Rewrites TypeMethodReference and ExpressionMethodReference nodes as L…

…ambdaExpression nodes.

	Change on 2016/05/24 by kstanger <kstanger@google.com>

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=123131528

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

@@ -560,9 +560,8 @@ public boolean visit(EnhancedForStatement node) {
 
   @Override
   public boolean visit(ExpressionMethodReference node) {
-    assert Options
-        .isJava8Translator() : "ExpressionMethodReference in translator with -source less than 8.";
-    return printMethodReference(node);
+    throw new AssertionError(
+        "ExpressionMethodReference nodes are rewritten by MethodReferenceRewriter.");
   }
 
   @Override
@@ -1353,9 +1352,7 @@ public boolean visit(TypeLiteral node) {
 
   @Override
   public boolean visit(TypeMethodReference node) {
-    assert Options
-        .isJava8Translator() : "TypeMethodReference in translator with -source less than 8.";
-    return printMethodReference(node);
+    throw new AssertionError("TypeMethodReference nodes are rewritten by MethodReferenceRewriter.");
   }
 
   @Override

translator/src/main/java/com/google/devtools/j2objc/translate/MethodReferenceRewriter.java

@@ -18,19 +18,26 @@
 import com.google.devtools.j2objc.ast.ClassInstanceCreation;
 import com.google.devtools.j2objc.ast.CreationReference;
 import com.google.devtools.j2objc.ast.Expression;
+import com.google.devtools.j2objc.ast.ExpressionMethodReference;
 import com.google.devtools.j2objc.ast.LambdaExpression;
+import com.google.devtools.j2objc.ast.MethodInvocation;
+import com.google.devtools.j2objc.ast.Name;
 import com.google.devtools.j2objc.ast.SimpleName;
+import com.google.devtools.j2objc.ast.TreeUtil;
 import com.google.devtools.j2objc.ast.TreeVisitor;
 import com.google.devtools.j2objc.ast.Type;
+import com.google.devtools.j2objc.ast.TypeMethodReference;
 import com.google.devtools.j2objc.ast.VariableDeclarationFragment;
 import com.google.devtools.j2objc.types.GeneratedVariableBinding;
-import com.google.devtools.j2objc.util.NameTable;
+import com.google.devtools.j2objc.util.BindingUtil;
 
+import org.eclipse.jdt.core.dom.IBinding;
 import org.eclipse.jdt.core.dom.IMethodBinding;
 import org.eclipse.jdt.core.dom.ITypeBinding;
 import org.eclipse.jdt.core.dom.IVariableBinding;
 
-import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 
 /**
@@ -44,7 +51,6 @@ public class MethodReferenceRewriter extends TreeVisitor {
   public void endVisit(CreationReference node) {
     ITypeBinding exprBinding = node.getTypeBinding();
     ITypeBinding creationType = node.getType().getTypeBinding();
-    IMethodBinding functionalInterface = exprBinding.getFunctionalInterfaceMethod();
     Expression invocation;
     List<Expression> invocationArguments;
     if (creationType.isArray()) {
@@ -60,20 +66,93 @@ public void endVisit(CreationReference node) {
     LambdaExpression lambda = new LambdaExpression(
         "CreationReference:" + node.getLineNumber(), exprBinding);
     lambda.setBody(invocation);
-    addRemainingLambdaParams(
-        Arrays.asList(functionalInterface.getParameterTypes()), invocationArguments, lambda, null);
+    addParamsToInvocation(createParameters(lambda), invocationArguments);
     node.replaceWith(lambda);
   }
 
