| // Copyright 2014 The Bazel Authors. 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.devtools.build.lib.analysis.actions; |
| |
| import com.google.devtools.build.lib.actions.Artifact; |
| import com.google.devtools.build.lib.actions.ArtifactPathResolver; |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable; |
| import com.google.devtools.build.lib.util.ResourceFileLoader; |
| import com.google.devtools.build.lib.vfs.FileSystemUtils; |
| import com.google.devtools.build.lib.vfs.Path; |
| import java.io.IOException; |
| import java.nio.charset.Charset; |
| import java.nio.charset.StandardCharsets; |
| import javax.annotation.Nullable; |
| |
| /** A template that contains text content, or alternatively throws an {@link IOException}. */ |
| @Immutable // all subclasses are immutable |
| public abstract class Template { |
| |
| static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8; |
| |
| /** We only allow subclasses in this file. */ |
| private Template() {} |
| |
| /** Returns the text content of the template. */ |
| protected abstract String getContent(ArtifactPathResolver resolver) throws IOException; |
| |
| @Nullable |
| public Artifact getTemplateArtifact() { |
| return null; |
| } |
| |
| /** |
| * Returns a string that is used for the action key. This must change if the getContent method |
| * returns something different, but is not allowed to throw an exception. |
| */ |
| protected abstract String getKey(); |
| |
| private static final class ErrorTemplate extends Template { |
| private final IOException e; |
| private final String templateName; |
| |
| ErrorTemplate(IOException e, String templateName) { |
| this.e = e; |
| this.templateName = templateName; |
| } |
| |
| @Override |
| protected String getContent(ArtifactPathResolver resolver) throws IOException { |
| throw new IOException( |
| "failed to load resource file '" + templateName + "' due to I/O error: " + e.getMessage(), |
| e); |
| } |
| |
| @Override |
| protected String getKey() { |
| return "ERROR: " + e.getMessage(); |
| } |
| } |
| |
| private static final class StringTemplate extends Template { |
| private final String templateText; |
| |
| StringTemplate(String templateText) { |
| this.templateText = templateText; |
| } |
| |
| @Override |
| protected String getContent(ArtifactPathResolver resolver) { |
| return templateText; |
| } |
| |
| @Override |
| protected String getKey() { |
| return templateText; |
| } |
| } |
| |
| private static final class ArtifactTemplate extends Template { |
| private final Artifact templateArtifact; |
| |
| ArtifactTemplate(Artifact templateArtifact) { |
| this.templateArtifact = templateArtifact; |
| } |
| |
| @Override |
| protected String getContent(ArtifactPathResolver resolver) throws IOException { |
| Path templatePath = resolver.toPath(templateArtifact); |
| try { |
| return FileSystemUtils.readContent(templatePath, DEFAULT_CHARSET); |
| } catch (IOException e) { |
| throw new IOException( |
| "failed to load template file '" |
| + templatePath.getPathString() |
| + "' due to I/O error: " |
| + e.getMessage(), |
| e); |
| } |
| } |
| |
| @Override |
| protected String getKey() { |
| // This isn't strictly necessary, because the action inputs are automatically considered. |
| return "ARTIFACT: " + templateArtifact.getExecPathString(); |
| } |
| |
| @Override |
| public Artifact getTemplateArtifact() { |
| return templateArtifact; |
| } |
| } |
| /** |
| * Loads a template from the given resource. The resource is looked up relative to the given |
| * class. If the resource cannot be loaded, the returned template throws an {@link IOException} |
| * when {@link #getContent} is called. This makes it safe to use this method in a constant |
| * initializer. |
| */ |
| public static Template forResource(final Class<?> relativeToClass, final String templateName) { |
| try { |
| String content = ResourceFileLoader.loadResource(relativeToClass, templateName); |
| return forString(content); |
| } catch (final IOException e) { |
| return new ErrorTemplate(e, templateName); |
| } |
| } |
| |
| /** Returns a template for the given text string. */ |
| public static Template forString(final String templateText) { |
| return new StringTemplate(templateText); |
| } |
| |
| /** |
| * Returns a template that loads the given artifact. It is important that the artifact is also an |
| * input for the action, or this won't work. Therefore this method is private, and you should use |
| * the corresponding {@link TemplateExpansionAction} constructor. |
| */ |
| static Template forArtifact(final Artifact templateArtifact) { |
| return new ArtifactTemplate(templateArtifact); |
| } |
| } |