Provide ol.expression.parse method

This is the only method needed in the API.

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

@@ -0,0 +1,70 @@
+goog.provide('ol.test.expression');
+
+
+describe('ol.expression.parse', function() {
+
+  it('parses a string and returns an expression', function() {
+    var expr = ol.expression.parse('foo');
+    expect(expr).to.be.a(ol.expression.Expression);
+  });
+
+  describe('primary expressions', function() {
+    // http://www.ecma-international.org/ecma-262/5.1/#sec-11.1
+
+    it('parses identifier expressions', function() {
+      var expr = ol.expression.parse('foo');
+      expect(expr).to.be.a(ol.expression.Identifier);
+      expect(expr.evaluate({foo: 'bar'})).to.be('bar');
+    });
+
+    it('throws on invalid identifier expressions', function() {
+      expect(function() {
+        ol.expression.parse('3foo');
+      }).throwException();
+    });
+
+    it('parses string literal expressions', function() {
+      var expr = ol.expression.parse('"foo"');
+      expect(expr).to.be.a(ol.expression.Literal);
+      expect(expr.evaluate({})).to.be('foo');
+    });
+
+    it('throws on unterminated string', function() {
+      expect(function() {
+        ol.expression.parse('"foo');
+      }).throwException();
+    });
+
+    it('parses numeric literal expressions', function() {
+      var expr = ol.expression.parse('.42e+2');
+      expect(expr).to.be.a(ol.expression.Literal);
+      expect(expr.evaluate({})).to.be(42);
+    });
+
+    it('throws on invalid number', function() {
+      expect(function() {
+        ol.expression.parse('.42eX');
+      }).throwException();
+    });
+
+    it('parses boolean literal expressions', function() {
+      var expr = ol.expression.parse('false');
+      expect(expr).to.be.a(ol.expression.Literal);
+      expect(expr.evaluate({})).to.be(false);
+    });
+
+    it('parses null literal expressions', function() {
+      var expr = ol.expression.parse('null');
+      expect(expr).to.be.a(ol.expression.Literal);
+      expect(expr.evaluate({})).to.be(null);
+    });
+
+  });
+
+});
+
+
+goog.require('ol.expression');
+goog.require('ol.expression.Expression');
+goog.require('ol.expression.Identifier');
+goog.require('ol.expression.Literal');