1 /* 2 * Copyright (C) 2014 Google, Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package dagger.internal.codegen; 17 18 import com.google.common.base.Function; 19 import com.google.common.base.Optional; 20 import com.google.common.base.Throwables; 21 import com.google.common.collect.ImmutableList; 22 import com.google.common.collect.ImmutableSet; 23 import com.google.common.collect.Iterables; 24 import dagger.internal.codegen.writer.ClassName; 25 import dagger.internal.codegen.writer.JavaWriter; 26 import dagger.internal.codegen.writer.TypeWriter; 27 import java.io.IOException; 28 import javax.annotation.processing.Filer; 29 import javax.lang.model.element.Element; 30 31 import static com.google.common.base.Preconditions.checkNotNull; 32 33 /** 34 * A template class that provides a framework for properly handling IO while generating source files 35 * from an annotation processor. Particularly, it makes a best effort to ensure that files that 36 * fail to write successfully are deleted. 37 * 38 * @param <T> The input type from which source is to be generated. 39 * @author Gregory Kick 40 * @since 2.0 41 */ 42 abstract class SourceFileGenerator<T> { 43 private final Filer filer; 44 SourceFileGenerator(Filer filer)45 SourceFileGenerator(Filer filer) { 46 this.filer = checkNotNull(filer); 47 } 48 generate(T input)49 final void generate(T input) throws SourceFileGenerationException { 50 ClassName generatedTypeName = nameGeneratedType(input); 51 ImmutableSet<Element> originatingElements = 52 ImmutableSet.<Element>copyOf(getOriginatingElements(input)); 53 try { 54 ImmutableSet<JavaWriter> writers = write(generatedTypeName, input); 55 for (JavaWriter javaWriter : writers) { 56 try { 57 javaWriter.file(filer, originatingElements); 58 } catch (IOException e) { 59 throw new SourceFileGenerationException(getNamesForWriters(javaWriter.getTypeWriters()), 60 e, getElementForErrorReporting(input)); 61 } 62 } 63 } catch (Exception e) { 64 // if the code above threw a SFGE, use that 65 Throwables.propagateIfPossible(e, SourceFileGenerationException.class); 66 // otherwise, throw a new one 67 throw new SourceFileGenerationException(ImmutableList.<ClassName>of(), e, 68 getElementForErrorReporting(input)); 69 } 70 } 71 getNamesForWriters(Iterable<TypeWriter> typeWriters)72 private static Iterable<ClassName> getNamesForWriters(Iterable<TypeWriter> typeWriters) { 73 return Iterables.transform(typeWriters, new Function<TypeWriter, ClassName>() { 74 @Override public ClassName apply(TypeWriter input) { 75 return input.name(); 76 } 77 }); 78 } 79 80 /** 81 * Implementations should return the {@link ClassName} for the top-level type to be generated. 82 */ 83 abstract ClassName nameGeneratedType(T input); 84 85 /** 86 * Implementations should return {@link Element} instances from which the source is to be 87 * generated. 88 */ 89 abstract Iterable<? extends Element> getOriginatingElements(T input); 90 91 /** 92 * Returns an optional element to be used for reporting errors. This returns a single element 93 * rather than a collection to reduce output noise. 94 */ 95 abstract Optional<? extends Element> getElementForErrorReporting(T input); 96 97 /** 98 */ 99 abstract ImmutableSet<JavaWriter> write(ClassName generatedTypeName, T input); 100 } 101