Migrated attachment for Guice issue 770, comment 0

override.patch

From 6c1c5f6d33e06481863a1a721fd2cf4087674797 Mon Sep 17 00:00:00 2001
From: Jakub Narloch <jmnarloch@gmail.com>
Date: Mon, 9 Sep 2013 00:03:21 +0200
Subject: [PATCH] Added functionality for runtime buinding override, by
 creating new child injector that can override/or hide the
 bindings of it's parent injector.

---
 core/src/com/google/inject/Binder.java             |   2 +
 .../inject/internal/AbstractBindingProcessor.java  |   7 +-
 .../google/inject/internal/BindingProcessor.java   |   4 +-
 .../inject/internal/InjectorOptionsProcessor.java  |   1 +
 .../com/google/inject/internal/InjectorShell.java  |   9 +-
 .../com/google/inject/internal/ModuleOptions.java  |  48 ++++++++
 .../inject/internal/ModuleOptionsProcessor.java    |  44 ++++++++
 .../internal/UntargettedBindingProcessor.java      |   4 +-
 .../google/inject/spi/DefaultElementVisitor.java   |   4 +
 core/src/com/google/inject/spi/ElementVisitor.java |   7 ++
 core/src/com/google/inject/spi/Elements.java       |   6 +-
 .../google/inject/spi/OverrideBindingOption.java   |  50 +++++++++
 .../com/google/inject/OverrideBindingTest.java     | 123 +++++++++++++++++++++
 13 files changed, 300 insertions(+), 9 deletions(-)
 create mode 100644 core/src/com/google/inject/internal/ModuleOptions.java
 create mode 100644 core/src/com/google/inject/internal/ModuleOptionsProcessor.java
 create mode 100644 core/src/com/google/inject/spi/OverrideBindingOption.java
 create mode 100644 core/test/com/google/inject/OverrideBindingTest.java

diff --git a/core/src/com/google/inject/Binder.java b/core/src/com/google/inject/Binder.java
index dae3812..c185af5 100644
--- a/core/src/com/google/inject/Binder.java
+++ b/core/src/com/google/inject/Binder.java
@@ -493,4 +493,6 @@ public interface Binder {
    * @since 4.0
    */
   void requireExactBindingAnnotations();
+
+  void allowBindingOverride();
 }
diff --git a/core/src/com/google/inject/internal/AbstractBindingProcessor.java b/core/src/com/google/inject/internal/AbstractBindingProcessor.java
index 72dae2b..ecfdb93 100644
--- a/core/src/com/google/inject/internal/AbstractBindingProcessor.java
+++ b/core/src/com/google/inject/internal/AbstractBindingProcessor.java
@@ -56,10 +56,13 @@ abstract class AbstractBindingProcessor extends AbstractProcessor {
       TypeLiteral.class);
   
   protected final ProcessedBindingData bindingData;
+
+  protected final ModuleOptions moduleOptions;
   
-  AbstractBindingProcessor(Errors errors, ProcessedBindingData bindingData) {
+  AbstractBindingProcessor(Errors errors, ProcessedBindingData bindingData, ModuleOptions moduleOptions) {
     super(errors);
     this.bindingData = bindingData;
+    this.moduleOptions = moduleOptions;
   }
 
   protected <T> UntargettedBindingImpl<T> invalidBinding(
@@ -119,7 +122,7 @@ abstract class AbstractBindingProcessor extends AbstractProcessor {
       // If no original at this level, the original was on a parent, and we don't
       // allow deduplication between parents & children.
       if(original == null) {
-        return false;
+        return moduleOptions.isOverrideBindings();
       } else {
         return original.equals(binding);
       }
diff --git a/core/src/com/google/inject/internal/BindingProcessor.java b/core/src/com/google/inject/internal/BindingProcessor.java
index 7ce3ea0..067ab1e 100644
--- a/core/src/com/google/inject/internal/BindingProcessor.java
+++ b/core/src/com/google/inject/internal/BindingProcessor.java
@@ -44,8 +44,8 @@ final class BindingProcessor extends AbstractBindingProcessor {
 
   private final Initializer initializer;
 
