Mojo JS Bindings: add support for associative arrays (Mojo map type)

mojo/public/js/bindings/codec.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 define("mojo/public/js/bindings/codec", [
   "mojo/public/js/bindings/unicode",
-  "mojo/public/js/bindings/buffer"
-  ], function(unicode, buffer) {
+  "mojo/public/js/bindings/buffer",
+], function(unicode, buffer) {
 
   var kErrorUnsigned = "Passing negative value to unsigned";
 
   // Memory -------------------------------------------------------------------
 
   var kAlignment = 8;
 
   function align(size) {
     return size + (kAlignment - (size % kAlignment)) % kAlignment;
   }
 
   function isAligned(offset) {
     return offset >= 0 && (offset % kAlignment) === 0;
   }
 
   // Constants ----------------------------------------------------------------
 
   var kArrayHeaderSize = 8;
   var kStructHeaderSize = 8;
   var kMessageHeaderSize = 16;
   var kMessageWithRequestIDHeaderSize = 24;
+  var kMapStructSize = 16;

[yzshen1, 2014/10/15 05:58:02]

It doesn't include the struct header itself, right? It seems
kMapStructPayloadSize is more suitable.

[hansmuller, 2014/10/15 21:45:46]

Done.

 
   var kStructHeaderNumBytesOffset = 0;
   var kStructHeaderNumFieldsOffset = 4;
 
   var kEncodedInvalidHandleValue = 0xFFFFFFFF;
 
   // Decoder ------------------------------------------------------------------
 
   function Decoder(buffer, handles, base) {
     this.buffer = buffer;
@@ skipping 133 matching lines @@
   };
 
   Decoder.prototype.decodeStringPointer = function() {
     var pointer = this.decodePointer();
     if (!pointer) {
       return null;
     }
     return this.decodeAndCreateDecoder(pointer).decodeString();
   };
 
+  Decoder.prototype.decodeMap = function(keyClass, valueClass) {
+    this.skip(4); // numberOfBytes
+    this.skip(4); // numberOfFields

[qsr, 2014/10/15 13:03:40]

Don't you want to check that the header is the one you expect?

[hansmuller, 2014/10/15 21:45:46]

Yes. That will happen when the incoming message is validated.

+    var keys = this.decodeArrayPointer(keyClass);
+    var values = this.decodeArrayPointer(valueClass);
+    var val = new Map();
+    for (var i = 0; i < keys.length; i++)
+      val.set(keys[i], values[i]);
+    return val;
+  };
+
+  Decoder.prototype.decodeMapPointer = function(keyClass, valueClass) {
+    var pointer = this.decodePointer();
+    if (!pointer) {
+      return null;
+    }
+    var decoder = this.decodeAndCreateDecoder(pointer);
+    return decoder.decodeMap(keyClass, valueClass);
+  };
+
   // Encoder ------------------------------------------------------------------
 
   function Encoder(buffer, handles, base) {
     this.buffer = buffer;
     this.handles = handles;
     this.base = base;
     this.next = base;
   }
 
   Encoder.prototype.skip = function(offset) {
@@ skipping 149 matching lines @@
     if (val == null) {
       // Also handles undefined, since undefined == null.
       this.encodePointer(val);
       return;
     }
     var encodedSize = kArrayHeaderSize + unicode.utf8Length(val);
     var encoder = this.createAndEncodeEncoder(encodedSize);
     encoder.encodeString(val);
   };
 
+  Encoder.prototype.encodeMap = function(keyClass, valueClass, val) {
+    var keys = new Array(val.size);
+    var values = new Array(val.size);
+    var i = 0;
+    val.forEach(function(value, key) {
+      values[i] = value;
+      keys[i++] = key;
+    });

[abarth-chromium, 2014/10/15 04:53:26]

for (var [key, value] of val) {
  ...
}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Obje...

Not sure if that works in V8, but it's worth a try.  :)

[hansmuller, 2014/10/15 21:45:46]

That would be nicer. I gave it a try; it doesn't appear to supported yet.

+    this.writeUint32(kMapStructSize);

[yzshen1, 2014/10/15 05:58:02]

num_bytes should also include the header size.

[hansmuller, 2014/10/15 21:45:46]

Yes it should! Sorry about that.

+    this.writeUint32(2);
+    this.encodeArrayPointer(keyClass, keys);
+    this.encodeArrayPointer(valueClass, values);
+  }
+
+  Encoder.prototype.encodeMapPointer = function(keyClass, valueClass, val) {
+    if (val == null) {
+      // Also handles undefined, since undefined == null.
+      this.encodePointer(val);
+      return;
+    }
+    var encodedSize = kStructHeaderSize + kMapStructSize;
+    var encoder = this.createAndEncodeEncoder(encodedSize);
+    encoder.encodeMap(keyClass, valueClass, val);
+  };
+
   // Message ------------------------------------------------------------------
 
   var kMessageNameOffset = kStructHeaderSize;
   var kMessageFlagsOffset = kMessageNameOffset + 4;
   var kMessageRequestIDOffset = kMessageFlagsOffset + 4;
 
   var kMessageExpectsResponse = 1 << 0;
   var kMessageIsResponse      = 1 << 1;
 
   function Message(buffer, handles) {
@@ skipping 368 matching lines @@
   exports.NullableString = NullableString;
   exports.PointerTo = PointerTo;
   exports.NullablePointerTo = NullablePointerTo;
   exports.ArrayOf = ArrayOf;
   exports.NullableArrayOf = NullableArrayOf;
   exports.PackedBool = PackedBool;
   exports.Handle = Handle;
   exports.NullableHandle = NullableHandle;
   return exports;
 });