/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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.android.jack.dx.rop.cst;

import com.android.jack.dx.dex.file.ValueEncoder.ValueType;
import com.android.jack.dx.util.ToHuman;

import javax.annotation.Nonnull;

/**
 * Base class for constants of all sorts.
 */
public abstract class Constant implements ToHuman, Comparable<Constant> {
  /**
   * Returns {@code true} if this instance is a category-2 constant,
   * meaning it takes up two slots in the constant pool, or
   * {@code false} if this instance is category-1.
   *
   * @return {@code true} iff this instance is category-2
   */
  public abstract boolean isCategory2();

  /**
   * Returns the human name for the particular type of constant
   * this instance is.
   *
   * @return {@code non-null;} the name
   */
  public abstract String typeName();

  /**
   * {@inheritDoc}
   *
   * This compares in class-major and value-minor order.
   */
  @Override
  public final int compareTo(Constant other) {
    Class<? extends Constant> clazz = getClass();
    Class<? extends Constant> otherClazz = other.getClass();

    if (clazz != otherClazz) {
      return clazz.getName().compareTo(otherClazz.getName());
    }

    return compareTo0(other);
  }

  /**
   * Compare the values of this and another instance, which are guaranteed
   * to be of the same class. Subclasses must implement this.
   *
   * @param other {@code non-null;} the instance to compare to
   * @return {@code -1}, {@code 0}, or {@code 1}, as usual
   * for a comparison
   */
  protected abstract int compareTo0(Constant other);

  /**
   * Return the value type of this constant.
   */
  @Nonnull
  public abstract ValueType getEncodedValueType();
}