bshell/bshell.runtime/parse/syntax/if-else.c

#include "../syntax.h"

static bool add_branch(
	struct bshell_if_ast_node *group,
	struct bshell_ast_node *cond,
	struct bshell_ast_node *body)
{
	struct bshell_if_branch_ast_node *branch
		= (struct bshell_if_branch_ast_node *)bshell_ast_node_create(
			BSHELL_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 bshell_parse_ctx *ctx, struct bshell_ast_node **out)
{
	if (!parse_keyword(ctx, BSHELL_KW_IF)) {
		return false;
	}

	if (!parse_symbol(ctx, BSHELL_SYM_LEFT_PAREN)) {
		report_error(ctx, "expected `(` after `if`");
		return false;
	}

	struct bshell_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, BSHELL_SYM_RIGHT_PAREN)) {
		report_error(ctx, "expected `)` after if-condition");
		bshell_ast_node_destroy(if_cond);
		return false;
	}

	if (!parse_block(ctx, &if_body)) {
		report_error(ctx, "invalid if body");
		bshell_ast_node_destroy(if_cond);
		return false;
	}

	struct bshell_if_ast_node *if_group
		= (struct bshell_if_ast_node *)bshell_ast_node_create(
			BSHELL_AST_IF);
	if (!if_group) {
		ctx->p_status = BSHELL_ERR_NO_MEMORY;
		bshell_ast_node_destroy(if_cond);
		bshell_ast_node_destroy(if_body);
		return false;
	}

	if (!add_branch(if_group, if_cond, if_body)) {
		ctx->p_status = BSHELL_ERR_NO_MEMORY;
		bshell_ast_node_destroy(if_cond);
		bshell_ast_node_destroy(if_body);
		bshell_ast_node_destroy((struct bshell_ast_node *)if_group);
		return false;
	}

	bool done = false;
	while (!done) {
		struct bshell_ast_node *cond = NULL, *body = NULL;
		if (parse_keyword(ctx, BSHELL_KW_ELSE)) {
			done = true;
		} else if (parse_keyword(ctx, BSHELL_KW_ELSEIF)) {
			if (!parse_symbol(ctx, BSHELL_SYM_LEFT_PAREN)) {
				report_error(
					ctx,
					"expected `(` after `elseif`");
				return false;
			}

			if (!parse_expr(ctx, &cond)) {
				report_error(
					ctx,
					"invalid conditional expression");
				bshell_ast_node_destroy(
					(struct bshell_ast_node *)if_group);
				return false;
			}

			if (!parse_symbol(ctx, BSHELL_SYM_RIGHT_PAREN)) {
				report_error(
					ctx,
					"expected `)` after elseif-condition");
				bshell_ast_node_destroy(if_cond);
				return false;
			}
		} else {
			done = true;
			break;
		}

		if (!parse_block(ctx, &body)) {
			report_error(ctx, "invalid conditional body");
			if (cond) {
				bshell_ast_node_destroy(cond);
			}

			bshell_ast_node_destroy(
				(struct bshell_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) {
				bshell_ast_node_destroy(cond);
			}

			bshell_ast_node_destroy(body);
			bshell_ast_node_destroy(
				(struct bshell_ast_node *)if_group);
			return false;
		}
	}

	*out = (struct bshell_ast_node *)if_group;

	return true;
}