Refactoring: use selectors for chain scope behaviour implementation

core/descriptors/src/org/jetbrains/jet/lang/resolve/scopes/ChainedScope.java

@@ -30,6 +30,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
+import static org.jetbrains.jet.lang.resolve.scopes.JetScopeSelectorUtil.*;
+
 public class ChainedScope implements JetScope {
     private final DeclarationDescriptor containingDeclaration;
     private final String debugName;
@@ -46,57 +48,29 @@ public class ChainedScope implements JetScope {
 
     @Override
     public ClassifierDescriptor getClassifier(@NotNull Name name) {
-        for (JetScope scope : scopeChain) {
+        return getFirstMatch(scopeChain, name, CLASSIFIER_DESCRIPTOR_SCOPE_SELECTOR);
-            ClassifierDescriptor classifier = scope.getClassifier(name);
-            if (classifier != null) return classifier;
-        }
-        return null;
     }
 
     @Override
     public PackageViewDescriptor getPackage(@NotNull Name name) {
-        for (JetScope jetScope : scopeChain) {
+        return getFirstMatch(scopeChain, name, PACKAGE_SCOPE_SELECTOR);
-            PackageViewDescriptor aPackage = jetScope.getPackage(name);
-            if (aPackage != null) {
-                return aPackage;
-            }
-        }
-        return null;
     }
 
     @NotNull
     @Override
     public Set<VariableDescriptor> getProperties(@NotNull Name name) {
-        Set<VariableDescriptor> properties = Sets.newLinkedHashSet();
+        return getFromAllScopes(scopeChain, name, NAMED_PROPERTIES_SCOPE_SELECTOR);
-        for (JetScope jetScope : scopeChain) {
-            properties.addAll(jetScope.getProperties(name));
-        }
-        return properties;
     }
 
     @Override
     public VariableDescriptor getLocalVariable(@NotNull Name name) {
-        for (JetScope jetScope : scopeChain) {
+        return getFirstMatch(scopeChain, name, VARIABLE_DESCRIPTOR_SCOPE_SELECTOR);
-            VariableDescriptor variable = jetScope.getLocalVariable(name);
-            if (variable != null) {
-                return variable;
-            }
-        }
-        return null;
     }
 
     @NotNull
     @Override
     public Set<FunctionDescriptor> getFunctions(@NotNull Name name) {
-        if (scopeChain.length == 0) {
+        return getFromAllScopes(scopeChain, name, NAMED_FUNCTION_SCOPE_SELECTOR);
-            return Collections.emptySet();
-        }
-
-        Set<FunctionDescriptor> result = Sets.newLinkedHashSet();
-        for (JetScope jetScope : scopeChain) {
-            result.addAll(jetScope.getFunctions(name));
-        }
-        return result;
     }
 
     @NotNull

core/descriptors/src/org/jetbrains/jet/lang/resolve/scopes/JetScopeSelectorUtil.java

@@ -23,6 +23,7 @@ import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.resolve.name.Name;
 
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Set;
 
 public class JetScopeSelectorUtil {
@@ -84,6 +85,15 @@ public class JetScopeSelectorUtil {
                 }
             };
 
+    public static final ScopeByNameSelector<VariableDescriptor> VARIABLE_DESCRIPTOR_SCOPE_SELECTOR =
+            new ScopeByNameSelector<VariableDescriptor>() {
+                @Nullable
+                @Override
+                public VariableDescriptor get(@NotNull JetScope scope, @NotNull Name name) {
+                    return scope.getLocalVariable(name);
+                }
+            };
+
     public static final ScopeByNameMultiSelector<FunctionDescriptor> NAMED_FUNCTION_SCOPE_SELECTOR =
             new ScopeByNameMultiSelector<FunctionDescriptor>() {
                 @NotNull
@@ -110,4 +120,38 @@ public class JetScopeSelectorUtil {
                     return scope.getAllDescriptors();
                 }
             };
+
+    @Nullable
+    public static <D extends DeclarationDescriptor> D getFirstMatch(
+            @NotNull JetScope[] scopes,
+            @NotNull Name name,
+            @NotNull ScopeByNameSelector<D> descriptorSelector
+    ) {
+        for (JetScope scope : scopes) {
+            D descriptor = descriptorSelector.get(scope, name);
+
+            if (descriptor != null) {
+                return descriptor;
+            }
+        }
+
+        return null;
+    }
+
+    @NotNull
+    public static <D extends DeclarationDescriptor> Set<D> getFromAllScopes(
+            @NotNull JetScope[] scopes,
+            @NotNull Name name,
+            @NotNull ScopeByNameMultiSelector<D> descriptorsSelector
+    ) {
+        if (scopes.length == 0) return Collections.emptySet();
+
+        Set<D> descriptors = Sets.newLinkedHashSet();
+
+        for (JetScope jetScope : scopes) {
+            descriptors.addAll(descriptorsSelector.get(jetScope, name));
+        }
+
+        return descriptors;
+    }
 }