <fx/string.h>
+
+void alloc_empty_history_entry(struct line_ed *ed)
+{
+	fx_string *str = (fx_string *)fx_array_at(
+		ed->l_history,
+		fx_array_size(ed->l_history) - 1);
+	if (!str || fx_string_get_size(str, FX_STRLEN_NORMAL) > 0) {
+		str = fx_string_create();
+		fx_array_append(ed->l_history, (fx_object *)str);
+	}
+
+	ed->l_history_pos = fx_array_size(ed->l_history) - 1;
+}
+
+void save_buf_to_history(struct line_ed *ed)
+{
+	fx_string *cur
+		= (fx_string *)fx_array_get(ed->l_history, ed->l_history_pos);
+	fx_string_replace_all(cur, ed->l_buf);
+}
+
+void append_buf_to_history(struct line_ed *ed)
+{
+	fx_string *cur
+		= (fx_string *)fx_array_get(ed->l_history, ed->l_history_pos);
+	char s[] = {'\n', 0};
+	fx_string_append_cstr(cur, s);
+	fx_string_append_cstr(cur, ed->l_buf);
+}
+
+void load_buf_from_history(struct line_ed *ed)
+{
+	fx_string *cur
+		= (fx_string *)fx_array_at(ed->l_history, ed->l_history_pos);
+	size_t len
+		= MIN((size_t)(ed->l_buf_end - ed->l_buf - 1),
+	              fx_string_get_size(cur, FX_STRLEN_NORMAL));
+
+	memcpy(ed->l_buf, fx_string_get_cstr(cur), len);
+	ed->l_buf[len] = '\0';
+
+	unsigned int x = 0, y = 0;
+	for (size_t i = 0; ed->l_buf[i]; i++) {
+		if (ed->l_buf[i] == '\n') {
+			x = 0;
+			y++;
+		} else {
+			x++;
+		}
+	}
+
+	ed->l_buf_ptr = ed->l_buf + len;
+	ed->l_line_end = ed->l_buf_ptr;
+	ed->l_cursor_x = x;
+	ed->l_cursor_y = y;
+}
+
+const char *last_history_line(struct line_ed *ed)
+{
+	size_t nlines = fx_array_size(ed->l_history);
+	if (nlines < 2) {
+		return NULL;
+	}
+
+	fx_string *last = (fx_string *)fx_array_at(ed->l_history, nlines - 2);
+	return fx_string_get_cstr(last);
+}

bshell/line-ed/history.h

@@ -0,0 +1,12 @@
+#ifndef LINE_ED_HISTORY_H_
+#define LINE_ED_HISTORY_H_
+
+struct line_ed;
+
+extern void alloc_empty_history_entry(struct line_ed *ed);
+extern void save_buf_to_history(struct line_ed *ed);
+extern void append_buf_to_history(struct line_ed *ed);
+extern void load_buf_from_history(struct line_ed *ed);
+extern const char *last_history_line(struct line_ed *ed);
+
+#endif

bshell/line-ed/hook.c

@@ -0,0 +1,41 @@
+#include "hook.h"
+
+#include "line-ed.h"
+
+void line_ed_add_hook(struct line_ed *ed, struct line_ed_hook *hook)
+{
+	fx_queue_push_back(&ed->l_hooks, &hook->hook_entry);
+}
+
+void line_ed_remove_hook(struct line_ed *ed, struct line_ed_hook *hook)
+{
+	fx_queue_delete(&ed->l_hooks, &hook->hook_entry);
+}
+
+void hook_keypress(struct line_ed *ed, fx_keycode key)
+{
+	fx_queue_entry *entry = fx_queue_first(&ed->l_hooks);
+	while (entry) {
+		struct line_ed_hook *hook
+			= fx_unbox(struct line_ed_hook, entry, hook_entry);
+		if (hook->hook_keypress) {
+			hook->hook_keypress(ed, hook, key);
+		}
+
+		entry = fx_queue_next(entry);
+	}
+}
+
+void hook_buffer_modified(struct line_ed *ed)
+{
+	fx_queue_entry *entry = fx_queue_first(&ed->l_hooks);
+	while (entry) {
+		struct line_ed_hook *hook
+			= fx_unbox(struct line_ed_hook, entry, hook_entry);
+		if (hook->hook_buffer_modified) {
+			hook->hook_buffer_modified(ed, hook);
+		}
+
+		entry = fx_queue_next(entry);
+	}
+}

bshell/line-ed/hook.h

@@ -0,0 +1,16 @@
+#ifndef LINE_ED_HOOK_H_
+#define LINE_ED_HOOK_H_
+
+#include <fx/term/tty.h>
+
+enum hook_id {
+	HOOK_KEYPRESS,
+	HOOK_BEFORE_PAINT,
+};
+
+struct line_ed;
+
+extern void hook_keypress(struct line_ed *ed, fx_keycode key);
+extern void hook_buffer_modified(struct line_ed *ed);
+
+#endif

