webcoding
diff --git a/‎lib/source-map/source-map-consumer.js‎
Lines changed: 30 additions & 10 deletions b/‎lib/source-map/source-map-consumer.js‎
Lines changed: 30 additions & 10 deletions
diff --git a/‎test/source-map/test-source-map-consumer.js‎
Lines changed: 24 additions & 0 deletions b/‎test/source-map/test-source-map-consumer.js‎
Lines changed: 24 additions & 0 deletions
@@ -337,25 +337,45 @@ define(function (require, exports, module) {
     function SourceMapConsumer_fromSourceMap(aSourceMap) {
       var smc = Object.create(BasicSourceMapConsumer.prototype);
 
-      smc._names = ArraySet.fromArray(aSourceMap._names.toArray(), true);
-      smc._sources = ArraySet.fromArray(aSourceMap._sources.toArray(), true);
+      var names = smc._names = ArraySet.fromArray(aSourceMap._names.toArray(), true);
+      var sources = smc._sources = ArraySet.fromArray(aSourceMap._sources.toArray(), true);
       smc.sourceRoot = aSourceMap._sourceRoot;
       smc.sourcesContent = aSourceMap._generateSourcesContent(smc._sources.toArray(),
                                                               smc.sourceRoot);
       smc.file = aSourceMap._file;
 
-      smc.__generatedMappings = aSourceMap._mappings.toArray().slice();
-      smc.__originalMappings = aSourceMap._mappings.toArray().slice().sort();
+      // Because we are modifying the entries (by converting string sources and
+      // names to indices into the sources and names ArraySets), we have to make
+      // a copy of the entry or else bad things happen. Shared mutable state
+      // strikes again! See github issue #191.
 
-      smc.__generatedMappings.forEach(function (m) {
-        if (m.source !== null) {
-          m.source = smc._sources.indexOf(m.source);
+      var generatedMappings = aSourceMap._mappings.toArray().slice();
+      var destGeneratedMappings = smc.__generatedMappings = [];
+      var destOriginalMappings = smc.__originalMappings = [];
 
-          if (m.name !== null) {
-            m.name = smc._names.indexOf(m.name);
+      for (var i = 0, length = generatedMappings.length; i < length; i++) {
+        var srcMapping = generatedMappings[i];
+        var destMapping = new Mapping;
+        destMapping.generatedLine = srcMapping.generatedLine;
+        destMapping.generatedColumn = srcMapping.generatedColumn;
+
+        if (srcMapping.source) {
+          destMapping.source = sources.indexOf(srcMapping.source);
+          destMapping.originalLine = srcMapping.originalLine;
+          destMapping.originalColumn = srcMapping.originalColumn;
+
+          if (srcMapping.name) {
+            destMapping.name = names.indexOf(srcMapping.name);
           }
+
+          destOriginalMappings.push(destMapping);
         }
-      });
+
+        destGeneratedMappings.push(destMapping);
+      }
+
+      quickSort(smc.__originalMappings, util.compareByOriginalPositions);
+
       return smc;
     };
 
 
@@ -1057,4 +1057,28 @@ define(function (require, exports, module) {
     assert.equal(pos.column, 4);
   };
 
+  exports['test issue #191'] = function (assert, util) {
+    var generator = new SourceMapGenerator({ file: 'a.css' });
+    generator.addMapping({
+      source:   'b.css',
+      original: {
+        line:   1,
+        column: 0
+      },
+      generated: {
+        line:   1,
+        column: 0
+      }
+    });
+
+    // Create a SourceMapConsumer from the SourceMapGenerator, ...
+    var consumer  = SourceMapConsumer.fromSourceMap(generator);
+    // ... and then try and use the SourceMapGenerator again. This should not
+    // throw.
+    generator.toJSON();
+
+    assert.ok(true, "Using a SourceMapGenerator again after creating a " +
+                    "SourceMapConsumer from it should not throw");
+  };
+
 });