-  private void addRemainingLambdaParams(
-      Iterable<ITypeBinding> paramTypes, List<Expression> invocationArguments,
-      LambdaExpression lambda, char[] lastVar) {
-    for (ITypeBinding paramType : paramTypes) {
-      lastVar = NameTable.incrementVariable(lastVar);
-      IVariableBinding variableBinding = new GeneratedVariableBinding(
-          new String(lastVar), 0, paramType, false, true, null, null);
-      lambda.getParameters().add(new VariableDeclarationFragment(variableBinding, null));
-      invocationArguments.add(new SimpleName(variableBinding));
+  @Override
+  public void endVisit(ExpressionMethodReference node) {
+    ITypeBinding exprBinding = node.getTypeBinding();
+    IMethodBinding methodBinding = node.getMethodBinding();
+    LambdaExpression lambda = new LambdaExpression(
+        "ExpressionMethodReference:" + node.getLineNumber(), exprBinding);
+    Iterator<IVariableBinding> params = createParameters(lambda);
+    Expression target = TreeUtil.remove(node.getExpression());
+    if (!BindingUtil.isStatic(methodBinding) && target instanceof Name
+        && ((Name) target).getBinding().getKind() == IBinding.TYPE) {
+      // The expression is actually a type name and doesn't evaluate to an invocable object.
+      target = new SimpleName(params.next());
+    }
+    MethodInvocation invocation = new MethodInvocation(methodBinding, target);
+    lambda.setBody(invocation);
+    addParamsToInvocation(params, invocation.getArguments());
+    node.replaceWith(lambda);
+  }
+
+  @Override
+  public void endVisit(TypeMethodReference node) {
+    ITypeBinding exprBinding = node.getTypeBinding();
+    IMethodBinding methodBinding = getMethodBinding(node);
+    LambdaExpression lambda = new LambdaExpression(
+        "TypeMethodReference:" + node.getLineNumber(), exprBinding);
+    Iterator<IVariableBinding> params = createParameters(lambda);
+    Expression target = null;
+    if (!BindingUtil.isStatic(methodBinding)) {
+      target = new SimpleName(params.next());
+    }
+    MethodInvocation invocation = new MethodInvocation(methodBinding, target);
+    lambda.setBody(invocation);
+    addParamsToInvocation(params, invocation.getArguments());
+    node.replaceWith(lambda);
+  }
+
+  private IMethodBinding getMethodBinding(TypeMethodReference node) {
+    if (node.getType().getTypeBinding().isArray()) {
+      // JDT does not provide the correct method binding on array types, so we find it from
+      // java.lang.Object.
+      String name = node.getName().getIdentifier();
+      IMethodBinding functionalInterface = node.getTypeBinding().getFunctionalInterfaceMethod();
+      int numParams = functionalInterface.getParameterTypes().length - 1;
+      for (IMethodBinding method : typeEnv.getJavaObject().getDeclaredMethods()) {
+        if (method.getName().equals(name) && method.getParameterTypes().length == numParams) {
+          return method;
+        }
+      }
+      throw new AssertionError("Can't find method finding for method: " + name);
+    }
+    return node.getMethodBinding();
+  }
+
+  private Iterator<IVariableBinding> createParameters(LambdaExpression lambda) {
+    IMethodBinding functionalInterface = lambda.getTypeBinding().getFunctionalInterfaceMethod();
+    ITypeBinding[] paramTypes = functionalInterface.getParameterTypes();
+    List<IVariableBinding> params = new ArrayList<>(paramTypes.length);
+    for (int i = 0; i < paramTypes.length; i++) {
+      GeneratedVariableBinding param = new GeneratedVariableBinding(
+          getParamName(i), 0, paramTypes[i], false, true, null, null);
+      params.add(param);
+      lambda.getParameters().add(new VariableDeclarationFragment(param, null));
+    }
+    return params.iterator();
+  }
+
+  private void addParamsToInvocation(
+      Iterator<IVariableBinding> params, List<Expression> invocationArguments) {
+    while (params.hasNext()) {
+      invocationArguments.add(new SimpleName(params.next()));
+    }
+  }
+
+  private static String getParamName(int i) {
+    StringBuilder sb = new StringBuilder();
+    while (true) {
+      sb.append((char) ('a' + (i % 26)));
+      i = i / 26;
+      if (i == 0) {
+        break;
+      }
+      i--;
     }
+    return sb.reverse().toString();
   }
 }

