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// Copyright 2020 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.skyframe;
import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
import com.google.devtools.build.lib.cmdline.RepositoryName;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.SerializationConstant;
import com.google.devtools.build.skyframe.SkyFunctionName;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import net.starlark.java.eval.StarlarkSemantics;
/**
* A Skyframe value representing the result of evaluating the {@code @_builtins} pseudo-repository.
*
* <p>To avoid unnecessary Skyframe edges, the {@code StarlarkSemantics} are included in this value,
* so that a caller who obtains a StarlarkBuiltinsValue can also access the StarlarkSemantics
* without an additional dependency.
*
* <p>These are parsed from {@code @_builtins//:exports.bzl}.
*/
public final class StarlarkBuiltinsValue implements SkyValue {
static final String BUILTINS_NAME = "@_builtins";
/**
* The builtins pseudo-repository.
*
* <p>It is illegal to declare a repository in WORKSPACE whose name collides with this one.
* Whether a collision has in fact occurred is determined by {@link RepositoryName#equals}, and
* hence depends on the OS path policy (i.e. the case sensitivity of the host system).
*
* <p>Regardless of path policy, all actual uses of the builtins pseudo-repo are case sensitive
* and must match {@link #BUILTINS_NAME} exactly.
*/
// TODO(#11437): Add actual enforcement that users cannot define a repo named "@_builtins".
@SerializationConstant static final RepositoryName BUILTINS_REPO;
/** Reports whether the given repository is the special builtins pseudo-repository. */
static boolean isBuiltinsRepo(RepositoryName repo) {
// Use String.equals(), not RepositoryName.equals(), to force case sensitivity.
return repo.getName().equals(BUILTINS_NAME);
}
static {
try {
BUILTINS_REPO = RepositoryName.create(BUILTINS_NAME);
} catch (LabelSyntaxException e) {
throw new IllegalStateException(e);
}
}
// These are all (except transitiveDigest) deeply immutable since the Starlark values are already
// frozen, so let's skip the accessors and mutators.
/**
* Top-level predeclared symbols for a .bzl file loaded on behalf of a BUILD file, after builtins
* injection has been applied.
*/
public final ImmutableMap<String, Object> predeclaredForBuildBzl;
/**
* Top-level predeclared symbols for a BUILD file, after builtins injection but before any prelude
* file has been applied.
*/
public final ImmutableMap<String, Object> predeclaredForBuild;
/** Contents of the {@code exported_to_java} dict. */
public final ImmutableMap<String, Object> exportedToJava;
/** Transitive digest of all .bzl files in {@code @_builtins}. */
public final byte[] transitiveDigest;
/** The StarlarkSemantics used for {@code @_builtins} evaluation. */
public final StarlarkSemantics starlarkSemantics;
private StarlarkBuiltinsValue(
ImmutableMap<String, Object> predeclaredForBuildBzl,
ImmutableMap<String, Object> predeclaredForBuild,
ImmutableMap<String, Object> exportedToJava,
byte[] transitiveDigest,
StarlarkSemantics starlarkSemantics) {
this.predeclaredForBuildBzl = predeclaredForBuildBzl;
this.predeclaredForBuild = predeclaredForBuild;
this.exportedToJava = exportedToJava;
this.transitiveDigest = transitiveDigest;
this.starlarkSemantics = starlarkSemantics;
}
public static StarlarkBuiltinsValue create(
ImmutableMap<String, Object> predeclaredForBuildBzl,
ImmutableMap<String, Object> predeclaredForBuild,
ImmutableMap<String, Object> exportedToJava,
byte[] transitiveDigest,
StarlarkSemantics starlarkSemantics) {
return new StarlarkBuiltinsValue(
predeclaredForBuildBzl,
predeclaredForBuild,
exportedToJava,
transitiveDigest,
starlarkSemantics);
}
/**
* Constructs a placeholder builtins value to be used when builtins injection is disabled, or for
* use within builtins evaluation itself.
*
* <p>The placeholder simply wraps the StarlarkSemantics object. This lets code paths that don't
* use injection still conveniently access the semantics without incurring a separate Skyframe
* edge.
*/
public static StarlarkBuiltinsValue createEmpty(StarlarkSemantics starlarkSemantics) {
return new StarlarkBuiltinsValue(
/*predeclaredForBuildBzl=*/ ImmutableMap.of(),
/*predeclaredForBuild=*/ ImmutableMap.of(),
/*exportedToJava=*/ ImmutableMap.of(),
/*transitiveDigest=*/ new byte[] {},
starlarkSemantics);
}
/** Returns the singleton SkyKey for this type of value. */
public static Key key() {
return Key.INSTANCE;
}
/**
* Skyframe key for retrieving the {@code @_builtins} definitions.
*
* <p>This has no fields since there is only one {@code StarlarkBuiltinsValue} at a time.
*/
static final class Key implements SkyKey {
private static final Key INSTANCE = new Key();
private Key() {}
@Override
public SkyFunctionName functionName() {
return SkyFunctions.STARLARK_BUILTINS;
}
@Override
public String toString() {
return "Starlark @_builtins";
}
@Override
public boolean equals(Object other) {
return other instanceof Key;
}
@Override
public int hashCode() {
return 7727; // more or less xkcd/221
}
}
}