| // 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.cmdline; |
| |
| import com.google.auto.value.AutoValue; |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.ImmutableList; |
| import com.google.errorprone.annotations.CanIgnoreReturnValue; |
| import javax.annotation.Nullable; |
| import net.starlark.java.eval.EvalException; |
| import net.starlark.java.eval.Module; |
| import net.starlark.java.eval.Starlark; |
| import net.starlark.java.eval.StarlarkThread; |
| |
| /** |
| * BazelModuleContext records Bazel-specific information associated with a .bzl {@link |
| * net.starlark.java.eval.Module}. |
| * |
| * <p>Maintainer's note: This object is determined prior to the module's evaluation in |
| * BzlLoadFunction. It is saved in the {@code Module} as {@link Module#getClientData client data}. |
| * The {@code Module} used during .bzl compilation is separate and uses {@link BazelCompileContext} |
| * as client data. For data that is computed after the module's evaluation and which need not be |
| * exposed outside the module-loading machinery, consider {@link BzlLoadValue}. |
| */ |
| // Immutability is useful because this object is retrievable from a Module and therefore from a |
| // BzlLoadValue. |
| @AutoValue |
| public abstract class BazelModuleContext { |
| /** Label associated with the Starlark {@link net.starlark.java.eval.Module}. */ |
| public abstract Label label(); |
| |
| /** The repository mapping applicable to the repo where the .bzl file is located in. */ |
| public abstract RepositoryMapping repoMapping(); |
| |
| /** |
| * The repository mapping applicable to the main repository, possibly without WORKSPACE repos or |
| * null. This is purely meant to support {@link Label#getDisplayFormForStarlark(StarlarkThread)}. |
| */ |
| @Nullable |
| public abstract RepositoryMapping bestEffortMainRepoMapping(); |
| |
| /** Returns the name of the module's .bzl file, as provided to the parser. */ |
| public abstract String filename(); |
| |
| /** |
| * Returns a list of modules loaded by this .bzl file, in source order. |
| * |
| * <p>By traversing these modules' loads, it is possible to reconstruct the complete load DAG (not |
| * including {@code @_builtins} .bzl files). See {@link #visitLoadGraphRecursively}. |
| */ |
| public abstract ImmutableList<Module> loads(); |
| |
| /** |
| * Consumes labels of loaded Starlark files during a call to {@link #visitLoadGraphRecursively}. |
| * |
| * <p>The value returned by {@link #visit} determines whether the traversal should continue (true) |
| * or backtrack (false). Using a method reference to {@link Set#add} is a convenient way to |
| * aggregate Starlark files while pruning branches when a file was already seen. The same set may |
| * be reused across multiple calls to {@link #visitLoadGraphRecursively} in order to prune the |
| * graph at files already seen during a previous traversal. |
| */ |
| @FunctionalInterface |
| public interface LoadGraphVisitor<E1 extends Exception, E2 extends Exception> { |
| /** |
| * Processes a single loaded Starlark file and determines whether to recurse into that file's |
| * loads. |
| * |
| * @return true if the visitation should recurse into the loads of the given file |
| */ |
| @CanIgnoreReturnValue |
| boolean visit(Label load) throws E1, E2; |
| } |
| |
| /** Performs an online visitation of the load graph rooted at a given list of loads. */ |
| public static <E1 extends Exception, E2 extends Exception> void visitLoadGraphRecursively( |
| Iterable<Module> loads, LoadGraphVisitor<E1, E2> visitor) throws E1, E2 { |
| for (Module module : loads) { |
| BazelModuleContext ctx = BazelModuleContext.of(module); |
| if (visitor.visit(ctx.label())) { |
| visitLoadGraphRecursively(ctx.loads(), visitor); |
| } |
| } |
| } |
| |
| /** |
| * Transitive digest of the .bzl file of the {@link net.starlark.java.eval.Module} itself and all |
| * files it transitively loads. |
| */ |
| @SuppressWarnings({"AutoValueImmutableFields", "mutable"}) |
| @AutoValue.CopyAnnotations |
| public abstract byte[] bzlTransitiveDigest(); |
| |
| /** |
| * Returns a label for a {@link net.starlark.java.eval.Module}. |
| * |
| * <p>This is a user-facing value and we rely on this string to be a valid label for the {@link |
| * net.starlark.java.eval.Module} (and that only). |
| */ |
| @Override |
| public final String toString() { |
| return label().toString(); |
| } |
| |
| /** |
| * Returns the {@code BazelModuleContext} associated with the specified Starlark module, or null |
| * if there isn't any. |
| */ |
| @Nullable |
| public static BazelModuleContext of(Module m) { |
| @Nullable Object data = m.getClientData(); |
| if (data instanceof BazelModuleContext) { |
| return (BazelModuleContext) data; |
| } else { |
| return null; |
| } |
| } |
| |
| /** |
| * Returns the {@code BazelModuleContext} associated with the innermost Starlark function on the |
| * call stack of the given thread. |
| * |
| * <p>Usage note: Following the example of {@link Module#ofInnermostEnclosingStarlarkFunction}, |
| * the name of this method is intentionally clumsy to remind the reader that introspecting the |
| * current module is a dubious practice. We went with a different name here because the null |
| * tolerance of the two methods differs. |
| * |
| * @throws NullPointerException if there is no currently executing Starlark function, or the |
| * innermost Starlark function's module has no {@code BazelModuleContext}. |
| */ |
| public static BazelModuleContext ofInnermostBzlOrThrow(StarlarkThread thread) { |
| Module m = Preconditions.checkNotNull(Module.ofInnermostEnclosingStarlarkFunction(thread)); |
| return Preconditions.checkNotNull(of(m)); |
| } |
| |
| /** |
| * Returns the {@code BazelModuleContext} associated with the innermost Starlark function on the |
| * call stack of the given thread. If not present, throws {@code EvalException} with an error |
| * message indicating that {@code what} can't be used in this Starlark environment. |
| */ |
| @CanIgnoreReturnValue |
| public static BazelModuleContext ofInnermostBzlOrFail(StarlarkThread thread, String what) |
| throws EvalException { |
| BazelModuleContext ctx = null; |
| Module m = Module.ofInnermostEnclosingStarlarkFunction(thread); |
| if (m != null) { |
| ctx = of(m); |
| } |
| if (ctx == null) { |
| throw Starlark.errorf( |
| "%s can only be used during .bzl initialization (top-level evaluation)", what); |
| } |
| return ctx; |
| } |
| |
| public static BazelModuleContext create( |
| Label label, |
| RepositoryMapping repoMapping, |
| @Nullable RepositoryMapping bestEffortMainRepoMapping, |
| String filename, |
| ImmutableList<Module> loads, |
| byte[] bzlTransitiveDigest) { |
| return new AutoValue_BazelModuleContext( |
| label, repoMapping, bestEffortMainRepoMapping, filename, loads, bzlTransitiveDigest); |
| } |
| |
| public final Label.PackageContext packageContext() { |
| return Label.PackageContext.of(label().getPackageIdentifier(), repoMapping()); |
| } |
| } |