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.
/***
 * 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;

import java.io.IOException;
import java.io.InputStream;

A Java class parser to make a ClassVisitor visit an existing class. This class parses a byte array conforming to the Java class file format and calls the appropriate visit methods of a given class visitor for each field, method and bytecode instruction encountered. 
Author:
Eric Bruneton, Eugene Kuleshov/**
 * A Java class parser to make a {@link ClassVisitor} visit an existing class.
 * This class parses a byte array conforming to the Java class file format and
 * calls the appropriate visit methods of a given class visitor for each field,
 * method and bytecode instruction encountered.
 * 
 * @author Eric Bruneton
 * @author Eugene Kuleshov
 */
public class ClassReader {

    
True to enable signatures support.
/**
     * True to enable signatures support.
     */
    static final boolean SIGNATURES = true;

    
True to enable annotations support.
/**
     * True to enable annotations support.
     */
    static final boolean ANNOTATIONS = true;

    
True to enable stack map frames support.
/**
     * True to enable stack map frames support.
     */
    static final boolean FRAMES = true;

    
True to enable bytecode writing support.
/**
     * True to enable bytecode writing support.
     */
    static final boolean WRITER = true;

    
True to enable JSR_W and GOTO_W support.
/**
     * True to enable JSR_W and GOTO_W support.
     */
    static final boolean RESIZE = true;

    
Flag to skip method code. If this class is set CODE
attribute won't be visited. This can be used, for example, to retrieve
annotations for methods and method parameters.
/**
     * Flag to skip method code. If this class is set <code>CODE</code>
     * attribute won't be visited. This can be used, for example, to retrieve
     * annotations for methods and method parameters.
     */
    public static final int SKIP_CODE = 1;

    
Flag to skip the debug information in the class. If this flag is set the debug information of the class is not visited, i.e. the visitLocalVariable and visitLineNumber methods will not be called. /**
     * Flag to skip the debug information in the class. If this flag is set the
     * debug information of the class is not visited, i.e. the
     * {@link MethodVisitor#visitLocalVariable visitLocalVariable} and
     * {@link MethodVisitor#visitLineNumber visitLineNumber} methods will not be
     * called.
     */
    public static final int SKIP_DEBUG = 2;

    
Flag to skip the stack map frames in the class. If this flag is set the stack map frames of the class is not visited, i.e. the visitFrame method will not be called. This flag is useful when the ClassWriter.COMPUTE_FRAMES option is used: it avoids visiting frames that will be ignored and recomputed from scratch in the class writer. /**
     * Flag to skip the stack map frames in the class. If this flag is set the
     * stack map frames of the class is not visited, i.e. the
     * {@link MethodVisitor#visitFrame visitFrame} method will not be called.
     * This flag is useful when the {@link ClassWriter#COMPUTE_FRAMES} option is
     * used: it avoids visiting frames that will be ignored and recomputed from
     * scratch in the class writer.
     */
    public static final int SKIP_FRAMES = 4;

    
Flag to expand the stack map frames. By default stack map frames are
visited in their original format (i.e. "expanded" for classes whose
version is less than V1_6, and "compressed" for the other classes). If
this flag is set, stack map frames are always visited in expanded format
(this option adds a decompression/recompression step in ClassReader and
ClassWriter which degrades performances quite a lot).
/**
     * Flag to expand the stack map frames. By default stack map frames are
     * visited in their original format (i.e. "expanded" for classes whose
     * version is less than V1_6, and "compressed" for the other classes). If
     * this flag is set, stack map frames are always visited in expanded format
     * (this option adds a decompression/recompression step in ClassReader and
     * ClassWriter which degrades performances quite a lot).
     */
    public static final int EXPAND_FRAMES = 8;

    
The class to be parsed. The content of this array must not be modified. This field is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
/**
     * The class to be parsed. <i>The content of this array must not be
     * modified. This field is intended for {@link Attribute} sub classes, and
     * is normally not needed by class generators or adapters.</i>
     */
    public final byte[] b;

    
The start index of each constant pool item in b, plus one. The one byte offset skips the constant pool item tag that indicates its type. /**
     * The start index of each constant pool item in {@link #b b}, plus one. The
     * one byte offset skips the constant pool item tag that indicates its type.
     */
    private final int[] items;

