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

mojo/public/js/bindings/codec.js

Index: mojo/public/js/bindings/codec.js
diff --git a/mojo/public/js/bindings/codec.js b/mojo/public/js/bindings/codec.js
index b922a821d683095065a48846949c78c3451529b1..7a01693fcc98e3c7190efd12bbb79e673d2a9483 100644
--- a/mojo/public/js/bindings/codec.js
+++ b/mojo/public/js/bindings/codec.js
@@ -27,6 +27,7 @@ define("mojo/public/js/bindings/codec", [
   var kStructHeaderSize = 8;
   var kMessageHeaderSize = 16;
   var kMessageWithRequestIDHeaderSize = 24;
+  var kMapStructPayloadSize = 16;
 
   var kStructHeaderNumBytesOffset = 0;
   var kStructHeaderNumFieldsOffset = 4;
@@ -180,6 +181,26 @@ define("mojo/public/js/bindings/codec", [
     return this.decodeAndCreateDecoder(pointer).decodeString();
   };
 
+  Decoder.prototype.decodeMap = function(keyClass, valueClass) {
+    this.skip(4); // numberOfBytes
+    this.skip(4); // numberOfFields
+    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) {
@@ -349,6 +370,31 @@ define("mojo/public/js/bindings/codec", [
     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;
+    });
+    this.writeUint32(kStructHeaderSize + kMapStructPayloadSize);
+    this.writeUint32(2); // two fields: keys, values
+    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 + kMapStructPayloadSize;
+    var encoder = this.createAndEncodeEncoder(encodedSize);
+    encoder.encodeMap(keyClass, valueClass, val);
+  };
+
   // Message ------------------------------------------------------------------
 
   var kMessageNameOffset = kStructHeaderSize;
@@ -710,6 +756,7 @@ define("mojo/public/js/bindings/codec", [
   exports.MessageWithRequestIDBuilder = MessageWithRequestIDBuilder;
   exports.MessageReader = MessageReader;
   exports.kArrayHeaderSize = kArrayHeaderSize;
+  exports.kMapStructPayloadSize = kMapStructPayloadSize;
   exports.kStructHeaderSize = kStructHeaderSize;
   exports.kEncodedInvalidHandleValue = kEncodedInvalidHandleValue;
   exports.kMessageHeaderSize = kMessageHeaderSize;