Accept an expression string for rule filter

examples/style-rules.js

@@ -3,9 +3,6 @@ goog.require('ol.RendererHint');
 goog.require('ol.View2D');
 goog.require('ol.control.defaults');
 goog.require('ol.expression');
-goog.require('ol.filter.Filter');
-goog.require('ol.filter.Geometry');
-goog.require('ol.geom.GeometryType');
 goog.require('ol.layer.Vector');
 goog.require('ol.parser.GeoJSON');
 goog.require('ol.proj');
@@ -19,9 +16,7 @@ goog.require('ol.style.Text');
 
 var style = new ol.style.Style({rules: [
   new ol.style.Rule({
-    filter: new ol.filter.Filter(function(feature) {
-      return feature.get('where') == 'outer';
-    }),
+    filter: 'where == "outer"',
     symbolizers: [
       new ol.style.Line({
         strokeColor: ol.expression.parse('color'),
@@ -31,9 +26,7 @@ var style = new ol.style.Style({rules: [
     ]
   }),
   new ol.style.Rule({
-    filter: new ol.filter.Filter(function(feature) {
-      return feature.get('where') == 'inner';
-    }),
+    filter: 'where == "inner"',
     symbolizers: [
       new ol.style.Line({
         strokeColor: '#013',
@@ -48,7 +41,7 @@ var style = new ol.style.Style({rules: [
     ]
   }),
   new ol.style.Rule({
-    filter: new ol.filter.Geometry(ol.geom.GeometryType.POINT),
+    filter: 'geometryType("point")',
     symbolizers: [
       new ol.style.Shape({
         size: 40,

src/objectliterals.jsdoc

@@ -552,7 +552,7 @@
 
 /**
  * @typedef {Object} ol.style.RuleOptions
- * @property {ol.filter.Filter|undefined} filter Filter.
+ * @property {ol.expression.Expression|string|undefined} filter Filter.
  * @property {Array.<ol.style.Symbolizer>|undefined} symbolizers Symbolizers.
  */
 

src/ol/expression.jsdoc

@@ -0,0 +1,3 @@
+/**
+ * @namespace ol.expression
+ */

src/ol/style/rule.js

@@ -1,7 +1,10 @@
 goog.provide('ol.style.Rule');
 
+goog.require('goog.asserts');
+
 goog.require('ol.Feature');
-goog.require('ol.filter.Filter');
+goog.require('ol.expression');
+goog.require('ol.expression.Expression');
 goog.require('ol.style.Symbolizer');
 
 
@@ -12,11 +15,22 @@ goog.require('ol.style.Symbolizer');
  */
 ol.style.Rule = function(options) {
 
+
+  var filter = null;
+  if (goog.isDef(options.filter)) {
+    if (goog.isString(options.filter)) {
+      filter = ol.expression.parse(options.filter);
+    } else {
+      goog.asserts.assert(options.filter instanceof ol.expression.Expression);
+      filter = options.filter;
+    }
+  }
+
   /**
-   * @type {ol.filter.Filter}
+   * @type {ol.expression.Expression}
    * @private
    */
-  this.filter_ = goog.isDef(options.filter) ? options.filter : null;
+  this.filter_ = filter;
 
   /**
    * @type {Array.<ol.style.Symbolizer>}
@@ -33,7 +47,8 @@ ol.style.Rule = function(options) {
  * @return {boolean} Does the rule apply to the feature?
  */
 ol.style.Rule.prototype.applies = function(feature) {
-  return goog.isNull(this.filter_) ? true : this.filter_.applies(feature);
+  return goog.isNull(this.filter_) ?
+      true : !!ol.expression.evaluateFeature(this.filter_, feature);
 };
 
 

test/spec/ol/style/rule.test.js

@@ -13,14 +13,14 @@ describe('ol.style.Rule', function() {
 
     it('returns false when the rule does not apply', function() {
       rule = new ol.style.Rule({
-        filter: new ol.filter.Filter(function() { return false; })
+        filter: new ol.expression.Literal(false)
       });
       expect(rule.applies(feature)).to.be(false);
     });
 
     it('returns true when the rule applies', function() {
       rule = new ol.style.Rule({
-        filter: new ol.filter.Filter(function() { return true; })
+        filter: new ol.expression.Literal(true)
       });
       expect(rule.applies(feature)).to.be(true);
     });
@@ -29,5 +29,5 @@ describe('ol.style.Rule', function() {
 });
 
 goog.require('ol.Feature');
-goog.require('ol.filter.Filter');
+goog.require('ol.expression.Literal');
 goog.require('ol.style.Rule');

test/spec/ol/style/style.test.js

@@ -9,9 +9,7 @@ describe('ol.style.Style', function() {
       var style = new ol.style.Style({
         rules: [
           new ol.style.Rule({
-            filter: new ol.filter.Filter(function(feature) {
-              return feature.get('foo') == 'bar';
-            }),
+            filter: 'foo == "bar"',
             symbolizers: [
               new ol.style.Shape({
                 size: 4,
@@ -66,7 +64,6 @@ goog.require('ol.Feature');
 goog.require('ol.geom.LineString');
 goog.require('ol.geom.Point');
 goog.require('ol.geom.Polygon');
-goog.require('ol.filter.Filter');
 goog.require('ol.style.Rule');
 goog.require('ol.style.Shape');
 goog.require('ol.style.ShapeLiteral');