Emit static interface methods in companion classes

	Change on 2016/03/10 by lukhnos <lukhnos@google.com>
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=116868937

translator/src/main/java/com/google/devtools/j2objc/gen/TypeDeclarationGenerator.java

@@ -30,6 +30,7 @@
 import com.google.devtools.j2objc.ast.Name;
 import com.google.devtools.j2objc.ast.NativeDeclaration;
 import com.google.devtools.j2objc.ast.PropertyAnnotation;
+import com.google.devtools.j2objc.ast.TreeNode;
 import com.google.devtools.j2objc.ast.TreeUtil;
 import com.google.devtools.j2objc.ast.VariableDeclarationFragment;
 import com.google.devtools.j2objc.util.BindingUtil;
@@ -201,6 +202,14 @@ private void printImplementedProtocols() {
     }
   }
 
+  protected void printStaticInterfaceMethods() {
+    for (BodyDeclaration declaration : getInnerDeclarations()) {
+      if (declaration.getKind().equals(TreeNode.Kind.METHOD_DECLARATION)) {
+        printMethodDeclaration((MethodDeclaration) declaration, true);
+      }
+    }
+  }
+
   /**
    * Prints the list of static variable and/or enum constant accessor methods.
    */
@@ -355,6 +364,7 @@ protected void printCompanionClassDeclaration() {
     } else {
       newline();
     }
+    printStaticInterfaceMethods();
     printStaticAccessors();
     println("\n@end");
   }
@@ -582,12 +592,29 @@ private void printAnnotationAccessors(List<AnnotationTypeMemberDeclaration> memb
     }
   }
 
-  @Override
-  protected void printMethodDeclaration(MethodDeclaration m) {
+  /**
+   * Emit method declaration.
+   *
+   * @param m The method.
+   * @param isCompanionClass If true, emit only if m is a static interface method.
+   */
+  private void printMethodDeclaration(MethodDeclaration m, boolean isCompanionClass) {
+    IMethodBinding methodBinding = m.getMethodBinding();
+    ITypeBinding typeBinding = methodBinding.getDeclaringClass();
+
+    if (typeBinding.isInterface()) {
+      // isCompanion and isStatic must be both false (i.e. this prints a non-static method decl
+      // in @protocol) or must both be true (i.e. this prints a static method decl in the
+      // companion class' @interface).
+      if (isCompanionClass != BindingUtil.isStatic(methodBinding)) {
+        return;
+      }
+    }
+
     newline();
     JavadocGenerator.printDocComment(getBuilder(), m.getJavadoc());
     print(getMethodSignature(m));
-    String methodName = nameTable.getMethodSelector(m.getMethodBinding());
+    String methodName = nameTable.getMethodSelector(methodBinding);
     if (!m.isConstructor() && !BindingUtil.isSynthetic(m.getModifiers())
         && needsObjcMethodFamilyNoneAttribute(methodName)) {
       // Getting around a clang warning.
@@ -607,6 +634,11 @@ && needsObjcMethodFamilyNoneAttribute(methodName)) {
     println(";");
   }
 
+  @Override
+  protected void printMethodDeclaration(MethodDeclaration m) {
+    printMethodDeclaration(m, false);
+  }
+
   private boolean needsObjcMethodFamilyNoneAttribute(String name) {
      return FAMILY_METHOD_REGEX.matcher(name).matches();
   }

translator/src/main/java/com/google/devtools/j2objc/gen/TypeGenerator.java

@@ -109,6 +109,7 @@ private List<BodyDeclaration> filterDeclarations(Iterable<BodyDeclaration> decla
 
   private static final Predicate<VariableDeclarationFragment> IS_STATIC_FIELD =
       new Predicate<VariableDeclarationFragment>() {
+    @Override
     public boolean apply(VariableDeclarationFragment frag) {
       // isGlobalVar includes non-static but final primitives, which are treated
       // like static fields in J2ObjC.
@@ -118,12 +119,14 @@ public boolean apply(VariableDeclarationFragment frag) {
 
