Add m-esr52 at 52.6.0

1 files changed, 1645 insertions, 0 deletions

diff --git a/toolkit/components/places/PlacesTransactions.jsm b/toolkit/components/places/PlacesTransactions.jsm
new file mode 100644
index 000000000..c355d92b6
--- /dev/null
+++ b/toolkit/components/places/PlacesTransactions.jsm
@@ -0,0 +1,1645 @@
+/* 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";
+
+this.EXPORTED_SYMBOLS = ["PlacesTransactions"];
+
+/**
+ * Overview
+ * --------
+ * This modules serves as the transactions manager for Places (hereinafter PTM).
+ * It implements all the elementary transactions for its UI commands: creating
+ * items, editing their various properties, and so forth.
+ *
+ * Note that since the effect of invoking a Places command is not limited to the
+ * window in which it was performed (e.g. a folder created in the Library may be
+ * the parent of a bookmark created in some browser window), PTM is a singleton.
+ * It's therefore unnecessary to initialize PTM in any way apart importing this
+ * module.
+ *
+ * PTM shares most of its semantics with common command pattern implementations.
+ * However, the asynchronous design of contemporary and future APIs, combined
+ * with the commitment to serialize all UI operations, does make things a little
+ * bit different.  For example, when |undo| is called in order to undo the top
+ * undo entry, the caller cannot tell for sure what entry would it be, because
+ * the execution of some transactions is either in process, or enqueued to be.
+ *
+ * Also note that unlike the nsITransactionManager, for example, this API is by
+ * no means generic.  That is, it cannot be used to execute anything but the
+ * elementary transactions implemented here (Please file a bug if you find
+ * anything uncovered).  More-complex transactions (e.g. creating a folder and
+ * moving a bookmark into it) may be implemented as a batch (see below).
+ *
+ * A note about GUIDs and item-ids
+ * -------------------------------
+ * There's an ongoing effort (see bug 1071511) to deprecate item-ids in Places
+ * in favor of GUIDs.  Both because new APIs (e.g. Bookmark.jsm) expose them to
+ * the minimum necessary, and because GUIDs play much better with implementing
+ * |redo|, this API doesn't support item-ids at all, and only accepts bookmark
+ * GUIDs, both for input (e.g. for setting the parent folder for a new bookmark)
+ * and for output (when the GUID for such a bookmark is propagated).
+ *
+ * When working in conjugation with older Places API which only expose item ids,
+ * use PlacesUtils.promiseItemGuid for converting those to GUIDs (note that
+ * for result nodes, the guid is available through their bookmarkGuid getter).
+ * Should you need to convert GUIDs to item-ids, use PlacesUtils.promiseItemId.
+ *
+ * Constructing transactions
+ * -------------------------
+ * At the bottom of this module you will find transactions for all Places UI
+ * commands.  They are exposed as constructors set on the PlacesTransactions
+ * object (e.g. PlacesTransactions.NewFolder).  The input for this constructors
+ * is taken in the form of a single argument, a plain object consisting of the
+ * properties for the transaction.  Input properties may be either required or
+ * optional (for example, |keyword| is required for the EditKeyword transaction,
+ * but optional for the NewBookmark transaction).
+ *
+ * To make things simple, a given input property has the same basic meaning and
+ * valid values across all transactions which accept it in the input object.
+ * Here is a list of all supported input properties along with their expected
+ * values:
+ *  - url: a URL object, an nsIURI object, or a href.
+ *  - urls: an array of urls, as above.
+ *  - feedUrl: an url (as above), holding the url for a live bookmark.
+ *  - siteUrl an url (as above), holding the url for the site with which
+ *            a live bookmark is associated.
+ *  - tag - a string.
+ *  - tags: an array of strings.
+ *  - guid, parentGuid, newParentGuid: a valid Places GUID string.
+ *  - guids: an array of valid Places GUID strings.
+ *  - title: a string
+ *  - index, newIndex: the position of an item in its containing folder,
+ *    starting from 0.
+ *    integer and PlacesUtils.bookmarks.DEFAULT_INDEX
+ *  - annotation: see PlacesUtils.setAnnotationsForItem
+ *  - annotations: an array of annotation objects as above.
+ *  - excludingAnnotation: a string (annotation name).
+ *  - excludingAnnotations: an array of string (annotation names).
+ *
+ * If a required property is missing in the input object (e.g. not specifying
+ * parentGuid for NewBookmark), or if the value for any of the input properties
+ * is invalid "on the surface" (e.g. a numeric value for GUID, or a string that
+ * isn't 12-characters long), the transaction constructor throws right way.
+ * More complex errors (e.g. passing a non-existent GUID for parentGuid) only
+ * reveal once the transaction is executed.
+ *
+ * Executing Transactions (the |transact| method of transactions)
+ * --------------------------------------------------------------
+ * Once a transaction is created, you must call its |transact| method for it to
+ * be executed and take effect.  |transact| is an asynchronous method that takes
+ * no arguments, and returns a promise that resolves once the transaction is
+ * executed.  Executing one of the transactions for creating items (NewBookmark,
+ * NewFolder, NewSeparator or NewLivemark) resolve to the new item's GUID.
+ * There's no resolution value for other transactions.
+ * If a transaction fails to execute, |transact| rejects and the transactions
+ * history is not affected.
+ *
+ * |transact| throws if it's called more than once (successfully or not) on the
+ * same transaction object.
+ *
+ * Batches
+ * -------
+ * Sometimes it is useful to "batch" or "merge" transactions.  For example,
+ * something like "Bookmark All Tabs" may be implemented as one NewFolder
+ * transaction followed by numerous NewBookmark transactions - all to be undone
+ * or redone in a single undo or redo command.  Use |PlacesTransactions.batch|
+ * in such cases.  It can take either an array of transactions which will be
+ * executed in the given order and later be treated a a single entry in the
+ * transactions history, or a generator function that is passed to Task.spawn,
+ * that is to "contain" the batch: once the generator function is called a batch
+ * starts, and it lasts until the asynchronous generator iteration is complete
+ * All transactions executed by |transact| during this time are to be treated as
+ * a single entry in the transactions history.
+ *
+ * In both modes, |PlacesTransactions.batch| returns a promise that is to be
+ * resolved when the batch ends.  In the array-input mode, there's no resolution
+ * value.  In the generator mode, the resolution value is whatever the generator
+ * function returned (the semantics are the same as in Task.spawn, basically).
+ *
+ * The array-input mode of |PlacesTransactions.batch| is useful for implementing
+ * a batch of mostly-independent transaction (for example, |paste| into a folder
+ * can be implemented as a batch of multiple NewBookmark transactions).
+ * The generator mode is useful when the resolution value of executing one
+ * transaction is the input of one more subsequent transaction.
+ *
+ * In the array-input mode, if any transactions fails to execute, the batch
+ * continues (exceptions are logged).  Only transactions that were executed
+ * successfully are added to the transactions history.
+ *
+ * WARNING: "nested" batches are not supported, if you call batch while another
+ * batch is still running, the new batch is enqueued with all other PTM work
+ * and thus not run until the running batch ends. The same goes for undo, redo
+ * and clearTransactionsHistory (note batches cannot be done partially, meaning
+ * undo and redo calls that during a batch are just enqueued).
+ *
+ * *****************************************************************************
+ * IT"S PARTICULARLY IMPORTANT NOT TO YIELD ANY PROMISE RETURNED BY ANY OF
+ * THESE METHODS (undo, redo, clearTransactionsHistory) FROM A BATCH FUNCTION.
+ * UNTIL WE FIND A WAY TO THROW IN THAT CASE (SEE BUG 1091446) DOING SO WILL
+ * COMPLETELY BREAK PTM UNTIL SHUTDOWN, NOT ALLOWING THE EXECUTION OF ANY
+ * TRANSACTION!