    
The String objects corresponding to the CONSTANT_Utf8 items. This cache
avoids multiple parsing of a given CONSTANT_Utf8 constant pool item,
which GREATLY improves performances (by a factor 2 to 3). This caching
strategy could be extended to all constant pool items, but its benefit
would not be so great for these items (because they are much less
expensive to parse than CONSTANT_Utf8 items).
/**
     * The String objects corresponding to the CONSTANT_Utf8 items. This cache
     * avoids multiple parsing of a given CONSTANT_Utf8 constant pool item,
     * which GREATLY improves performances (by a factor 2 to 3). This caching
     * strategy could be extended to all constant pool items, but its benefit
     * would not be so great for these items (because they are much less
     * expensive to parse than CONSTANT_Utf8 items).
     */
    private final String[] strings;

    
Maximum length of the strings contained in the constant pool of the
class.
/**
     * Maximum length of the strings contained in the constant pool of the
     * class.
     */
    private final int maxStringLength;

    
Start index of the class header information (access, name...) in b. /**
     * Start index of the class header information (access, name...) in
     * {@link #b b}.
     */
    public final int header;

    // ------------------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------------------

    
Constructs a new ClassReader object. 
Params:
b – 
           the bytecode of the class to be read./**
     * Constructs a new {@link ClassReader} object.
     * 
     * @param b
     *            the bytecode of the class to be read.
     */
    public ClassReader(final byte[] b) {
        this(b, 0, b.length);
    }

    
Constructs a new ClassReader object. 
Params:
b – 
           the bytecode of the class to be read.
off – 
           the start offset of the class data.
len – 
           the length of the class data./**
     * Constructs a new {@link ClassReader} object.
     * 
     * @param b
     *            the bytecode of the class to be read.
     * @param off
     *            the start offset of the class data.
     * @param len
     *            the length of the class data.
     */
    public ClassReader(final byte[] b, final int off, final int len) {
        this.b = b;
        // checks the class version
        if (readShort(off + 6) > Opcodes.V1_7) {
            throw new IllegalArgumentException();
        }
        // parses the constant pool
        items = new int[readUnsignedShort(off + 8)];
        int n = items.length;
        strings = new String[n];
        int max = 0;
        int index = off + 10;
        for (int i = 1; i < n; ++i) {
            items[i] = index + 1;
            int size;
            switch (b[index]) {
            case ClassWriter.FIELD:
            case ClassWriter.METH:
            case ClassWriter.IMETH:
            case ClassWriter.INT:
            case ClassWriter.FLOAT:
            case ClassWriter.NAME_TYPE:
            case ClassWriter.INDY:
                size = 5;
                break;
            case ClassWriter.LONG:
            case ClassWriter.DOUBLE:
                size = 9;
                ++i;
                break;
            case ClassWriter.UTF8:
                size = 3 + readUnsignedShort(index + 1);
                if (size > max) {
                    max = size;
                }
                break;
            case ClassWriter.HANDLE:
                size = 4;
                break;
            // case ClassWriter.CLASS:
            // case ClassWriter.STR:
            // case ClassWriter.MTYPE
            default:
                size = 3;
                break;
            }
            index += size;
        }
        maxStringLength = max;
        // the class header information starts just after the constant pool
        header = index;
    }

    
Returns the class's access flags (see Opcodes). This value may not reflect Deprecated and Synthetic flags when bytecode is before 1.5 and those flags are represented by attributes. 
See Also:
ClassVisitor.visit(int, int, String, String, String, String[])
Returns:
the class access flags/**
     * Returns the class's access flags (see {@link Opcodes}). This value may
     * not reflect Deprecated and Synthetic flags when bytecode is before 1.5
     * and those flags are represented by attributes.
     * 
     * @return the class access flags
     * 
     * @see ClassVisitor#visit(int, int, String, String, String, String[])
     */
    public int getAccess() {
        return readUnsignedShort(header);
    }

    
Returns the internal name of the class (see getInternalName). 
See Also:
ClassVisitor.visit(int, int, String, String, String, String[])
Returns:
the internal class name/**
     * Returns the internal name of the class (see
     * {@link Type#getInternalName() getInternalName}).
     * 
     * @return the internal class name
     * 
     * @see ClassVisitor#visit(int, int, String, String, String, String[])
     */
    public String getClassName() {
        return readClass(header + 2, new char[maxStringLength]);
    }

