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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.dx.rop.cst;
     18 
     19 import com.android.dx.util.ToHuman;
     20 
     21 /**
     22  * Base class for constants of all sorts.
     23  */
     24 public abstract class Constant
     25         implements ToHuman, Comparable<Constant> {
     26     /**
     27      * Returns {@code true} if this instance is a category-2 constant,
     28      * meaning it takes up two slots in the constant pool, or
     29      * {@code false} if this instance is category-1.
     30      *
     31      * @return {@code true} iff this instance is category-2
     32      */
     33     public abstract boolean isCategory2();
     34 
     35     /**
     36      * Returns the human name for the particular type of constant
     37      * this instance is.
     38      *
     39      * @return {@code non-null;} the name
     40      */
     41     public abstract String typeName();
     42 
     43     /**
     44      * {@inheritDoc}
     45      *
     46      * This compares in class-major and value-minor order.
     47      */
     48     public final int compareTo(Constant other) {
     49         Class clazz = getClass();
     50         Class otherClazz = other.getClass();
     51 
     52         if (clazz != otherClazz) {
     53             return clazz.getName().compareTo(otherClazz.getName());
     54         }
     55 
     56         return compareTo0(other);
     57     }
     58 
     59     /**
     60      * Compare the values of this and another instance, which are guaranteed
     61      * to be of the same class. Subclasses must implement this.
     62      *
     63      * @param other {@code non-null;} the instance to compare to
     64      * @return {@code -1}, {@code 0}, or {@code 1}, as usual
     65      * for a comparison
     66      */
     67     protected abstract int compareTo0(Constant other);
     68 }
     69