ASM: a very small and fast Java bytecode manipulation framework
Copyright (c) 2000-2011 INRIA, France Telecom
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/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.objectweb.asm.tree.analysis;

import java.util.List;

import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;

A semantic bytecode interpreter. More precisely, this interpreter only manages the computation of values from other values: it does not manage the transfer of values to or from the stack, and to or from the local variables. This separation allows a generic bytecode Analyzer to work with various semantic interpreters, without needing to duplicate the code to simulate the transfer of values. 
Author:
Eric Bruneton
Type parameters:
<V> – 
           type of the Value used for the analysis./**
 * A semantic bytecode interpreter. More precisely, this interpreter only
 * manages the computation of values from other values: it does not manage the
 * transfer of values to or from the stack, and to or from the local variables.
 * This separation allows a generic bytecode {@link Analyzer} to work with
 * various semantic interpreters, without needing to duplicate the code to
 * simulate the transfer of values.
 * 
 * @param <V>
 *            type of the Value used for the analysis.
 * 
 * @author Eric Bruneton
 */
public abstract class Interpreter<V extends Value> {

    protected final int api;

    protected Interpreter(final int api) {
        this.api = api;
    }

    
Creates a new value that represents the given type.
Called for method parameters (including this), exception
handler variable and with null type for variables reserved
by long and double types.
Params:
type – 
           a primitive or reference type, or null to represent
           an uninitialized value.
Returns:
a value that represents the given type. The size of the returned
        value must be equal to the size of the given type./**
     * Creates a new value that represents the given type.
     * 
     * Called for method parameters (including <code>this</code>), exception
     * handler variable and with <code>null</code> type for variables reserved
     * by long and double types.
     * 
     * @param type
     *            a primitive or reference type, or <tt>null</tt> to represent
     *            an uninitialized value.
     * @return a value that represents the given type. The size of the returned
     *         value must be equal to the size of the given type.
     */
    public abstract V newValue(Type type);

    
Interprets a bytecode instruction without arguments. This method is
called for the following opcodes:
ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4,
ICONST_5, LCONST_0, LCONST_1, FCONST_0, FCONST_1, FCONST_2, DCONST_0,
DCONST_1, BIPUSH, SIPUSH, LDC, JSR, GETSTATIC, NEW
Params:
insn – 
           the bytecode instruction to be interpreted.
Throws:
AnalyzerException – 
            if an error occured during the interpretation.
Returns:
the result of the interpretation of the given instruction./**
     * Interprets a bytecode instruction without arguments. This method is
     * called for the following opcodes:
     * 
     * ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4,
     * ICONST_5, LCONST_0, LCONST_1, FCONST_0, FCONST_1, FCONST_2, DCONST_0,
     * DCONST_1, BIPUSH, SIPUSH, LDC, JSR, GETSTATIC, NEW
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @return the result of the interpretation of the given instruction.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract V newOperation(AbstractInsnNode insn)
            throws AnalyzerException;

    
Interprets a bytecode instruction that moves a value on the stack or to
or from local variables. This method is called for the following opcodes:
ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, LSTORE, FSTORE, DSTORE,
ASTORE, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP
Params:
insn – 
           the bytecode instruction to be interpreted.
value – 
           the value that must be moved by the instruction.
Throws:
AnalyzerException – 
            if an error occured during the interpretation.
Returns:
the result of the interpretation of the given instruction. The
        returned value must be equal to the given value./**
     * Interprets a bytecode instruction that moves a value on the stack or to
     * or from local variables. This method is called for the following opcodes:
     * 
     * ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, LSTORE, FSTORE, DSTORE,
     * ASTORE, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @param value
     *            the value that must be moved by the instruction.
     * @return the result of the interpretation of the given instruction. The
     *         returned value must be <tt>equal</tt> to the given value.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract V copyOperation(AbstractInsnNode insn, V value)
            throws AnalyzerException;

    
Interprets a bytecode instruction with a single argument. This method is
called for the following opcodes:
INEG, LNEG, FNEG, DNEG, IINC, I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L,
F2D, D2I, D2L, D2F, I2B, I2C, I2S, IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE,
TABLESWITCH, LOOKUPSWITCH, IRETURN, LRETURN, FRETURN, DRETURN, ARETURN,
PUTSTATIC, GETFIELD, NEWARRAY, ANEWARRAY, ARRAYLENGTH, ATHROW, CHECKCAST,
INSTANCEOF, MONITORENTER, MONITOREXIT, IFNULL, IFNONNULL
Params:
insn – 
           the bytecode instruction to be interpreted.
value – 
           the argument of the instruction to be interpreted.
Throws:
AnalyzerException – 
            if an error occured during the interpretation.
Returns:
the result of the interpretation of the given instruction./**
     * Interprets a bytecode instruction with a single argument. This method is
     * called for the following opcodes:
     * 
     * INEG, LNEG, FNEG, DNEG, IINC, I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L,
     * F2D, D2I, D2L, D2F, I2B, I2C, I2S, IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE,
     * TABLESWITCH, LOOKUPSWITCH, IRETURN, LRETURN, FRETURN, DRETURN, ARETURN,
     * PUTSTATIC, GETFIELD, NEWARRAY, ANEWARRAY, ARRAYLENGTH, ATHROW, CHECKCAST,
     * INSTANCEOF, MONITORENTER, MONITOREXIT, IFNULL, IFNONNULL
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @param value
     *            the argument of the instruction to be interpreted.
     * @return the result of the interpretation of the given instruction.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract V unaryOperation(AbstractInsnNode insn, V value)
            throws AnalyzerException;

