Provide ol.expression.parse method

This is the only method needed in the API.

src/ol/expression/expression.js

@@ -0,0 +1,15 @@
+goog.provide('ol.expression');
+
+goog.require('ol.expression.Parser');
+
+
+/**
+ * Parse an expression
+ * @param {string} source The expression source (e.g. `'foo + 2'`).
+ * @return {ol.expression.Expression} An expression instance that can be
+ *     evaluated within some scope to provide a value.
+ */
+ol.expression.parse = function(source) {
+  var parser = new ol.expression.Parser();
+  return parser.parse(source);
+};

src/ol/expression/parser.js

@@ -453,15 +453,3 @@ ol.expression.Parser.prototype.parseUnaryExpression_ = function(lexer) {
 ol.expression.Parser.prototype.parseExpression_ = function(lexer) {
   return this.parseBinaryExpression_(lexer);
 };
-
-
-/**
- * Parse an expression
- * @param {string} source The expression source (e.g. `'foo + 2'`).
- * @return {ol.expression.Expression} An expression instance that can be
- *     evaluated within some scope to provide a value.
- */
-ol.expression.parse = function(source) {
-  var parser = new ol.expression.Parser();
-  return parser.parse(source);
-};