--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/djol/DynamicStyle.js	Mon Aug 21 17:47:00 2017 +0300
@@ -0,0 +1,119 @@
+define([ "./declare-style", "dojo/_base/declare", "ol", "implab/safe" ],
+
+function(declare, dojoDeclare, ol, safe) {
+    return declare([], {
+        _cache : null,
+        _getKey : null,
+        _getZoom : null,
+        
+        defaultStyle : null,
+        
+        style : null,
+        
+        styleFunction : null,
+        
+        filter : null,
+
+        constructor : function(opts) {
+            if (opts)
+                dojoDeclare.safeMixin(this, opts);
+
+            this._cache = {};
+
+            if (this.zoom) {
+                if (this.zoom instanceof Function) {
+                    this._getZoom = this.zoom;
+                } else {
+                    var levels = [], max = "max";
+                    for ( var p in this.zoom) {
+                        if (safe.isNumber(this.zoom[p]))
+                            levels.push({
+                                name : p,
+                                zoom : Number(this.zoom[p])
+                            });
+                        else if (this.zoom[p] == "max")
+                            max = p;
+                    }
+
+                    levels.sort(function(x, y) {
+                        return x.zoom - y.zoom;
+                    });
+
+                    this.zoomMax = max;
+                    this.zoomLevels = levels;
+
+                    this._getZoom = function(z) {
+                        for (var i = 0; i < levels.length; i++) {
+                            if (z <= levels[i].zoom)
+                                return levels[i].name;
+                        }
+                        return max;
+                    };
+                }
+            } else {
+                this._getZoom = function(z) {
+                    return "max";
+                };
+            }
+
+            if (this.key) {
+                if (this.key instanceof Function) {
+                    this._getKey = this.key;
+                } else if (typeof this.key === "string") {
+                    this._getKey = function(ft) {
+                        return ft.get(this.key);
+                    };
+                } else {
+                    this._getKey = function(ft, z) {
+                        var k = this.key[z];
+                        if (k instanceof Function)
+                            return k.call(this, ft, z);
+                        else if (typeof k == "string")
+                            return ft.get(k);
+                        else
+                            return this.defaultStyle;
+                    };
+                }
+            } else {
+                this._getKey = function() {
+                    return this.defaultStyle;
+                };
+            }
+
+            if (this.style) {
+                if (this.style instanceof Function) {
+                    this._style = this.style;
+                } else {
+                    this._style = function(ft, res, key, zoom) {
+                        var s = this.style[zoom];
+                        return s && (s instanceof Function) ? s.apply(
+                            this,
+                            arguments) : s;
+                    };
+                }
+            }
+        },
+
+        getFeatureStyle : function(ft, res) {
+            safe.argumentNotNull(ft, "ft");
+            
+            if (this.filter && this.filter(ft) === false)
+                return null;
+
+            var z = this._getZoom(res);
+            var k = this._getKey(ft, z);
+
+            var cid = [ k, z ].join('-');
+
+            var style = this._cache[cid];
+            if (!style) {
+                style = this._style ? this._style(ft, res, k, z) : null;
+                this._cache[cid] = style;
+            }
+
+
+            return safe.isNull(style) || style instanceof Array ? style : [ style ];
+        }
+
+    });
+});
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