    
Returns the internal of name of the super class (see getInternalName). For interfaces, the super class is Object. 
See Also:
ClassVisitor.visit(int, int, String, String, String, String[])
Returns:
the internal name of super class, or null for Object class./**
     * Returns the internal of name of the super class (see
     * {@link Type#getInternalName() getInternalName}). For interfaces, the
     * super class is {@link Object}.
     * 
     * @return the internal name of super class, or <tt>null</tt> for
     *         {@link Object} class.
     * 
     * @see ClassVisitor#visit(int, int, String, String, String, String[])
     */
    public String getSuperName() {
        return readClass(header + 4, new char[maxStringLength]);
    }

    
Returns the internal names of the class's interfaces (see getInternalName). 
See Also:
ClassVisitor.visit(int, int, String, String, String, String[])
Returns:
the array of internal names for all implemented interfaces or
        null./**
     * Returns the internal names of the class's interfaces (see
     * {@link Type#getInternalName() getInternalName}).
     * 
     * @return the array of internal names for all implemented interfaces or
     *         <tt>null</tt>.
     * 
     * @see ClassVisitor#visit(int, int, String, String, String, String[])
     */
    public String[] getInterfaces() {
        int index = header + 6;
        int n = readUnsignedShort(index);
        String[] interfaces = new String[n];
        if (n > 0) {
            char[] buf = new char[maxStringLength];
            for (int i = 0; i < n; ++i) {
                index += 2;
                interfaces[i] = readClass(index, buf);
            }
        }
        return interfaces;
    }

    
Copies the constant pool data into the given ClassWriter. Should be called before the accept(ClassVisitor, int) method. 
Params:
classWriter –  the ClassWriter to copy constant pool into./**
     * Copies the constant pool data into the given {@link ClassWriter}. Should
     * be called before the {@link #accept(ClassVisitor,int)} method.
     * 
     * @param classWriter
     *            the {@link ClassWriter} to copy constant pool into.
     */
    void copyPool(final ClassWriter classWriter) {
        char[] buf = new char[maxStringLength];
        int ll = items.length;
        Item[] items2 = new Item[ll];
        for (int i = 1; i < ll; i++) {
            int index = items[i];
            int tag = b[index - 1];
            Item item = new Item(i);
            int nameType;
            switch (tag) {
            case ClassWriter.FIELD:
            case ClassWriter.METH:
            case ClassWriter.IMETH:
                nameType = items[readUnsignedShort(index + 2)];
                item.set(tag, readClass(index, buf), readUTF8(nameType, buf),
                        readUTF8(nameType + 2, buf));
                break;
            case ClassWriter.INT:
                item.set(readInt(index));
                break;
            case ClassWriter.FLOAT:
                item.set(Float.intBitsToFloat(readInt(index)));
                break;
            case ClassWriter.NAME_TYPE:
                item.set(tag, readUTF8(index, buf), readUTF8(index + 2, buf),
                        null);
                break;
            case ClassWriter.LONG:
                item.set(readLong(index));
                ++i;
                break;
            case ClassWriter.DOUBLE:
                item.set(Double.longBitsToDouble(readLong(index)));
                ++i;
                break;
            case ClassWriter.UTF8: {
                String s = strings[i];
                if (s == null) {
                    index = items[i];
                    s = strings[i] = readUTF(index + 2,
                            readUnsignedShort(index), buf);
                }
                item.set(tag, s, null, null);
                break;
            }
            case ClassWriter.HANDLE: {
                int fieldOrMethodRef = items[readUnsignedShort(index + 1)];
                nameType = items[readUnsignedShort(fieldOrMethodRef + 2)];
                item.set(ClassWriter.HANDLE_BASE + readByte(index),
                        readClass(fieldOrMethodRef, buf),
                        readUTF8(nameType, buf), readUTF8(nameType + 2, buf));
                break;
            }
            case ClassWriter.INDY:
                if (classWriter.bootstrapMethods == null) {
                    copyBootstrapMethods(classWriter, items2, buf);
                }
                nameType = items[readUnsignedShort(index + 2)];
                item.set(readUTF8(nameType, buf), readUTF8(nameType + 2, buf),
                        readUnsignedShort(index));
                break;
            // case ClassWriter.STR:
            // case ClassWriter.CLASS:
            // case ClassWriter.MTYPE
            default:
                item.set(tag, readUTF8(index, buf), null, null);
                break;
            }

            int index2 = item.hashCode % items2.length;
            item.next = items2[index2];
            items2[index2] = item;
        }

        int off = items[1] - 1;
        classWriter.pool.putByteArray(b, off, header - off);
        classWriter.items = items2;
        classWriter.threshold = (int) (0.75d * ll);
        classWriter.index = ll;
    }

