Naive support for nested variables in templates

cf #600

umap/static/umap/js/umap.core.js

@@ -125,11 +125,16 @@ L.Util.usableOption = function (options, option) {
 
 L.Util.greedyTemplate = function (str, data, ignore) {
     // Don't throw error if some key is missing
-    return str.replace(/\{ *([\w_\:]+) *\}/g, function (str, key) {
+    return str.replace(/\{ *([\w_\:\.]+) *\}/g, function (str, key) {
-        var value = data[key];
+        var path = key.split('.'),
+            leaf = path.length - 1, value = data;
+        for (var i = 0; i < path.length; i++) {
+            value = value[path[i]]
             if (value === undefined) {
                 if (ignore) value = str;
                 else value = '';
+                break;
+            }
         }
         return value;
     });

umap/static/umap/test/Util.js

@@ -146,6 +146,18 @@ describe('L.Util', function () {
             assert.equal(L.Util.greedyTemplate('A phrase with a {variable:fr}.', {}, true), 'A phrase with a {variable:fr}.');
         });
 
+        it('should replace nested variables', function () {
+            assert.equal(L.Util.greedyTemplate('A phrase with a {fr.var}.', {fr: {var: 'value'}}), 'A phrase with a value.');
+        });
+
+        it('should not fail if nested variable is missing', function () {
+            assert.equal(L.Util.greedyTemplate('A phrase with a {fr.var.foo}.', {fr: {var: 'value'}}), 'A phrase with a .');
+        });
+
+        it('should not fail with nested variables and no data', function () {
+            assert.equal(L.Util.greedyTemplate('A phrase with a {fr.var.foo}.', {}), 'A phrase with a .');
+        });
+
     });
 
     describe('#TextColorFromBackgroundColor', function () {