bshell/line-ed/input.c

@@ -0,0 +1,218 @@
+#include "buffer.h"
+#include "cursor.h"
+#include "history.h"
+#include "hook.h"
+#include "line-ed.h"
+#include "prompt.h"
+#include "refresh.h"
+
+#include <stdio.h>
+
+void put_char(struct line_ed *ed, char c)
+{
+	if (ed->l_buf_ptr > ed->l_line_end + 1) {
+		return;
+	}
+
+	struct refresh_state state = {
+		.r_prev_cursor_x = ed->l_cursor_x,
+		.r_prev_cursor_y = ed->l_cursor_y,
+	};
+
+	size_t prev_cursor = ed->l_buf_ptr - ed->l_buf;
+
+	char *dest = ed->l_buf_ptr;
+	size_t len = ed->l_line_end - ed->l_buf_ptr + 1;
+
+	if (dest < ed->l_line_end) {
+		memmove(dest + 1, dest, len);
+	}
+
+	ed->l_cursor_x++;
+	ed->l_line_end++;
+	ed->l_buf_ptr++;
+	*dest = c;
+
+	if (ed->l_buf_ptr == ed->l_line_end) {
+		*ed->l_buf_ptr = '\0';
+	}
+
+	hook_buffer_modified(ed);
+
+	put_refresh(ed, &state);
+}
+
+static void backspace_simple(struct line_ed *ed)
+{
+	if (ed->l_buf_ptr == ed->l_buf) {
+		return;
+	}
+
+	struct refresh_state state = {
+		.r_prev_cursor_x = ed->l_cursor_x,
+		.r_prev_cursor_y = ed->l_cursor_y,
+	};
+
+	size_t prev_cursor = ed->l_buf_ptr - ed->l_buf;
+
+	char *dest = ed->l_buf_ptr;
+	size_t len = ed->l_line_end - ed->l_buf_ptr + 1;
+	memmove(dest - 1, dest, len);
+
+	ed->l_cursor_x--;
+	ed->l_line_end--;
+	ed->l_buf_ptr--;
+
+	hook_buffer_modified(ed);
+
+	backspace_simple_refresh(ed, &state);
+}
+
+static void backspace_nl(struct line_ed *ed)
+{
+	size_t prev_line_len = line_length(ed, ed->l_cursor_y - 1);
+
+	struct refresh_state state = {
+		.r_prev_cursor_x = ed->l_cursor_x,
+		.r_prev_cursor_y = ed->l_cursor_y,
+		.r_prev_line_len = prev_line_len,
+	};
+
+	char *dest = ed->l_buf_ptr;
+	size_t len = ed->l_line_end - ed->l_buf_ptr + 1;
+	memmove(dest - 1, dest, len);
+
+	ed->l_cursor_x = prev_line_len - 1;
+	ed->l_cursor_y--;
+	ed->l_buf_ptr--;
+	ed->l_line_end--;
+
+	hook_buffer_modified(ed);
+
+	backspace_nl_refresh(ed, &state);
+}
+
+void backspace(struct line_ed *ed)
+{
+	if (ed->l_buf_ptr == ed->l_buf) {
+		return;
+	}
+
+	if (ed->l_cursor_x == 0 && ed->l_cursor_y <= ed->l_continuations) {
+		return;
+	}
+
+	if (ed->l_cursor_x == 0 && ed->l_cursor_y > 0) {
+		backspace_nl(ed);
+	} else {
+		backspace_simple(ed);
+	}
+}
+
+void cursor_left(struct line_ed *ed)
+{
+	if (ed->l_cursor_x != 0) {
+		//fputs("\010", stdout);
+		fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_CURSOR, -1);
+		fflush(stdout);
+		ed->l_cursor_x--;
+		ed->l_buf_ptr--;
+		return;
+	}
+
+	if (ed->l_cursor_y <= ed->l_continuations || ed->l_buf_ptr <= ed->l_buf) {
+		return;
+	}
+
+	ed->l_cursor_y--;
+	ed->l_buf_ptr--;
+	size_t prompt_len = 0;
+	if (ed->l_cursor_y == 0) {
+		prompt_len = prompt_length(ed, PROMPT_MAIN);
+	}
+
+	size_t len = line_length(ed, ed->l_cursor_y);
+	ed->l_cursor_x = len - 1;
+
+	//printf("\033[A\033[%dG", len + prompt_len);
+	fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, -1);
+	fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_START, (int)(len + prompt_len));
+
+	fflush(stdout);
+}
+
+void cursor_right(struct line_ed *ed)
+{
+	if (ed->l_buf_ptr >= ed->l_line_end) {
+		return;
+	}
+
+	if (*ed->l_buf_ptr != '\n') {
+		ed->l_cursor_x++;
+		ed->l_buf_ptr++;
+		//fputs("\033[C", stdout);
+		fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_CURSOR, 1);
+		fflush(stdout);
+		return;
+	}
+
+	if (ed->l_buf_ptr >= ed->l_line_end) {
+		return;
+	}
+
+	ed->l_cursor_y++;
+	ed->l_cursor_x = 0;
+	ed->l_buf_ptr++;
+
+	//printf("\033[B\033[G");
+	fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, 1);
+	fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_START, 0);
+	fflush(stdout);
+}
+
+void arrow_up(struct line_ed *ed)
+{
+	if (ed->l_history_pos == 0) {
+		return;
+	}
+
+	if (ed->l_cursor_y > 0) {
+		//printf("\033[%uA", ed->l_cursor_y);
+		fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, (long long)ed->l_cursor_y);
+	}
+
+	//printf("\033[%zuG\033[J", prompt_length(ed, PROMPT_MAIN) + 1);
+	fx_tty_move_cursor_x(
+		ed->l_tty, FX_TTY_POS_START, (long long)prompt_length(ed, PROMPT_MAIN));
+	fx_tty_clear(ed->l_tty, FX_TTY_CLEAR_SCREEN | FX_TTY_CLEAR_FROM_CURSOR);
+
+	save_buf_to_history(ed);
+	ed->l_history_pos--;
+	load_buf_from_history(ed);
+
+	print_buffer(ed);
+	fflush(stdout);
+}
+
+void arrow_down(struct line_ed *ed)
+{
+	if (ed->l_history_pos == fx_array_size(ed->l_history) - 1) {
+		return;
+	}
+
+	if (ed->l_cursor_y > 0) {
+		//printf("\033[%uA", ed->l_cursor_y);
+		fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, (int)ed->l_cursor_y);
+	}
+
+	//printf("\033[%zuG\033[J", prompt_length(ed, PROMPT_MAIN) + 1);
+	fx_tty_move_cursor_x(
+		ed->l_tty, FX_TTY_POS_START, prompt_length(ed, PROMPT_MAIN) + 1);
+
+	save_buf_to_history(ed);
+	ed->l_history_pos++;
+	load_buf_from_history(ed);
+
+	print_buffer(ed);
+	fflush(stdout);
+}

