1 files changed, 123 insertions, 0 deletions
diff --git a/devtools/client/fronts/page-style.js b/devtools/client/fronts/page-style.js
new file mode 100644
index 0000000000..dfe9f593e4
--- /dev/null
+++ b/devtools/client/fronts/page-style.js
@@ -0,0 +1,123 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  FrontClassWithSpec,
+  registerFront,
+} = require("resource://devtools/shared/protocol.js");
+const {
+  pageStyleSpec,
+} = require("resource://devtools/shared/specs/page-style.js");
+
+/**
+ * PageStyleFront, the front object for the PageStyleActor
+ */
+class PageStyleFront extends FrontClassWithSpec(pageStyleSpec) {
+  _attributesCache = new Map();
+
+  constructor(conn, targetFront, parentFront) {
+    super(conn, targetFront, parentFront);
+    this.inspector = this.getParent();
+
+    this._clearAttributesCache = this._clearAttributesCache.bind(this);
+    this.on("stylesheet-updated", this._clearAttributesCache);
+    this.walker.on("new-mutations", this._clearAttributesCache);
+  }
+
+  form(form) {
+    this._form = form;
+  }
+
+  get walker() {
+    return this.inspector.walker;
+  }
+
+  get supportsFontStretchLevel4() {
+    return this._form.traits && this._form.traits.fontStretchLevel4;
+  }
+
+  get supportsFontStyleLevel4() {
+    return this._form.traits && this._form.traits.fontStyleLevel4;
+  }
+
+  get supportsFontVariations() {
+    return this._form.traits && this._form.traits.fontVariations;
+  }
+
+  get supportsFontWeightLevel4() {
+    return this._form.traits && this._form.traits.fontWeightLevel4;
+  }
+
+  getMatchedSelectors(node, property, options) {
+    return super.getMatchedSelectors(node, property, options).then(ret => {
+      return ret.matched;
+    });
+  }
+
+  async getApplied(node, options = {}) {
+    const ret = await super.getApplied(node, options);
+    return ret.entries;
+  }
+
+  addNewRule(node, pseudoClasses) {
+    return super.addNewRule(node, pseudoClasses).then(ret => {
+      return ret.entries[0];
+    });
+  }
+
+  /**
+   * Get an array of existing attribute values in a node document, given an attribute type.
+   *
+   * @param {String} search: A string to filter attribute value on.
+   * @param {String} attributeType: The type of attribute we want to retrieve the values.
+   * @param {Element} node: The element we want to get possible attributes for. This will
+   *        be used to get the document where the search is happening.
+   * @returns {Array<String>} An array of strings
+   */
+  async getAttributesInOwnerDocument(search, attributeType, node) {
+    if (!attributeType) {
+      throw new Error("`type` should not be empty");
+    }
+
+    if (!search) {
+      return [];
+    }
+
+    const lcFilter = search.toLowerCase();
+
+    // If the new filter includes the string that was used on our last trip to the server,
+    // we can filter the cached results instead of calling the server again.
+    if (
+      this._attributesCache &&
+      this._attributesCache.has(attributeType) &&
+      search.startsWith(this._attributesCache.get(attributeType).search)
+    ) {
+      const cachedResults = this._attributesCache
+        .get(attributeType)
+        .results.filter(item => item.toLowerCase().startsWith(lcFilter));
+      this.emitForTests(
+        "getAttributesInOwnerDocument-cache-hit",
+        cachedResults
+      );
+      return cachedResults;
+    }
+
+    const results = await super.getAttributesInOwnerDocument(
+      search,
+      attributeType,
+      node
+    );
+    this._attributesCache.set(attributeType, { search, results });
+    return results;
+  }
+
+  _clearAttributesCache() {
+    this._attributesCache.clear();
+  }
+}
+
+exports.PageStyleFront = PageStyleFront;
+registerFront(PageStyleFront);