+ * *****************************************************************************
+ *
+ * Serialization
+ * -------------
+ * All |PlacesTransaction| operations are serialized.  That is, even though the
+ * implementation is asynchronous, the order in which PlacesTransactions methods
+ * is called does guarantee the order in which they are to be invoked.
+ *
+ * The only exception to this rule is |transact| calls done during a batch (see
+ * above).  |transact| calls are serialized with each other (and with undo, redo
+ * and clearTransactionsHistory), but they  are, of course, not serialized with
+ * batches.
+ *
+ * The transactions-history structure
+ * ----------------------------------
+ * The transactions-history is a two-dimensional stack of transactions: the
+ * transactions are ordered in reverse to the order they were committed.
+ * It's two-dimensional because PTM allows batching transactions together for
+ * the purpose of undo or redo (see Batches above).
+ *
+ * The undoPosition property is set to the index of the top entry. If there is
+ * no entry at that index, there is nothing to undo.
+ * Entries prior to undoPosition, if any, are redo entries, the first one being
+ * the top redo entry.
+ *
+ * [ [2nd redo txn, 1st redo txn],  <= 2nd redo entry
+ *   [2nd redo txn, 1st redo txn],  <= 1st redo entry
+ *   [1st undo txn, 2nd undo txn],  <= 1st undo entry
+ *   [1st undo txn, 2nd undo txn]   <= 2nd undo entry ]
+ * undoPostion: 2.
+ *
+ * Note that when a new entry is created, all redo entries are removed.
+ */
+
+Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Promise",
+                                  "resource://gre/modules/Promise.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Task",
+                                  "resource://gre/modules/Task.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
+                                  "resource://gre/modules/NetUtil.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "PlacesUtils",
+                                  "resource://gre/modules/PlacesUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "console",
+                                  "resource://gre/modules/Console.jsm");
+
+Components.utils.importGlobalProperties(["URL"]);
+
+var TransactionsHistory = [];
+TransactionsHistory.__proto__ = {
+  __proto__: Array.prototype,
+
+  // The index of the first undo entry (if any) - See the documentation
+  // at the top of this file.
+  _undoPosition: 0,
+  get undoPosition() {
+    return this._undoPosition;
+  },
+
+  // Handy shortcuts
+  get topUndoEntry() {
+    return this.undoPosition < this.length ? this[this.undoPosition] : null;
+  },
+  get topRedoEntry() {
+    return this.undoPosition > 0 ? this[this.undoPosition - 1] : null;
+  },
+
+  // Outside of this module, the API of transactions is inaccessible, and so
+  // are any internal properties.  To achieve that, transactions are proxified
+  // in their constructors.  This maps the proxies to their respective raw
+  // objects.
+  proxifiedToRaw: new WeakMap(),
+
+  /**
+   * Proxify a transaction object for consumers.
+   * @param aRawTransaction
+   *        the raw transaction object.
+   * @return the proxified transaction object.
+   * @see getRawTransaction for retrieving the raw transaction.
+   */
+  proxifyTransaction: function (aRawTransaction) {
+    let proxy = Object.freeze({
+      transact() {
+        return TransactionsManager.transact(this);
+      }
+    });
+    this.proxifiedToRaw.set(proxy, aRawTransaction);
+    return proxy;
+  },
+
+  /**
+   * Check if the given object is a the proxy object for some transaction.
+   * @param aValue
+   *        any JS value.
+   * @return true if aValue is the proxy object for some transaction, false
+   * otherwise.
+   */
+  isProxifiedTransactionObject(aValue) {
+    return this.proxifiedToRaw.has(aValue);
+  },
+
+  /**
+   * Get the raw transaction for the given proxy.
+   * @param aProxy
+   *        the proxy object
+   * @return the transaction proxified by aProxy; |undefined| is returned if
+   * aProxy is not a proxified transaction.
+   */
+  getRawTransaction(aProxy) {
+    return this.proxifiedToRaw.get(aProxy);
+  },
+
+  /**
+   * Add a transaction either as a new entry, if forced or if there are no undo
+   * entries, or to the top undo entry.
+   *
+   * @param aProxifiedTransaction
+   *        the proxified transaction object to be added to the transaction
+   *        history.
+   * @param [optional] aForceNewEntry
+   *        Force a new entry for the transaction. Default: false.
+   *        If false, an entry will we created only if there's no undo entry
+   *        to extend.
+   */
+  add(aProxifiedTransaction, aForceNewEntry = false) {
+    if (!this.isProxifiedTransactionObject(aProxifiedTransaction))
+      throw new Error("aProxifiedTransaction is not a proxified transaction");
+
+    if (this.length == 0 || aForceNewEntry) {
+      this.clearRedoEntries();
+      this.unshift([aProxifiedTransaction]);
+    }
+    else {
+      this[this.undoPosition].unshift(aProxifiedTransaction);
+    }
+  },
+
+  /**
+   * Clear all undo entries.
+   */
+  clearUndoEntries() {
+    if (this.undoPosition < this.length)
+      this.splice(this.undoPosition);
+  },
+
+  /**
+   * Clear all redo entries.
+   */
+  clearRedoEntries() {
+    if (this.undoPosition > 0) {
+      this.splice(0, this.undoPosition);
+      this._undoPosition = 0;
+    }
+  },
+
+  /**
+   * Clear all entries.
+   */
+  clearAllEntries() {
+    if (this.length > 0) {
+      this.splice(0);
+      this._undoPosition = 0;
+    }
+  }
+};
+
+
+var PlacesTransactions = {
+  /**
+   * @see Batches in the module documentation.
+   */
+  batch(aToBatch) {
+    if (Array.isArray(aToBatch)) {
+      if (aToBatch.length == 0)
+        throw new Error("aToBatch must not be an empty array");
+
+      if (aToBatch.some(
+           o => !TransactionsHistory.isProxifiedTransactionObject(o))) {
+        throw new Error("aToBatch contains non-transaction element");
+      }
+      return TransactionsManager.batch(function* () {
+        for (let txn of aToBatch) {
+          try {
+            yield txn.transact();
+          }
+          catch (ex) {
+            console.error(ex);
+          }
+        }
+      });
+    }
+    if (typeof(aToBatch) == "function") {
+      return TransactionsManager.batch(aToBatch);
+    }
+
+    throw new Error("aToBatch must be either a function or a transactions array");
+  },
+
+  /**
+   * Asynchronously undo the transaction immediately after the current undo
+   * position in the transactions history in the reverse order, if any, and
+   * adjusts the undo position.
+   *
+   * @return {Promises).  The promise always resolves.
+   * @note All undo manager operations are queued. This means that transactions
+   * history may change by the time your request is fulfilled.
+   */
+  undo() {
+    return TransactionsManager.undo();
+  },
+
+  /**
+   * Asynchronously redo the transaction immediately before the current undo
+   * position in the transactions history, if any, and adjusts the undo
+   * position.
+   *
+   * @return {Promises).  The promise always resolves.
+   * @note All undo manager operations are queued. This means that transactions
+   * history may change by the time your request is fulfilled.
+   */
+  redo() {
+    return TransactionsManager.redo();
+  },
+
+  /**
+   * Asynchronously clear the undo, redo, or all entries from the transactions
+   * history.
+   *
+   * @param [optional] aUndoEntries
+   *        Whether or not to clear undo entries.  Default: true.
+   * @param [optional] aRedoEntries
+   *        Whether or not to clear undo entries.  Default: true.
+   *
+   * @return {Promises).  The promise always resolves.
+   * @throws if both aUndoEntries and aRedoEntries are false.
+   * @note All undo manager operations are queued. This means that transactions
+   * history may change by the time your request is fulfilled.
+   */
+  clearTransactionsHistory(aUndoEntries = true, aRedoEntries = true) {
+    return TransactionsManager.clearTransactionsHistory(aUndoEntries, aRedoEntries);
+  },
+
+  /**
+   * The numbers of entries in the transactions history.