translator/src/main/java/com/google/devtools/j2objc/translate/Rewriter.java

@@ -23,7 +23,6 @@
 import com.google.devtools.j2objc.ast.CastExpression;
 import com.google.devtools.j2objc.ast.ClassInstanceCreation;
 import com.google.devtools.j2objc.ast.Expression;
-import com.google.devtools.j2objc.ast.ExpressionMethodReference;
 import com.google.devtools.j2objc.ast.ExpressionStatement;
 import com.google.devtools.j2objc.ast.FieldAccess;
 import com.google.devtools.j2objc.ast.FieldDeclaration;
@@ -47,11 +46,9 @@
 import com.google.devtools.j2objc.ast.TreeUtil;
 import com.google.devtools.j2objc.ast.TreeVisitor;
 import com.google.devtools.j2objc.ast.Type;
-import com.google.devtools.j2objc.ast.TypeMethodReference;
 import com.google.devtools.j2objc.ast.VariableDeclarationExpression;
 import com.google.devtools.j2objc.ast.VariableDeclarationFragment;
 import com.google.devtools.j2objc.ast.VariableDeclarationStatement;
-import com.google.devtools.j2objc.types.GeneratedMethodBinding;
 import com.google.devtools.j2objc.types.GeneratedVariableBinding;
 import com.google.devtools.j2objc.util.BindingUtil;
 import com.google.devtools.j2objc.util.ErrorUtil;
@@ -60,11 +57,9 @@
 import com.google.j2objc.annotations.RetainedLocalRef;
 import com.google.j2objc.annotations.Weak;
 
-import org.eclipse.jdt.core.dom.IBinding;
 import org.eclipse.jdt.core.dom.IMethodBinding;
 import org.eclipse.jdt.core.dom.ITypeBinding;
 import org.eclipse.jdt.core.dom.IVariableBinding;
-import org.eclipse.jdt.core.dom.Modifier;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -413,22 +408,6 @@ private String getLambdaUniqueName(LambdaExpression node) {
     return nameTable.getFullName(owningType) + "$$Lambda$" + count;
   }
 
-  @Override
-  public boolean visit(ExpressionMethodReference node) {
-    IMethodBinding methodBinding = node.getMethodBinding().getMethodDeclaration();
-    Expression expression = node.getExpression().copy();
-    MethodInvocation invocation = new MethodInvocation(methodBinding, expression);
-    List<Expression> invocationArguments = invocation.getArguments();
-    buildMethodReferenceInvocationArguments(invocationArguments, node, invocation);
-    IMethodBinding functionalInterface = node.getTypeBinding().getFunctionalInterfaceMethod();
-    if (BindingUtil.isVoid(functionalInterface.getReturnType())) {
-      node.setInvocation(new ExpressionStatement(invocation));
-    } else {
-      node.setInvocation(new ReturnStatement(invocation));
-    }
-    return true;
-  }
-
   @Override
   public boolean visit(SuperMethodReference node) {
     IMethodBinding methodBinding = node.getMethodBinding().getMethodDeclaration();
@@ -446,75 +425,6 @@ public boolean visit(SuperMethodReference node) {
     return true;
   }
 
