Issue 147 - [Typed objects] Implement object types

lib/typedObjects/objectTypes.js

+/*
+ * This file is part of Adblock Plus <http://adblockplus.org/>,
+ * Copyright (C) 2006-2014 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+let {fixedPropertyDescriptor, getViewsForType, defineProperties} = require("typedObjects/utils");
+let {Reference, TypedReference} = require("typedObjects/references");
+
+/**
+ * List of registered types (typeId is the index in that array).
+ */
+let types = [];
+
+function fromReference(reference)
+{
+  let typeInfo = reference.typeInfo;
+  if (typeInfo)
+  {
+    return Object.create(typeInfo.proto, {
+      typeId: fixedPropertyDescriptor(typeInfo.typeId),
+      bufferIndex: fixedPropertyDescriptor(reference.targetBufferIndex),
+      byteOffset: fixedPropertyDescriptor(reference.targetByteOffset)
+    });
+  }
+  else
+    return null;
+}
+
+function create()
+{
+  let {bufferIndex, byteOffset} = this.firstFree;
+  if (bufferIndex >= 0)
+  {
+    // There is still a free spot, simply move on firstFree reference
+    [this.firstFree.bufferIndex, this.firstFree.byteOffset] =
+        [this.firstFree.targetBufferIndex, this.firstFree.targetByteOffset];
+  }
+  else
+  {
+    let viewTypes = this.viewTypes;
+    let views = this.views;
+    let byteLength = this.byteLength | 0;
+    let bufferSize = this.bufferSize | 0;
+
+    // Create new buffer and use the first element of it
+    let buffer = new ArrayBuffer(byteLength * bufferSize);
+    bufferIndex = (this.buffers.push(buffer) | 0) - 1;
+    byteOffset = 0;
+    for (let i = 0, l = viewTypes.length | 0; i < l; i++)
+      views[i].push(new viewTypes[i](buffer));
+
+    // Mark last element of the new buffer as the last free spot
+    this.firstFree.bufferIndex = bufferIndex;
+    this.firstFree.byteOffset = (bufferSize - 1) * byteLength;
+    this.firstFree.targetBufferIndex = -1;
+
+    // Make each remaining element of the new buffer point to the next one
+    for (let i = bufferSize - 2; i >= 1; i--)
+    {
+      let nextByteOffset = this.firstFree.byteOffset;
+      this.firstFree.byteOffset = nextByteOffset - byteLength;
+      this.firstFree.targetBufferIndex = bufferIndex;
+      this.firstFree.targetByteOffset = nextByteOffset;
+    }
+  }
+
+  let result = Object.create(this.proto, {
+    typeId: fixedPropertyDescriptor(this.typeId),
+    bufferIndex: fixedPropertyDescriptor(bufferIndex),
+    byteOffset: fixedPropertyDescriptor(byteOffset)
+  });
+  if (this.constructor)
+    this.constructor.apply(result, arguments);
+  return result;
+}
+
+function createGetter(offset)
+{
+  offset = offset | 0;
+
+  let views = Array.prototype.slice.call(arguments, 1);
+  let reference = new Reference(types, views);
+  return function()
+  {
+    reference.bufferIndex = this.bufferIndex | 0;
+    reference.byteOffset = (this.byteOffset | 0) + offset;
+    return fromReference(reference);
+  };
+}
+
+function createSetter(typeId, offset)
+{
+  typeId = typeId | 0;
+  offset = offset | 0;
+
+  let views = Array.prototype.slice.call(arguments, 2);
+  let reference = new Reference(types, views);
+  return function(value)
+  {
+    if (value && value.typeId != typeId)
+      throw new Error("Incompatible type");
+
+    reference.bufferIndex = this.bufferIndex | 0;
+    reference.byteOffset = (this.byteOffset | 0) + offset;
+    if (value)
+    {
+      reference.typeId = value.typeId;
+      reference.targetBufferIndex = value.bufferIndex;
+      reference.targetByteOffset = value.byteOffset;
+    }
+    else
+      reference.typeId = -1;
+  };
+}
+
+function ObjectType(properties, meta)
+{
+  if (typeof meta != "object" || meta == null)
+    meta = {};
+
+  let propList = [];
+  let proto = {};
+  let maxReferenceLength = TypedReference.byteLength | 0;
+  for (let name in properties)
+  {
+    let type = properties[name];
+    if (type && typeof type.referenceLength == "number")
+    {
+      // Property with type
+      propList.push([name, type]);
+
+      let referenceLength = type.referenceLength | 0;
+      if (referenceLength > maxReferenceLength)
+        maxReferenceLength = referenceLength;
+    }
+    else if (typeof type == "function")
+    {
+      // Method
+      Object.defineProperty(proto, name, fixedPropertyDescriptor(type));
+    }
+    else
+      throw new Error("Unrecognized type " + type + " given for property " + name);
+  }
+
+  let buffers = [];
+  let viewTypes = [];
+  let views = [];
+  let byteLength = defineProperties(proto, propList, viewTypes, views, 0);
+
+  // Round up to be a multiple of the maximal property size
+  byteLength = ((byteLength - 1) | (maxReferenceLength - 1)) + 1;
+
+  // We need to be able to store a typed reference in the object's buffer
+  byteLength = Math.max(byteLength, TypedReference.byteLength) | 0;
+  let typedReferenceViews = getViewsForType(TypedReference, viewTypes, views);
+
+  let typeId = types.length | 0;
+  let typeInfo = {
+    byteLength: byteLength,
+    bufferSize: "bufferSize" in meta ? Math.max(meta.bufferSize | 0, 2) : 128,
+    firstFree: new TypedReference(typeId, typedReferenceViews),
+    proto: proto,
+    buffers: buffers,
+    viewTypes: viewTypes,
+    views: views,
+    typeId: typeId,
+    constructor: (meta.hasOwnProperty("constructor") && typeof meta.constructor == "function" ? meta.constructor : null)
+  };
+
+  let result = create.bind(typeInfo);
+  Object.defineProperties(result, {
+    byteLength: fixedPropertyDescriptor(byteLength),
+
+    referenceLength: fixedPropertyDescriptor(Reference.byteLength),
+    viewTypes: fixedPropertyDescriptor(Reference.viewTypes),
+
+    typeId: fixedPropertyDescriptor(typeId),
+
+    createGetter: fixedPropertyDescriptor(createGetter),
+    createSetter: fixedPropertyDescriptor(createSetter.bind(null, typeId))
+  });
+  types.push(typeInfo);
+  return result;
+}
+exports.ObjectType = ObjectType;