bshell: re-organise build into three separate components

bshell: the front-end binary
bshell.runtime: contains the parser, compiler, and classes needed to run bshell scripts
bshell.core: contains the builtin commandlets and aliases

bshell.runtime/parse/syntax/statement.c

@@ -0,0 +1,100 @@
+#include "../syntax.h"
+
+bool peek_statement(struct bshell_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 bshell_parse_ctx *ctx, struct bshell_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, BSHELL_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 bshell_ast_node *convert_single_statement(
+	struct bshell_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 bshell_ast_node *)list;
+	}
+
+	fx_queue_delete(&list->n_statements, first_entry);
+	struct bshell_ast_node *first
+		= fx_unbox(struct bshell_ast_node, first_entry, n_entry);
+	bshell_ast_node_destroy((struct bshell_ast_node *)list);
+
+	return first;
+}
+
+bool parse_statement_list(struct bshell_parse_ctx *ctx, struct bshell_ast_node **out)
+{
+	struct bshell_stmt_list_ast_node *stmt_list
+		= (struct bshell_stmt_list_ast_node *)bshell_ast_node_create(
+			BSHELL_AST_STMT_LIST);
+
+	bool ok = true;
+	while (ok) {
+		parse_linefeed(ctx);
+
+		struct bshell_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, BSHELL_SYM_SEMICOLON)) {
+			break;
+		}
+	}
+
+	if (!ok) {
+		bshell_ast_node_destroy((struct bshell_ast_node *)stmt_list);
+		return false;
+	}
+
+	*out = convert_single_statement(stmt_list);
+	return true;
+}