Member expressions

src/ol/expression/expression.js

@@ -8,6 +8,7 @@ goog.provide('ol.expression.Logical');
 goog.provide('ol.expression.LogicalOp');
 goog.provide('ol.expression.Math');
 goog.provide('ol.expression.MathOp');
+goog.provide('ol.expression.Member');
 goog.provide('ol.expression.Not');
 
 
@@ -377,6 +378,43 @@ ol.expression.Math.prototype.evaluate = function(scope, opt_fns, opt_this) {
 
 
 
+/**
+ * A member expression (e.g. `foo.bar`).
+ *
+ * @constructor
+ * @extends {ol.expression.Expression}
+ * @param {ol.expression.Expression} expr An expression that resolves to an
+ *     object.
+ * @param {ol.expression.Identifier} property Identifier with name of property.
+ */
+ol.expression.Member = function(expr, property) {
+
+  /**
+   * @type {ol.expression.Expression}
+   * @private
+   */
+  this.expr_ = expr;
+
+  /**
+   * @type {ol.expression.Identifier}
+   * @private
+   */
+  this.property_ = property;
+
+};
+goog.inherits(ol.expression.Member, ol.expression.Expression);
+
+
+/**
+ * @inheritDoc
+ */
+ol.expression.Member.prototype.evaluate = function(scope, opt_fns, opt_this) {
+  var obj = this.expr_.evaluate(scope, opt_fns, opt_this);
+  return this.property_.evaluate(obj);
+};
+
+
+
 /**
  * A logical not expression (e.g. `!foo`).
  *

src/ol/expression/parser.js

@@ -28,6 +28,7 @@ goog.require('ol.expression.Logical');
 goog.require('ol.expression.LogicalOp');
 goog.require('ol.expression.Math');
 goog.require('ol.expression.MathOp');
+goog.require('ol.expression.Member');
 goog.require('ol.expression.Not');
 goog.require('ol.expression.Token');
 goog.require('ol.expression.TokenType');
@@ -187,11 +188,12 @@ ol.expression.Parser.prototype.createLiteral_ = function(value) {
  * // TODO: make exp {ol.expression.Member|ol.expression.Identifier}
  * @param {ol.expression.Expression} expr Expression.
  * @param {ol.expression.Identifier} property Member name.
+ * @return {ol.expression.Member} The member expression.
  * @private
  */
 ol.expression.Parser.prototype.createMemberExpression_ = function(expr,
     property) {
-  throw new Error('Not implemented');
+  return new ol.expression.Member(expr, property);
 };
 
 

test/spec/ol/expression/expression.test.js

@@ -392,6 +392,32 @@ describe('ol.expression.Math', function() {
 
 });
 
+describe('ol.expression.Member', function() {
+  describe('constructor', function() {
+    it('creates a new expression', function() {
+      var expr = new ol.expression.Member(
+          new ol.expression.Identifier('foo'),
+          new ol.expression.Identifier('bar'));
+
+      expect(expr).to.be.a(ol.expression.Expression);
+      expect(expr).to.be.a(ol.expression.Member);
+    });
+  });
+
+  describe('#evaluate()', function() {
+    it('accesses an object property', function() {
+
+      var expr = new ol.expression.Member(
+          new ol.expression.Identifier('foo'),
+          new ol.expression.Identifier('bar'));
+
+      var scope = {foo: {bar: 42}};
+      expect(expr.evaluate(scope)).to.be(42);
+    });
+  });
+});
+
+
 describe('ol.expression.Not', function() {
 
   describe('constructor', function() {
@@ -446,4 +472,5 @@ goog.require('ol.expression.Logical');
 goog.require('ol.expression.LogicalOp');
 goog.require('ol.expression.Math');
 goog.require('ol.expression.MathOp');
+goog.require('ol.expression.Member');
 goog.require('ol.expression.Not');