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/*
* Copyright 2016 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 com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.common.collect.ImmutableList;
import com.google.turbine.binder.sym.ClassSymbol;
import com.google.turbine.tree.Tree;
import com.google.turbine.tree.Tree.ImportDecl;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A scope that provides best-effort lookup for on-demand imported types in a compilation unit.
*
* <p>Resolution is lazy, imports are not evaluated until the first request for a matching simple
* name.
*
* <p>Static on-demand imports of types are not supported.
*/
public class WildImportIndex implements ImportScope {
/** {@link ImportScope}s for all on-demand imports in the compilation unit. */
private final ImmutableList<Supplier<ImportScope>> packages;
public WildImportIndex(ImmutableList<Supplier<ImportScope>> packages) {
this.packages = packages;
}
/** Creates an import index for the given top-level environment. */
public static WildImportIndex create(
CanonicalSymbolResolver importResolver,
final TopLevelIndex cpi,
ImmutableList<ImportDecl> imports) {
ImmutableList.Builder<Supplier<@Nullable ImportScope>> packageScopes = ImmutableList.builder();
for (final ImportDecl i : imports) {
if (i.wild()) {
packageScopes.add(
Suppliers.memoize(
new Supplier<@Nullable ImportScope>() {
@Override
public @Nullable ImportScope get() {
if (i.stat()) {
return staticOnDemandImport(cpi, i, importResolver);
} else {
return onDemandImport(cpi, i, importResolver);
}
}
}));
}
}
return new WildImportIndex(packageScopes.build());
}
/** Full resolve the type for a non-static on-demand import. */
private static @Nullable ImportScope onDemandImport(
TopLevelIndex cpi, ImportDecl i, final CanonicalSymbolResolver importResolver) {
ImmutableList.Builder<String> flatNames = ImmutableList.builder();
for (Tree.Ident ident : i.type()) {
flatNames.add(ident.value());
}
Scope packageIndex = cpi.lookupPackage(flatNames.build());
if (packageIndex != null) {
// a wildcard import of a package
return new ImportScope() {
@Override
public @Nullable LookupResult lookup(LookupKey lookupKey, ResolveFunction resolve) {
return packageIndex.lookup(lookupKey);
}
};
}
LookupResult result = cpi.scope().lookup(new LookupKey(i.type()));
if (result == null) {
return null;
}
ClassSymbol member = resolveImportBase(result, importResolver, importResolver);
if (member == null) {
return null;
}
return new ImportScope() {
@Override
public @Nullable LookupResult lookup(LookupKey lookupKey, ResolveFunction unused) {
return resolveMember(member, importResolver, importResolver, lookupKey);
}
};
}
/**
* Resolve the base class symbol of a possibly non-canonical static on-demand import (see {@code
* ImportScope#staticNamedImport} for an explanation of why the possibly non-canonical part is
* deferred).
*/
private static @Nullable ImportScope staticOnDemandImport(
TopLevelIndex cpi, ImportDecl i, final CanonicalSymbolResolver importResolver) {
LookupResult result = cpi.scope().lookup(new LookupKey(i.type()));
if (result == null) {
return null;
}
return new ImportScope() {
@Override
public @Nullable LookupResult lookup(LookupKey lookupKey, ResolveFunction resolve) {
ClassSymbol member = resolveImportBase(result, resolve, importResolver);
if (member == null) {
return null;
}
return resolveMember(member, resolve, importResolver, lookupKey);
}
};
}
private static @Nullable LookupResult resolveMember(
ClassSymbol base,
ResolveFunction resolve,
CanonicalSymbolResolver importResolver,
LookupKey lookupKey) {
ClassSymbol member = resolve.resolveOne(base, lookupKey.first());
if (member == null) {
return null;
}
if (!importResolver.visible(member)) {
return null;
}
return new LookupResult(member, lookupKey);
}
static @Nullable ClassSymbol resolveImportBase(
LookupResult result, ResolveFunction resolve, CanonicalSymbolResolver importResolver) {
ClassSymbol member = (ClassSymbol) result.sym();
for (Tree.Ident bit : result.remaining()) {
member = resolve.resolveOne(member, bit);
if (member == null) {
return null;
}
if (!importResolver.visible(member)) {
return null;
}
}
return member;
}
@Override
public @Nullable LookupResult lookup(LookupKey lookup, ResolveFunction resolve) {
for (Supplier<ImportScope> packageScope : packages) {
ImportScope scope = packageScope.get();
if (scope == null) {
continue;
}
LookupResult result = scope.lookup(lookup, resolve);
if (result != null) {
return result;
}
}
return null;
}
}
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