    
Copies the bootstrap method data into the given ClassWriter. Should be called before the accept(ClassVisitor, int) method. 
Params:
classWriter –  the ClassWriter to copy bootstrap methods into./**
     * Copies the bootstrap method data into the given {@link ClassWriter}.
     * Should be called before the {@link #accept(ClassVisitor,int)} method.
     * 
     * @param classWriter
     *            the {@link ClassWriter} to copy bootstrap methods into.
     */
    private void copyBootstrapMethods(final ClassWriter classWriter,
            final Item[] items, final char[] c) {
        // finds the "BootstrapMethods" attribute
        int u = getAttributes();
        boolean found = false;
        for (int i = readUnsignedShort(u); i > 0; --i) {
            String attrName = readUTF8(u + 2, c);
            if ("BootstrapMethods".equals(attrName)) {
                found = true;
                break;
            }
            u += 6 + readInt(u + 4);
        }
        if (!found) {
            return;
        }
        // copies the bootstrap methods in the class writer
        int boostrapMethodCount = readUnsignedShort(u + 8);
        for (int j = 0, v = u + 10; j < boostrapMethodCount; j++) {
            int position = v - u - 10;
            int hashCode = readConst(readUnsignedShort(v), c).hashCode();
            for (int k = readUnsignedShort(v + 2); k > 0; --k) {
                hashCode ^= readConst(readUnsignedShort(v + 4), c).hashCode();
                v += 2;
            }
            v += 4;
            Item item = new Item(j);
            item.set(position, hashCode & 0x7FFFFFFF);
            int index = item.hashCode % items.length;
            item.next = items[index];
            items[index] = item;
        }
        int attrSize = readInt(u + 4);
        ByteVector bootstrapMethods = new ByteVector(attrSize + 62);
        bootstrapMethods.putByteArray(b, u + 10, attrSize - 2);
        classWriter.bootstrapMethodsCount = boostrapMethodCount;
        classWriter.bootstrapMethods = bootstrapMethods;
    }

    
Constructs a new ClassReader object. 
Params:
is – 
           an input stream from which to read the class.
Throws:
IOException – 
            if a problem occurs during reading./**
     * Constructs a new {@link ClassReader} object.
     * 
     * @param is
     *            an input stream from which to read the class.
     * @throws IOException
     *             if a problem occurs during reading.
     */
    public ClassReader(final InputStream is) throws IOException {
        this(readClass(is, false));
    }

    
Constructs a new ClassReader object. 
Params:
name – 
           the binary qualified name of the class to be read.
Throws:
IOException – 
            if an exception occurs during reading./**
     * Constructs a new {@link ClassReader} object.
     * 
     * @param name
     *            the binary qualified name of the class to be read.
     * @throws IOException
     *             if an exception occurs during reading.
     */
    public ClassReader(final String name) throws IOException {
        this(readClass(
                ClassLoader.getSystemResourceAsStream(name.replace('.', '/')
                        + ".class"), true));
    }

    
Reads the bytecode of a class.
Params:
is – 
           an input stream from which to read the class.
close – 
           true to close the input stream after reading.
Throws:
IOException – 
            if a problem occurs during reading.
Returns:
the bytecode read from the given input stream./**
     * Reads the bytecode of a class.
     * 
     * @param is
     *            an input stream from which to read the class.
     * @param close
     *            true to close the input stream after reading.
     * @return the bytecode read from the given input stream.
     * @throws IOException
     *             if a problem occurs during reading.
     */
    private static byte[] readClass(final InputStream is, boolean close)
            throws IOException {
        if (is == null) {
            throw new IOException("Class not found");
        }
        try {
            byte[] b = new byte[is.available()];
            int len = 0;
            while (true) {
                int n = is.read(b, len, b.length - len);
                if (n == -1) {
                    if (len < b.length) {
                        byte[] c = new byte[len];
                        System.arraycopy(b, 0, c, 0, len);
                        b = c;
                    }
                    return b;
                }
                len += n;
                if (len == b.length) {
                    int last = is.read();
                    if (last < 0) {
                        return b;
                    }
                    byte[] c = new byte[b.length + 1000];
                    System.arraycopy(b, 0, c, 0, len);
                    c[len++] = (byte) last;
                    b = c;
                }
            }
        } finally {
            if (close) {
                is.close();
            }
        }
    }