-  @Override
-  public boolean visit(TypeMethodReference node) {
-    IMethodBinding originalMethodBinding = node.getMethodBinding();
-    GeneratedMethodBinding methodBinding = GeneratedMethodBinding.newNamedMethod(
-        node.getName().toString(), originalMethodBinding);
-    methodBinding.addParameters(originalMethodBinding);
-    methodBinding.setModifiers(methodBinding.getModifiers() & ~Modifier.STATIC);
-    IMethodBinding functionalInterface = node.getTypeBinding().getFunctionalInterfaceMethod();
-    ITypeBinding[] functionalParams = functionalInterface.getParameterTypes();
-
-    // When node is a TypedMethodReference, the first parameter in the functional interface method
-    // should always be the object. Because of this, we expect this invariant to be held:
-    //
-    //   functionalParams.length == originalMethodBinding.getParameterTypes().length + 1
-    //
-    // However, there are cases when JDT still puts one parameter in originalMethodBinding.
-    // Compare this:
-    //
-    //   /* functionalParams.length == 2, originalMethodBinding.getParameterTypes().length == 1 */
-    //   BiConsumer<Collection<T>, T> bc = Collection<T>::add;
-    //
-    // With this:
-    //
-    //   /* functionalParams.length == 1, originalMethodBinding.getParameterTypes().length == 1 */
-    //   interface H { Object copy(int[] i); }
-    //   H h = int[]::clone;
-    //
-    // In the second case, we have to remove the first parameter in the mutable methodBinding.
-    //
-    // TODO(user): This may be a JDT quirk. Need more test cases and further investigation.
-    // TODO(user): This very likely won't support varargs correctly.
-    if (functionalParams.length == originalMethodBinding.getParameterTypes().length) {
-      methodBinding.getParameters().remove(0);
-    }
-    ITypeBinding[] methodParams = methodBinding.getParameterTypes();
-
-    char[] var = NameTable.incrementVariable(null);
-    ITypeBinding functionalParam = functionalParams[0];
-    IVariableBinding variableBinding = new GeneratedVariableBinding(new String(var), 0,
-        functionalParam, false, true, null, null);
-    SimpleName expression = new SimpleName(variableBinding);
-    MethodInvocation invocation = new MethodInvocation(methodBinding, expression);
-    List<Expression> invocationArguments = invocation.getArguments();
-    if (BindingUtil.isVoid(functionalInterface.getReturnType())) {
-      node.setInvocation(new ExpressionStatement(invocation));
-    } else {
-      node.setInvocation(new ReturnStatement(invocation));
-    }
-    int methodParamStopIndex = methodBinding.isVarargs() ? methodParams.length
-        : methodParams.length + 1;
-    for (int i = 1; i < methodParamStopIndex; i++) {
-      functionalParam = functionalParams[i];
-      variableBinding = new GeneratedVariableBinding(new String(var), 0, functionalParam, false,
-          true, null, null);
-      invocationArguments.add(new SimpleName(variableBinding));
-      var = NameTable.incrementVariable(var);
-    }
-    if (methodBinding.isVarargs()) {
-      for (int i = methodParamStopIndex; i < functionalInterface.getParameterTypes().length; i++) {
-        functionalParam = functionalParams[i];
-        variableBinding = new GeneratedVariableBinding(new String(var), 0,
-            functionalParam, false, true, null, null);
-        invocationArguments.add(new SimpleName(variableBinding));
-        var = NameTable.incrementVariable(var);
-      }
-    }
-    return true;
-  }
-
   /**
    * Fill in the arguments in a method reference invocation. The argument list must come from the
    * functional interface's method, not the invoked method: this is because it is possible to
@@ -529,38 +439,11 @@ public boolean visit(TypeMethodReference node) {
   public void buildMethodReferenceInvocationArguments(List<Expression> invocationArguments,
                                                       MethodReference node,
                                                       MethodInvocation invocation) {
-    IMethodBinding methodBinding = node.getMethodBinding();
     IMethodBinding functionalInterface = node.getTypeBinding().getFunctionalInterfaceMethod();
     ITypeBinding[] functionalParams = functionalInterface.getParameterTypes();
     char[] var = NameTable.incrementVariable(null);
     int paramIdx = 0;
 
-    // If this is an ExpressionMethodReference EXP::METHOD, and if EXP is a type binding and
-    // METHOD is an instance method, then EXP should be replaced with the first parameter in
-    // functionalParams. For example, String::compareTo matches the functional interface
-    // int Comparator<T>::compare(T a, T b), but the JDT method invocation node is actually
-    // String.compareTo() at this point. We need to fix that to a.compareTo(), so that in the
-    // code that follows the second functional parameter b will be filled correctly into the
-    // the invocation, resulting in the invocation a.compareTo(b).
-    if (node instanceof ExpressionMethodReference) {
-      Expression expression = ((ExpressionMethodReference) node).getExpression();
-      if (expression instanceof Name) {
-        IBinding binding = ((Name) expression).getBinding();
-        if (binding.getKind() == IBinding.TYPE) {
-          // Only ExpressionMethodReference needs this potential invocation fix.
-          assert invocation != null;
-          if (!BindingUtil.isStatic(methodBinding)) {
-            ITypeBinding functionalParam = functionalParams[paramIdx];
-            IVariableBinding variableBinding = new GeneratedVariableBinding(new String(var), 0,
-                functionalParam, false, true, null, null);
-            invocation.setExpression(new SimpleName(variableBinding));
-            var = NameTable.incrementVariable(var);
-            paramIdx++;
-          }
-        }
-      }
-    }
-
     // Fill in the invocation parameters.
     for (; paramIdx < functionalParams.length; paramIdx++) {
       ITypeBinding functionalParam = functionalParams[paramIdx];