    
Interprets a bytecode instruction with two arguments. This method is
called for the following opcodes:
IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IADD,
LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV,
LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, ISHL, LSHL, ISHR, LSHR, IUSHR,
LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, LCMP, FCMPL, FCMPG, DCMPL,
DCMPG, IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE,
IF_ACMPEQ, IF_ACMPNE, PUTFIELD
Params:
insn – 
           the bytecode instruction to be interpreted.
value1 – 
           the first argument of the instruction to be interpreted.
value2 – 
           the second argument of the instruction to be interpreted.
Throws:
AnalyzerException – 
            if an error occured during the interpretation.
Returns:
the result of the interpretation of the given instruction./**
     * Interprets a bytecode instruction with two arguments. This method is
     * called for the following opcodes:
     * 
     * IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IADD,
     * LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV,
     * LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, ISHL, LSHL, ISHR, LSHR, IUSHR,
     * LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, LCMP, FCMPL, FCMPG, DCMPL,
     * DCMPG, IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE,
     * IF_ACMPEQ, IF_ACMPNE, PUTFIELD
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @param value1
     *            the first argument of the instruction to be interpreted.
     * @param value2
     *            the second argument of the instruction to be interpreted.
     * @return the result of the interpretation of the given instruction.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract V binaryOperation(AbstractInsnNode insn, V value1, V value2)
            throws AnalyzerException;

    
Interprets a bytecode instruction with three arguments. This method is
called for the following opcodes:
IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE, SASTORE
Params:
insn – 
           the bytecode instruction to be interpreted.
value1 – 
           the first argument of the instruction to be interpreted.
value2 – 
           the second argument of the instruction to be interpreted.
value3 – 
           the third argument of the instruction to be interpreted.
Throws:
AnalyzerException – 
            if an error occured during the interpretation.
Returns:
the result of the interpretation of the given instruction./**
     * Interprets a bytecode instruction with three arguments. This method is
     * called for the following opcodes:
     * 
     * IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE, SASTORE
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @param value1
     *            the first argument of the instruction to be interpreted.
     * @param value2
     *            the second argument of the instruction to be interpreted.
     * @param value3
     *            the third argument of the instruction to be interpreted.
     * @return the result of the interpretation of the given instruction.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract V ternaryOperation(AbstractInsnNode insn, V value1,
            V value2, V value3) throws AnalyzerException;

    
Interprets a bytecode instruction with a variable number of arguments.
This method is called for the following opcodes:
INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC, INVOKEINTERFACE,
MULTIANEWARRAY and INVOKEDYNAMIC
Params:
insn – 
           the bytecode instruction to be interpreted.
values – 
           the arguments of the instruction to be interpreted.
Throws:
AnalyzerException – 
            if an error occured during the interpretation.
Returns:
the result of the interpretation of the given instruction./**
     * Interprets a bytecode instruction with a variable number of arguments.
     * This method is called for the following opcodes:
     * 
     * INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC, INVOKEINTERFACE,
     * MULTIANEWARRAY and INVOKEDYNAMIC
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @param values
     *            the arguments of the instruction to be interpreted.
     * @return the result of the interpretation of the given instruction.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract V naryOperation(AbstractInsnNode insn,
            List<? extends V> values) throws AnalyzerException;

    
Interprets a bytecode return instruction. This method is called for the
following opcodes:
IRETURN, LRETURN, FRETURN, DRETURN, ARETURN
Params:
insn – 
           the bytecode instruction to be interpreted.
value – 
           the argument of the instruction to be interpreted.
expected – 
           the expected return type of the analyzed method.
Throws:
AnalyzerException – 
            if an error occured during the interpretation./**
     * Interprets a bytecode return instruction. This method is called for the
     * following opcodes:
     * 
     * IRETURN, LRETURN, FRETURN, DRETURN, ARETURN
     * 
     * @param insn
     *            the bytecode instruction to be interpreted.
     * @param value
     *            the argument of the instruction to be interpreted.
     * @param expected
     *            the expected return type of the analyzed method.
     * @throws AnalyzerException
     *             if an error occured during the interpretation.
     */
    public abstract void returnOperation(AbstractInsnNode insn, V value,
            V expected) throws AnalyzerException;

    
Merges two values. The merge operation must return a value that
represents both values (for instance, if the two values are two types,
the merged value must be a common super type of the two types. If the two
values are integer intervals, the merged value must be an interval that
contains the previous ones. Likewise for other types of values).
Params:
v – 
           a value.
w – 
           another value.
Returns:
the merged value. If the merged value is equal to v,
        this method must return v./**
     * Merges two values. The merge operation must return a value that
     * represents both values (for instance, if the two values are two types,
     * the merged value must be a common super type of the two types. If the two
     * values are integer intervals, the merged value must be an interval that
     * contains the previous ones. Likewise for other types of values).
     * 
     * @param v
     *            a value.
     * @param w
     *            another value.
     * @return the merged value. If the merged value is equal to <tt>v</tt>,
     *         this method <i>must</i> return <tt>v</tt>.
     */
    public abstract V merge(V v, V w);
}