src/main/java/com/google/devtools/build/lib/analysis/actions/CommandLineItem.java

// Copyright 2018 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.analysis.actions;

/** An interface for an object that customizes how it is expanded into a command line. */
public interface CommandLineItem {
  /**
   * A map function that allows caller customization how a type is expanded into the command line.
   */
  interface MapFn<T> {
    MapFn<Object> DEFAULT = CommandLineItem::expandToCommandLine;

    String expandToCommandLine(T object);
  }

  /** Expands the object into the command line as a string. */
  String expandToCommandLine();

  /**
   * The default method of expanding types.
   *
   * <p>If the object is a {@link CommandLineItem} we use its {@link
   * CommandLineItem#expandToCommandLine} method, else we call {@link Object#toString()}.
   */
  static String expandToCommandLine(Object object) {
    if (object instanceof CommandLineItem) {
      return ((CommandLineItem) object).expandToCommandLine();
    } else {
      return object.toString();
    }
  }
}