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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
There is a newer version: 9.1.6
/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * 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 proguard.evaluation.value;

/**
 * This abstract class represents a partially evaluated value.
 *
 * @author Eric Lafortune
 */
public abstract class Value {
  public static final int NEVER = -1;
  public static final int MAYBE = 0;
  public static final int ALWAYS = 1;

  public static final int TYPE_UNKNOWN = -1;
  public static final int TYPE_INTEGER = 1;
  public static final int TYPE_LONG = 2;
  public static final int TYPE_FLOAT = 3;
  public static final int TYPE_DOUBLE = 4;
  public static final int TYPE_REFERENCE = 5;
  public static final int TYPE_INSTRUCTION_OFFSET = 6;
  public static final int TYPE_TOP = 7;

  /** Returns this Value as a Category1Value. */
  public Category1Value category1Value() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not a Category 1 value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as a Category2Value. */
  public Category2Value category2Value() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not a Category 2 value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as an IntegerValue. */
  public IntegerValue integerValue() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not an integer value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as a LongValue. */
  public LongValue longValue() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not a long value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as a FloatValue. */
  public FloatValue floatValue() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not a float value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as a DoubleValue. */
  public DoubleValue doubleValue() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not a double value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as a ReferenceValue. */
  public ReferenceValue referenceValue() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not a reference value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns this Value as an InstructionOffsetValue. */
  public InstructionOffsetValue instructionOffsetValue() {
    throw new IllegalArgumentException(
        "Value \""
            + this.toString()
            + "\" is not an instruction offset value ["
            + this.getClass().getName()
            + "]");
  }

  /** Returns whether this Value represents a single specific (but possibly unknown) value. */
  public boolean isSpecific() {
    return false;
  }

  /** Returns whether this Value represents a single particular (known) value. */
  public boolean isParticular() {
    return false;
  }

  /** Returns the generalization of this Value and the given other Value. */
  public abstract Value generalize(Value other);

  /**
   * Returns whether the computational type of this Value is a category 2 type. This means that it
   * takes up the space of two category 1 types on the stack, for instance.
   */
  public abstract boolean isCategory2();

  /**
   * Returns the computational type of this Value.
   *
   * @return TYPE_INTEGER, TYPE_LONG, TYPE_FLOAT, 
   *     TYPE_DOUBLE, TYPE_REFERENCE, or TYPE_INSTRUCTION_OFFSET.
   */
  public abstract int computationalType();

  /**
   * Returns the internal type of this Value.
   *
   * @return TypeConstants.BOOLEAN, TypeConstants.BYTE, 
   *     TypeConstants.CHAR, TypeConstants.SHORT, TypeConstants.INT
   *     , TypeConstants.LONG, TypeConstants.FLOAT, 
   *     TypeConstants.DOUBLE, TypeConstants.CLASS_START ... TypeConstants.CLASS_END
   *     , or an array type containing any of these types (always as String).
   */
  public abstract String internalType();

  /** Returns a deep copy of the value if it mutable, returns the value itself otherwise. */
  public Value copyIfMutable() {
    return this;
  }
}