lang: replace stack-based parser with a recursive parser

lang/parse/try-catch.c

@@ -0,0 +1,49 @@
+#include "ctx.h"
+
+#include <ivy/lang/ast.h>
+
+bool parse_try(struct ivy_parser *parser, struct ivy_ast_node **out)
+{
+	if (!parse_keyword(parser, IVY_KW_TRY)) {
+		parse_trace(parser, "expected `try` keyword");
+		return false;
+	}
+
+	struct ivy_ast_try_node *try = create_node(IVY_AST_TRY);
+
+	if (!parse_expr(parser, EXPR_PARSE_STOP_KW_CONTROL, &try->n_try)) {
+		parse_trace(parser, "invalid try block");
+		return false;
+	}
+
+	bool ok = true;
+	while (1) {
+		if (!parse_keyword(parser, IVY_KW_CATCH)) {
+			break;
+		}
+
+		struct ivy_ast_node *catch_guard = NULL;
+		struct ivy_ast_node *catch_block = NULL;
+
+		if (!parse_expr(parser, EXPR_PARSE_STOP_LEFT_BRACKET, &catch_guard)) {
+			parse_trace(parser, "invalid catch guard");
+			ok = false;
+			break;
+		}
+
+		if (!parse_block(parser, &catch_block)) {
+			parse_trace(parser, "invalid catch block");
+			ok = false;
+			break;
+		}
+
+		struct ivy_ast_try_catch_node *catch
+			= create_node(IVY_AST_TRY_CATCH);
+		catch->n_pattern = catch_guard;
+		catch->n_block = catch_block;
+		fx_queue_push_back(&try->n_catch, &catch->n_base.n_entry);
+	}
+
+	*out = generic_node(try);
+	return true;
+}