-  BindingProcessor(Errors errors, Initializer initializer, ProcessedBindingData bindingData) {
-    super(errors, bindingData);
+  BindingProcessor(Errors errors, Initializer initializer, ProcessedBindingData bindingData, ModuleOptions moduleOptions) {
+    super(errors, bindingData, moduleOptions);
     this.initializer = initializer;
   }
 
diff --git a/core/src/com/google/inject/internal/InjectorOptionsProcessor.java b/core/src/com/google/inject/internal/InjectorOptionsProcessor.java
index 61cc6ee..8239940 100644
--- a/core/src/com/google/inject/internal/InjectorOptionsProcessor.java
+++ b/core/src/com/google/inject/internal/InjectorOptionsProcessor.java
@@ -87,3 +87,4 @@ class InjectorOptionsProcessor extends AbstractProcessor {
   }
 
 }
+
diff --git a/core/src/com/google/inject/internal/InjectorShell.java b/core/src/com/google/inject/internal/InjectorShell.java
index 4675b11..9e9ab18 100644
--- a/core/src/com/google/inject/internal/InjectorShell.java
+++ b/core/src/com/google/inject/internal/InjectorShell.java
@@ -76,6 +76,7 @@ final class InjectorShell {
 
     private InjectorImpl parent;
     private InjectorOptions options;
+    private ModuleOptions moduleOptions;
     private Stage stage;
 
     /** null unless this exists in a {@link Binder#newPrivateBinder private environment} */
@@ -139,6 +140,10 @@ final class InjectorShell {
       InjectorOptionsProcessor optionsProcessor = new InjectorOptionsProcessor(errors);
       optionsProcessor.process(null, elements);
       options = optionsProcessor.getOptions(stage, options);
+
+      ModuleOptionsProcessor moduleOptionsProcessor = new ModuleOptionsProcessor(errors);
+      moduleOptionsProcessor.process(null, elements);
+      moduleOptions = moduleOptionsProcessor.getOptions();
       
       InjectorImpl injector = new InjectorImpl(parent, state, options);
       if (privateElements != null) {
@@ -181,8 +186,8 @@ final class InjectorShell {
       // Process all normal bindings, then UntargettedBindings.
       // This is necessary because UntargettedBindings can create JIT bindings
       // and need all their other dependencies set up ahead of time.
-      new BindingProcessor(errors, initializer, bindingData).process(injector, elements);
-      new UntargettedBindingProcessor(errors, bindingData).process(injector, elements);
+      new BindingProcessor(errors, initializer, bindingData, moduleOptions).process(injector, elements);
+      new UntargettedBindingProcessor(errors, bindingData, moduleOptions).process(injector, elements);
       stopwatch.resetAndLog("Binding creation");
 
       List<InjectorShell> injectorShells = Lists.newArrayList();
diff --git a/core/src/com/google/inject/internal/ModuleOptions.java b/core/src/com/google/inject/internal/ModuleOptions.java
new file mode 100644
index 0000000..a96836f
--- /dev/null
+++ b/core/src/com/google/inject/internal/ModuleOptions.java
@@ -0,0 +1,48 @@
+/**
+ * Copyright (C) 2013 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.inject.internal;
+
+/**
+ * Gathers the modules options.
+ *
+ * @author jmnarloch@gmail.com (Jakub Narloch)
+ */
+public class ModuleOptions {
+
+    /**
+     * Flag indicating whether the binding override is enabled in the child module.
+     */
+    private final boolean overrideBindings;
+
+    /**
+     * Creates new instance of {@link ModuleOptions} class.
+     *
+     * @param overrideBindings whether to override the bindings
+     */
+    public ModuleOptions(boolean overrideBindings) {
+        this.overrideBindings = overrideBindings;
+    }
+
+    /**
+     * Returns whether the binding override has been enabled
+     *
+     * @return whether the binding override has been enabled
+     */
+    public boolean isOverrideBindings() {
+        return overrideBindings;
+    }
+}
diff --git a/core/src/com/google/inject/internal/ModuleOptionsProcessor.java b/core/src/com/google/inject/internal/ModuleOptionsProcessor.java
new file mode 100644
index 0000000..3ddf80e
--- /dev/null
+++ b/core/src/com/google/inject/internal/ModuleOptionsProcessor.java
@@ -0,0 +1,44 @@
+/**
+ * Copyright (C) 2013 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.inject.internal;
+
+import com.google.inject.spi.OverrideBindingOption;
+
+/**
+ * A processor to gather module options.
+ *
+ * @author jmnarloch@gmail.com (Jakub Narloch)
+ */
+public class ModuleOptionsProcessor extends AbstractProcessor {
+
+    private boolean overrideBindings = false;
+
+    ModuleOptionsProcessor(Errors errors) {
+        super(errors);
+    }
+
+    @Override
+    public Boolean visit(OverrideBindingOption option) {
+        overrideBindings = true;
+        return true;
+    }
+
+    ModuleOptions getOptions() {
+
+        return new ModuleOptions(overrideBindings);
+    }
+}
diff --git a/core/src/com/google/inject/internal/UntargettedBindingProcessor.java b/core/src/com/google/inject/internal/UntargettedBindingProcessor.java
index 8ca2ecc..fcee11d 100644
--- a/core/src/com/google/inject/internal/UntargettedBindingProcessor.java
+++ b/core/src/com/google/inject/internal/UntargettedBindingProcessor.java
@@ -26,8 +26,8 @@ import com.google.inject.spi.UntargettedBinding;
  */
 class UntargettedBindingProcessor extends AbstractBindingProcessor {
   
