Bindings layer for declarative events API

chrome/renderer/resources/extensions/experimental.declarative_custom_bindings.js

+// Copyright (c) 2012 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.
+
+// Custom bindings for the declarative API.
+
+(function() {
+
+native function GetChromeHidden();
+
+var chromeHidden = GetChromeHidden();
+
+chromeHidden.registerCustomHook(
+    'experimental.declarative',
+    function(bindingsAPI) {
+  var apiFunctions = bindingsAPI.apiFunctions;
+  var sendRequest = bindingsAPI.sendRequest;
+  var apiDefinitions = bindingsAPI.apiDefinitions;
+  var cachedEventOptions = {};
+
+  function getEventOptions(qualifiedEventName) {
+    if (cachedEventOptions[qualifiedEventName])
+      return cachedEventOptions[qualifiedEventName];
+
+    // Parse qualifiedEventName into namespace and event name.
+    var lastSeparator = qualifiedEventName.lastIndexOf(".");
+    var eventName = qualifiedEventName.substr(lastSeparator + 1);
+    var namespace = qualifiedEventName.substr(0, lastSeparator);
+
+    // Lookup schema definition.
+    var filterNamespace = function(val) {return val.namespace === namespace;};
+    var apiSchema = apiDefinitions.filter(filterNamespace)[0];
+    var filterEventName = function (val) {return val.name === eventName;};
+    var eventSchema = apiSchema.events.filter(filterEventName)[0];
+
+    cachedEventOptions[qualifiedEventName] = eventSchema.options;
+    return eventSchema.options;
+  }
+
+  // Takes a list of JSON datatype identifiers and returns a schema fragment
+  // that verifies that a JSON object corresponds to an array of only these
+  // data types.
+  function buildArrayOfChoicesSchema(typesList) {
+    return {
+      "type": "array",
+      "items": {
+        "choices": typesList.map(function(el) {return {"$ref": el};})
+      }
+    };
+  }
+
+  // Validate conditions and actions against specific schemas of this
+  // event object type.
+  // |rules| is an array of JSON objects that follow the Rule type of the
+  // declarative extension APIs. |conditions| is an array of JSON type
+  // identifiers that are allowed to occur in the conditions attribute of each
+  // rule. Likewise, |actions| is an array of JSON type identifiers that are
+  // allowed to occur in the actions attribute of each rule.
+  function validateRules(rules, conditions, actions) {
+    var conditionsSchema = buildArrayOfChoicesSchema(conditions);
+    var actionsSchema = buildArrayOfChoicesSchema(actions);
+    rules.forEach(function(rule) {
+      chromeHidden.validate([rule.conditions], [conditionsSchema]);
+      chromeHidden.validate([rule.actions], [actionsSchema]);
+    })
+  }
+
+  apiFunctions.setHandleRequest("experimental.declarative.addRules",
+      function(eventName, rules, opt_callback) {
+    var eventOptions = getEventOptions(eventName);
+    if (!eventOptions.conditions || !eventOptions.actions) {
+      throw new Error("Event " + eventName + " misses conditions or " +
+                      "actions in the API specification.");
+    }
+    validateRules(rules,
+                  eventOptions.conditions,
+                  eventOptions.actions);
+    sendRequest(this.name, [eventName, rules, opt_callback],
+                this.definition.parameters);
+  });
+});
+
+})();