Cache constructed scopes for files

compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/ScopeProvider.java

@@ -26,6 +26,9 @@ import org.jetbrains.jet.lang.resolve.ImportsResolver;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.scopes.*;
 
+import java.util.Map;
+import java.util.WeakHashMap;
+
 /**
  * @author abreslav
  */
@@ -37,9 +40,12 @@ public class ScopeProvider {
         this.resolveSession = resolveSession;
     }
 
+    private final Map<JetFile, JetScope> fileScopeCache = new WeakHashMap<JetFile, JetScope>();
+
     // This scope does not contain imported functions
     @NotNull
     public JetScope getFileScopeForDeclarationResolution(JetFile file) {
+        if (!fileScopeCache.containsKey(file)) {
             // package
             JetNamespaceHeader header = file.getNamespaceHeader();
             if (header == null) {
@@ -74,9 +80,10 @@ public class ScopeProvider {
                                                  resolveSession.getInjector().getQualifiedExpressionResolver());
 
             fileScope.changeLockLevel(WritableScope.LockLevel.READING);
+            fileScopeCache.put(file, new ChainedScope(packageDescriptor, packageDescriptor.getMemberScope(), fileScope));
+        }
 
-        // TODO: Cache
+        return fileScopeCache.get(file);
-        return new ChainedScope(packageDescriptor, packageDescriptor.getMemberScope(), fileScope);
     }
 
     @NotNull