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-rw-r--r--toolkit/modules/Dict.jsm249
-rw-r--r--toolkit/modules/moz.build1
2 files changed, 250 insertions, 0 deletions
diff --git a/toolkit/modules/Dict.jsm b/toolkit/modules/Dict.jsm
new file mode 100644
index 000000000..2d276113a
--- /dev/null
+++ b/toolkit/modules/Dict.jsm
@@ -0,0 +1,249 @@
+/* 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 = ["Dict"];
+
+/**
+ * Transforms a given key into a property name guaranteed not to collide with
+ * any built-ins.
+ */
+function convert(aKey) {
+ return ":" + aKey;
+}
+
+/**
+ * Transforms a property into a key suitable for providing to the outside world.
+ */
+function unconvert(aProp) {
+ return aProp.substr(1);
+}
+
+/**
+ * A dictionary of strings to arbitrary JS objects. This should be used whenever
+ * the keys are potentially arbitrary, to avoid collisions with built-in
+ * properties.
+ *
+ * @param aInitial An object containing the initial keys and values of this
+ * dictionary. Only the "own" enumerable properties of the
+ * object are considered.
+ * If |aInitial| is a string, it is assumed to be JSON and parsed into an object.
+ */
+this.Dict = function Dict(aInitial) {
+ if (aInitial === undefined)
+ aInitial = {};
+ if (typeof aInitial == "string")
+ aInitial = JSON.parse(aInitial);
+ var items = {}, count = 0;
+ // That we don't look up the prototype chain is guaranteed by Iterator.
+ for (var [key, val] in Iterator(aInitial)) {
+ items[convert(key)] = val;
+ count++;
+ }
+ this._state = {count: count, items: items};
+ return Object.freeze(this);
+}
+
+Dict.prototype = Object.freeze({
+ /**
+ * The number of items in the dictionary.
+ */
+ get count() {
+ return this._state.count;
+ },
+
+ /**
+ * Gets the value for a key from the dictionary. If the key is not a string,
+ * it will be converted to a string before the lookup happens.
+ *
+ * @param aKey The key to look up
+ * @param [aDefault] An optional default value to return if the key is not
+ * present. Defaults to |undefined|.
+ * @returns The item, or aDefault if it isn't found.
+ */
+ get: function Dict_get(aKey, aDefault) {
+ var prop = convert(aKey);
+ var items = this._state.items;
+ return items.hasOwnProperty(prop) ? items[prop] : aDefault;
+ },
+
+ /**
+ * Sets the value for a key in the dictionary. If the key is a not a string,
+ * it will be converted to a string before the set happens.
+ */
+ set: function Dict_set(aKey, aValue) {
+ var prop = convert(aKey);
+ var items = this._state.items;
+ if (!items.hasOwnProperty(prop))
+ this._state.count++;
+ items[prop] = aValue;
+ },
+
+ /**
+ * Sets a lazy getter function for a key's value. If the key is a not a string,
+ * it will be converted to a string before the set happens.
+ * @param aKey
+ * The key to set
+ * @param aThunk
+ * A getter function to be called the first time the value for aKey is
+ * retrieved. It is guaranteed that aThunk wouldn't be called more
+ * than once. Note that the key value may be retrieved either
+ * directly, by |get|, or indirectly, by |listvalues| or by iterating
+ * |values|. For the later, the value is only retrieved if and when
+ * the iterator gets to the value in question. Also note that calling
+ * |has| for a lazy-key does not invoke aThunk.
+ *
+ * @note No context is provided for aThunk when it's invoked.
+ * Use Function.bind if you wish to run it in a certain context.
+ */
+ setAsLazyGetter: function Dict_setAsLazyGetter(aKey, aThunk) {
+ let prop = convert(aKey);
+ let items = this._state.items;
+ if (!items.hasOwnProperty(prop))
+ this._state.count++;
+
+ Object.defineProperty(items, prop, {
+ get: function() {
+ delete items[prop];
+ return items[prop] = aThunk();
+ },
+ configurable: true,
+ enumerable: true
+ });
+ },
+
+ /**
+ * Returns whether a key is set as a lazy getter. This returns
+ * true only if the getter function was not called already.
+ * @param aKey
+ * The key to look up.
+ * @returns whether aKey is set as a lazy getter.
