lang: ast: implement for-loop parsing

lang/ast/expr/stmt.c

@@ -6,6 +6,42 @@
 #include <ivy/lang/operator.h>
 #include <stdio.h>
 
+struct token_parse_result stmt_parse_for(
+	struct ivy_parser *ctx, struct ivy_token *tok)
+{
+	struct expr_parser_state *state
+		= parser_get_state(ctx, struct expr_parser_state);
+
+	if (state->s_sub_type == EXPR_SUBTYPE_KEYWORD_ARG) {
+		/* keyword messages have a higher precedence than inline
+		 * conditionals, so treat this as a statement terminator. */
+		struct token_parse_result result
+			= expr_finalise_and_return(ctx, state);
+		result.r_flags |= PARSE_REPEAT_TOKEN;
+		return result;
+	}
+
+	struct ivy_ast_node *expr = NULL;
+	struct token_parse_result result
+		= expr_finalise(ctx, state, IVY_PRECEDENCE_IF_ELSE, &expr);
+	if (result.r_status != IVY_OK) {
+		return result;
+	}
+
+	state->s_prev_token = IVY_KW_FOR;
+
+	if (b_queue_empty(&state->s_operator_stack)
+	    && b_queue_empty(&state->s_output_queue)) {
+		parser_pop_state(ctx, 0);
+	}
+
+	/* if expr is NULL, this is an if-then-else-end statement,
+	 * otherwise, this is an expr-if-else-expr. */
+	parser_push_state(ctx, IVY_AST_FOR_LOOP, (uintptr_t)expr);
+
+	return PARSE_RESULT(IVY_OK, PARSE_REPEAT_TOKEN);
+}
+
 struct token_parse_result stmt_parse_while(
 	struct ivy_parser *ctx, struct ivy_token *tok)
 {