    // ------------------------------------------------------------------------
    // Public methods
    // ------------------------------------------------------------------------

    
Makes the given visitor visit the Java class of this ClassReader . This class is the one specified in the constructor (see ClassReader). 
Params:
classVisitor – 
           the visitor that must visit this class.
flags –  option flags that can be used to modify the default behavior of this class. See SKIP_DEBUG, EXPAND_FRAMES , SKIP_FRAMES, SKIP_CODE./**
     * Makes the given visitor visit the Java class of this {@link ClassReader}
     * . This class is the one specified in the constructor (see
     * {@link #ClassReader(byte[]) ClassReader}).
     * 
     * @param classVisitor
     *            the visitor that must visit this class.
     * @param flags
     *            option flags that can be used to modify the default behavior
     *            of this class. See {@link #SKIP_DEBUG}, {@link #EXPAND_FRAMES}
     *            , {@link #SKIP_FRAMES}, {@link #SKIP_CODE}.
     */
    public void accept(final ClassVisitor classVisitor, final int flags) {
        accept(classVisitor, new Attribute[0], flags);
    }

    
Makes the given visitor visit the Java class of this ClassReader. This class is the one specified in the constructor (see ClassReader). 
Params:
classVisitor – 
           the visitor that must visit this class.
attrs – 
           prototypes of the attributes that must be parsed during the
           visit of the class. Any attribute whose type is not equal to
           the type of one the prototypes will not be parsed: its byte
           array value will be passed unchanged to the ClassWriter.
           This may corrupt it if this value contains references to
           the constant pool, or has syntactic or semantic links with a
           class element that has been transformed by a class adapter
           between the reader and the writer.
flags –  option flags that can be used to modify the default behavior of this class. See SKIP_DEBUG, EXPAND_FRAMES , SKIP_FRAMES, SKIP_CODE./**
     * Makes the given visitor visit the Java class of this {@link ClassReader}.
     * This class is the one specified in the constructor (see
     * {@link #ClassReader(byte[]) ClassReader}).
     * 
     * @param classVisitor
     *            the visitor that must visit this class.
     * @param attrs
     *            prototypes of the attributes that must be parsed during the
     *            visit of the class. Any attribute whose type is not equal to
     *            the type of one the prototypes will not be parsed: its byte
     *            array value will be passed unchanged to the ClassWriter.
     *            <i>This may corrupt it if this value contains references to
     *            the constant pool, or has syntactic or semantic links with a
     *            class element that has been transformed by a class adapter
     *            between the reader and the writer</i>.
     * @param flags
     *            option flags that can be used to modify the default behavior
     *            of this class. See {@link #SKIP_DEBUG}, {@link #EXPAND_FRAMES}
     *            , {@link #SKIP_FRAMES}, {@link #SKIP_CODE}.
     */
    public void accept(final ClassVisitor classVisitor,
            final Attribute[] attrs, final int flags) {
        int u = header; // current offset in the class file
        char[] c = new char[maxStringLength]; // buffer used to read strings

        Context context = new Context();
        context.attrs = attrs;
        context.flags = flags;
        context.buffer = c;

        // reads the class declaration
        int access = readUnsignedShort(u);
        String name = readClass(u + 2, c);
        String superClass = readClass(u + 4, c);
        String[] interfaces = new String[readUnsignedShort(u + 6)];
        u += 8;
        for (int i = 0; i < interfaces.length; ++i) {
            interfaces[i] = readClass(u, c);
            u += 2;
        }