+ */
+ isLazyGetter: function Dict_isLazyGetter(aKey) {
+ let descriptor = Object.getOwnPropertyDescriptor(this._state.items,
+ convert(aKey));
+ return (descriptor && descriptor.get != null);
+ },
+
+ /**
+ * Returns whether a key is in the dictionary. If the key is a not a string,
+ * it will be converted to a string before the lookup happens.
+ */
+ has: function Dict_has(aKey) {
+ return (this._state.items.hasOwnProperty(convert(aKey)));
+ },
+
+ /**
+ * Deletes a key from the dictionary. If the key is a not a string, it will be
+ * converted to a string before the delete happens.
+ *
+ * @returns true if the key was found, false if it wasn't.
+ */
+ del: function Dict_del(aKey) {
+ var prop = convert(aKey);
+ if (this._state.items.hasOwnProperty(prop)) {
+ delete this._state.items[prop];
+ this._state.count--;
+ return true;
+ }
+ return false;
+ },
+
+ /**
+ * Returns a shallow copy of this dictionary.
+ */
+ copy: function Dict_copy() {
+ var newItems = {};
+ for (var [key, val] in this.items)
+ newItems[key] = val;
+ return new Dict(newItems);
+ },
+
+ /*
+ * List and iterator functions
+ *
+ * No guarantees whatsoever are made about the order of elements.
+ */
+
+ /**
+ * Returns a list of all the keys in the dictionary in an arbitrary order.
+ */
+ listkeys: function Dict_listkeys() {
+ return [unconvert(k) for (k in this._state.items)];
+ },
+
+ /**
+ * Returns a list of all the values in the dictionary in an arbitrary order.
+ */
+ listvalues: function Dict_listvalues() {
+ var items = this._state.items;
+ return [items[k] for (k in items)];
+ },
+
+ /**
+ * Returns a list of all the items in the dictionary as key-value pairs
+ * in an arbitrary order.
+ */
+ listitems: function Dict_listitems() {
+ var items = this._state.items;
+ return [[unconvert(k), items[k]] for (k in items)];
+ },
+
+ /**
+ * Returns an iterator over all the keys in the dictionary in an arbitrary
+ * order. No guarantees are made about what happens if the dictionary is
+ * mutated during iteration.
+ */
+ get keys() {
+ // If we don't capture this._state.items here then the this-binding will be
+ // incorrect when the generator is executed
+ var items = this._state.items;
+ return (unconvert(k) for (k in items));
+ },
+
+ /**
+ * Returns an iterator over all the values in the dictionary in an arbitrary
+ * order. No guarantees are made about what happens if the dictionary is
+ * mutated during iteration.
+ */
+ get values() {
+ // If we don't capture this._state.items here then the this-binding will be
+ // incorrect when the generator is executed
+ var items = this._state.items;
+ return (items[k] for (k in items));
+ },
+
+ /**
+ * Returns an iterator over all the items in the dictionary as key-value pairs
+ * in an arbitrary order. No guarantees are made about what happens if the
+ * dictionary is mutated during iteration.
+ */
+ get items() {
+ // If we don't capture this._state.items here then the this-binding will be
+ // incorrect when the generator is executed
+ var items = this._state.items;
+ return ([unconvert(k), items[k]] for (k in items));
+ },
+
+ /**
+ * Returns a String representation of this dictionary.
+ */
+ toString: function Dict_toString() {
+ return "{" +
+ [(key + ": " + val) for ([key, val] in this.items)].join(", ") +
+ "}";
+ },
+
+ /**
+ * Returns a JSON representation of this dictionary.
+ */
+ toJSON: function Dict_toJSON() {
+ let obj = {};
+ for (let [key, item] of Iterator(this._state.items)) {
+ obj[unconvert(key)] = item;
+ }
+ return JSON.stringify(obj);
+ },
+});
diff --git a/toolkit/modules/moz.build b/toolkit/modules/moz.build
index 60f3cc3da..88ee984c1 100644
--- a/toolkit/modules/moz.build
+++ b/toolkit/modules/moz.build
@@ -40,6 +40,7 @@ EXTRA_JS_MODULES += [
'debug.js',
'DeferredTask.jsm',
'Deprecated.jsm',
+ 'Dict.jsm',
'FileUtils.jsm',
'Finder.jsm',
'FinderHighlighter.jsm',