bshell/bshell.runtime/parse/syntax/statement.c

#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;
}