Package org.drools.asm.util

Source Code of org.drools.asm.util.AbstractVisitor

/***
* ASM: a very small and fast Java bytecode manipulation framework
* Copyright (c) 2000-2005 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.drools.asm.util;

import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

import org.drools.asm.Attribute;
import org.drools.asm.util.attrs.ASMStackMapAttribute;
import org.drools.asm.util.attrs.ASMStackMapTableAttribute;
import org.drools.asm.util.attrs.ASMifiable;

/**
* An abstract visitor.
*
* @author Eric Bruneton
*/
public abstract class AbstractVisitor {

    /**
     * The names of the Java Virtual Machine opcodes.
     */
    public final static String[] OPCODES;
    /**
     * Types for <code>operand</code> parameter of the
     * {@link org.drools.asm.MethodVisitor#visitIntInsn} method when
     * <code>opcode</code> is <code>NEWARRAY</code>.
     */
    public final static String[] TYPES;

    static {
        String s = "NOP,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,,,"
                   + "ILOAD,LLOAD,FLOAD,DLOAD,ALOAD,,,,,,,,,,,,,,,,,,,,,IALOAD," + "LALOAD,FALOAD,DALOAD,AALOAD,BALOAD,CALOAD,SALOAD,ISTORE," + "LSTORE,FSTORE,DSTORE,ASTORE,,,,,,,,,,,,,,,,,,,,,IASTORE,"
                   + "LASTORE,FASTORE,DASTORE,AASTORE,BASTORE,CASTORE,SASTORE,POP," + "POP2,DUP,DUP_X1,DUP_X2,DUP2,DUP2_X1,DUP2_X2,SWAP,IADD,LADD," + "FADD,DADD,ISUB,LSUB,FSUB,DSUB,IMUL,LMUL,FMUL,DMUL,IDIV,LDIV,"
                   + "FDIV,DDIV,IREM,LREM,FREM,DREM,INEG,LNEG,FNEG,DNEG,ISHL,LSHL," + "ISHR,LSHR,IUSHR,LUSHR,IAND,LAND,IOR,LOR,IXOR,LXOR,IINC,I2L," + "I2F,I2D,L2I,L2F,L2D,F2I,F2L,F2D,D2I,D2L,D2F,I2B,I2C,I2S,LCMP,"
                   + "FCMPL,FCMPG,DCMPL,DCMPG,IFEQ,IFNE,IFLT,IFGE,IFGT,IFLE," + "IF_ICMPEQ,IF_ICMPNE,IF_ICMPLT,IF_ICMPGE,IF_ICMPGT,IF_ICMPLE," + "IF_ACMPEQ,IF_ACMPNE,GOTO,JSR,RET,TABLESWITCH,LOOKUPSWITCH,"
                   + "IRETURN,LRETURN,FRETURN,DRETURN,ARETURN,RETURN,GETSTATIC," + "PUTSTATIC,GETFIELD,PUTFIELD,INVOKEVIRTUAL,INVOKESPECIAL," + "INVOKESTATIC,INVOKEINTERFACE,,NEW,NEWARRAY,ANEWARRAY,"
                   + "ARRAYLENGTH,ATHROW,CHECKCAST,INSTANCEOF,MONITORENTER," + "MONITOREXIT,,MULTIANEWARRAY,IFNULL,IFNONNULL,";
        OPCODES = new String[200];
        int i = 0;
        int j = 0;
        int l;
        while ( (l = s.indexOf( ',',
                                j )) > 0 ) {
            AbstractVisitor.OPCODES[i++] = j + 1 == l ? null : s.substring( j,
                                                                            l );
            j = l + 1;
        }

        s = "T_BOOLEAN,T_CHAR,T_FLOAT,T_DOUBLE,T_BYTE,T_SHORT,T_INT,T_LONG,";
        TYPES = new String[12];
        j = 0;
        i = 4;
        while ( (l = s.indexOf( ',',
                                j )) > 0 ) {
            AbstractVisitor.TYPES[i++] = s.substring( j,
                                                      l );
            j = l + 1;
        }
    }

    /**
     * The text to be printed. Since the code of methods is not necessarily
     * visited in sequential order, one method after the other, but can be
     * interlaced (some instructions from method one, then some instructions
     * from method two, then some instructions from method one again...), it is
     * not possible to print the visited instructions directly to a sequential
     * stream. A class is therefore printed in a two steps process: a string
     * tree is constructed during the visit, and printed to a sequential stream
     * at the end of the visit. This string tree is stored in this field, as a
     * string list that can contain other string lists, which can themselves
     * contain other string lists, and so on.
     */
    public final List            text;

    /**
     * A buffer that can be used to create strings.
     */
    protected final StringBuffer buf;

    /**
     * Constructs a new {@link AbstractVisitor}.
     */
    protected AbstractVisitor() {
        this.text = new ArrayList();
        this.buf = new StringBuffer();
    }

    /**
     * Returns the text printed by this visitor.
     *
     * @return the text printed by this visitor.
     */
    public List getText() {
        return this.text;
    }

    /**
     * Appends a quoted string to a given buffer.
     *
     * @param buf the buffer where the string must be added.
     * @param s the string to be added.
     */
    public static void appendString(final StringBuffer buf,
                                    final String s) {
        buf.append( "\"" );
        for ( int i = 0; i < s.length(); ++i ) {
            final char c = s.charAt( i );
            if ( c == '\n' ) {
                buf.append( "\\n" );
            } else if ( c == '\r' ) {
                buf.append( "\\r" );
            } else if ( c == '\\' ) {
                buf.append( "\\\\" );
            } else if ( c == '"' ) {
                buf.append( "\\\"" );
            } else if ( c < 0x20 || c > 0x7f ) {
                buf.append( "\\u" );
                if ( c < 0x10 ) {
                    buf.append( "000" );
                } else if ( c < 0x100 ) {
                    buf.append( "00" );
                } else if ( c < 0x1000 ) {
                    buf.append( "0" );
                }
                buf.append( Integer.toString( c,
                                              16 ) );
            } else {
                buf.append( c );
            }
        }
        buf.append( "\"" );
    }

    /**
     * Prints the given string tree.
     *
     * @param pw the writer to be used to print the tree.
     * @param l a string tree, i.e., a string list that can contain other string
     *        lists, and so on recursively.
     */
    void printList(final PrintWriter pw,
                   final List l) {
        for ( int i = 0; i < l.size(); ++i ) {
            final Object o = l.get( i );
            if ( o instanceof List ) {
                printList( pw,
                           (List) o );
            } else {
                pw.print( o.toString() );
            }
        }
    }

    /**
     * Returns the default {@link ASMifiable} prototypes.
     *
     * @return the default {@link ASMifiable} prototypes.
     */
    public static Attribute[] getDefaultAttributes() {
        try {
            return new Attribute[]{new ASMStackMapAttribute(), new ASMStackMapTableAttribute()};
        } catch ( final Exception e ) {
            return new Attribute[0];
        }
    }
}
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