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fun/src/vm/json/parse.c

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C

/*
* This file is part of the Fun programming language.
* https://fun-lang.xyz/
*
* Copyright 2025 Johannes Findeisen <you@hanez.org>
* Licensed under the terms of the Apache-2.0 license.
* https://opensource.org/license/apache-2-0
*/
/**
* @file parse.c
* @brief VM opcode snippet for parsing a JSON string into a Fun Value.
*
* Implements the OP_JSON_PARSE instruction. Expects a string (or any value
* convertible to string) on the stack, parses it with json-c, converts the
* resulting json_object to a Fun Value and pushes it.
*
* Build gating: compiled only when FUN_WITH_JSON is enabled. Otherwise the
* opcode consumes its argument and pushes Nil.
*
* Stack effect (with FUN_WITH_JSON):
* - Pops: text (any; converted to string)
* - Pushes: Value converted from JSON, or Nil on error
*
* Errors and edge cases:
* - If allocation fails, tokenization fails, or the text is not valid JSON,
* the opcode pushes Nil.
* - The temporary json-c objects are released after conversion; ownership of
* the pushed Fun Value follows normal VM semantics.
*/
/* JSON_PARSE */
case OP_JSON_PARSE: {
#ifdef FUN_WITH_JSON
Value text = pop_value(vm);
char *s = value_to_string_alloc(&text);
free_value(text);
if (!s) {
push_value(vm, make_nil());
break;
}
struct json_tokener *tok = json_tokener_new();
json_object *root = json_tokener_parse_ex(tok, s, (int)strlen(s));
enum json_tokener_error jerr = json_tokener_get_error(tok);
json_tokener_free(tok);
free(s);
if (jerr != json_tokener_success) {
push_value(vm, make_nil());
} else {
Value v = json_to_fun(root);
push_value(vm, v);
json_object_put(root);
}
#else
/* Fallback when JSON is disabled: consume arg, push Nil */
Value drop = pop_value(vm);
free_value(drop);
push_value(vm, make_nil());
#endif
break;
}