bshell/line-ed/input.h

@@ -0,0 +1,13 @@
+#ifndef LINE_ED_INPUT_H_
+#define LINE_ED_INPUT_H_
+
+struct line_ed;
+
+extern void put_char(struct line_ed *ed, char c);
+extern void backspace(struct line_ed *ed);
+extern void cursor_left(struct line_ed *ed);
+extern void cursor_right(struct line_ed *ed);
+extern void arrow_up(struct line_ed *ed);
+extern void arrow_down(struct line_ed *ed);
+
+#endif

bshell/line-ed/line-ed.c

@@ -0,0 +1,301 @@
+#include "line-ed.h"
+
+#include "history.h"
+#include "hook.h"
+#include "input.h"
+#include "prompt.h"
+
+#include <ctype.h>
+#include <fx/term/tty.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+#define LINE_ED_FROM_LEX_SOURCE(p)                                             \
+	((struct line_ed *)((char *)p                                          \
+	                    - offsetof(struct line_ed, l_line_source)))
+
+static enum bshell_status readline(
+	struct line_source *src,
+	fx_stringstream *out)
+{
+	struct line_ed *ed = LINE_ED_FROM_LEX_SOURCE(src);
+
+	long r = line_ed_readline(ed, out);
+	line_ed_set_scope_type(ed, NULL);
+
+	if (r < 0) {
+		return BSHELL_ERR_EOF;
+	}
+
+	return BSHELL_SUCCESS;
+}
+
+struct line_ed *line_ed_create(void)
+{
+	struct line_ed *out = malloc(sizeof *out);
+	if (!out) {
+		return NULL;
+	}
+
+	memset(out, 0x0, sizeof *out);
+
+	out->l_buf = malloc(LINE_MAX);
+	if (!out->l_buf) {
+		free(out);
+		return NULL;
+	}
+
+	out->l_history = fx_array_create();
+	if (!out->l_history) {
+		free(out->l_buf);
+		free(out);
+		return NULL;
+	}
+
+	out->l_tty = fx_stdtty;
+	out->l_buf_end = out->l_buf + LINE_MAX;
+	out->l_buf_ptr = out->l_buf;
+	out->l_line_end = out->l_buf;
+
+	out->l_prompt[PROMPT_MAIN] = ">>> ";
+	out->l_prompt[PROMPT_CONT] = "> ";
+
+	out->l_line_source.s_readline = readline;
+
+	return out;
+}
+
+void line_ed_destroy(struct line_ed *ed)
+{
+	fx_array_unref(ed->l_history);
+	free(ed->l_buf);
+	free(ed);
+}
+
+void line_ed_set_flags(struct line_ed *ed, enum line_ed_flags flags)
+{
+	ed->l_flags |= flags;
+}
+
+void line_ed_set_scope_type(struct line_ed *ed, const char *scope_type)
+{
+	ed->l_scope_type = scope_type;
+}
+
+static void clear_buffer(struct line_ed *ed)
+{
+	memset(ed->l_buf, 0x0, ed->l_buf_end - ed->l_buf);
+
+	ed->l_buf_ptr = ed->l_buf;
+	ed->l_line_end = ed->l_buf;
+
+	ed->l_cursor_x = 0;
+	ed->l_cursor_y = 0;
+
+	ed->l_continuations = 0;
+}
+
+static void convert_continuation_feeds(char *s, size_t max)
+{
+	char *end = s + max;
+	size_t len = strlen(s);
+
+	while (1) {
+		size_t r = strcspn(s, "\\");
+		if (s + r > end) {
+			break;
+		}
+
+		s += r;
+		len -= r;
+
+		if (*s == '\0') {
+			break;
+		}
+
+		if (*(s + 1) != '\n') {
+			s++;
+			continue;
+		}
+
+		memmove(s, s + 1, len);
+		s += 1;
+	}
+}
+
+static void remove_continuation_feeds(char *s, size_t max)
+{
+	char *end = s + max;
+	size_t len = strlen(s);
+
+	while (1) {
+		size_t r = strcspn(s, "\\");
+		if (s + r > end) {
+			break;
+		}
+
+		s += r;
+		len -= r;
+
+		if (*s == '\0') {
+			break;
+		}
+
+		if (*(s + 1) != '\n') {
+			s++;
+			continue;
+		}
+
+		memmove(s, s + 2, len);
+		s += 2;
+	}
+}
+
+static bool input_is_empty(struct line_ed *ed)
+{
+	const char *p = ed->l_buf;
+	while (p < ed->l_line_end) {
+		if (!isspace(*p)) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+size_t line_ed_readline(struct line_ed *ed, fx_stringstream *out)
+{
+	clear_buffer(ed);
+
+	bool append_history = false;
+	size_t append_to_index = (size_t)-1;
+	if (!ed->l_scope_type) {
+		alloc_empty_history_entry(ed);
+	} else {
+		append_history = true;
+		append_to_index = ed->l_history_pos;
+	}
+
+	fx_tty *tty = ed->l_tty;
+	fx_tty_set_mode(tty, FX_TTY_RAW);
+	show_prompt(ed);
+
+	for (int i = 0; ed->l_buf[i]; i++) {
+		if (ed->l_buf[i] == '\n') {
+			fputc('\r', stdout);
+		}
+
+		fputc(ed->l_buf[i], stdout);
+	}
+	fflush(stdout);
+
+	bool end = false;
+	bool eof = false;
+
+	while (!end) {
+		fx_keycode key = fx_tty_read_key(tty);
+		hook_keypress(ed, key);
+
+		if (key == FX_TTY_CTRL_KEY('d')) {
+			if (!input_is_empty(ed)) {
+				continue;
+			}
+
+			eof = true;
+			break;
+		}
+
+		if (key & FX_MOD_CTRL) {
+			continue;
+		}
+
+		switch (key) {
+		case FX_KEY_RETURN:
+			fx_tty_reset_vmode(tty);
+			if (ed->l_line_end > ed->l_buf
+			    && *(ed->l_line_end - 1) != '\\') {
+				end = true;
+				break;
+			}
+
+			if (input_is_empty(ed)) {
+				fputc('\r', stdout);
+				fputc('\n', stdout);
+				clear_buffer(ed);
+				show_prompt(ed);
+				break;
+			}
+
+			*ed->l_line_end = '\n';
+			ed->l_line_end++;
+			ed->l_buf_ptr = ed->l_line_end;
+
+			ed->l_cursor_x = 0;
+			ed->l_cursor_y++;
+			ed->l_continuations++;
+			fputc('\r', stdout);
+			fputc('\n', stdout);
+			// fputs("\033[G\n", stdout);
+			show_prompt(ed);
+			break;
+		case FX_KEY_BACKSPACE:
+			backspace(ed);
+			break;
+		case FX_KEY_ARROW_LEFT:
+			cursor_left(ed);
+			break;
+		case FX_KEY_ARROW_RIGHT:
+			cursor_right(ed);
+			break;
+		case FX_KEY_ARROW_UP:
+			arrow_up(ed);
+			break;
+		case FX_KEY_ARROW_DOWN:
+			arrow_down(ed);
+			break;
+		default:
+			if (iswgraph(key) || key == ' ') {
+				put_char(ed, key);
+			}
+			break;
+		}
+	}
+
+	fx_tty_set_mode(tty, FX_TTY_CANONICAL);
+	fputc('\n', stdout);
+
+	if (*ed->l_buf == '\0') {
+		return eof ? -1 : 0;
+	}
+
+	if (append_history) {
+		ed->l_history_pos = append_to_index;
+		append_buf_to_history(ed);
+	} else {
+		ed->l_history_pos = fx_array_size(ed->l_history) - 1;
+
+		const char *last = last_history_line(ed);
+		if (!last || strcmp(last, ed->l_buf) != 0) {
+			save_buf_to_history(ed);
+		}
+	}
+
+	size_t sz = ed->l_line_end - ed->l_buf + 1;
+
+	if ((ed->l_flags & LINE_ED_REMOVE_CONTINUATIONS)
+	    == LINE_ED_REMOVE_CONTINUATIONS) {
+		remove_continuation_feeds(ed->l_buf, sz);
+	} else if (
+		(ed->l_flags & LINE_ED_CONVERT_CONTINUATIONS)
+		== LINE_ED_CONVERT_CONTINUATIONS) {
+		convert_continuation_feeds(ed->l_buf, sz);
+	}
+
+	fx_stream_write_cstr(out, ed->l_buf, NULL);
+	fx_stream_write_char(out, '\n');
+
+	return sz;
+}