        // reads the class attributes
        String signature = null;
        String sourceFile = null;
        String sourceDebug = null;
        String enclosingOwner = null;
        String enclosingName = null;
        String enclosingDesc = null;
        int anns = 0;
        int ianns = 0;
        int innerClasses = 0;
        Attribute attributes = null;

        u = getAttributes();
        for (int i = readUnsignedShort(u); i > 0; --i) {
            String attrName = readUTF8(u + 2, c);
            // tests are sorted in decreasing frequency order
            // (based on frequencies observed on typical classes)
            if ("SourceFile".equals(attrName)) {
                sourceFile = readUTF8(u + 8, c);
            } else if ("InnerClasses".equals(attrName)) {
                innerClasses = u + 8;
            } else if ("EnclosingMethod".equals(attrName)) {
                enclosingOwner = readClass(u + 8, c);
                int item = readUnsignedShort(u + 10);
                if (item != 0) {
                    enclosingName = readUTF8(items[item], c);
                    enclosingDesc = readUTF8(items[item] + 2, c);
                }
            } else if (SIGNATURES && "Signature".equals(attrName)) {
                signature = readUTF8(u + 8, c);
            } else if (ANNOTATIONS
                    && "RuntimeVisibleAnnotations".equals(attrName)) {
                anns = u + 8;
            } else if ("Deprecated".equals(attrName)) {
                access |= Opcodes.ACC_DEPRECATED;
            } else if ("Synthetic".equals(attrName)) {
                access |= Opcodes.ACC_SYNTHETIC
                        | ClassWriter.ACC_SYNTHETIC_ATTRIBUTE;
            } else if ("SourceDebugExtension".equals(attrName)) {
                int len = readInt(u + 4);
                sourceDebug = readUTF(u + 8, len, new char[len]);
            } else if (ANNOTATIONS
                    && "RuntimeInvisibleAnnotations".equals(attrName)) {
                ianns = u + 8;
            } else if ("BootstrapMethods".equals(attrName)) {
                int[] bootstrapMethods = new int[readUnsignedShort(u + 8)];
                for (int j = 0, v = u + 10; j < bootstrapMethods.length; j++) {
                    bootstrapMethods[j] = v;
                    v += 2 + readUnsignedShort(v + 2) << 1;
                }
                context.bootstrapMethods = bootstrapMethods;
            } else {
                Attribute attr = readAttribute(attrs, attrName, u + 8,
                        readInt(u + 4), c, -1, null);
                if (attr != null) {
                    attr.next = attributes;
                    attributes = attr;
                }
            }
            u += 6 + readInt(u + 4);
        }

        // visits the class declaration
        classVisitor.visit(readInt(items[1] - 7), access, name, signature,
                superClass, interfaces);

        // visits the source and debug info
        if ((flags & SKIP_DEBUG) == 0
                && (sourceFile != null || sourceDebug != null)) {
            classVisitor.visitSource(sourceFile, sourceDebug);
        }

        // visits the outer class
        if (enclosingOwner != null) {
            classVisitor.visitOuterClass(enclosingOwner, enclosingName,
                    enclosingDesc);
        }

        // visits the class annotations
        if (ANNOTATIONS && anns != 0) {
            for (int i = readUnsignedShort(anns), v = anns + 2; i > 0; --i) {
                v = readAnnotationValues(v + 2, c, true,
                        classVisitor.visitAnnotation(readUTF8(v, c), true));
            }
        }
        if (ANNOTATIONS && ianns != 0) {
            for (int i = readUnsignedShort(ianns), v = ianns + 2; i > 0; --i) {
                v = readAnnotationValues(v + 2, c, true,
                        classVisitor.visitAnnotation(readUTF8(v, c), false));
            }
        }

        // visits the attributes
        while (attributes != null) {
            Attribute attr = attributes.next;
            attributes.next = null;
            classVisitor.visitAttribute(attributes);
            attributes = attr;
        }

        // visits the inner classes
        if (innerClasses != 0) {
            int v = innerClasses + 2;
            for (int i = readUnsignedShort(innerClasses); i > 0; --i) {
                classVisitor.visitInnerClass(readClass(v, c),
                        readClass(v + 2, c), readUTF8(v + 4, c),
                        readUnsignedShort(v + 6));
                v += 8;
            }
        }

        // visits the fields and methods
        u = header + 10 + 2 * interfaces.length;
        for (int i = readUnsignedShort(u - 2); i > 0; --i) {
            u = readField(classVisitor, context, u);
        }
        u += 2;
        for (int i = readUnsignedShort(u - 2); i > 0; --i) {
            u = readMethod(classVisitor, context, u);
        }

