1 files changed, 209 insertions, 0 deletions
diff --git a/devtools/client/framework/source-map-service.js b/devtools/client/framework/source-map-service.js
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+++ b/devtools/client/framework/source-map-service.js
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+/* 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 { Task } = require("devtools/shared/task");
+const EventEmitter = require("devtools/shared/event-emitter");
+const { LocationStore, serialize, deserialize } = require("./location-store");
+
+/**
+ * A manager class that wraps a TabTarget and listens to source changes
+ * from source maps and resolves non-source mapped locations to the source mapped
+ * versions and back and forth, and creating smart elements with a location that
+ * auto-update when the source changes (from pretty printing, source maps loading, etc)
+ *
+ * @param {TabTarget} target
+ */
+
+function SourceMapService(target) {
+  this._target = target;
+  this._locationStore = new LocationStore();
+  this._isNotSourceMapped = new Map();
+
+  EventEmitter.decorate(this);
+
+  this._onSourceUpdated = this._onSourceUpdated.bind(this);
+  this._resolveLocation = this._resolveLocation.bind(this);
+  this._resolveAndUpdate = this._resolveAndUpdate.bind(this);
+  this.subscribe = this.subscribe.bind(this);
+  this.unsubscribe = this.unsubscribe.bind(this);
+  this.reset = this.reset.bind(this);
+  this.destroy = this.destroy.bind(this);
+
+  target.on("source-updated", this._onSourceUpdated);
+  target.on("navigate", this.reset);
+  target.on("will-navigate", this.reset);
+}
+
+/**
+ * Clears the store containing the cached promised locations
+ */
+SourceMapService.prototype.reset = function () {
+  // Guard to prevent clearing the store when it is not initialized yet.
+  if (!this._locationStore) {
+    return;
+  }
+  this._locationStore.clear();
+  this._isNotSourceMapped.clear();
+};
+
+SourceMapService.prototype.destroy = function () {
+  this.reset();
+  this._target.off("source-updated", this._onSourceUpdated);
+  this._target.off("navigate", this.reset);
+  this._target.off("will-navigate", this.reset);
+  this._target.off("close", this.destroy);
+  this._target = this._locationStore = this._isNotSourceMapped = null;
+};
+
+/**
+ * Sets up listener for the callback to update the FrameView
+ * and tries to resolve location, if it is source-mappable
+ * @param location
+ * @param callback
+ */
+SourceMapService.prototype.subscribe = function (location, callback) {
+  // A valid candidate location for source-mapping should have a url and line.
+  // Abort if there's no `url`, which means it's unsourcemappable anyway,
+  // like an eval script.
+  // From previous attempts to source-map locations, we also determine if a location
+  // is not source-mapped.
+  if (!location.url || !location.line || this._isNotSourceMapped.get(location.url)) {
+    return;
+  }
+  this.on(serialize(location), callback);
+  this._locationStore.set(location);
+  this._resolveAndUpdate(location);
+};
+
+/**
+ * Removes the listener for the location and clears cached locations
+ * @param location
+ * @param callback
+ */
+SourceMapService.prototype.unsubscribe = function (location, callback) {
+  this.off(serialize(location), callback);
+  // Check to see if the store exists before attempting to clear a location
+  // Sometimes un-subscribe happens during the destruction cascades and this
+  // condition is to protect against that. Could be looked into in the future.
+  if (!this._locationStore) {
+    return;
+  }
+  this._locationStore.clearByURL(location.url);
+};
+
+/**
+ * Tries to resolve the location and if successful,
+ * emits the resolved location
+ * @param location
+ * @private
+ */
+SourceMapService.prototype._resolveAndUpdate = function (location) {
+  this._resolveLocation(location).then(resolvedLocation => {
+    // We try to source map the first console log to initiate the source-updated
+    // event from target. The isSameLocation check is to make sure we don't update
+    // the frame, if the location is not source-mapped.
+    if (resolvedLocation && !isSameLocation(location, resolvedLocation)) {
+      this.emit(serialize(location), location, resolvedLocation);
+    }
+  });
+};
+
+/**
+ * Checks if there is existing promise to resolve location, if so returns cached promise
+ * if not, tries to resolve location and returns a promised location
+ * @param location
+ * @return Promise<Object>
+ * @private
+ */
+SourceMapService.prototype._resolveLocation = Task.async(function* (location) {
+  let resolvedLocation;
+  const cachedLocation = this._locationStore.get(location);
+  if (cachedLocation) {
+    resolvedLocation = cachedLocation;
+  } else {
+    const promisedLocation = resolveLocation(this._target, location);
+    if (promisedLocation) {
+      this._locationStore.set(location, promisedLocation);
+      resolvedLocation = promisedLocation;
+    }
+  }
+  return resolvedLocation;
+});
+
+/**
+ * Checks if the `source-updated` event is fired from the target.
+ * Checks to see if location store has the source url in its cache,
+ * if so, tries to update each stale location in the store.
+ * Determines if the source should be source-mapped or not.
+ * @param _
+ * @param sourceEvent
+ * @private
+ */
+SourceMapService.prototype._onSourceUpdated = function (_, sourceEvent) {
+  let { type, source } = sourceEvent;
+
+  // If we get a new source, and it's not a source map, abort;
+  // we can have no actionable updates as this is just a new normal source.
+  // Check Source Actor for sourceMapURL property (after Firefox 48)
+  // If not present, utilize isSourceMapped and isPrettyPrinted properties
+  // to estimate if a source is not source-mapped.
+  const isNotSourceMapped = !(source.sourceMapURL ||
+    source.isSourceMapped || source.isPrettyPrinted);
+  if (type === "newSource" && isNotSourceMapped) {
+    this._isNotSourceMapped.set(source.url, true);
+    return;
+  }
+  let sourceUrl = null;
+  if (source.generatedUrl && source.isSourceMapped) {
+    sourceUrl = source.generatedUrl;
+  } else if (source.url && source.isPrettyPrinted) {
+    sourceUrl = source.url;
+  }
+  const locationsToResolve = this._locationStore.getByURL(sourceUrl);
+  if (locationsToResolve.length) {
+    this._locationStore.clearByURL(sourceUrl);
+    for (let location of locationsToResolve) {
+      this._resolveAndUpdate(deserialize(location));
+    }
+  }
+};
+
+exports.SourceMapService = SourceMapService;
+
+/**
+ * Take a TabTarget and a location, containing a `url`, `line`, and `column`, resolve
+ * the location to the latest location (so a source mapped location, or if pretty print
+ * status has been updated)
+ *
+ * @param {TabTarget} target
+ * @param {Object} location
+ * @return {Promise<Object>}
+ */
+function resolveLocation(target, location) {
+  return Task.spawn(function* () {
+    let newLocation = yield target.resolveLocation({
+      url: location.url,
+      line: location.line,
+      column: location.column || Infinity
+    });
+    // Source or mapping not found, so don't do anything
+    if (newLocation.error) {
+      return null;
+    }
+    return newLocation;
+  });
+}
+
+/**
+ * Returns true if the original location and resolved location are the same
+ * @param location
+ * @param resolvedLocation
+ * @returns {boolean}
+ */
+function isSameLocation(location, resolvedLocation) {
+  return location.url === resolvedLocation.url &&
+    location.line === resolvedLocation.line &&
+    location.column === resolvedLocation.column;
+}