bshell/line-ed/line-ed.h

@@ -0,0 +1,107 @@
+#ifndef LINE_ED_H_
+#define LINE_ED_H_
+
+#define LINE_MAX 4096
+
+#include "../line-source.h"
+
+#include <fx/collections/array.h>
+#include <fx/queue.h>
+#include <fx/term/tty.h>
+#include <stddef.h>
+
+struct s_tty;
+struct fx_tty_vmode;
+
+struct line_ed;
+
+struct line_ed_hook {
+	void (*hook_keypress)(
+		struct line_ed *,
+		struct line_ed_hook *,
+		fx_keycode);
+	void (*hook_buffer_modified)(struct line_ed *, struct line_ed_hook *);
+	fx_queue_entry hook_entry;
+};
+
+enum line_ed_flags {
+	/* always reprint an entire line when a character is added/deleted.
+	 * without this flag, only the modified character any subsequent
+	 * characters are reprinted. */
+	LINE_ED_FULL_REPRINT = 0x01u,
+
+	/* keep line continuation (backslash-newline) tokens in the output
+	 * buffer (default behaviour) */
+	LINE_ED_KEEP_CONTINUATIONS = 0x00u,
+	/* convert line continuation tokens in the output buffer to simple
+	 * linefeeds. */
+	LINE_ED_CONVERT_CONTINUATIONS = 0x02u,
+	/* remove line continuation tokens from the output buffer, so that all
+	 * chars are on a single line */
+	LINE_ED_REMOVE_CONTINUATIONS = 0x06u,
+};
+
+struct line_ed {
+	enum line_ed_flags l_flags;
+
+	/* array of basic prompt strings */
+	const char *l_prompt[2];
+	/* input buffer, pointer to the buffer cell that corresponds to
+	 * the current cursor position, and pointer to the byte AFTER the last
+	 * usable byte in the buffer */
+	char *l_buf, *l_buf_ptr, *l_buf_end;
+	/* pointer to the byte AFTER the last byte of the user's input */
+	char *l_line_end;
+	/* 2-dimensional coordinates of the current cursor position.
+	 * this does NOT include any prompts that are visible on the terminal */
+	size_t l_cursor_x, l_cursor_y;
+	/* the number of line continuations that have been inputted */
+	unsigned int l_continuations;
+
+	struct line_source l_line_source;
+
+	/* pointer to tty interface */
+	fx_tty *l_tty;
+
+	/* the lexical scope that we are currently in.
+	 * this is provided by components further up the input pipeline,
+	 * for example, when we are inside a string or if-statement. */
+	const char *l_scope_type;
+
+	/* array of previously entered commands */
+	fx_array *l_history;
+	/* index of the currently selected history entry */
+	size_t l_history_pos;
+
+	/* list of defined highlight ranges */
+	fx_queue l_hl_ranges;
+	/* list of installed hooks */
+	fx_queue l_hooks;
+};
+
+extern struct line_ed *line_ed_create(void);
+extern void line_ed_destroy(struct line_ed *ed);
+extern void line_ed_set_flags(struct line_ed *ed, enum line_ed_flags flags);
+extern void line_ed_set_scope_type(struct line_ed *ed, const char *scope_type);
+
+extern void line_ed_put_highlight(
+	struct line_ed *ed,
+	unsigned long start_x,
+	unsigned long start_y,
+	unsigned long end_x,
+	unsigned long end_y,
+	const struct fx_tty_vmode *vmode);
+extern void line_ed_clear_highlights(struct line_ed *ed);
+extern void line_ed_print_highlights(struct line_ed *ed);
+
+extern void line_ed_add_hook(struct line_ed *ed, struct line_ed_hook *hook);
+extern void line_ed_remove_hook(struct line_ed *ed, struct line_ed_hook *hook);
+
+extern size_t line_ed_readline(struct line_ed *ed, fx_stringstream *out);
+
+static inline struct line_source *line_ed_to_line_source(struct line_ed *ed)
+{
+	return &ed->l_line_source;
+}
+
+#endif