        // visits the end of the class
        classVisitor.visitEnd();
    }

    
Reads a field and makes the given visitor visit it.
Params:
classVisitor – 
           the visitor that must visit the field.
context – 
           information about the class being parsed.
u – 
           the start offset of the field in the class file.
Returns:
the offset of the first byte following the field in the class./**
     * Reads a field and makes the given visitor visit it.
     * 
     * @param classVisitor
     *            the visitor that must visit the field.
     * @param context
     *            information about the class being parsed.
     * @param u
     *            the start offset of the field in the class file.
     * @return the offset of the first byte following the field in the class.
     */
    private int readField(final ClassVisitor classVisitor,
            final Context context, int u) {
        // reads the field declaration
        char[] c = context.buffer;
        int access = readUnsignedShort(u);
        String name = readUTF8(u + 2, c);
        String desc = readUTF8(u + 4, c);
        u += 6;

        // reads the field attributes
        String signature = null;
        int anns = 0;
        int ianns = 0;
        Object value = null;
        Attribute attributes = null;

        for (int i = readUnsignedShort(u); i > 0; --i) {
            String attrName = readUTF8(u + 2, c);
            // tests are sorted in decreasing frequency order
            // (based on frequencies observed on typical classes)
            if ("ConstantValue".equals(attrName)) {
                int item = readUnsignedShort(u + 8);
                value = item == 0 ? null : readConst(item, c);
            } else if (SIGNATURES && "Signature".equals(attrName)) {
                signature = readUTF8(u + 8, c);
            } else if ("Deprecated".equals(attrName)) {
                access |= Opcodes.ACC_DEPRECATED;
            } else if ("Synthetic".equals(attrName)) {
                access |= Opcodes.ACC_SYNTHETIC
                        | ClassWriter.ACC_SYNTHETIC_ATTRIBUTE;
            } else if (ANNOTATIONS
                    && "RuntimeVisibleAnnotations".equals(attrName)) {
                anns = u + 8;
            } else if (ANNOTATIONS
                    && "RuntimeInvisibleAnnotations".equals(attrName)) {
                ianns = u + 8;
            } else {
                Attribute attr = readAttribute(context.attrs, attrName, u + 8,
                        readInt(u + 4), c, -1, null);
                if (attr != null) {
                    attr.next = attributes;
                    attributes = attr;
                }
            }
            u += 6 + readInt(u + 4);
        }
        u += 2;

        // visits the field declaration
        FieldVisitor fv = classVisitor.visitField(access, name, desc,
                signature, value);
        if (fv == null) {
            return u;
        }

        // visits the field annotations
        if (ANNOTATIONS && anns != 0) {
            for (int i = readUnsignedShort(anns), v = anns + 2; i > 0; --i) {
                v = readAnnotationValues(v + 2, c, true,
                        fv.visitAnnotation(readUTF8(v, c), true));
            }
        }
        if (ANNOTATIONS && ianns != 0) {
            for (int i = readUnsignedShort(ianns), v = ianns + 2; i > 0; --i) {
                v = readAnnotationValues(v + 2, c, true,
                        fv.visitAnnotation(readUTF8(v, c), false));
            }
        }

        // visits the field attributes
        while (attributes != null) {
            Attribute attr = attributes.next;
            attributes.next = null;
            fv.visitAttribute(attributes);
            attributes = attr;
        }

        // visits the end of the field
        fv.visitEnd();

        return u;
    }

    
Reads a method and makes the given visitor visit it.
Params:
classVisitor – 
           the visitor that must visit the method.
context – 
           information about the class being parsed.
u – 
           the start offset of the method in the class file.
Returns:
the offset of the first byte following the method in the class./**
     * Reads a method and makes the given visitor visit it.
     * 
     * @param classVisitor
     *            the visitor that must visit the method.
     * @param context
     *            information about the class being parsed.
     * @param u
     *            the start offset of the method in the class file.
     * @return the offset of the first byte following the method in the class.
     */
    private int readMethod(final ClassVisitor classVisitor,
            final Context context, int u) {
        // reads the method declaration
        char[] c = context.buffer;
        int access = readUnsignedShort(u);
        String name = readUTF8(u + 2, c);
        String desc = readUTF8(u + 4, c);
        u += 6;

