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// Copyright 2016 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.android.desugar;
import static com.google.common.base.Preconditions.checkArgument;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterators;
import java.io.IOException;
import java.lang.invoke.MethodHandle;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;
class LambdaClassMaker {
static final String LAMBDA_METAFACTORY_DUMPER_PROPERTY = "jdk.internal.lambda.dumpProxyClasses";
private final Path rootDirectory;
private final Map<Path, LambdaInfo> generatedClasses = new LinkedHashMap<>();
public LambdaClassMaker(Path rootDirectory) {
checkArgument(Files.isDirectory(rootDirectory));
this.rootDirectory = rootDirectory;
}
public void generateLambdaClass(String invokerInternalName, LambdaInfo lambdaInfo,
MethodHandle bootstrapMethod, ArrayList<Object> bsmArgs) throws IOException {
// Invoking the bootstrap method will dump the generated class
try {
bootstrapMethod.invokeWithArguments(bsmArgs);
} catch (Throwable e) {
throw new IllegalStateException("Failed to generate lambda class for class "
+ invokerInternalName + " using " + bootstrapMethod + " with arguments " + bsmArgs, e);
}
Path generatedClassFile = findOnlyUnprocessed(invokerInternalName + "$$Lambda$");
generatedClasses.put(generatedClassFile, lambdaInfo);
}
/**
* Returns relative paths to .class files generated since the last call to this method together
* with a string descriptor of the factory method.
*/
public Map<Path, LambdaInfo> drain() {
ImmutableMap<Path, LambdaInfo> result = ImmutableMap.copyOf(generatedClasses);
generatedClasses.clear();
return result;
}
private Path findOnlyUnprocessed(final String pathPrefix) throws IOException {
// TODO(kmb): Investigate making this faster in the case of many lambdas
// TODO(bazel-team): This could be much nicer with lambdas
try (Stream<Path> results =
Files.walk(rootDirectory)
.map(
new Function<Path, Path>() {
@Override
public Path apply(Path path) {
return rootDirectory.relativize(path);
}
})
.filter(
new Predicate<Path>() {
@Override
public boolean test(Path path) {
return path.toString().startsWith(pathPrefix)
&& !generatedClasses.containsKey(path);
}
})) {
return Iterators.getOnlyElement(results.iterator());
}
}
}
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