bshell/line-ed/prompt.c

@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include "line-ed.h"
+#include "prompt.h"
+
+void show_prompt(struct line_ed *ed)
+{
+	int type = PROMPT_MAIN;
+	if (ed->l_scope_type) {
+		type = PROMPT_CONT;
+
+		/* this is a temporary solution to show the current
+		 * scope type, until prompts are implemented properly. */
+		fputs(ed->l_scope_type, stdout);
+	}
+
+	if (ed->l_continuations > 0) {
+		type = PROMPT_CONT;
+	}
+
+	fputs(ed->l_prompt[type], stdout);
+	fflush(stdout);
+}
+
+size_t prompt_length(struct line_ed *ed, int prompt_id)
+{
+	return strlen(ed->l_prompt[prompt_id]);
+}

bshell/line-ed/prompt.h

@@ -0,0 +1,12 @@
+#ifndef LINE_ED_PROMPT_H_
+#define LINE_ED_PROMPT_H_
+
+#define PROMPT_MAIN 0
+#define PROMPT_CONT 1
+
+struct line_ed;
+
+extern void show_prompt(struct line_ed *ed);
+extern size_t prompt_length(struct line_ed *ed, int prompt_id);
+
+#endif

bshell/line-ed/refresh.c

@@ -0,0 +1,265 @@
+#include "refresh.h"
+
+#include "buffer.h"
+#include "cursor.h"
+#include "line-ed.h"
+
+#include <fx/term/tty.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* prints the provided string to the terminal, applying any relevant highlight
+ * ranges. this function prints all characters in `s` until it encounters a null
+ * char (\0) or linefeed (\n).
+ *
+ * the (x, y) coordinates provided should be the data coordinates of the
+ * first character in `s`.
+ */
+void print_text(struct line_ed *ed, size_t x, size_t y, const char *s)
+{
+	fx_tty *tty = ed->l_tty;
+
+	for (size_t i = 0; s[i] != '\n' && s[i] != '\0'; i++) {
+		fputc(s[i], stdout);
+	}
+}
+
+void print_buffer(struct line_ed *ed)
+{
+	const char *line_buf = ed->l_buf;
+	size_t line_len = strcspn(line_buf, "\n");
+
+	unsigned int y = 0;
+
+	while (1) {
+		print_text(ed, 0, y, line_buf);
+
+		line_buf += line_len;
+		if (*line_buf == '\n') {
+			line_buf++;
+		}
+
+		if (*line_buf == '\0') {
+			break;
+		}
+
+		y++;
+		line_len = strcspn(line_buf, "\n");
+
+		fputc('\r', stdout);
+		fputc('\n', stdout);
+	}
+}
+
+/* this function is called after a character is inserted into the line_ed
+ *buffer. the function performs the following steps:
+ *	1. get a pointer to the start of the line that was modified.
+ *	2. determine the first character in the line that needs to be redrawn.
+ *	   this may result in an append, a partial reprint, or a full reprint.
+ *	3. re-print the relevant portion of the buffer:
+ *	   for an append (a character added to the end of the line):
+ *		* write the inserted char to the terminal.
+ *		* done.
+ *	   for a partial reprint:
+ *		* clear all printed chars from the logical cursor position to
+ *the end of the line.
+ *		* print the portion of the line corresponding to the cleared
+ *section.
+ *		* move the physical (terminal) cursor backwards until its
+ *position matches the logical (line_ed) cursor. for a full reprint:
+ *		* same as a partial reprint except that, rather than reprinting
+ *		  from the logical cursor position, the entire line is
+ *reprinted.
+ */
+void put_refresh(struct line_ed *ed, struct refresh_state *state)
+{
+	/* get the data for the line that is being refreshed */
+	const char *line_buf = line_start(ed, ed->l_cursor_y);
+	size_t line_len = strcspn(line_buf, "\n");
+
+	/* the index of the first char in line_buf that needs to be reprinted */
+	size_t start_x = state->r_prev_cursor_x;
+
+	/* the distance between the first char to be reprinted and the end
+	 * of the line.
+	 * the physical cursor will be moved back by this amount after the
+	 * line is reprinted. */
+	long cursor_rdelta = (long)(line_len - start_x);
+
+	if (ed->l_flags & LINE_ED_FULL_REPRINT) {
+		if (start_x) {
+			// fprintf(stdout, "\033[%uD", start_x);
+			fx_tty_move_cursor_x(
+				ed->l_tty,
+				FX_TTY_POS_CURSOR,
+				-(long long)start_x);
+		}
+
+		start_x = 0;
+	}
+
+	print_text(ed, start_x, ed->l_cursor_y, line_buf + start_x);
+
+	/* decrement the rdelta (move the cursor back one fewer cells),
+	 * so that the physical cursor will be placed AFTER the character that
+	 * was just inserted. */
+	cursor_rdelta--;
+	fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_CURSOR, -cursor_rdelta);
+
+#if 0
+	for (unsigned int i = 0; i < cursor_rdelta; i++) {
+		fputs("\010", stdout);
+	}
+#endif
+
+	fflush(stdout);
+}
+
+/* this function is called after a character is removed from the line_ed buffer.
+ * IF the character was a linefeed.
+ *
+ * this is separate from backspace_simple_refresh because, in this situation,
