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

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Here is the source code for com.google.errorprone.refaster.CodeTransformerTestHelper.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 java.nio.charset.StandardCharsets.UTF_8;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.io.CharStreams;
import com.google.errorprone.CodeTransformer;
import com.google.errorprone.apply.DescriptionBasedDiff;
import com.google.errorprone.apply.SourceFile;
import com.google.testing.compile.JavaFileObjects;
import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.api.JavacTaskImpl;
import com.sun.tools.javac.api.JavacTool;
import com.sun.tools.javac.tree.JCTree.JCClassDecl;
import com.sun.tools.javac.tree.JCTree.JCCompilationUnit;
import java.io.IOException;
import java.util.Locale;
import javax.tools.DiagnosticCollector;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;

/**
 * Test helper for {@link CodeTransformer} implementations.
 *
 * @author lowasser@google.com (Louis Wasserman)
 */
@AutoValue
public abstract class CodeTransformerTestHelper {
    public static CodeTransformerTestHelper create(CodeTransformer transformer) {
        return new AutoValue_CodeTransformerTestHelper(transformer);
    }

    abstract CodeTransformer transformer();

    public JavaFileObject transform(JavaFileObject original) {
        JavaCompiler compiler = JavacTool.create();
        DiagnosticCollector<JavaFileObject> diagnosticsCollector = new DiagnosticCollector<JavaFileObject>();
        StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnosticsCollector, Locale.ENGLISH,
                UTF_8);
        JavacTaskImpl task = (JavacTaskImpl) compiler.getTask(CharStreams.nullWriter(), fileManager,
                diagnosticsCollector, ImmutableList.<String>of(), null, ImmutableList.of(original));

        try {
            SourceFile sourceFile = SourceFile.create(original);
            Iterable<? extends CompilationUnitTree> trees = task.parse();
            task.analyze();
            JCCompilationUnit tree = Iterables.getOnlyElement(Iterables.filter(trees, JCCompilationUnit.class));
            DescriptionBasedDiff diff = DescriptionBasedDiff.create(tree);
            transformer().apply(new TreePath(tree), task.getContext(), diff);
            diff.applyDifferences(sourceFile);

            return JavaFileObjects.forSourceString(
                    Iterables.getOnlyElement(Iterables.filter(tree.getTypeDecls(), JCClassDecl.class)).sym
                            .getQualifiedName().toString(),
                    sourceFile.getSourceText());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}