Giving vector layers the style they deserve

Now vector layers can have a style. ol.Style instances have an
apply method to get the symbolizer literals for a feature. If the
layer does not have a style defined, there is also a static
applyDefaultStyle function on ol.Style to get the default
symbolizer literals for a feature. The vector layer also got a
groupFeaturesBySymbolizerLiteral method, which returns an array
with features grouped by symbolizer, as needed by the canvas
renderer.

src/ol/style/style.js

@@ -1,6 +1,9 @@
 goog.provide('ol.style.Style');
 
+goog.require('ol.Feature');
+goog.require('ol.geom.GeometryType');
 goog.require('ol.style.Rule');
+goog.require('ol.style.SymbolizerLiteral');
 
 
 /**
@@ -23,3 +26,46 @@ ol.style.Style = function(options) {
   this.rules_ = goog.isDef(options.rules) ? options.rules : [];
 
 };
+
+
+/**
+ * @param {ol.Feature} feature Feature.
+ * @return {Array.<ol.style.SymbolizerLiteral>} Symbolizer literals for the
+ *     feature.
+ */
+ol.style.Style.prototype.apply = function(feature) {
+  var rules = this.rules_,
+      literals = [],
+      rule, symbolizers;
+  for (var i = 0, ii = rules.length; i < ii; ++i) {
+    rule = rules[i];
+    if (rule.applies(feature)) {
+      symbolizers = rule.getSymbolizers();
+      for (var j = 0, jj = symbolizers.length; j < jj; ++j) {
+        literals.push(symbolizers[j].createLiteral(feature));
+      }
+    }
+  }
+  return literals;
+};
+
+
+/**
+ * @param {ol.Feature} feature Feature.
+ * @return {Array.<ol.style.SymbolizerLiteral>} Default symbolizer literals for
+ *     the feature.
+ */
+ol.style.Style.applyDefaultStyle = function(feature) {
+  var type = feature.getGeometry().getType();
+  if (type === ol.geom.GeometryType.POINT ||
+      type === ol.geom.GeometryType.MULTIPOINT) {
+    return [ol.style.ShapeDefaults];
+  } else if (type === ol.geom.GeometryType.LINESTRING ||
+      type === ol.geom.GeometryType.MULTILINESTRING) {
+    return [ol.style.LineDefaults];
+  } else if (type === ol.geom.GeometryType.LINEARRING ||
+      type === ol.geom.GeometryType.POLYGON ||
+      type === ol.geom.GeometryType.MULTIPOLYGON) {
+    return [ol.style.PolygonDefaults];
+  }
+};