+ * the cursor position depends on the length of the previous line before
+ * the linefeed was deleted, and we have to reprint every line following the
+ * two that were combined.
+ */
+void backspace_nl_refresh(struct line_ed *ed, struct refresh_state *state)
+{
+	/* get the data for the line that is being refreshed.
+	 * relative to where the cursor was before the linefeed was deleted,
+	 * this is the PREVIOUS line. */
+	const char *line_buf = line_start(ed, ed->l_cursor_y);
+	size_t line_len = strcspn(line_buf, "\n");
+
+	/* the index of the first char in line_buf that needs to be reprinted.
+	 * subtract one to account for the linefeed that has since been deleted.
+	 */
+	size_t start_x = state->r_prev_line_len - 1;
+
+	/* the column to move the physical cursor to after it has been moved
+	 * to the previous line.
+	 * NOTE that this number includes the length of the prompt!
+	 * we add 1 to start_x to ensure that the cursor is moved to the cell
+	 * AFTER the last char of the line. */
+	size_t new_x;
+	line_ed_coords_to_physical_coords(
+		ed,
+		start_x + 1,
+		ed->l_cursor_y,
+		&new_x,
+		NULL);
+
+	/* the physical cursor is currently at the beginning of the line that
+	 * has just been moved up. from here, clear this line and the rest
+	 * from the screen. */
+	// fputs("\033[J", stdout);
+	fx_tty_clear(ed->l_tty, FX_TTY_CLEAR_SCREEN | FX_TTY_CLEAR_FROM_CURSOR);
+
+	if (ed->l_flags & LINE_ED_FULL_REPRINT) {
+		/* next, move the physical cursor up and to the beginning of the
+		 * previous line */
+		size_t tmp_x;
+		line_ed_coords_to_physical_coords(
+			ed,
+			0,
+			ed->l_cursor_y,
+			&tmp_x,
+			NULL);
+		fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, -1);
+		fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_START, tmp_x);
+		// fprintf(stdout, "\033[A\033[%uG", tmp_x + 1);
+		start_x = 0;
+	} else {
+		/* next, move the physical cursor up and to the end of the
+		 * previous line */
+		// fprintf(stdout, "\033[A\033[%uG", new_x);
+		fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, -1);
+		fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_START, new_x);
+	}
+
+	/* now reprint all of the buffer lines, starting with the first of the
+	 * two lines that were concatenated. */
+	size_t ydiff = 0;
+	while (1) {
+		print_text(
+			ed,
+			start_x,
+			ed->l_cursor_y + ydiff,
+			line_buf + start_x);
+
+		line_buf += line_len + 1;
+		line_len = strcspn(line_buf, "\n");
+		start_x = 0;
+
+		if (*line_buf == '\0') {
+			break;
+		}
+
+		fputc('\r', stdout);
+		fputc('\n', stdout);
+		ydiff++;
+	}
+
+	/* finally, move the cursor BACK to the point where the two lines
+	 * were concatenated. */
+	if (ydiff) {
+		// fprintf(stdout, "\033[%uA", ydiff);
+		fx_tty_move_cursor_y(ed->l_tty, FX_TTY_POS_CURSOR, ydiff);
+	}
+
+	// fprintf(stdout, "\033[%uG", new_x);
+	fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_START, new_x);
+	fflush(stdout);
+}
+
+/* this function is called after a character is removed from the line_ed buffer.
+ * IF the character was not a linefeed.
+ */
+void backspace_simple_refresh(struct line_ed *ed, struct refresh_state *state)
+{
+	/* get the data for the line that is being refreshed */
+	const char *line_buf = line_start(ed, ed->l_cursor_y);
+	size_t line_len = strcspn(line_buf, "\n");
+
+	/* the index of the first char in line_buf that needs to be reprinted */
+	size_t start_x = ed->l_cursor_x;
+	// get_data_cursor_position(ed, &start_x, NULL);
+
+	/* the distance between the first char to be reprinted and the end
+	 * of the line.
+	 * the physical cursor will be moved back by this amount after the
+	 * line is reprinted. */
+	long long cursor_rdelta = (long long)(line_len - start_x);
+
+	if (ed->l_flags & LINE_ED_FULL_REPRINT) {
+		if (start_x) {
+			// fprintf(stdout, "\033[%uD", start_x);
+			fx_tty_move_cursor_x(
+				ed->l_tty,
+				FX_TTY_POS_CURSOR,
+				-(long long)start_x);
+		}
+
+		start_x = 0;
+	}
+
+	// fputc('\010', stdout);
+	fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_CURSOR, -1);
+	print_text(ed, start_x, ed->l_cursor_y, line_buf + start_x);
+	fputc(' ', stdout);
+
+	/* increment the rdelta (move the cursor back one more cell), so
+	 * that the cursor will appear to move back one cell (to accord with
+	 * the fact that backspace was just pressed) */
+	cursor_rdelta++;
+
+	fx_tty_move_cursor_x(ed->l_tty, FX_TTY_POS_CURSOR, -cursor_rdelta);
+
+#if 0
+	for (unsigned int i = 0; i < cursor_rdelta; i++) {
+		fputs("\010", stdout);
+	}
+#endif
+
+	fflush(stdout);
+}