+   */
+  get length() {
+    return TransactionsHistory.length;
+  },
+
+  /**
+   * Get the transaction history entry at a given index.  Each entry consists
+   * of one or more transaction objects.
+   *
+   * @param aIndex
+   *        the index of the entry to retrieve.
+   * @return an array of transaction objects in their undo order (that is,
+   * reversely to the order they were executed).
+   * @throw if aIndex is invalid (< 0 or >= length).
+   * @note the returned array is a clone of the history entry and is not
+   * kept in sync with the original entry if it changes.
+   */
+  entry(aIndex) {
+    if (!Number.isInteger(aIndex) || aIndex < 0 || aIndex >= this.length)
+      throw new Error("Invalid index");
+
+    return TransactionsHistory[aIndex];
+  },
+
+  /**
+   * The index of the top undo entry in the transactions history.
+   * If there are no undo entries, it equals to |length|.
+   * Entries past this point
+   * Entries at and past this point are redo entries.
+   */
+  get undoPosition() {
+    return TransactionsHistory.undoPosition;
+  },
+
+  /**
+   * Shortcut for accessing the top undo entry in the transaction history.
+   */
+  get topUndoEntry() {
+    return TransactionsHistory.topUndoEntry;
+  },
+
+  /**
+   * Shortcut for accessing the top redo entry in the transaction history.
+   */
+  get topRedoEntry() {
+    return TransactionsHistory.topRedoEntry;
+  }
+};
+
+/**
+ * Helper for serializing the calls to TransactionsManager methods. It allows
+ * us to guarantee that the order in which TransactionsManager asynchronous
+ * methods are called also enforces the order in which they're executed, and
+ * that they are never executed in parallel.
+ *
+ * In other words: Enqueuer.enqueue(aFunc1); Enqueuer.enqueue(aFunc2) is roughly
+ * the same as Task.spawn(aFunc1).then(Task.spawn(aFunc2)).
+ */
+function Enqueuer() {
+  this._promise = Promise.resolve();
+}
+Enqueuer.prototype = {
+  /**
+   * Spawn a functions once all previous functions enqueued are done running,
+   * and all promises passed to alsoWaitFor are no longer pending.
+   *
+   * @param   aFunc
+   *          @see Task.spawn.
+   * @return  a promise that resolves once aFunc is done running. The promise
+   *          "mirrors" the promise returned by aFunc.
+   */
+  enqueue(aFunc) {
+    let promise = this._promise.then(Task.async(aFunc));
+
+    // Propagate exceptions to the caller, but dismiss them internally.
+    this._promise = promise.catch(console.error);
+    return promise;
+  },
+
+  /**
+   * Same as above, but for a promise returned by a function that already run.
+   * This is useful, for example, for serializing transact calls with undo calls,
+   * even though transact has its own Enqueuer.
+   *
+   * @param aPromise
+   *        any promise.
+   */
+  alsoWaitFor(aPromise) {
+    // We don't care if aPromise resolves or rejects, but just that is not
+    // pending anymore.
+    let promise = aPromise.catch(console.error);
+    this._promise = Promise.all([this._promise, promise]);
+  },
+
+  /**
+   * The promise for this queue.
+   */
+  get promise() {
+    return this._promise;
+  }
+};
+
+var TransactionsManager = {
+  // See the documentation at the top of this file. |transact| calls are not
+  // serialized with |batch| calls.
+  _mainEnqueuer: new Enqueuer(),
+  _transactEnqueuer: new Enqueuer(),
+
+  // Is a batch in progress? set when we enter a batch function and unset when
+  // it's execution is done.
+  _batching: false,
+
+  // If a batch started, this indicates if we've already created an entry in the
+  // transactions history for the batch (i.e. if at least one transaction was
+  // executed successfully).
+  _createdBatchEntry: false,
+
+  // Transactions object should never be recycled (that is, |execute| should
+  // only be called once (or not at all) after they're constructed.
+  // This keeps track of all transactions which were executed.
+  _executedTransactions: new WeakSet(),
+
+  transact(aTxnProxy) {
+    let rawTxn = TransactionsHistory.getRawTransaction(aTxnProxy);
+    if (!rawTxn)
+      throw new Error("|transact| was called with an unexpected object");
+
+    if (this._executedTransactions.has(rawTxn))
+      throw new Error("Transactions objects may not be recycled.");
+
+    // Add it in advance so one doesn't accidentally do
+    // sameTxn.transact(); sameTxn.transact();
+    this._executedTransactions.add(rawTxn);
+
+    let promise = this._transactEnqueuer.enqueue(function* () {
+      // Don't try to catch exceptions. If execute fails, we better not add the
+      // transaction to the undo stack.
+      let retval = yield rawTxn.execute();
+
+      let forceNewEntry = !this._batching || !this._createdBatchEntry;
+      TransactionsHistory.add(aTxnProxy, forceNewEntry);
+      if (this._batching)
+        this._createdBatchEntry = true;
+
+      this._updateCommandsOnActiveWindow();
+      return retval;
+    }.bind(this));
+    this._mainEnqueuer.alsoWaitFor(promise);
+    return promise;
+  },
+
+  batch(aTask) {
+    return this._mainEnqueuer.enqueue(function* () {
+      this._batching = true;
+      this._createdBatchEntry = false;
+      let rv;
+      try {
+        // We should return here, but bug 958949 makes that impossible.
+        rv = (yield Task.spawn(aTask));
+      }
+      finally {
+        this._batching = false;
+        this._createdBatchEntry = false;
+      }
+      return rv;
+    }.bind(this));
+  },
+
+  /**
+   * Undo the top undo entry, if any, and update the undo position accordingly.
+   */
+  undo() {
+    let promise = this._mainEnqueuer.enqueue(function* () {
+      let entry = TransactionsHistory.topUndoEntry;
+      if (!entry)
+        return;
+
+      for (let txnProxy of entry) {
+        try {
+          yield TransactionsHistory.getRawTransaction(txnProxy).undo();
+        }
+        catch (ex) {
+          // If one transaction is broken, it's not safe to work with any other
+          // undo entry.  Report the error and clear the undo history.
+          console.error(ex,
+                        "Couldn't undo a transaction, clearing all undo entries.");
+          TransactionsHistory.clearUndoEntries();
+          return;
+        }
+      }
+      TransactionsHistory._undoPosition++;
+      this._updateCommandsOnActiveWindow();
+    }.bind(this));
+    this._transactEnqueuer.alsoWaitFor(promise);
+    return promise;
+  },
+
+  /**
+   * Redo the top redo entry, if any, and update the undo position accordingly.
+   */
+  redo() {
+    let promise = this._mainEnqueuer.enqueue(function* () {
+      let entry = TransactionsHistory.topRedoEntry;
+      if (!entry)
+        return;
+
+      for (let i = entry.length - 1; i >= 0; i--) {
+        let transaction = TransactionsHistory.getRawTransaction(entry[i]);
+        try {
+          if (transaction.redo)
+            yield transaction.redo();
+          else
+            yield transaction.execute();
+        }
+        catch (ex) {
+          // If one transaction is broken, it's not safe to work with any other
+          // redo entry. Report the error and clear the undo history.
+          console.error(ex,
+                        "Couldn't redo a transaction, clearing all redo entries.");
+          TransactionsHistory.clearRedoEntries();
+          return;
+        }
+      }
+      TransactionsHistory._undoPosition--;
+      this._updateCommandsOnActiveWindow();
+    }.bind(this));
+
+    this._transactEnqueuer.alsoWaitFor(promise);
+    return promise;
+  },
+
+  clearTransactionsHistory(aUndoEntries, aRedoEntries) {
+    let promise = this._mainEnqueuer.enqueue(function* () {
+      if (aUndoEntries && aRedoEntries)
+        TransactionsHistory.clearAllEntries();
+      else if (aUndoEntries)
+        TransactionsHistory.clearUndoEntries();
+      else if (aRedoEntries)
+        TransactionsHistory.clearRedoEntries();
+      else
+        throw new Error("either aUndoEntries or aRedoEntries should be true");
+    }.bind(this));
+
+    this._transactEnqueuer.alsoWaitFor(promise);
+    return promise;
+  },
+
+  // Updates commands in the undo group of the active window commands.
