com.google.errorprone.refaster.ULambda.java Source code

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Here is the source code for com.google.errorprone.refaster.ULambda.java

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/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * 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.errorprone.refaster;

import static com.google.errorprone.refaster.Unifier.unifications;
import static com.google.errorprone.refaster.Unifier.unifyList;

import com.google.auto.value.AutoValue;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.sun.source.tree.LambdaExpressionTree;
import com.sun.source.tree.TreeVisitor;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.JCExpressionStatement;
import com.sun.tools.javac.tree.JCTree.JCLambda;
import com.sun.tools.javac.tree.JCTree.JCLambda.ParameterKind;
import com.sun.tools.javac.tree.JCTree.JCReturn;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.ListBuffer;

/**
 * {@code UTree} representation of a {@code LambdaExpressionTree}.
 * 
 * @author lowasser@google.com (Louis Wasserman)
 */
@AutoValue
abstract class ULambda extends UExpression implements LambdaExpressionTree {
    public static ULambda create(ParameterKind parameterKind, Iterable<UVariableDecl> parameters, UTree<?> body) {
        return new AutoValue_ULambda(parameterKind, ImmutableList.copyOf(parameters), body);
    }

    @Override
    public Kind getKind() {
        return Kind.LAMBDA_EXPRESSION;
    }

    @Override
    public <R, D> R accept(TreeVisitor<R, D> visitor, D data) {
        return visitor.visitLambdaExpression(this, data);
    }

    @Override
    public Choice<Unifier> visitLambdaExpression(LambdaExpressionTree node, Unifier unifier) {
        return unifyList(unifier, getParameters(), node.getParameters())
                .thenChoose(unifications(getBody(), node.getBody()));
    }

    @Override
    public JCLambda inline(Inliner inliner) throws CouldNotResolveImportException {
        return inliner.maker().Lambda(inlineParams(inliner), inlineBody(inliner));
    }

    public List<JCVariableDecl> inlineParams(Inliner inliner) throws CouldNotResolveImportException {
        if (parameterKind() == ParameterKind.EXPLICIT) {
            return List.convert(JCVariableDecl.class, inliner.inlineList(getParameters()));
        }
        ListBuffer<JCVariableDecl> params = new ListBuffer<>();
        for (UVariableDecl param : getParameters()) {
            params.add(param.inlineImplicitType(inliner));
        }
        return params.toList();
    }

    JCTree inlineBody(Inliner inliner) throws CouldNotResolveImportException {
        if (getBody() instanceof UPlaceholderExpression) {
            UPlaceholderExpression body = (UPlaceholderExpression) getBody();
            Optional<List<JCStatement>> blockBinding = inliner.getOptionalBinding(body.placeholder().blockKey());
            if (blockBinding.isPresent()) {
                // this lambda is of the form args -> blockPlaceholder();
                List<JCStatement> blockInlined = UPlaceholderExpression.copier(body.arguments(), inliner)
                        .copy(blockBinding.get(), inliner);
                if (blockInlined.size() == 1) {
                    if (blockInlined.get(0) instanceof JCReturn) {
                        return ((JCReturn) blockInlined.get(0)).getExpression();
                    } else if (blockInlined.get(0) instanceof JCExpressionStatement) {
                        return ((JCExpressionStatement) blockInlined.get(0)).getExpression();
                    }
                }
                return inliner.maker().Block(0, blockInlined);
            }
        }
        return getBody().inline(inliner);
    }

    abstract ParameterKind parameterKind();

    @Override
    public abstract ImmutableList<UVariableDecl> getParameters();

    @Override
    public abstract UTree<?> getBody();

    @Override
    public BodyKind getBodyKind() {
        return getBody().getKind() == Kind.BLOCK ? BodyKind.STATEMENT : BodyKind.EXPRESSION;
    }
}