bshell/line-ed/refresh.h

@@ -0,0 +1,28 @@
+#ifndef LINE_ED_REFRESH_H_
+#define LINE_ED_REFRESH_H_
+
+#include <stddef.h>
+
+struct line_ed;
+
+struct refresh_state {
+	/* cursor position before the update was performed (excluding the
+	 * prompt) */
+	size_t r_prev_cursor_x, r_prev_cursor_y;
+	/* when a backspace results in two separate lines being combined,
+	 * this property contains the length of the first of the two combined
+	 * lines BEFORE the concotenation was performed */
+	size_t r_prev_line_len;
+};
+
+extern void print_text(struct line_ed *ed, size_t x, size_t y, const char *s);
+extern void print_buffer(struct line_ed *ed);
+extern void put_refresh(struct line_ed *ed, struct refresh_state *state);
+extern void backspace_nl_refresh(
+	struct line_ed *ed,
+	struct refresh_state *state);
+extern void backspace_simple_refresh(
+	struct line_ed *ed,
+	struct refresh_state *state);
+
+#endif

bshell/line-source.c

@@ -0,0 +1,39 @@
+#include "line-source.h"
+
+enum bshell_status line_source_get_name(
+	struct line_source *src,
+	char *buf,
+	size_t count,
+	size_t *nr_read)
+{
+	if (src->s_get_name) {
+		return src->s_get_name(src, buf, count, nr_read);
+	}
+
+	return BSHELL_ERR_NOT_SUPPORTED;
+}
+
+enum bshell_status line_source_readline(
+	struct line_source *src,
+	fx_stringstream *out)
+{
+	if (src->s_readline) {
+		return src->s_readline(src, out);
+	}
+
+	return BSHELL_ERR_NOT_SUPPORTED;
+}
+
+enum bshell_status line_source_get_row(
+	struct line_source *src,
+	size_t row,
+	char *buf,
+	size_t count,
+	size_t *nr_read)
+{
+	if (src->s_get_row) {
+		return src->s_get_row(src, row, buf, count, nr_read);
+	}
+
+	return BSHELL_ERR_NOT_SUPPORTED;
+}

bshell/line-source.h

@@ -0,0 +1,37 @@
+#ifndef LINE_SOURCE_H_
+#define LINE_SOURCE_H_
+
+#include "status.h"
+
+#include <fx/stringstream.h>
+#include <stddef.h>
+
+struct line_source {
+	enum bshell_status (
+		*s_get_name)(struct line_source *, char *, size_t, size_t *);
+	enum bshell_status (
+		*s_readline)(struct line_source *, fx_stringstream *);
+	enum bshell_status (*s_get_row)(
+		struct line_source *,
+		size_t,
+		char *,
+		size_t,
+		size_t *);
+};
+
+extern enum bshell_status line_source_get_name(
+	struct line_source *src,
+	char *buf,
+	size_t count,
+	size_t *nr_read);
+extern enum bshell_status line_source_readline(
+	struct line_source *src,
+	fx_stringstream *out);
+extern enum bshell_status line_source_get_row(
+	struct line_source *src,
+	size_t row,
+	char *buf,
+	size_t count,
+	size_t *nr_read);
+
+#endif

bshell/main.c

@@ -0,0 +1,38 @@
+#include "file.h"
+#include "line-ed/line-ed.h"
+
+#include <stdio.h>
+
+int main(int argc, const char **argv)
+{
+	printf("B Shell " BSHELL_VERSION "\n");
+
+	struct line_source *linesrc = NULL;
+
+	enum bshell_status status = BSHELL_SUCCESS;
+
+	if (argc > 1) {
+		struct file *file = NULL;
+		status = file_open(argv[1], &file);
+		linesrc = &file->f_base;
+	} else {
+		struct line_ed *ed = line_ed_create();
+		linesrc = line_ed_to_line_source(ed);
+	}
+
+	fx_stringstream *linebuf = fx_stringstream_create();
+
+	while (1) {
+		enum bshell_status status
+			= line_source_readline(linesrc, linebuf);
+
+		if (status != BSHELL_SUCCESS) {
+			break;
+		}
+
+		printf("%s", fx_stringstream_ptr(linebuf));
+		fx_stringstream_reset(linebuf);
+	}
+
+	return 0;
+}

bshell/misc.h

@@ -0,0 +1,7 @@
+#ifndef MISC_H_
+#define MISC_H_
+
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+
+#endif

bshell/status.c

@@ -0,0 +1,20 @@
+#include "status.h"
+
+#include <errno.h>
+
+enum bshell_status bshell_status_from_errno(int err)
+{
+	switch (err) {
+	case 0:
+		return BSHELL_SUCCESS;
+	case EIO:
+		return BSHELL_ERR_IO_FAILURE;
+	case ENOENT:
+		return BSHELL_ERR_NO_ENTRY;
+	case EPERM:
+	case EACCES:
+		return BSHELL_ERR_ACCESS_DENIED;
+	default:
+		return BSHELL_ERR_INTERNAL_FAILURE;
+	}
+}

bshell/status.h

@@ -0,0 +1,24 @@
+#ifndef STATUS_H_
+#define STATUS_H_
+
+enum bshell_status {
+	BSHELL_SUCCESS = 0,
+	BSHELL_ERR_EOF,
+	BSHELL_ERR_BAD_SYNTAX,
+	BSHELL_ERR_BAD_FORMAT,
+	BSHELL_ERR_BAD_STATE,
+	BSHELL_ERR_INVALID_VALUE,
+	BSHELL_ERR_INVALID_ARGUMENT,
+	BSHELL_ERR_NO_MEMORY,
+	BSHELL_ERR_NO_ENTRY,
+	BSHELL_ERR_NO_DATA,
+	BSHELL_ERR_NAME_EXISTS,
+	BSHELL_ERR_NOT_SUPPORTED,
+	BSHELL_ERR_IO_FAILURE,
+	BSHELL_ERR_ACCESS_DENIED,
+	BSHELL_ERR_INTERNAL_FAILURE,
+};
+
+extern enum bshell_status bshell_status_from_errno(int err);
+
+#endif

