1 files changed, 98 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java b/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java
new file mode 100644
index 0000000000..0a25669615
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java
@@ -0,0 +1,98 @@
+// Copyright 2017 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.rules.config;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Predicate;
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
+import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
+import com.google.devtools.build.lib.packages.ClassObjectConstructor;
+import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
+import com.google.devtools.build.lib.packages.SkylarkClassObject;
+import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
+import com.google.devtools.build.lib.skylarkinterface.Param;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.util.Preconditions;
+
+/** Provider for exporting value and valid value predicate of feature flags to consuming targets. */
+@SkylarkModule(
+  name = "FeatureFlagInfo",
+  doc = "A provider used to access information about config_feature_flag rules."
+)
+@AutoValue
+@Immutable
+public abstract class ConfigFeatureFlagProvider extends SkylarkClassObject
+    implements TransitiveInfoProvider {
+
+  /** Name used in Skylark for accessing ConfigFeatureFlagProvider. */
+  static final String SKYLARK_NAME = "FeatureFlagInfo";
+
+  /** Skylark constructor and identifier for ConfigFeatureFlagProvider. */
+  static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor(SKYLARK_NAME) {};
+
+  /** Identifier used to retrieve this provider from rules which export it. */
+  private static final SkylarkProviderIdentifier SKYLARK_IDENTIFIER =
+      SkylarkProviderIdentifier.forKey(SKYLARK_CONSTRUCTOR.getKey());
+
+  ConfigFeatureFlagProvider() {
+    super(SKYLARK_CONSTRUCTOR, ImmutableMap.<String, Object>of());
+  }
+
+  /** Creates a new ConfigFeatureFlagProvider with the given value and valid value predicate. */
+  public static ConfigFeatureFlagProvider create(String value, Predicate<String> isValidValue) {
+    return new AutoValue_ConfigFeatureFlagProvider(value, isValidValue);
+  }
+
+  /** Retrieves and casts the provider from the given target. */
+  public static ConfigFeatureFlagProvider fromTarget(TransitiveInfoCollection target) {
+    Object provider = target.get(SKYLARK_IDENTIFIER);
+    if (provider == null) {
+      return null;
+    }
+    Preconditions.checkState(provider instanceof ConfigFeatureFlagProvider);
+    return (ConfigFeatureFlagProvider) provider;
+  }
+
+  /** Gets the current value of the flag in the flag's current configuration. */
+  @SkylarkCallable(
+    name = "value",
+    structField = true,
+    doc = "The value of the flag in the configuration used by the flag rule."
+  )
+  public abstract String getValue();
+
+  /** Returns whether this value is valid for this flag. */
+  @SkylarkCallable(
+    name = "is_valid_value",
+    doc = "The value of the flag in the configuration used by the flag rule.",
+    parameters = {
+      @Param(
+        name = "value",
+        type = String.class,
+        doc = "String, the value to check for validity for this flag."
+      ),
+    }
+  )
+  public boolean isValidValue(String value) {
+    return getIsValidValue().apply(value);
+  }
+
+  /** Gets the predicate which determines valid values for this flag. */
+  abstract Predicate<String> getIsValidValue();
+}