-  UntargettedBindingProcessor(Errors errors, ProcessedBindingData bindingData) {
-    super(errors, bindingData);
+  UntargettedBindingProcessor(Errors errors, ProcessedBindingData bindingData, ModuleOptions moduleOptions) {
+    super(errors, bindingData, moduleOptions);
   }
   
   @Override
diff --git a/core/src/com/google/inject/spi/DefaultElementVisitor.java b/core/src/com/google/inject/spi/DefaultElementVisitor.java
index 0780bf8..13f4b4d 100644
--- a/core/src/com/google/inject/spi/DefaultElementVisitor.java
+++ b/core/src/com/google/inject/spi/DefaultElementVisitor.java
@@ -102,4 +102,8 @@ public abstract class DefaultElementVisitor<V> implements ElementVisitor<V> {
   public V visit(RequireExactBindingAnnotationsOption option) {
     return visitOther(option);
   }
+
+  public V visit(OverrideBindingOption option) {
+      return visitOther(option);
+  }
 }
diff --git a/core/src/com/google/inject/spi/ElementVisitor.java b/core/src/com/google/inject/spi/ElementVisitor.java
index 5e99086..de153bf 100644
--- a/core/src/com/google/inject/spi/ElementVisitor.java
+++ b/core/src/com/google/inject/spi/ElementVisitor.java
@@ -120,4 +120,11 @@ public interface ElementVisitor<V> {
    * @since 4.0
    */
   V visit(RequireExactBindingAnnotationsOption option);
+
+  /**
+   * Visit a override binding option.
+   *
+   * @since 4.0
+   */
+  V visit(OverrideBindingOption option);
 }
diff --git a/core/src/com/google/inject/spi/Elements.java b/core/src/com/google/inject/spi/Elements.java
index 73999b3..0d9e829 100644
--- a/core/src/com/google/inject/spi/Elements.java
+++ b/core/src/com/google/inject/spi/Elements.java
@@ -360,7 +360,11 @@ public final class Elements {
       elements.add(new RequireExactBindingAnnotationsOption(getElementSource()));
     }
 
-    public void expose(Key<?> key) {
+    public void allowBindingOverride() {
+        elements.add(new OverrideBindingOption(getElementSource()));
+    }
+
+      public void expose(Key<?> key) {
       exposeInternal(key);
     }
 