+  // Inactive windows commands will be updated on focus.
+  _updateCommandsOnActiveWindow() {
+    // Updating "undo" will cause a group update including "redo".
+    try {
+      let win = Services.focus.activeWindow;
+      if (win)
+        win.updateCommands("undo");
+    }
+    catch (ex) { console.error(ex, "Couldn't update undo commands"); }
+  }
+};
+
+/**
+ * Internal helper for defining the standard transactions and their input.
+ * It takes the required and optional properties, and generates the public
+ * constructor (which takes the input in the form of a plain object) which,
+ * when called, creates the argument-less "public" |execute| method by binding
+ * the input properties to the function arguments (required properties first,
+ * then the optional properties).
+ *
+ * If this seems confusing, look at the consumers.
+ *
+ * This magic serves two purposes:
+ * (1) It completely hides the transactions' internals from the module
+ *     consumers.
+ * (2) It keeps each transaction implementation to what is about, bypassing
+ *     all this bureaucracy while still validating input appropriately.
+ */
+function DefineTransaction(aRequiredProps = [], aOptionalProps = []) {
+  for (let prop of [...aRequiredProps, ...aOptionalProps]) {
+    if (!DefineTransaction.inputProps.has(prop))
+      throw new Error("Property '" + prop + "' is not defined");
+  }
+
+  let ctor = function (aInput) {
+    // We want to support both syntaxes:
+    // let t = new PlacesTransactions.NewBookmark(),
+    // let t = PlacesTransactions.NewBookmark()
+    if (this == PlacesTransactions)
+      return new ctor(aInput);
+
+    if (aRequiredProps.length > 0 || aOptionalProps.length > 0) {
+      // Bind the input properties to the arguments of execute.
+      let input = DefineTransaction.verifyInput(aInput, aRequiredProps,
+                                                aOptionalProps);
+      let executeArgs = [this,
+                         ...aRequiredProps.map(prop => input[prop]),
+                         ...aOptionalProps.map(prop => input[prop])];
+      this.execute = Function.bind.apply(this.execute, executeArgs);
+    }
+    return TransactionsHistory.proxifyTransaction(this);
+  };
+  return ctor;
+}
+
+function simpleValidateFunc(aCheck) {
+  return v => {
+    if (!aCheck(v))
+      throw new Error("Invalid value");
+    return v;
+  };
+}
+
+DefineTransaction.strValidate = simpleValidateFunc(v => typeof(v) == "string");
+DefineTransaction.strOrNullValidate =
+  simpleValidateFunc(v => typeof(v) == "string" || v === null);
+DefineTransaction.indexValidate =
+  simpleValidateFunc(v => Number.isInteger(v) &&
+                          v >= PlacesUtils.bookmarks.DEFAULT_INDEX);
+DefineTransaction.guidValidate =
+  simpleValidateFunc(v => /^[a-zA-Z0-9\-_]{12}$/.test(v));
+
+function isPrimitive(v) {
+  return v === null || (typeof(v) != "object" && typeof(v) != "function");
+}
+
+DefineTransaction.annotationObjectValidate = function (obj) {
+  let checkProperty = (aPropName, aRequired, aCheckFunc) => {
+    if (aPropName in obj)
+      return aCheckFunc(obj[aPropName]);
+
+    return !aRequired;
+  };
+
+  if (obj &&
+      checkProperty("name", true, v => typeof(v) == "string" && v.length > 0) &&
+      checkProperty("expires", false, Number.isInteger) &&
+      checkProperty("flags", false, Number.isInteger) &&
+      checkProperty("value", false, isPrimitive) ) {
+    // Nothing else should be set
+    let validKeys = ["name", "value", "flags", "expires"];
+    if (Object.keys(obj).every( (k) => validKeys.includes(k)))
+      return obj;
+  }
+  throw new Error("Invalid annotation object");
+};
+
+DefineTransaction.urlValidate = function(url) {
+  // When this module is updated to use Bookmarks.jsm, we should actually
+  // convert nsIURIs/spec to URL objects.
+  if (url instanceof Components.interfaces.nsIURI)
+    return url;
+  let spec = url instanceof URL ? url.href : url;
+  return NetUtil.newURI(spec);
+};
+
+DefineTransaction.inputProps = new Map();
+DefineTransaction.defineInputProps =
+function (aNames, aValidationFunction, aDefaultValue) {
+  for (let name of aNames) {
+    // Workaround bug 449811.
+    let propName = name;
+    this.inputProps.set(propName, {
+      validateValue: function (aValue) {
+        if (aValue === undefined)
+          return aDefaultValue;
+        try {
+          return aValidationFunction(aValue);
+        }
+        catch (ex) {
+          throw new Error(`Invalid value for input property ${propName}`);
+        }
+      },
+
+      validateInput: function (aInput, aRequired) {
+        if (aRequired && !(propName in aInput))
+          throw new Error(`Required input property is missing: ${propName}`);
+        return this.validateValue(aInput[propName]);
+      },
+
+      isArrayProperty: false
+    });
+  }
+};
+
+DefineTransaction.defineArrayInputProp =
+function (aName, aBasePropertyName) {
+  let baseProp = this.inputProps.get(aBasePropertyName);
+  if (!baseProp)
+    throw new Error(`Unknown input property: ${aBasePropertyName}`);
+
+  this.inputProps.set(aName, {
+    validateValue: function (aValue) {
+      if (aValue == undefined)
+        return [];
+
+      if (!Array.isArray(aValue))
+        throw new Error(`${aName} input property value must be an array`);
+
+      // This also takes care of abandoning the global scope of the input
+      // array (through Array.prototype).
+      return aValue.map(baseProp.validateValue);
+    },
+
+    // We allow setting either the array property itself (e.g. urls), or a
+    // single element of it (url, in that example), that is then transformed
+    // into a single-element array.
+    validateInput: function (aInput, aRequired) {
+      if (aName in aInput) {
+        // It's not allowed to set both though.
+        if (aBasePropertyName in aInput) {
+          throw new Error(`It is not allowed to set both ${aName} and
+                          ${aBasePropertyName} as  input properties`);
+        }
+        let array = this.validateValue(aInput[aName]);
+        if (aRequired && array.length == 0) {
+          throw new Error(`Empty array passed for required input property:
+                           ${aName}`);
+        }
+        return array;
+      }
+      // If the property is required and it's not set as is, check if the base
+      // property is set.
+      if (aRequired && !(aBasePropertyName in aInput))
+        throw new Error(`Required input property is missing: ${aName}`);
+
+      if (aBasePropertyName in aInput)
+        return [baseProp.validateValue(aInput[aBasePropertyName])];
+
+      return [];
+    },
+
+    isArrayProperty: true
+  });
+};
+
+DefineTransaction.validatePropertyValue =
+function (aProp, aInput, aRequired) {
+  return this.inputProps.get(aProp).validateInput(aInput, aRequired);
+};
+
+DefineTransaction.getInputObjectForSingleValue =
+function (aInput, aRequiredProps, aOptionalProps) {
+  // The following input forms may be deduced from a single value:
+  // * a single required property with or without optional properties (the given
+  //   value is set to the required property).
+  // * a single optional property with no required properties.
+  if (aRequiredProps.length > 1 ||
+      (aRequiredProps.length == 0 && aOptionalProps.length > 1)) {
+    throw new Error("Transaction input isn't an object");
+  }
+
+  let propName = aRequiredProps.length == 1 ?