   private static final Predicate<VariableDeclarationFragment> IS_INSTANCE_FIELD =
       new Predicate<VariableDeclarationFragment>() {
+    @Override
     public boolean apply(VariableDeclarationFragment frag) {
       return BindingUtil.isInstanceVar(frag.getVariableBinding());
     }
   };
 
   private static final Predicate<BodyDeclaration> IS_OUTER_DECL = new Predicate<BodyDeclaration>() {
+    @Override
     public boolean apply(BodyDeclaration decl) {
       switch (decl.getKind()) {
         case FUNCTION_DECLARATION:
@@ -137,6 +140,7 @@ public boolean apply(BodyDeclaration decl) {
   };
 
   private static final Predicate<BodyDeclaration> IS_INNER_DECL = new Predicate<BodyDeclaration>() {
+    @Override
     public boolean apply(BodyDeclaration decl) {
       switch (decl.getKind()) {
         case METHOD_DECLARATION:
@@ -233,6 +237,7 @@ private boolean hasStaticAccessorMethods() {
 
   protected boolean needsPublicCompanionClass() {
     return BindingUtil.hasDefaultMethodsInFamily(typeBinding)
+        || BindingUtil.hasStaticInterfaceMethods(typeBinding)
         || (!typeNode.hasPrivateDeclaration()
             && (hasInitializeMethod() || BindingUtil.isRuntimeAnnotation(typeBinding)
                 || hasStaticAccessorMethods()));

translator/src/main/java/com/google/devtools/j2objc/util/BindingUtil.java

@@ -652,4 +652,19 @@ public static boolean hasDefaultMethodsInFamily(ITypeBinding type) {
 
     return false;
   }
+
+  /**
+   * Returns true if any of the declared methods in the interface is static.
+   */
+  public static boolean hasStaticInterfaceMethods(ITypeBinding type) {
+    assert type.isInterface();
+
+    for (IMethodBinding method : type.getDeclaredMethods()) {
+      if (isStatic(method)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
 }

translator/src/test/java/com/google/devtools/j2objc/gen/ObjectiveCHeaderGeneratorTest.java

@@ -19,6 +19,7 @@
 import com.google.common.collect.Lists;
 import com.google.devtools.j2objc.GenerationTest;
 import com.google.devtools.j2objc.Options;
+import com.google.devtools.j2objc.util.FileUtil;
 import com.google.devtools.j2objc.util.HeaderMap;
 
 import java.io.File;
@@ -32,6 +33,19 @@
  */
 public class ObjectiveCHeaderGeneratorTest extends GenerationTest {
 
+  @Override
+  protected void setUp() throws IOException {
+    tempDir = FileUtil.createTempDir("testout");
+    Options.load(new String[]{
+        "-d", tempDir.getAbsolutePath(),
+        "-sourcepath", tempDir.getAbsolutePath(),
+        "-q", // Suppress console output.
+        "-encoding", "UTF-8", // Translate strings correctly when encodings are nonstandard.
+        "-source", "8" // Treat as Java 8 source.
+    });
+    parser = initializeParser(tempDir);
+  }
+
   public void testInnerEnumWithPackage() throws IOException {
     String translation = translateSourceFile(
         "package mypackage;"
@@ -845,4 +859,19 @@ public void testConstructorsDisallowed() throws IOException {
         "withBoolean:(jboolean)arg2",
         "withBoolean:(jboolean)arg3 NS_UNAVAILABLE;");
   }
+
+  public void testStaticInterfaceMethodDeclaredInCompanionClass() throws IOException {
+    String source = "interface Foo { static void f() {} }"
+        + "class Bar implements Foo { void g() { Foo.f(); } }";
+    String header = translateSourceFile(source, "Test", "Test.h");
+    String impl =  getTranslatedFile("Test.m");
+
+    assertTranslation(header, "@protocol Foo < NSObject, JavaObject >");
+    assertTranslatedSegments(header, "@interface Foo : NSObject", "+ (void)f;", "@end");
+    // Should only have one occurrence from the companion class.
+    assertOccurrences(header, "+ (void)f;", 1);
+
+    // The companion class of Foo still has the class method +[Foo f].
+    assertTranslatedLines(impl, "+ (void)f {", "Foo_f();", "}");
+  }
 }