diff --git a/core/src/com/google/inject/spi/OverrideBindingOption.java b/core/src/com/google/inject/spi/OverrideBindingOption.java
new file mode 100644
index 0000000..aa74141
--- /dev/null
+++ b/core/src/com/google/inject/spi/OverrideBindingOption.java
@@ -0,0 +1,50 @@
+/**
+ * Copyright (C) 2013 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.inject.spi;
+
+import com.google.inject.Binder;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * A setting for enabling binding override in the child injector.
+ *
+ * @author jmnarloch@gmail.com (Jakub Narloch)
+ * @since 4.0
+ */
+public class OverrideBindingOption implements Element {
+    private final Object source;
+
+    OverrideBindingOption(Object source) {
+        this.source = checkNotNull(source, "source");
+    }
+
+    public Object getSource() {
+        if (source instanceof ElementSource) {
+            return ((ElementSource) source).getDeclaringSource();
+        }
+        return source;
+    }
+
+    public void applyTo(Binder binder) {
+        binder.withSource(getSource()).allowBindingOverride();
+    }
+
+    public <T> T acceptVisitor(ElementVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+}
diff --git a/core/test/com/google/inject/OverrideBindingTest.java b/core/test/com/google/inject/OverrideBindingTest.java
new file mode 100644
index 0000000..21c6b7e
--- /dev/null
+++ b/core/test/com/google/inject/OverrideBindingTest.java
@@ -0,0 +1,123 @@
+/**
+ * Copyright (C) 2013 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.inject;
+
+import junit.framework.TestCase;
+
+/**
+ * This tests verifies the whether the overriding the bindings works correctly.
+ *
+ * @author jmnarloch@gmail.com (Jakub Narloch)
+ */
+public class OverrideBindingTest extends TestCase {
+
+    /**
+     * Tests the simple injector creation.
+     */
+    public void testNoBindingOverride() {
+
+        Injector injector = Guice.createInjector(new BaseModule());
+
+        SimpleService instance = injector.getInstance(SimpleService.class);
+        assertEquals("Wrong type has been resolved.", BaseService.class, instance.getClass());
+    }
+
+    /**
+     * Tests the simple injector creation, when the child injector overrides the binding of the parent injector.
+     */
+    public void testBindingOverride() {
+
+        // creates the base injector
+        Injector baseInjector = Guice.createInjector(new BaseModule());
+
+        // creates new child injector with overridden binding
+        Injector injector = baseInjector.createChildInjector(new OverrideModule());
+
+        SimpleService instance = injector.getInstance(SimpleService.class);
+        assertEquals("Wrong type has been resolved.", MoreSpecificService.class, instance.getClass());
+    }
+
+    /**
+     * Tests the simple injector creation, when the child injector tries to overrides the binding of the parent
+     * injector, but does not turn configures the module to support it.
+     */
+    public void testBindingOverrideDisabled() {
+
+        // creates base injector
+        Injector baseInjector = Guice.createInjector(new BaseModule());
+
+        try {
+            // creates new injector that tries to override the binding, but did not enable that feature
+            Injector injector = baseInjector.createChildInjector(new OverrideModuleWithDisabledBindingOverride());
+            fail("An CreationException was expected.");
+        } catch (CreationException ex) {
+            // expected exception
+        }
+    }
+
+    /**
+     * A simple module that is used for configuring the 'parent' injector.
+     */
+    private static class BaseModule extends AbstractModule {
+
+        @Override
+        protected void configure() {
+            binder().bind(SimpleService.class).to(BaseService.class);
+        }
+    }
+
+    /**
+     * A simple module that is used for configuring the child injector with overriding turing on.
+     */
+    private static class OverrideModule extends AbstractModule {
+
+        @Override
+        protected void configure() {
+            binder().allowBindingOverride();
+            binder().bind(SimpleService.class).to(MoreSpecificService.class);
+        }
+    }
+
+    /**
+     * A simple module that is used for configuring the child injector and that tries to override the parent binding.
+     */
+    private static class OverrideModuleWithDisabledBindingOverride extends AbstractModule {
+
+        @Override
+        protected void configure() {
+            binder().bind(SimpleService.class).to(MoreSpecificService.class);
+        }
+    }
+
+    /**
+     * Imitates a some service layer interface.
+     */
+    public static interface SimpleService {
+    }
+
+    /**
+     * Imitates a some implementation of the {@link SimpleService}.
+     */
+    public static class BaseService implements SimpleService {
+    }
+
+    /**
+     * Imitates a some implementation of the {@link SimpleService}.
+     */
+    public static class MoreSpecificService implements SimpleService {
+    }
+}
-- 
1.7.11.msysgit.0