+                 aRequiredProps[0] : aOptionalProps[0];
+  let propValue =
+    this.inputProps.get(propName).isArrayProperty && !Array.isArray(aInput) ?
+    [aInput] : aInput;
+  return { [propName]: propValue };
+};
+
+DefineTransaction.verifyInput =
+function (aInput, aRequiredProps = [], aOptionalProps = []) {
+  if (aRequiredProps.length == 0 && aOptionalProps.length == 0)
+    return {};
+
+  // If there's just a single required/optional property, we allow passing it
+  // as is, so, for example, one could do PlacesTransactions.RemoveItem(myGuid)
+  // rather than PlacesTransactions.RemoveItem({ guid: myGuid}).
+  // This shortcut isn't supported for "complex" properties - e.g. one cannot
+  // pass an annotation object this way (note there is no use case for this at
+  // the moment anyway).
+  let input = aInput;
+  let isSinglePropertyInput =
+    isPrimitive(aInput) ||
+    Array.isArray(aInput) ||
+    (aInput instanceof Components.interfaces.nsISupports);
+  if (isSinglePropertyInput) {
+    input =  this.getInputObjectForSingleValue(aInput,
+                                               aRequiredProps,
+                                               aOptionalProps);
+  }
+
+  let fixedInput = { };
+  for (let prop of aRequiredProps) {
+    fixedInput[prop] = this.validatePropertyValue(prop, input, true);
+  }
+  for (let prop of aOptionalProps) {
+    fixedInput[prop] = this.validatePropertyValue(prop, input, false);
+  }
+
+  return fixedInput;
+};
+
+// Update the documentation at the top of this module if you add or
+// remove properties.
+DefineTransaction.defineInputProps(["url", "feedUrl", "siteUrl"],
+                                   DefineTransaction.urlValidate, null);
+DefineTransaction.defineInputProps(["guid", "parentGuid", "newParentGuid"],
+                                   DefineTransaction.guidValidate);
+DefineTransaction.defineInputProps(["title"],
+                                   DefineTransaction.strOrNullValidate, null);
+DefineTransaction.defineInputProps(["keyword", "oldKeyword", "postData", "tag",
+                                    "excludingAnnotation"],
+                                   DefineTransaction.strValidate, "");
+DefineTransaction.defineInputProps(["index", "newIndex"],
+                                   DefineTransaction.indexValidate,
+                                   PlacesUtils.bookmarks.DEFAULT_INDEX);
+DefineTransaction.defineInputProps(["annotation"],
+                                   DefineTransaction.annotationObjectValidate);
+DefineTransaction.defineArrayInputProp("guids", "guid");
+DefineTransaction.defineArrayInputProp("urls", "url");
+DefineTransaction.defineArrayInputProp("tags", "tag");
+DefineTransaction.defineArrayInputProp("annotations", "annotation");
+DefineTransaction.defineArrayInputProp("excludingAnnotations",
+                                       "excludingAnnotation");
+
+/**
+ * Internal helper for implementing the execute method of NewBookmark, NewFolder
+ * and NewSeparator.
+ *
+ * @param aTransaction
+ *        The transaction object
+ * @param aParentGuid
+ *        The GUID of the parent folder
+ * @param aCreateItemFunction(aParentId, aGuidToRestore)
+ *        The function to be called for creating the item on execute and redo.
+ *        It should return the itemId for the new item
+ *        - aGuidToRestore - the GUID to set for the item (used for redo).
+ * @param [optional] aOnUndo
+ *        an additional function to call after undo
+ * @param [optional] aOnRedo
+ *        an additional function to call after redo
+ */
+function* ExecuteCreateItem(aTransaction, aParentGuid, aCreateItemFunction,
+                            aOnUndo = null, aOnRedo = null) {
+  let parentId = yield PlacesUtils.promiseItemId(aParentGuid),
+      itemId = yield aCreateItemFunction(parentId, ""),
+      guid = yield PlacesUtils.promiseItemGuid(itemId);
+
+  // On redo, we'll restore the date-added and last-modified properties.
+  let dateAdded = 0, lastModified = 0;
+  aTransaction.undo = function* () {
+    if (dateAdded == 0) {
+      dateAdded = PlacesUtils.bookmarks.getItemDateAdded(itemId);
+      lastModified = PlacesUtils.bookmarks.getItemLastModified(itemId);
+    }
+    PlacesUtils.bookmarks.removeItem(itemId);
+    if (aOnUndo) {
+      yield aOnUndo();
+    }
+  };
+  aTransaction.redo = function* () {
+    parentId = yield PlacesUtils.promiseItemId(aParentGuid);
+    itemId = yield aCreateItemFunction(parentId, guid);
+    if (aOnRedo)
+      yield aOnRedo();
+
+    // aOnRedo is called first to make sure it doesn't override
+    // lastModified.
+    PlacesUtils.bookmarks.setItemDateAdded(itemId, dateAdded);
+    PlacesUtils.bookmarks.setItemLastModified(itemId, lastModified);
+    PlacesUtils.bookmarks.setItemLastModified(parentId, dateAdded);
+  };
+  return guid;
+}
+
+/**
+ * Creates items (all types) from a bookmarks tree representation, as defined
+ * in PlacesUtils.promiseBookmarksTree.
+ *
+ * @param aBookmarksTree
+ *        the bookmarks tree object.  You may pass either a bookmarks tree
+ *        returned by promiseBookmarksTree, or a manually defined one.
+ * @param [optional] aRestoring (default: false)
+ *        Whether or not the items are restored.  Only in restore mode, are
+ *        the guid, dateAdded and lastModified properties honored.
+ * @param [optional] aExcludingAnnotations
+ *        Array of annotations names to ignore in aBookmarksTree. This argument
+ *        is ignored if aRestoring is set.
+ * @note the id, root and charset properties of items in aBookmarksTree are
+ *       always ignored.  The index property is ignored for all items but the
+ *       root one.
