reign/lib/builtins/object/index.js

A persistent, typed-objects implementation.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.make = make;

var _any = require("../../hash-functions/any");

var _any2 = _interopRequireDefault(_any);

var _backing = require("backing");

var _backing2 = _interopRequireDefault(_backing);

var _ = require("../..");

var _symbols = require("../../symbols");

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function make(realm) {
  const ObjectType = realm.ObjectType;
  const T = realm.T;


  function constructor(backingOrInput, address) {
    if (!(this instanceof TypedObject)) {
      return TypedObject.cast(backingOrInput);
    }
    if (backingOrInput instanceof _backing2.default) {
      this[_symbols.$Backing] = backingOrInput;
      this[_symbols.$Address] = address;
      createAccessors(this);
    } else if (backingOrInput == null) {
      this[_symbols.$Backing] = realm.backing;
      this[_symbols.$Address] = createEmptyObject(realm.backing);
    } else {
      this[_symbols.$Backing] = realm.backing;
      this[_symbols.$Address] = createObject(realm.backing, backingOrInput);
      // @fixme we should combine createObject and createAccessors to make this faster.
      createAccessors(this);
    }
  }

  const TypedObject = new ObjectType({
    name: 'Object',
    byteAlignment: 8, // Pointer
    byteLength: 8,
    constructor: constructor,
    cast: function cast(input) {
      return input == null ? null : Object(input);
    },
    accepts: function accepts(input) {
      return typeof input === 'object';
    },
    initialize: function initialize(backing, pointerAddress, initialValue) {
      if (initialValue == null) {
        backing.setFloat64(pointerAddress, 0);
      } else {
        backing.setFloat64(pointerAddress, createObject(backing, initialValue, true));
      }
    },
    store: function store(backing, pointerAddress, value) {
      const existing = backing.getFloat64(pointerAddress);
      if (existing === 0) {
        if (value == null) {
          // nothing to do
          return;
        }
      } else {
        backing.gc.unref(existing);
        backing.setFloat64(pointerAddress, 0); // safety: in case the store() fails.
        if (value == null) {
          // all done
          return;
        }
      }

      backing.setFloat64(pointerAddress, createObject(backing, value, true));
    },
    load: function load(backing, pointerAddress) {
      const address = backing.getFloat64(pointerAddress);
      if (address === 0) {
        return null;
      } else {
        return new TypedObject(backing, address);
      }
    },
    clear: function clear(backing, pointerAddress) {
      const address = backing.getFloat64(pointerAddress);
      if (address !== 0) {
        backing.setFloat64(pointerAddress, 0);
        backing.gc.unref(address);
      }
    },

    destructor: destroyObject,
    emptyValue: function emptyValue() {
      return null;
    },
    randomValue: function randomValue() {
      return null;
    },

    hashValue: _any2.default,
    flowType: function flowType() {
      return `Object`;
    }
  });

  function createAccessors(target) {
    const backing = target[_symbols.$Backing];
    const address = target[_symbols.$Address];
    const length = backing.getUint32(address);
    let current = address + 8;
    for (let i = 0; i < length; i++) {
      const name = T.String.load(backing, current);
      const offset = current + 8;
      Object.defineProperty(target, name, {
        enumerable: true,
        get: function get() {
          return T.Any.load(this[_symbols.$Backing], offset);
        },
        set: function set(value) {
          T.Any.store(this[_symbols.$Backing], offset, value);
        }
      });
      current += 24;
    }
  }

  function createEmptyObject(backing, hasReference) {
    return backing.gc.calloc(8, TypedObject.id, hasReference ? 1 : 0);
  }

  function createObject(backing, input, hasReference) {
    if (input instanceof TypedObject && input[_symbols.$Backing] === backing) {
      backing.gc.ref(input[_symbols.$Address]);
      return input[_symbols.$Address];
    }
    const keys = Object.keys(input);
    const length = keys.length;
    const address = backing.gc.alloc(length * 24 + 8, TypedObject.id, hasReference ? 1 : 0);
    backing.setUint32(address, length);
    let current = address + 8;
    for (let i = 0; i < length; i++) {
      const key = keys[i];
      backing.setFloat64(current, realm.strings.add(key));
      current += 8;
      T.Any.initialize(backing, current, input[key]);
      current += 16;
    }
    return address;
  }

  function loadObject(backing, address) {
    const output = {
      // Issue 252
      [_symbols.$Backing]: backing,
      // Issue 252
      [_symbols.$Address]: address
    };
    const length = backing.getUint32(address);
    let current = address + 8;
    for (let i = 0; i < length; i++) {
      output[T.String.load(backing, current)] = T.Any.load(backing, current + 8);
      current += 24;
    }
    return output;
  }

  function clearObject(backing, address) {
    const length = backing.getUint32(address);
    let current = address + 8;
    for (let i = 0; i < length; i++) {
      current += 8;
      T.Any.clear(backing, current);
      current += 16;
    }
  }

  function destroyObject(backing, address) {
    const length = backing.getUint32(address);
    backing.setUint32(address, 0); // prevent further reads.
    let current = address + 8;
    for (let i = 0; i < length; i++) {
      backing.setFloat64(current, 0);
      current += 8;
      T.Any.clear(backing, current);
      current += 16;
    }
  }

  TypedObject[_symbols.$CanBeEmbedded] = false;

  return TypedObject;
}