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/*
* Copyright 2018 Google Inc. 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.turbine.binder.lookup;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.collect.ImmutableList;
import org.checkerframework.checker.nullness.qual.Nullable;
/** A {@link TopLevelIndex} that aggregates multiple indices into one. */
// Note: this implementation doesn't detect if the indices contain incompatible information,
// e.g. a class name in one index that is a prefix of a package name in another index. This
// shouldn't matter in practice because we rely on javac to reject invalid input, but it would
// be nice to report an error in that case.
// TODO(cushon): improve error handling
public class CompoundTopLevelIndex implements TopLevelIndex {
private final ImmutableList<TopLevelIndex> indexes;
private CompoundTopLevelIndex(ImmutableList<TopLevelIndex> indexes) {
this.indexes = checkNotNull(indexes);
}
/** Creates a {@link CompoundTopLevelIndex}. */
public static CompoundTopLevelIndex of(TopLevelIndex... indexes) {
return new CompoundTopLevelIndex(ImmutableList.copyOf(indexes));
}
private final Scope scope =
new Scope() {
@Override
public @Nullable LookupResult lookup(LookupKey lookupKey) {
// Return the first matching symbol.
for (TopLevelIndex index : indexes) {
LookupResult result = index.scope().lookup(lookupKey);
if (result != null) {
return result;
}
}
return null;
}
};
@Override
public Scope scope() {
return scope;
}
@Override
public @Nullable PackageScope lookupPackage(Iterable<String> packagename) {
// When returning package scopes, build up a compound scope containing entries from all
// indices with matching packages.
PackageScope result = null;
for (TopLevelIndex index : indexes) {
PackageScope packageScope = index.lookupPackage(packagename);
if (packageScope == null) {
continue;
}
if (result == null) {
result = packageScope;
} else {
result = result.append(packageScope);
}
}
return result;
}
}
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