src/main/java/com/google/devtools/build/lib/syntax/SkylarkQueryable.java

// Copyright 2015 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.syntax;

import com.google.devtools.build.lib.events.Location;

/**
 * Skylark values that support querying by other objects, i.e. `foo in object`. Semantics of the
 * operation may differ, i.e. dicts check for keys and lists for values.
 */
// TODO(adonovan): merge with SkylarkIndexable: no type supports 'x in y' without y[x],
// and 'x in y' can be defined in terms of y[x], at least as a default implementation.
// (Implementations of 'x in y' may choose to interpret failure of y[x] as false or a failure.)
public interface SkylarkQueryable extends StarlarkValue {

  /** Returns whether the key is in the object. */
  boolean containsKey(Object key, Location loc) throws EvalException;

  // Variant used when called directly from a Starlark thread.
  // This is a temporary workaround to enable --incompatible_disallow_dict_lookup_unhashable_keys.
  // TODO(adonovan): remove when that flag is removed.
  default boolean containsKey(Object key, Location loc, StarlarkThread thread)
      throws EvalException {
    return this.containsKey(key, loc);
  }
}