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      1 // Copyright 2008 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 "use strict";
      6 
      7 // A more universal stringify that supports more types than JSON.
      8 // Used by the d8 shell to output results.
      9 var stringifyDepthLimit = 4;  // To avoid crashing on cyclic objects
     10 
     11 // Hacky solution to circumvent forcing --allow-natives-syntax for d8
     12 function isProxy(o) { return false };
     13 function JSProxyGetTarget(proxy) { };
     14 function JSProxyGetHandler(proxy) { };
     15 
     16 try {
     17   isProxy = Function(['object'], 'return %_IsJSProxy(object)');
     18   JSProxyGetTarget = Function(['proxy'],
     19     'return %JSProxyGetTarget(proxy)');
     20   JSProxyGetHandler = Function(['proxy'],
     21     'return %JSProxyGetHandler(proxy)');
     22 } catch(e) {};
     23 
     24 
     25 function Stringify(x, depth) {
     26   if (depth === undefined)
     27     depth = stringifyDepthLimit;
     28   else if (depth === 0)
     29     return "...";
     30   if (isProxy(x)) {
     31     return StringifyProxy(x, depth);
     32   }
     33   switch (typeof x) {
     34     case "undefined":
     35       return "undefined";
     36     case "boolean":
     37     case "number":
     38     case "function":
     39       return x.toString();
     40     case "string":
     41       return "\"" + x.toString() + "\"";
     42     case "symbol":
     43       return x.toString();
     44     case "object":
     45       if (IS_NULL(x)) return "null";
     46       if (x.constructor && x.constructor.name === "Array") {
     47         var elems = [];
     48         for (var i = 0; i < x.length; ++i) {
     49           elems.push(
     50             {}.hasOwnProperty.call(x, i) ? Stringify(x[i], depth - 1) : "");
     51         }
     52         return "[" + elems.join(", ") + "]";
     53       }
     54       try {
     55         var string = String(x);
     56         if (string && string !== "[object Object]") return string;
     57       } catch(e) {}
     58       var props = [];
     59       var names = Object.getOwnPropertyNames(x);
     60       names = names.concat(Object.getOwnPropertySymbols(x));
     61       for (var i in names) {
     62         var name = names[i];
     63         var desc = Object.getOwnPropertyDescriptor(x, name);
     64         if (IS_UNDEFINED(desc)) continue;
     65         if (IS_SYMBOL(name)) name = "[" + Stringify(name) + "]";
     66         if ("value" in desc) {
     67           props.push(name + ": " + Stringify(desc.value, depth - 1));
     68         }
     69         if (desc.get) {
     70           var getter = Stringify(desc.get);
     71           props.push("get " + name + getter.slice(getter.indexOf('(')));
     72         }
     73         if (desc.set) {
     74           var setter = Stringify(desc.set);
     75           props.push("set " + name + setter.slice(setter.indexOf('(')));
     76         }
     77       }
     78       return "{" + props.join(", ") + "}";
     79     default:
     80       return "[crazy non-standard value]";
     81   }
     82 }
     83 
     84 function StringifyProxy(proxy, depth) {
     85   var proxy_type = typeof proxy;
     86   var info_object = {
     87     target: JSProxyGetTarget(proxy),
     88     handler: JSProxyGetHandler(proxy)
     89   }
     90   return '[' + proxy_type + ' Proxy ' + Stringify(info_object, depth-1) + ']';
     91 }
     92