Create memoizer.js

www/fix/intl-format-cache/src/memoizer.js

@@ -0,0 +1,81 @@
+/*
+Copyright (c) 2014, Yahoo! Inc. All rights reserved.
+Copyrights licensed under the New BSD License.
+See the accompanying LICENSE file for terms.
+*/
+
+/* jshint esnext: true */
+
+import {bind, objCreate} from './es5';
+
+export default createFormatCache;
+
+// -----------------------------------------------------------------------------
+
+function createFormatCache(FormatConstructor) {
+    var cache = objCreate(null);
+
+    return function () {
+        var args    = Array.prototype.slice.call(arguments);
+        var cacheId = getCacheId(args);
+        var format  = cacheId && cache[cacheId];
+
+        if (!format) {
+            format = new (bind.apply(FormatConstructor, [null].concat(args)))();
+
+            if (cacheId) {
+                cache[cacheId] = format;
+            }
+        }
+
+        return format;
+    };
+}
+
+// -- Utilities ----------------------------------------------------------------
+
+function getCacheId(inputs) {
+    // When JSON is not available in the runtime, we will not create a cache id.
+    if (typeof JSON === 'undefined') { return; }
+
+    var cacheId = [];
+
+    var i, len, input;
+
+    for (i = 0, len = inputs.length; i < len; i += 1) {
+        input = inputs[i];
+
+        if (input && typeof input === 'object') {
+            cacheId.push(orderedProps(input));
+        } else {
+            cacheId.push(input);
+        }
+    }
+
+    return JSON.stringify(cacheId);
+}
+
+function orderedProps(obj) {
+    var props = [],
+        keys  = [];
+
+    var key, i, len, prop;
+
+    for (key in obj) {
+        if (obj.hasOwnProperty(key)) {
+            keys.push(key);
+        }
+    }
+
+    var orderedKeys = keys.sort();
+
+    for (i = 0, len = orderedKeys.length; i < len; i += 1) {
+        key  = orderedKeys[i];
+        prop = {};
+
+        prop[key] = obj[key];
+        props[i]  = prop;
+    }
+
+    return props;
+}