+ * @return {Promise}
+ */
+function* createItemsFromBookmarksTree(aBookmarksTree, aRestoring = false,
+                                       aExcludingAnnotations = []) {
+  function extractLivemarkDetails(aAnnos) {
+    let feedURI = null, siteURI = null;
+    aAnnos = aAnnos.filter(
+      aAnno => {
+        switch (aAnno.name) {
+        case PlacesUtils.LMANNO_FEEDURI:
+          feedURI = NetUtil.newURI(aAnno.value);
+          return false;
+        case PlacesUtils.LMANNO_SITEURI:
+          siteURI = NetUtil.newURI(aAnno.value);
+          return false;
+        default:
+          return true;
+        }
+      } );
+    return [feedURI, siteURI];
+  }
+
+  function* createItem(aItem,
+                       aParentGuid,
+                       aIndex = PlacesUtils.bookmarks.DEFAULT_INDEX) {
+    let itemId;
+    let guid = aRestoring ? aItem.guid : undefined;
+    let parentId = yield PlacesUtils.promiseItemId(aParentGuid);
+    let annos = aItem.annos ? [...aItem.annos] : [];
+    switch (aItem.type) {
+      case PlacesUtils.TYPE_X_MOZ_PLACE: {
+        let uri = NetUtil.newURI(aItem.uri);
+        itemId = PlacesUtils.bookmarks.insertBookmark(
+          parentId, uri, aIndex, aItem.title, guid);
+        if ("keyword" in aItem) {
+          yield PlacesUtils.keywords.insert({
+            keyword: aItem.keyword,
+            url: uri.spec
+          });
+        }
+        if ("tags" in aItem) {
+          PlacesUtils.tagging.tagURI(uri, aItem.tags.split(","));
+        }
+        break;
+      }
+      case PlacesUtils.TYPE_X_MOZ_PLACE_CONTAINER: {
+        // Either a folder or a livemark
+        let [feedURI, siteURI] = extractLivemarkDetails(annos);
+        if (!feedURI) {
+          itemId = PlacesUtils.bookmarks.createFolder(
+              parentId, aItem.title, aIndex, guid);
+          if (guid === undefined)
+            guid = yield PlacesUtils.promiseItemGuid(itemId);
+          if ("children" in aItem) {
+            for (let child of aItem.children) {
+              yield createItem(child, guid);
+            }
+          }
+        }
+        else {
+          let livemark =
+            yield PlacesUtils.livemarks.addLivemark({ title: aItem.title
+                                                    , feedURI: feedURI
+                                                    , siteURI: siteURI
+                                                    , parentId: parentId
+                                                    , index: aIndex
+                                                    , guid: guid});
+          itemId = livemark.id;
+        }
+        break;
+      }
+      case PlacesUtils.TYPE_X_MOZ_PLACE_SEPARATOR: {
+        itemId = PlacesUtils.bookmarks.insertSeparator(parentId, aIndex, guid);
+        break;
+      }
+    }
+    if (annos.length > 0) {
+      if (!aRestoring && aExcludingAnnotations.length > 0) {
+        annos = annos.filter(a => !aExcludingAnnotations.includes(a.name));
+
+      }
+
+      PlacesUtils.setAnnotationsForItem(itemId, annos);
+    }
+
+    if (aRestoring) {
+      if ("dateAdded" in aItem)
+        PlacesUtils.bookmarks.setItemDateAdded(itemId, aItem.dateAdded);
+      if ("lastModified" in aItem)
+        PlacesUtils.bookmarks.setItemLastModified(itemId, aItem.lastModified);
+    }
+    return itemId;
+  }
+  return yield createItem(aBookmarksTree,
+                          aBookmarksTree.parentGuid,
+                          aBookmarksTree.index);
+}
+
+/** ***************************************************************************
+ * The Standard Places Transactions.
+ *
+ * See the documentation at the top of this file. The valid values for input
+ * are also documented there.
+ *****************************************************************************/
+
+var PT = PlacesTransactions;
+
+/**
+ * Transaction for creating a bookmark.
+ *
+ * Required Input Properties: url, parentGuid.
+ * Optional Input Properties: index, title, keyword, annotations, tags.
+ *
+ * When this transaction is executed, it's resolved to the new bookmark's GUID.
+ */
+PT.NewBookmark = DefineTransaction(["parentGuid", "url"],
+                                   ["index", "title", "keyword", "postData",
+                                    "annotations", "tags"]);
+PT.NewBookmark.prototype = Object.seal({
+  execute: function (aParentGuid, aURI, aIndex, aTitle,
+                     aKeyword, aPostData, aAnnos, aTags) {
+    return ExecuteCreateItem(this, aParentGuid,
+      function* (parentId, guidToRestore = "") {
+        let itemId = PlacesUtils.bookmarks.insertBookmark(
+          parentId, aURI, aIndex, aTitle, guidToRestore);
+
+        if (aKeyword) {
+          yield PlacesUtils.keywords.insert({
+            url: aURI.spec,
+            keyword: aKeyword,
+            postData: aPostData
+          });
+        }
+        if (aAnnos.length) {
+          PlacesUtils.setAnnotationsForItem(itemId, aAnnos);
+        }
+        if (aTags.length > 0) {
+          let currentTags = PlacesUtils.tagging.getTagsForURI(aURI);
+          aTags = aTags.filter(t => !currentTags.includes(t));
+          PlacesUtils.tagging.tagURI(aURI, aTags);
+        }
+
+        return itemId;
+      },
+      function _additionalOnUndo() {
+        if (aTags.length > 0) {
+          PlacesUtils.tagging.untagURI(aURI, aTags);
+        }
+      });
+  }
+});
+
+/**
+ * Transaction for creating a folder.
+ *
+ * Required Input Properties: title, parentGuid.
+ * Optional Input Properties: index, annotations.
+ *
+ * When this transaction is executed, it's resolved to the new folder's GUID.
+ */
+PT.NewFolder = DefineTransaction(["parentGuid", "title"],
+                                 ["index", "annotations"]);
+PT.NewFolder.prototype = Object.seal({
+  execute: function (aParentGuid, aTitle, aIndex, aAnnos) {
+    return ExecuteCreateItem(this,  aParentGuid,
+      function* (parentId, guidToRestore = "") {
+        let itemId = PlacesUtils.bookmarks.createFolder(
+          parentId, aTitle, aIndex, guidToRestore);
+        if (aAnnos.length > 0)
+          PlacesUtils.setAnnotationsForItem(itemId, aAnnos);
+        return itemId;
+      });
+  }
+});
+
+/**
+ * Transaction for creating a separator.
+ *
+ * Required Input Properties: parentGuid.
+ * Optional Input Properties: index.
+ *
+ * When this transaction is executed, it's resolved to the new separator's
+ * GUID.
+ */
+PT.NewSeparator = DefineTransaction(["parentGuid"], ["index"]);
+PT.NewSeparator.prototype = Object.seal({
+  execute: function (aParentGuid, aIndex) {
+    return ExecuteCreateItem(this, aParentGuid,
+      function* (parentId, guidToRestore = "") {
+        let itemId = PlacesUtils.bookmarks.insertSeparator(
+          parentId, aIndex, guidToRestore);
+        return itemId;
+      });
+  }
+});
+
+/**
+ * Transaction for creating a live bookmark (see mozIAsyncLivemarks for the
+ * semantics).
+ *
+ * Required Input Properties: feedUrl, title, parentGuid.
+ * Optional Input Properties: siteUrl, index, annotations.
+ *
+ * When this transaction is executed, it's resolved to the new livemark's
+ * GUID.
+ */
+PT.NewLivemark = DefineTransaction(["feedUrl", "title", "parentGuid"],
+                                   ["siteUrl", "index", "annotations"]);
+PT.NewLivemark.prototype = Object.seal({
+  execute: function* (aFeedURI, aTitle, aParentGuid, aSiteURI, aIndex, aAnnos) {
+    let livemarkInfo = { title: aTitle
+                       , feedURI: aFeedURI
+                       , siteURI: aSiteURI
+                       , index: aIndex };
+    let createItem = function* () {
+      livemarkInfo.parentId = yield PlacesUtils.promiseItemId(aParentGuid);
+      let livemark = yield PlacesUtils.livemarks.addLivemark(livemarkInfo);
+      if (aAnnos.length > 0)
+        PlacesUtils.setAnnotationsForItem(livemark.id, aAnnos);
+
+      if ("dateAdded" in livemarkInfo) {
+        PlacesUtils.bookmarks.setItemDateAdded(livemark.id,
+                                               livemarkInfo.dateAdded);
+        PlacesUtils.bookmarks.setItemLastModified(livemark.id,
+                                                  livemarkInfo.lastModified);
+      }
+      return livemark;
+    };
+
+    let livemark = yield createItem();
+    this.undo = function* () {
+      livemarkInfo.guid = livemark.guid;
+      if (!("dateAdded" in livemarkInfo)) {
+        livemarkInfo.dateAdded =
+          PlacesUtils.bookmarks.getItemDateAdded(livemark.id);
+        livemarkInfo.lastModified =
+          PlacesUtils.bookmarks.getItemLastModified(livemark.id);
+      }
+      yield PlacesUtils.livemarks.removeLivemark(livemark);
+    };
+    this.redo = function* () {
+      livemark = yield createItem();
+    };
+    return livemark.guid;
+  }
+});
+
+/**
+ * Transaction for moving an item.
+ *
+ * Required Input Properties: guid, newParentGuid.
+ * Optional Input Properties  newIndex.
