bshell/bshell.runtime/compile/if.c

#include "compile-node.h"

enum bshell_status compile_if(
	struct compile_ctx *ctx,
	struct bshell_ast_node *src)
{
	struct bshell_if_ast_node *if_group;
	if_group = (struct bshell_if_ast_node *)src;
	size_t nr_labels = fx_queue_length(&if_group->n_branches);
	// add one extra label for the end of the if group
	nr_labels++;

	size_t *label_ids = calloc(nr_labels, sizeof *label_ids);
	if (!label_ids) {
		return BSHELL_ERR_NO_MEMORY;
	}

	size_t i;
	for (i = 0; i < nr_labels; i++) {
		label_ids[i] = compile_declare_label(ctx);
	}

	i = 0;
	fx_queue_entry *cur = fx_queue_first(&if_group->n_branches);
	while (cur) {
		struct bshell_if_branch_ast_node *branch;
		branch = fx_unbox(
			struct bshell_if_branch_ast_node,
			cur,
			n_base.n_entry);
		if (!branch->n_cond) {
			compile_block_immediate(ctx, branch->n_body);
			compile_ref_label(ctx, label_ids[nr_labels - 1]);
			bshell_scriptblock_push_instruction(
				ctx->c_block,
				BSHELL_OPCODE_BR,
				0);
			break;
		}

		compile_expression(ctx, branch->n_cond);
		compile_ref_label(ctx, label_ids[i++]);
		bshell_scriptblock_push_instruction(
			ctx->c_block,
			BSHELL_OPCODE_BR_TRUE,
			0);

		cur = fx_queue_next(cur);
	}

	i = 0;
	cur = fx_queue_first(&if_group->n_branches);
	while (cur) {
		struct bshell_if_branch_ast_node *branch = fx_unbox(
			struct bshell_if_branch_ast_node,
			cur,
			n_base.n_entry);
		if (!branch->n_cond) {
			break;
		}

		compile_define_label(ctx, label_ids[i++]);
		compile_block_immediate(ctx, branch->n_body);
		cur = fx_queue_next(cur);

		if (i < nr_labels - 2) {
			compile_ref_label(ctx, label_ids[nr_labels - 1]);
			bshell_scriptblock_push_instruction(
				ctx->c_block,
				BSHELL_OPCODE_BR,
				0);
		}
	}

	compile_define_label(ctx, label_ids[nr_labels - 1]);
	free(label_ids);

	return BSHELL_SUCCESS;
}