feat($parseProvider): add the additionalIsIdent configuration method

src/ng/parse.js

@@ -224,7 +224,8 @@ Lexer.prototype = {
   isIdent: function(ch) {
     return ('a' <= ch && ch <= 'z' ||
             'A' <= ch && ch <= 'Z' ||
-            '_' === ch || ch === '$');
+            '_' === ch || ch === '$' ||
+            this.options.additionalIsIdent(ch));
   },
 
   isExpOperator: function(ch) {
@@ -1120,7 +1121,8 @@ function $ParseProvider() {
   var $parseOptions = {
     csp: false,
     unwrapPromises: false,
-    logPromiseWarnings: true
+    logPromiseWarnings: true,
+    additionalIsIdent: noop
   };
 
 
@@ -1207,6 +1209,55 @@ function $ParseProvider() {
   };
 
 
+  /**
+   * @ngdoc method
+   * @name ng.$parseProvider#additionalIsIdent
+   * @methodOf ng.$parseProvider
+   * @description
+   *
+   * Allows extending of the set of character allowed in identifiers used in Angular expressions. The
+   * `fn` function will be passed a character as argument and is expected to return `true` or `false`,
+   * based on whether that character is allowed or not. It is useful when you want to have non-English
+   * Unicode letters in your identifiers.
+   *
+   * Since this function will be called with every characters outside of `/[a-zA-Z_$]/`, it’s a good
+   * idea to keep it simple and fast. When the character set you want to add is relativelly small, a
+   * string and `indexOf()` (as in the example below) is preferable to a regexp and `test()`. On the
+   * subject of performance, it is good to take advantage of how variable scope works in JS and
+   * define the character set — whether a large string or large regexp — *outside* of `fn` itself (as
+   * in the example below), so that we don’t have to create it on every function call.
+   *
+   * @param {function=} fn The function that the the caracter will be passed to, to decide whether it’s
+   *                       allowed or not. The default is set to `noop` function which returns falsy.
+   *
+   * @returns {function|self} Returns the current setting when used as getter and self if used as
+   *                         setter.
+   *
+   * @example
+   * Let’s say that you’re developing an app for some business that has a domain language
+   * that is just hard to translate to English, and you want to try to use natural terminology, in
+   * Romanian. This snippet will allow you to use Romanian charactes:
+   *
+   * <pre>
+   *   app.config(function($parseProvider) {
+   *     var romanianCharacters = 'şŞţŢîÎăĂâÂ';
+   *
+   *     $parseProvider.additionalIsIdent(function(ch) {
+   *       return romanianCharacters.indexOf(ch) > -1;
+   *     });
+   *   });
+   * </pre>
+   */
+  this.additionalIsIdent = function(fn) {
+    if (isFunction(fn)) {
+      $parseOptions.additionalIsIdent = fn;
+      return this;
+    } else {
+      return $parseOptions.additionalIsIdent;
+    }
+  };
+
+
   this.$get = ['$filter', '$sniffer', '$log', function($filter, $sniffer, $log) {
     $parseOptions.csp = $sniffer.csp;
 

test/ng/parseSpec.js

@@ -14,7 +14,7 @@ describe('parser', function() {
 
     beforeEach(function () {
       lex = function () {
-        var lexer = new Lexer({csp: false, unwrapPromises: false});
+        var lexer = new Lexer({csp: false, unwrapPromises: false, additionalIsIdent: noop});
         return lexer.lex.apply(lexer, arguments);
       };
     });
@@ -190,12 +190,45 @@ describe('parser', function() {
         lex("'\\u1''bla'");
       }).toThrowMinErr("$parse", "lexerr", "Lexer Error: Invalid unicode escape [\\u1''b] at column 2 in expression ['\\u1''bla'].");
     });
+
+    describe('with additionalIsIdent', function() {
+      beforeEach(function () {
+        lex = function () {
+          var mathCharacters = 'πΣε';
+
+          var lexer = new Lexer({csp: false, unwrapPromises: false, additionalIsIdent: function(ch) {
+            return mathCharacters.indexOf(ch) > -1;
+          }});
+
+          return lexer.lex.apply(lexer, arguments);
+        };
+      });
+
+      it('correctly tokenizes identifiers containing the specified special characters', function() {
+        var tokens = lex(" Σ == π + ε ");
+
+        expect(tokens.length).toEqual(5);
+        expect(tokens[0].text).toEqual('Σ');
+        expect(tokens[1].text).toEqual('==');
+        expect(tokens[2].text).toEqual('π');
+        expect(tokens[3].text).toEqual('+');
+        expect(tokens[4].text).toEqual('ε');
+      });
+
+    });
   });
 
   var $filterProvider, scope;
 
-  beforeEach(module(['$filterProvider', function (filterProvider) {
+  beforeEach(module(['$filterProvider', '$parseProvider', function (filterProvider, parseProvider) {
     $filterProvider = filterProvider;
+
+    var mathCharacters = 'Σπε';
+
+    parseProvider.additionalIsIdent(function(ch) {
+      return mathCharacters.indexOf(ch) > -1;
+    });
+
   }]));
 
 
@@ -335,6 +368,13 @@ describe('parser', function() {
         expect(scope.$eval("x.y.z", scope)).not.toBeDefined();
       });
 
+      it('correctly evaluates identifiers with non-English characters', function() {
+        scope.π = 3.14;
+        expect(scope.$eval("π", scope)).toEqual(scope.π);
+        expect(scope.$eval("Σ = π + π", scope)).toEqual(scope.π + scope.π);
+        expect(scope.Σ).toEqual(scope.π + scope.π);
+      });
+
       it('should resolve deeply nested paths (important for CSP mode)', function() {
         scope.a = {b: {c: {d: {e: {f: {g: {h: {i: {j: {k: {l: {m: {n: 'nooo!'}}}}}}}}}}}}};
         expect(scope.$eval("a.b.c.d.e.f.g.h.i.j.k.l.m.n", scope)).toBe('nooo!');