bshell/token.h

@@ -0,0 +1,86 @@
+#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_ARG,
+	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_INDEX_LIMIT,
+};
+
+enum token_symbol {
+	SYM_NONE = 0,
+	__SYM_INDEX_BASE = 300,
+	SYM_SQUOTE,
+	SYM_DQUOTE,
+	SYM_LEFT_BRACE,
+	SYM_RIGHT_BRACE,
+	SYM_LEFT_BRACKET,
+	SYM_RIGHT_BRACKET,
+	SYM_LEFT_PAREN,
+	SYM_RIGHT_PAREN,
+	__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;
+		long long tok_int;
+		double tok_double;
+		char *tok_str;
+	};
+};
+
+extern struct lex_token *lex_token_create_discard(void);
+extern struct lex_token *lex_token_create_ident(const char *s);
+extern void lex_token_destroy(struct lex_token *tok);
+
+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);
+}
+
+extern const char *lex_token_to_string(const struct lex_token *tok);
+extern const char *bshell_lex_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);
+
+#endif

cmake/FindFX.cmake

@@ -0,0 +1,124 @@
+#[=======================================================================[.rst:
+FindFX
+------------
+
+Find the FX library and header directories
+
+Imported Targets
+^^^^^^^^^^^^^^^^
+
+This module defines the following :prop_tgt:`IMPORTED` target:
+
+``FX::FX``
+The FX library, if found
+
+Result Variables
+^^^^^^^^^^^^^^^^
+
+This module will set the following variables in your project:
+
+``FX_FOUND``
+true if the FX C headers and libraries were found
+``FX_INCLUDE_DIR``
+directories containing the FX C headers.
+
+``FX_LIBRARY``
+the C library to link against
+
+Hints
+^^^^^
+
+The user may set the environment variable ``FX_PREFIX`` to the root
+directory of a FX library installation.
+#]=======================================================================]
+
+set (FX_SEARCH_PATHS
+	~/Library/Frameworks
+	/Library/Frameworks
+	/usr/local
+	/usr/local/share
+	/usr
+	/sw # Fink
+	/opt/local # DarwinPorts
+	/opt/csw # Blastwave
+	/opt
+	${FX_PREFIX}
+	$ENV{FX_PREFIX})
+
+if (FX_STATIC)
+	set(_lib_suffix "-s")
+endif ()
+
+set(assemblies ${FX_FIND_COMPONENTS})
+set(required_vars)
+
+if (NOT FX_INCLUDE_DIR)
+	find_path(FX_INCLUDE_DIR
+		NAMES fx/misc.h ${FX_FIND_ARGS}
+		PATH_SUFFIXES include
+		PATHS ${FX_SEARCH_PATHS})
+endif ()
+
+set(required_vars FX_INCLUDE_DIR)
+
+foreach (assembly ${assemblies})
+	string(TOLOWER ${assembly} header_name)
+	string(REPLACE "." "_" macro_name ${assembly})
+	string(TOUPPER ${macro_name} macro_name)
+
+	set(lib_name ${assembly}${_lib_suffix})
+
+	if (NOT ${macro_name}_LIBRARY)
+		find_library(${macro_name}_LIBRARY
+			NAMES ${lib_name} ${FX_FIND_ARGS}
+			PATH_SUFFIXES lib
+			PATHS ${FX_SEARCH_PATHS})
+	else ()
+		# on Windows, ensure paths are in canonical format (forward slahes):
+		file(TO_CMAKE_PATH "${${macro_name}_LIBRARY}" ${macro_name}_LIBRARY)
+	endif()
+
+	list(APPEND required_vars ${macro_name}_LIBRARY)
+endforeach (assembly)
+
+unset(FX_FIND_ARGS)
+
+include(FindPackageHandleStandardArgs)
+
+find_package_handle_standard_args(FX
+	REQUIRED_VARS ${required_vars})
+
+if (FX_FOUND)
+	set(created_targets)
+	foreach (assembly ${assemblies})
+		set(target_name ${assembly})
+		string(REPLACE "fx." "" target_name ${target_name})
+		string(SUBSTRING ${target_name} 0 1 target_name_prefix)
+		string(TOUPPER ${target_name_prefix} target_name_prefix)
+		string(SUBSTRING ${target_name} 1 -1 target_name_suffix)
+		set(target_name ${target_name_prefix}${target_name_suffix})
+
+		string(TOLOWER ${assembly} header_name)
+		string(REPLACE "." "_" macro_name ${assembly})
+		string(REPLACE "." "_" macro_name ${assembly})
+		string(TOUPPER ${macro_name} macro_name)
+
+		set(lib_name ${assembly}${_lib_suffix})
+
+		if (NOT TARGET FX::${target_name})
+			add_library(FX::${target_name} UNKNOWN IMPORTED)
+			set_target_properties(FX::${target_name} PROPERTIES
+				INTERFACE_INCLUDE_DIRECTORIES "${FX_INCLUDE_DIR}")
+			target_compile_definitions(FX::${target_name} INTERFACE _CRT_SECURE_NO_WARNINGS=1)
+
+			if (FX_STATIC)
+				target_compile_definitions(FX::${target_name} INTERFACE FX_STATIC=1)
+			endif ()
+
+			set_target_properties(FX::${target_name} PROPERTIES
+				IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+				IMPORTED_LOCATION "${${macro_name}_LIBRARY}")
+			set(created_targets ${created_targets} ${assembly})
+		endif ()
+	endforeach (assembly)
+endif()