+ */
+PT.Move = DefineTransaction(["guid", "newParentGuid"], ["newIndex"]);
+PT.Move.prototype = Object.seal({
+  execute: function* (aGuid, aNewParentGuid, aNewIndex) {
+    let itemId = yield PlacesUtils.promiseItemId(aGuid),
+        oldParentId = PlacesUtils.bookmarks.getFolderIdForItem(itemId),
+        oldIndex = PlacesUtils.bookmarks.getItemIndex(itemId),
+        newParentId = yield PlacesUtils.promiseItemId(aNewParentGuid);
+
+    PlacesUtils.bookmarks.moveItem(itemId, newParentId, aNewIndex);
+
+    let undoIndex = PlacesUtils.bookmarks.getItemIndex(itemId);
+    this.undo = () => {
+      // Moving down in the same parent takes in count removal of the item
+      // so to revert positions we must move to oldIndex + 1
+      if (newParentId == oldParentId && oldIndex > undoIndex)
+        PlacesUtils.bookmarks.moveItem(itemId, oldParentId, oldIndex + 1);
+      else
+        PlacesUtils.bookmarks.moveItem(itemId, oldParentId, oldIndex);
+    };
+  }
+});
+
+/**
+ * Transaction for setting the title for an item.
+ *
+ * Required Input Properties: guid, title.
+ */
+PT.EditTitle = DefineTransaction(["guid", "title"]);
+PT.EditTitle.prototype = Object.seal({
+  execute: function* (aGuid, aTitle) {
+    let itemId = yield PlacesUtils.promiseItemId(aGuid),
+        oldTitle = PlacesUtils.bookmarks.getItemTitle(itemId);
+    PlacesUtils.bookmarks.setItemTitle(itemId, aTitle);
+    this.undo = () => { PlacesUtils.bookmarks.setItemTitle(itemId, oldTitle); };
+  }
+});
+
+/**
+ * Transaction for setting the URI for an item.
+ *
+ * Required Input Properties: guid, url.
+ */
+PT.EditUrl = DefineTransaction(["guid", "url"]);
+PT.EditUrl.prototype = Object.seal({
+  execute: function* (aGuid, aURI) {
+    let itemId = yield PlacesUtils.promiseItemId(aGuid),
+        oldURI = PlacesUtils.bookmarks.getBookmarkURI(itemId),
+        oldURITags = PlacesUtils.tagging.getTagsForURI(oldURI),
+        newURIAdditionalTags = null;
+    PlacesUtils.bookmarks.changeBookmarkURI(itemId, aURI);
+
+    // Move tags from old URI to new URI.
+    if (oldURITags.length > 0) {
+      // Only untag the old URI if this is the only bookmark.
+      if (PlacesUtils.getBookmarksForURI(oldURI, {}).length == 0)
+        PlacesUtils.tagging.untagURI(oldURI, oldURITags);
+
+      let currentNewURITags = PlacesUtils.tagging.getTagsForURI(aURI);
+      newURIAdditionalTags = oldURITags.filter(t => !currentNewURITags.includes(t));
+      if (newURIAdditionalTags)
+        PlacesUtils.tagging.tagURI(aURI, newURIAdditionalTags);
+    }
+
+    this.undo = () => {
+      PlacesUtils.bookmarks.changeBookmarkURI(itemId, oldURI);
+      // Move tags from new URI to old URI.
+      if (oldURITags.length > 0) {
+        // Only untag the new URI if this is the only bookmark.
+        if (newURIAdditionalTags && newURIAdditionalTags.length > 0 &&
+            PlacesUtils.getBookmarksForURI(aURI, {}).length == 0) {
+          PlacesUtils.tagging.untagURI(aURI, newURIAdditionalTags);
+        }
+
+        PlacesUtils.tagging.tagURI(oldURI, oldURITags);
+      }
+    };
+  }
+});
+
+/**
+ * Transaction for setting annotations for an item.
+ *
+ * Required Input Properties: guid, annotationObject
+ */
+PT.Annotate = DefineTransaction(["guids", "annotations"]);
+PT.Annotate.prototype = {
+  *execute(aGuids, aNewAnnos) {
+    let undoAnnosForItem = new Map(); // itemId => undoAnnos;
+    for (let guid of aGuids) {
+      let itemId = yield PlacesUtils.promiseItemId(guid);
+      let currentAnnos = PlacesUtils.getAnnotationsForItem(itemId);
+
+      let undoAnnos = [];
+      for (let newAnno of aNewAnnos) {
+        let currentAnno = currentAnnos.find(a => a.name == newAnno.name);
+        if (currentAnno) {
+          undoAnnos.push(currentAnno);
+        }
+        else {
+          // An unset value removes the annotation.
+          undoAnnos.push({ name: newAnno.name });
+        }
+      }
+      undoAnnosForItem.set(itemId, undoAnnos);
+
+      PlacesUtils.setAnnotationsForItem(itemId, aNewAnnos);
+    }
+
+    this.undo = function() {
+      for (let [itemId, undoAnnos] of undoAnnosForItem) {
+        PlacesUtils.setAnnotationsForItem(itemId, undoAnnos);
+      }
+    };
+    this.redo = function* () {
+      for (let guid of aGuids) {
+        let itemId = yield PlacesUtils.promiseItemId(guid);
+        PlacesUtils.setAnnotationsForItem(itemId, aNewAnnos);
+      }
+    };
+  }
+};
+
+/**
+ * Transaction for setting the keyword for a bookmark.
+ *
+ * Required Input Properties: guid, keyword.
+ */
+PT.EditKeyword = DefineTransaction(["guid", "keyword"],
+                                   ["postData", "oldKeyword"]);
+PT.EditKeyword.prototype = Object.seal({
+  execute: function* (aGuid, aKeyword, aPostData, aOldKeyword) {
+    let url;
+    let oldKeywordEntry;
+    if (aOldKeyword) {
+      oldKeywordEntry = yield PlacesUtils.keywords.fetch(aOldKeyword);
+      url = oldKeywordEntry.url;
+      yield PlacesUtils.keywords.remove(aOldKeyword);
+    }
+
+    if (aKeyword) {
+      if (!url) {
+        url = (yield PlacesUtils.bookmarks.fetch(aGuid)).url;
+      }
+      yield PlacesUtils.keywords.insert({
+        url: url,
+        keyword: aKeyword,
+        postData: aPostData || (oldKeywordEntry ? oldKeywordEntry.postData : "")
+      });
+    }
+
+    this.undo = function* () {
+      if (aKeyword) {
+        yield PlacesUtils.keywords.remove(aKeyword);
+      }
+      if (oldKeywordEntry) {
+        yield PlacesUtils.keywords.insert(oldKeywordEntry);
+      }
+    };
+  }
+});
+
+/**
+ * Transaction for sorting a folder by name.
+ *
+ * Required Input Properties: guid.
+ */
+PT.SortByName = DefineTransaction(["guid"]);
+PT.SortByName.prototype = {
+  execute: function* (aGuid) {
+    let itemId = yield PlacesUtils.promiseItemId(aGuid),
+        oldOrder = [],  // [itemId] = old index
+        contents = PlacesUtils.getFolderContents(itemId, false, false).root,
+        count = contents.childCount;
+
+    // Sort between separators.
+    let newOrder = [], // nodes, in the new order.
+        preSep   = []; // Temporary array for sorting each group of nodes.
+    let sortingMethod = (a, b) => {
+      if (PlacesUtils.nodeIsContainer(a) && !PlacesUtils.nodeIsContainer(b))
+        return -1;
+      if (!PlacesUtils.nodeIsContainer(a) && PlacesUtils.nodeIsContainer(b))
+        return 1;
+      return a.title.localeCompare(b.title);
+    };
+
+    for (let i = 0; i < count; ++i) {
+      let node = contents.getChild(i);
+      oldOrder[node.itemId] = i;
+      if (PlacesUtils.nodeIsSeparator(node)) {
+        if (preSep.length > 0) {
+          preSep.sort(sortingMethod);
+          newOrder = newOrder.concat(preSep);
+          preSep.splice(0, preSep.length);
+        }
+        newOrder.push(node);
+      }
+      else
+        preSep.push(node);
+    }
+    contents.containerOpen = false;
+
+    if (preSep.length > 0) {
+      preSep.sort(sortingMethod);
+      newOrder = newOrder.concat(preSep);
+    }
+
+    // Set the nex indexes.
