Restore support for #layers=X with no map parameter

https://trac.openstreetmap.org/ticket/5056

app/assets/javascripts/leaflet.map.js.erb

@@ -243,6 +243,11 @@ L.OSM.Map = L.Map.extend({
       zoom: this.getZoom(),
       layers: this.getLayersCode()
     }
+  },
+
+  setState: function(state, options) {
+    if (state.center) this.setView(state.center, state.zoom, options);
+    this.updateLayers(state.layers);
   }
 });
 

app/assets/javascripts/osm.js.erb

@@ -111,41 +111,25 @@ OSM = {
   },
 
   parseHash: function(hash) {
+    var args = {};
+
     var i = hash.indexOf('#');
     if (i < 0) {
-      return false;
+      return args;
     }
 
-    hash = hash.substr(i + 1);
+    hash = querystring.parse(hash.substr(i + 1));
 
-    if (hash === '') {
+    var map = (hash.map || '').split('/'),
-      return false;
+      zoom = parseInt(map[0], 10),
+      lat = parseFloat(map[1]),
+      lon = parseFloat(map[2]);
+
+    if (!isNaN(zoom) && !isNaN(lat) && !isNaN(lon)) {
+      args.center = new L.LatLng(lat, lon);
+      args.zoom = zoom;
     }
 
-    hash = querystring.parse(hash);
-
-    if (hash.map === undefined) {
-      return false;
-    }
-
-    var args = hash.map.split("/");
-    if (args.length !== 3) {
-      return false;
-    }
-
-    var zoom = parseInt(args[0], 10),
-      lat = parseFloat(args[1]),
-      lon = parseFloat(args[2]);
-
-    if (isNaN(zoom) || isNaN(lat) || isNaN(lon)) {
-      return false;
-    }
-
-    args = {
-      center: new L.LatLng(lat, lon),
-      zoom: zoom
-    };
-
     if (hash.layers) {
       args.layers = hash.layers;
     }

app/assets/javascripts/router.js

@@ -106,18 +106,14 @@ OSM.Router = function(map, rts) {
       currentPath = path;
       currentRoute = routes.recognize(currentPath);
       currentRoute.run('popstate', currentPath);
-      var state = e.originalEvent.state;
+      map.setState(e.originalEvent.state, {animate: false});
-      if (state.center) {
-        map.setView(state.center, state.zoom, {animate: false});
-        map.updateLayers(state.layers);
-      }
     });
 
     router.route = function (url) {
       var path = url.replace(/#.*/, ''),
         route = routes.recognize(path);
       if (!route) return false;
-      window.history.pushState(OSM.parseHash(url) || {}, document.title, url);
+      window.history.pushState(OSM.parseHash(url), document.title, url);
       currentRoute.run('unload');
       currentPath = path;
       currentRoute = route;
@@ -154,9 +150,7 @@ OSM.Router = function(map, rts) {
     if (hash === currentHash) return;
     currentHash = hash;
     var state = OSM.parseHash(hash);
-    if (!state) return;
+    map.setState(state);
-    map.setView(state.center, state.zoom);
-    map.updateLayers(state.layers);
     router.stateChange(state, hash);
   };