src/d8.js

// Copyright 2008 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

"use strict";

// A more universal stringify that supports more types than JSON.
// Used by the d8 shell to output results.
var stringifyDepthLimit = 4;  // To avoid crashing on cyclic objects

function Stringify(x, depth) {
  if (depth === undefined)
    depth = stringifyDepthLimit;
  else if (depth === 0)
    return "*";
  if (IS_PROXY(x)) {
    return StringifyProxy(x, depth);
  }
  switch (typeof x) {
    case "undefined":
      return "undefined";
    case "boolean":
    case "number":
    case "function":
      return x.toString();
    case "string":
      return "\"" + x.toString() + "\"";
    case "symbol":
      return x.toString();
    case "object":
      if (IS_NULL(x)) return "null";
      try {
        return StringifyObject(x, depth);
      } catch(RangeError) {
        return "{*}"
      }
    default:
      return "[crazy non-standard value]";
  }
}

function StringifyObject(x, depth) {
  if (x.constructor && x.constructor.name === "Array") {
    var elems = [];
    for (var i = 0; i < x.length; ++i) {
      elems.push(
        {}.hasOwnProperty.call(x, i) ? Stringify(x[i], depth - 1) : "");
    }
    return "[" + elems.join(", ") + "]";
  }
  try {
    var string = String(x);
    if (string && string !== "[object Object]") return string;
  } catch(e) {}
  var props = [];
  var names = Object.getOwnPropertyNames(x);
  names = names.concat(Object.getOwnPropertySymbols(x));
  for (var i in names) {
    var name = names[i];
    var desc = Object.getOwnPropertyDescriptor(x, name);
    if (IS_UNDEFINED(desc)) continue;
    if (IS_SYMBOL(name)) name = "[" + Stringify(name) + "]";
    if ("value" in desc) {
      props.push(name + ": " + Stringify(desc.value, depth - 1));
    }
    if (desc.get) {
      var getter = Stringify(desc.get);
      props.push("get " + name + getter.slice(getter.indexOf('(')));
    }
    if (desc.set) {
      var setter = Stringify(desc.set);
      props.push("set " + name + setter.slice(setter.indexOf('(')));
    }
  }
  return "{" + props.join(", ") + "}";
}

function StringifyProxy(proxy, depth) {
  var proxy_type = typeof proxy;
  return '[' + proxy_type + ' Proxy ' + Stringify({
    target: %JSProxyGetTarget(proxy),
    handler: %JSProxyGetHandler(proxy)
  }, depth-1) + ']';
}