+    let callback = {
+      runBatched: function() {
+        for (let i = 0; i < newOrder.length; ++i) {
+          PlacesUtils.bookmarks.setItemIndex(newOrder[i].itemId, i);
+        }
+      }
+    };
+    PlacesUtils.bookmarks.runInBatchMode(callback, null);
+
+    this.undo = () => {
+      let callback = {
+        runBatched: function() {
+          for (let item in oldOrder) {
+            PlacesUtils.bookmarks.setItemIndex(item, oldOrder[item]);
+          }
+        }
+      };
+      PlacesUtils.bookmarks.runInBatchMode(callback, null);
+    };
+  }
+};
+
+/**
+ * Transaction for removing an item (any type).
+ *
+ * Required Input Properties: guids.
+ */
+PT.Remove = DefineTransaction(["guids"]);
+PT.Remove.prototype = {
+  *execute(aGuids) {
+    function promiseBookmarksTree(guid) {
+      try {
+        return PlacesUtils.promiseBookmarksTree(guid);
+      }
+      catch (ex) {
+        throw new Error("Failed to get info for the specified item (guid: " +
+                        guid + "). Ex: " + ex);
+      }
+    }
+
+    let toRestore = [];
+    for (let guid of aGuids) {
+      toRestore.push(yield promiseBookmarksTree(guid));
+    }
+
+    let removeThem = Task.async(function* () {
+      for (let guid of aGuids) {
+        PlacesUtils.bookmarks.removeItem(yield PlacesUtils.promiseItemId(guid));
+      }
+    });
+    yield removeThem();
+
+    this.undo = Task.async(function* () {
+      for (let info of toRestore) {
+        yield createItemsFromBookmarksTree(info, true);
+      }
+    });
+    this.redo = removeThem;
+  }
+};
+
+/**
+ * Transactions for removing all bookmarks for one or more urls.
+ *
+ * Required Input Properties: urls.
+ */
+PT.RemoveBookmarksForUrls = DefineTransaction(["urls"]);
+PT.RemoveBookmarksForUrls.prototype = {
+  *execute(aUrls) {
+    let guids = [];
+    for (let url of aUrls) {
+      yield PlacesUtils.bookmarks.fetch({ url }, info => {
+        guids.push(info.guid);
+      });
+    }
+    let removeTxn = TransactionsHistory.getRawTransaction(PT.Remove(guids));
+    yield removeTxn.execute();
+    this.undo = removeTxn.undo.bind(removeTxn);
+    this.redo = removeTxn.redo.bind(removeTxn);
+  }
+};
+
+/**
+ * Transaction for tagging urls.
+ *
+ * Required Input Properties: urls, tags.
+ */
+PT.Tag = DefineTransaction(["urls", "tags"]);
+PT.Tag.prototype = {
+  execute: function* (aURIs, aTags) {
+    let onUndo = [], onRedo = [];
+    for (let uri of aURIs) {
+      // Workaround bug 449811.
+      let currentURI = uri;
+
+      let promiseIsBookmarked = function* () {
+        let deferred = Promise.defer();
+        PlacesUtils.asyncGetBookmarkIds(
+          currentURI, ids => { deferred.resolve(ids.length > 0); });
+        return deferred.promise;
+      };
+
+      if (yield promiseIsBookmarked(currentURI)) {
+        // Tagging is only allowed for bookmarked URIs (but see 424160).
+        let createTxn = TransactionsHistory.getRawTransaction(
+          PT.NewBookmark({ url: currentURI
+                         , tags: aTags
+                         , parentGuid: PlacesUtils.bookmarks.unfiledGuid }));
+        yield createTxn.execute();
+        onUndo.unshift(createTxn.undo.bind(createTxn));
+        onRedo.push(createTxn.redo.bind(createTxn));
+      }
+      else {
+        let currentTags = PlacesUtils.tagging.getTagsForURI(currentURI);
+        let newTags = aTags.filter(t => !currentTags.includes(t));
+        PlacesUtils.tagging.tagURI(currentURI, newTags);
+        onUndo.unshift(() => {
+          PlacesUtils.tagging.untagURI(currentURI, newTags);
+        });
+        onRedo.push(() => {
+          PlacesUtils.tagging.tagURI(currentURI, newTags);
+        });
+      }
+    }
+    this.undo = function* () {
+      for (let f of onUndo) {
+        yield f();
+      }
+    };
+    this.redo = function* () {
+      for (let f of onRedo) {
+        yield f();
+      }
+    };
+  }
+};
+
+/**
+ * Transaction for removing tags from a URI.
+ *
+ * Required Input Properties: urls.
+ * Optional Input Properties: tags.
+ *
+ * If |tags| is not set, all tags set for |url| are removed.
+ */
+PT.Untag = DefineTransaction(["urls"], ["tags"]);
+PT.Untag.prototype = {
+  execute: function* (aURIs, aTags) {
+    let onUndo = [], onRedo = [];
+    for (let uri of aURIs) {
+      // Workaround bug 449811.
+      let currentURI = uri;
+      let tagsToRemove;
+      let tagsSet = PlacesUtils.tagging.getTagsForURI(currentURI);
+      if (aTags.length > 0)
+        tagsToRemove = aTags.filter(t => tagsSet.includes(t));
+      else
+        tagsToRemove = tagsSet;
+      PlacesUtils.tagging.untagURI(currentURI, tagsToRemove);
+      onUndo.unshift(() => {
+        PlacesUtils.tagging.tagURI(currentURI, tagsToRemove);
+      });
+      onRedo.push(() => {
+        PlacesUtils.tagging.untagURI(currentURI, tagsToRemove);
+      });
+    }
+    this.undo = function* () {
+      for (let f of onUndo) {
+        yield f();
+      }
+    };
+    this.redo = function* () {
+      for (let f of onRedo) {
+        yield f();
+      }
+    };
+  }
+};
+
+/**
+ * Transaction for copying an item.
+ *
+ * Required Input Properties: guid, newParentGuid
+ * Optional Input Properties: newIndex, excludingAnnotations.
+ */
+PT.Copy = DefineTransaction(["guid", "newParentGuid"],
+                            ["newIndex", "excludingAnnotations"]);
+PT.Copy.prototype = {
+  execute: function* (aGuid, aNewParentGuid, aNewIndex, aExcludingAnnotations) {
+    let creationInfo = null;
+    try {
+      creationInfo = yield PlacesUtils.promiseBookmarksTree(aGuid);
+    }
+    catch (ex) {
+      throw new Error("Failed to get info for the specified item (guid: " +
+                      aGuid + "). Ex: " + ex);
+    }
+    creationInfo.parentGuid = aNewParentGuid;
+    creationInfo.index = aNewIndex;
+
+    let newItemId =
+      yield createItemsFromBookmarksTree(creationInfo, false,
+                                         aExcludingAnnotations);
+    let newItemInfo = null;
+    this.undo = function* () {
+      if (!newItemInfo) {
+        let newItemGuid = yield PlacesUtils.promiseItemGuid(newItemId);
+        newItemInfo = yield PlacesUtils.promiseBookmarksTree(newItemGuid);
+      }
+      PlacesUtils.bookmarks.removeItem(newItemId);
+    };
+    this.redo = function* () {
+      newItemId = yield createItemsFromBookmarksTree(newItemInfo, true);
+    }
+
+    return yield PlacesUtils.promiseItemGuid(newItemId);
+  }
+};