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Utilities for testing compilation.
There is a newer version: 0.21.0
/*
 * 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.testing.compile;

import static com.google.common.base.Charsets.UTF_8;
import static javax.tools.Diagnostic.Kind.ERROR;
import static javax.tools.JavaFileObject.Kind.SOURCE;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import javax.annotation.processing.Processor;
import javax.tools.Diagnostic;
import javax.tools.DiagnosticCollector;
import javax.tools.JavaFileObject;
import javax.tools.ToolProvider;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Multimaps;
import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.util.JavacTask;
import com.sun.tools.javac.api.JavacTool;

/**
 * Utilities for performing compilation with {@code javac}.
 *
 * @author Gregory Kick
 */
@SuppressWarnings("restriction") // Sun APIs usage intended
final class Compilation {
  private Compilation() {}

  /**
   * Compile {@code sources} using {@code processors}.
   *
   * @throws RuntimeException if compilation fails.
   */
  static Result compile(Iterable processors,
      Iterable sources) {
    JavacTool compiler = (JavacTool) ToolProvider.getSystemJavaCompiler();
    DiagnosticCollector diagnosticCollector =
        new DiagnosticCollector();
    InMemoryJavaFileManager fileManager = new InMemoryJavaFileManager(
        compiler.getStandardFileManager(diagnosticCollector, Locale.getDefault(), UTF_8));
    JavacTask task = compiler.getTask(
        null, // Ignore output because the diagnostic collector gets it
        fileManager,
        diagnosticCollector,
        ImmutableSet.of(),
        ImmutableSet.of(),
        sources);
    task.setProcessors(processors);
    task.call();
    return new Result(diagnosticCollector.getDiagnostics(), fileManager.getOutputFiles());
  }

  /**
   * Parse {@code sources} into {@linkplain CompilationUnitTree compilation units}.  This method
   * does not compile the sources.
   */
  static Iterable parse(
      Iterable sources) {
    JavacTool compiler = (JavacTool) ToolProvider.getSystemJavaCompiler();
    DiagnosticCollector diagnosticCollector =
        new DiagnosticCollector();
    InMemoryJavaFileManager fileManager = new InMemoryJavaFileManager(
        compiler.getStandardFileManager(diagnosticCollector, Locale.getDefault(), UTF_8));
    JavacTask task = compiler.getTask(
        null, // Ignore output because the diagnostic collector gets it
        fileManager,
        diagnosticCollector,
        ImmutableSet.of(),
        ImmutableSet.of(),
        sources);
    try {
      Iterable parsedCompilationUnits = task.parse();
      List> diagnostics = diagnosticCollector.getDiagnostics();
      for (Diagnostic diagnostic : diagnostics) {
        if (Diagnostic.Kind.ERROR == diagnostic.getKind()) {
          throw new IllegalStateException("error while parsing:\n"
              + Diagnostics.toString(diagnostics));
        }
      }
      return parsedCompilationUnits;
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }

  /** The diagnostic and file output of a compilation. */
  static final class Result {
    final ImmutableListMultimap>
        diagnosticsByKind;
    final ImmutableListMultimap generatedFilesByKind;

    Result(
        Iterable> diagnostics,
        Iterable generatedFiles) {
      this.diagnosticsByKind = Multimaps.index(diagnostics,
          new Function, Diagnostic.Kind>() {
            @Override public Diagnostic.Kind apply(Diagnostic input) {
              return input.getKind();
            }
          });
      this.generatedFilesByKind = Multimaps.index(generatedFiles,
          new Function() {
            @Override public JavaFileObject.Kind apply(JavaFileObject input) {
              return input.getKind();
            }
          });
    }

    boolean successful() {
      return diagnosticsByKind.get(ERROR).isEmpty();
    }

    ImmutableList generatedSources() {
      return generatedFilesByKind.get(SOURCE);
    }
  }
}