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// 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.packages;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.StoredEventHandler;
import com.google.devtools.build.lib.packages.PackageFactory.Globber;
import com.google.devtools.build.lib.syntax.BuildFileAST;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.ParserInputSource;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.util.List;
import java.util.Set;
import javax.annotation.Nullable;
/** A Preprocessor is an interface to implement generic text-based preprocessing of BUILD files. */
public interface Preprocessor {
/** Factory for {@link Preprocessor} instances. */
interface Factory {
/** Supplier for {@link Factory} instances. */
interface Supplier {
/**
* Returns a Preprocessor factory to use for getting Preprocessor instances.
*
* <p>The CachingPackageLocator is provided so the constructed preprocessors can look up
* other BUILD files.
*/
Factory getFactory(CachingPackageLocator loc);
/** Supplier that always returns {@code NullFactory.INSTANCE}. */
static class NullSupplier implements Supplier {
public static final NullSupplier INSTANCE = new NullSupplier();
private NullSupplier() {
}
@Override
public Factory getFactory(CachingPackageLocator loc) {
return NullFactory.INSTANCE;
}
}
}
/**
* Returns whether this {@link Factory} is still suitable for providing {@link Preprocessor}s.
* If not, all previous preprocessing results should be assumed to be invalid and a new
* {@link Factory} should be created via {@link Supplier#getFactory}.
*/
boolean isStillValid();
/**
* Returns a Preprocessor instance capable of preprocessing a BUILD file independently (e.g. it
* ought to be fine to call {@link #getPreprocessor} for each BUILD file).
*/
@Nullable
Preprocessor getPreprocessor();
/** Factory that always returns {@code null} {@link Preprocessor}s. */
static class NullFactory implements Factory {
public static final NullFactory INSTANCE = new NullFactory();
private NullFactory() {
}
@Override
public boolean isStillValid() {
return true;
}
@Override
public Preprocessor getPreprocessor() {
return null;
}
}
}
/**
* A (result, success) tuple indicating the outcome of preprocessing.
*/
static class Result {
private static final char[] EMPTY_CHARS = new char[0];
public final ParserInputSource result;
public final boolean preprocessed;
public final boolean containsErrors;
public final List<Event> events;
private Result(
ParserInputSource result,
boolean preprocessed,
boolean containsErrors,
List<Event> events) {
this.result = result;
this.preprocessed = preprocessed;
this.containsErrors = containsErrors;
this.events = ImmutableList.copyOf(events);
}
public static Result noPreprocessing(PathFragment buildFilePathFragment,
byte[] buildFileBytes) {
return noPreprocessing(ParserInputSource.create(
FileSystemUtils.convertFromLatin1(buildFileBytes), buildFilePathFragment));
}
/** Convenience factory for a {@link Result} wrapping non-preprocessed BUILD file contents. */
public static Result noPreprocessing(ParserInputSource buildFileSource) {
return new Result(
buildFileSource,
/*preprocessed=*/ false,
/*containsErrors=*/ false,
ImmutableList.<Event>of());
}
/**
* Factory for a successful preprocessing result, meaning that the BUILD file was able to be
* read and has valid syntax and was preprocessed. But note that there may have been be errors
* during preprocessing.
*/
public static Result success(ParserInputSource result, boolean containsErrors,
List<Event> events) {
return new Result(result, /*preprocessed=*/true, containsErrors, events);
}
public static Result invalidSyntax(PathFragment buildFile, List<Event> events) {
return new Result(
ParserInputSource.create(EMPTY_CHARS, buildFile),
/*preprocessed=*/true,
/*containsErrors=*/true,
events);
}
}
/**
* Returns a Result resulting from applying Python preprocessing to the contents of "in". If
* errors happen, they must be reported both as an event on eventHandler and in the function
* return value. An IOException is only thrown when preparing for preprocessing. Once
* preprocessing actually begins, any I/O problems encountered will be reflected in the return
* value, not manifested as exceptions.
*
* @param buildFilePath the BUILD file to be preprocessed.
* @param buildFileBytes the raw contents of the BUILD file to be preprocessed.
* @param packageName the BUILD file's package.
* @param globber a globber for evaluating globs.
* @param globals the global bindings for the Python environment.
* @param ruleNames the set of names of all rules in the build language.
* @throws IOException if there was an I/O problem preparing for preprocessing.
* @return a pair of the ParserInputSource and a map of subincludes seen during the evaluation
*/
Result preprocess(
Path buildFilePath,
byte[] buildFileBytes,
String packageName,
Globber globber,
Environment.Frame globals,
Set<String> ruleNames)
throws IOException, InterruptedException;
/** The result of parsing a preprocessed BUILD file. */
static class AstAfterPreprocessing {
public final boolean preprocessed;
public final boolean containsPreprocessingErrors;
public final BuildFileAST ast;
public final boolean containsAstParsingErrors;
public final Iterable<Event> allEvents;
@Nullable
public final Globber globber;
public AstAfterPreprocessing(Result preprocessingResult, BuildFileAST ast,
StoredEventHandler astParsingEventHandler, @Nullable Globber globber) {
this.ast = ast;
this.preprocessed = preprocessingResult.preprocessed;
this.containsPreprocessingErrors = preprocessingResult.containsErrors;
this.containsAstParsingErrors = astParsingEventHandler.hasErrors();
this.allEvents = Iterables.concat(
preprocessingResult.events, astParsingEventHandler.getEvents());
this.globber = globber;
}
}
}
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