Move LabelConversionContext to a new top-level class.
Also add a convenience method to create a label converter for a starlark
thread.
This makes it more easily available for other uses.
Part of Optional Toolchains (#14726).
Closes #14815.
PiperOrigin-RevId: 429410754
diff --git a/src/main/java/com/google/devtools/build/lib/packages/LabelConverter.java b/src/main/java/com/google/devtools/build/lib/packages/LabelConverter.java
new file mode 100644
index 0000000..b3a8e9a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/packages/LabelConverter.java
@@ -0,0 +1,90 @@
+// Copyright 2022 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.packages;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
+import com.google.devtools.build.lib.cmdline.RepositoryMapping;
+import java.util.HashMap;
+import java.util.Map;
+import net.starlark.java.eval.Module;
+import net.starlark.java.eval.StarlarkThread;
+
+/** Class which can evaluate a label with repository remappings. */
+public class LabelConverter {
+
+ public static LabelConverter forThread(StarlarkThread thread) {
+ BazelModuleContext moduleContext =
+ BazelModuleContext.of(Module.ofInnermostEnclosingStarlarkFunction(thread));
+ BazelStarlarkContext bazelStarlarkContext = BazelStarlarkContext.from(thread);
+ return new LabelConverter(
+ moduleContext.label(),
+ moduleContext.repoMapping(),
+ bazelStarlarkContext.getConvertedLabelsInPackage());
+ }
+
+ public static LabelConverter forModuleContext(BazelModuleContext moduleContext) {
+ return new LabelConverter(moduleContext.label(), moduleContext.repoMapping());
+ }
+
+ private final Label base;
+ private final RepositoryMapping repositoryMapping;
+ private final Map<String, Label> labelCache;
+
+ public LabelConverter(Label base, RepositoryMapping repositoryMapping) {
+ this(
+ base,
+ repositoryMapping,
+ // Only cache labels seen by this converter.
+ new HashMap<>());
+ }
+
+ public LabelConverter(
+ Label base, RepositoryMapping repositoryMapping, Map<String, Label> labelCache) {
+ this.base = base;
+ this.repositoryMapping = repositoryMapping;
+ this.labelCache = labelCache;
+ }
+
+ /** Returns the base label that relative labels will be resolved against. */
+ Label getBase() {
+ return base;
+ }
+
+ /** Returns the Label corresponding to the input, using the current conversion context. */
+ public Label convert(String input) throws LabelSyntaxException {
+ // Optimization: First check the package-local map, avoiding Label validation, Label
+ // construction, and global Interner lookup. This approach tends to be very profitable
+ // overall, since it's common for the targets in a single package to have duplicate
+ // label-strings across all their attribute values.
+ Label converted = labelCache.get(input);
+ if (converted == null) {
+ converted = base.getRelativeWithRemapping(input, repositoryMapping);
+ labelCache.put(input, converted);
+ }
+ return converted;
+ }
+
+ @VisibleForTesting
+ Map<String, Label> getLabelCache() {
+ return labelCache;
+ }
+
+ @Override
+ public String toString() {
+ return base.toString();
+ }
+}