translator/src/test/java/com/google/devtools/j2objc/ast/MethodReferenceTest.java

@@ -65,12 +65,12 @@ public void testExpressionReferenceStaticResolution() throws IOException {
     String staticTranslation = translateSourceFile(
         expressionReferenceHeader + "class Test { F fun = Q::o; }",
         "Test", "Test.m");
-    assertTranslatedSegments(staticTranslation, "GetNonCapturingLambda", "@\"Q_oWithId_\"",
+    assertTranslatedSegments(staticTranslation, "GetNonCapturingLambda", "@\"Test$$Lambda$1\"",
         "@selector(fWithId:)", "return Q_oWithId_(a);");
     String instanceTranslation = translateSourceFile(
         expressionReferenceHeader + "class Test { F fun = new Q()::o2; }",
         "Test", "Test.m");
-    assertTranslatedSegments(instanceTranslation, "GetNonCapturingLambda", "@\"Q_o2WithId_\"",
+    assertTranslatedSegments(instanceTranslation, "GetNonCapturingLambda", "@\"Test$$Lambda$1\"",
         "@selector(fWithId:)", "return [create_Q_init() o2WithId:a];");
   }
 
@@ -106,8 +106,8 @@ public void testReferenceToInstanceMethodOfGenericType() throws IOException {
         + "}";
 
     String impl = translateSourceFile(source, "Test", "Test.m");
-    assertTranslation(impl, "[((id<Collection>) nil_chk(a)) addWithId:a];");
-    assertNotInTranslation(impl, "return [((id<Collection>) nil_chk(a)) addWithId:a];");
+    assertTranslation(impl, "[((id<Collection>) nil_chk(a)) addWithId:b];");
+    assertNotInTranslation(impl, "return [((id<Collection>) nil_chk(a)) addWithId:b];");
   }
 
   public void testReferenceToInstanceMethodOfGenericTypeWithReturnType() throws IOException {
@@ -120,7 +120,7 @@ public void testReferenceToInstanceMethodOfGenericTypeWithReturnType() throws IO
         + "}";
 
     String impl = translateSourceFile(source, "Test", "Test.m");
-    assertTranslation(impl, "return [((id<Collection>) nil_chk(a)) addWithId:a];");
+    assertTranslation(impl, "return [((id<Collection>) nil_chk(a)) addWithId:b];");
   }
 
   public void testVarArgs() throws IOException {
@@ -132,15 +132,14 @@ public void testVarArgs() throws IOException {
         "Test", "Test.m");
     assertTranslatedLines(translation,
         "JreStrongAssign(&self->i_, GetNonCapturingLambda(NULL, @protocol(I), "
-        + "@\"Y_mWithInt_withNSString_withNSString_\", "
-        + "@selector(fooWithInt:withNSString:withNSString:),",
+        + "@\"Test$$Lambda$1\", @selector(fooWithInt:withNSString:withNSString:),",
         "^void(id _self, jint a, NSString * b, NSString * c) {",
         "Y_mWithInt_withNSStringArray_(a, [IOSObjectArray arrayWithObjects:(id[]){ b, c } "
         + "count:2 type:NSString_class_()]);",
-        "}));",
+        "}",
+        "));",
         "JreStrongAssign(&self->i2_, GetNonCapturingLambda(NULL, @protocol(I2), "
-        + "@\"Y_mWithInt_withNSString_withNSString_withNSString_\", "
-        + "@selector(fooWithInt:withNSString:withNSString:withNSString:),",
+        + "@\"Test$$Lambda$2\", @selector(fooWithInt:withNSString:withNSString:withNSString:),",
         "^void(id _self, jint a, NSString * b, NSString * c, NSString * d) {",
         "Y_mWithInt_withNSStringArray_(a, [IOSObjectArray arrayWithObjects:(id[]){ b, c, d } "
         + "count:3 type:NSString_class_()]);");