        // reads the method attributes
        int code = 0;
        int exception = 0;
        String[] exceptions = null;
        String signature = null;
        int anns = 0;
        int ianns = 0;
        int dann = 0;
        int mpanns = 0;
        int impanns = 0;
        int firstAttribute = u;
        Attribute attributes = null;

        for (int i = readUnsignedShort(u); i > 0; --i) {
            String attrName = readUTF8(u + 2, c);
            // tests are sorted in decreasing frequency order
            // (based on frequencies observed on typical classes)
            if ("Code".equals(attrName)) {
                if ((context.flags & SKIP_CODE) == 0) {
                    code = u + 8;
                }
            } else if ("Exceptions".equals(attrName)) {
                exceptions = new String[readUnsignedShort(u + 8)];
                exception = u + 10;
                for (int j = 0; j < exceptions.length; ++j) {
                    exceptions[j] = readClass(exception, c);
                    exception += 2;
                }
            } else if (SIGNATURES && "Signature".equals(attrName)) {
                signature = readUTF8(u + 8, c);
            } else if ("Deprecated".equals(attrName)) {
                access |= Opcodes.ACC_DEPRECATED;
            } else if (ANNOTATIONS
                    && "RuntimeVisibleAnnotations".equals(attrName)) {
                anns = u + 8;
            } else if (ANNOTATIONS && "AnnotationDefault".equals(attrName)) {
                dann = u + 8;
            } else if ("Synthetic".equals(attrName)) {
                access |= Opcodes.ACC_SYNTHETIC
                        | ClassWriter.ACC_SYNTHETIC_ATTRIBUTE;
            } else if (ANNOTATIONS
                    && "RuntimeInvisibleAnnotations".equals(attrName)) {
                ianns = u + 8;
            } else if (ANNOTATIONS
                    && "RuntimeVisibleParameterAnnotations".equals(attrName)) {
                mpanns = u + 8;
            } else if (ANNOTATIONS
                    && "RuntimeInvisibleParameterAnnotations".equals(attrName)) {
                impanns = u + 8;
            } else {
                Attribute attr = readAttribute(context.attrs, attrName, u + 8,
                        readInt(u + 4), c, -1, null);
                if (attr != null) {
                    attr.next = attributes;
                    attributes = attr;
                }
            }
            u += 6 + readInt(u + 4);
        }
        u += 2;

        // visits the method declaration
        MethodVisitor mv = classVisitor.visitMethod(access, name, desc,
                signature, exceptions);
        if (mv == null) {
            return u;
        }

        /*
         * if the returned MethodVisitor is in fact a MethodWriter, it means
         * there is no method adapter between the reader and the writer. If, in
         * addition, the writer's constant pool was copied from this reader
         * (mw.cw.cr == this), and the signature and exceptions of the method
         * have not been changed, then it is possible to skip all visit events
         * and just copy the original code of the method to the writer (the
         * access, name and descriptor can have been changed, this is not
         * important since they are not copied as is from the reader).
         */
        if (WRITER && mv instanceof MethodWriter) {
            MethodWriter mw = (MethodWriter) mv;
            if (mw.cw.cr == this && signature == mw.signature) {
                boolean sameExceptions = false;
                if (exceptions == null) {
                    sameExceptions = mw.exceptionCount == 0;
                } else if (exceptions.length == mw.exceptionCount) {
                    sameExceptions = true;
                    for (int j = exceptions.length - 1; j >= 0; --j) {
                        exception -= 2;
                        if (mw.exceptions[j] != readUnsignedShort(exception)) {
                            sameExceptions = false;
                            break;
                        }
                    }
                }
                if (sameExceptions) {
                    /*
                     * we do not copy directly the code into MethodWriter to
                     * save a byte array copy operation. The real copy will be
                     * done in ClassWriter.toByteArray().
                     */
                    mw.classReaderOffset = firstAttribute;
                    mw.classReaderLength = u - firstAttribute;
                    return u;
                }
            }
        }

        // visits the method annotations
        if (ANNOTATIONS && dann != 0) {
            AnnotationVisitor dv = mv.visitAnnotationDefault();
            readAnnotationValue(dann, c, null, dv);
            if (dv != null) {
                dv.visitEnd();
            }
        }
        if (ANNOTATIONS && anns != 0) {
            for (int i = readUnsignedShort(anns), v = anns + 2; i > 0; --i) {
                v = readAnnotationValues(v + 2, c, true,
                        mv.visitAnnotation(readUTF8(v, c), true));
            }
        }
        if (ANNOTATIONS && ianns != 0) {
            for (int i = readUnsignedShort(ianns), v = ianns + 2; i > 0; --i) {
                v = readAnnotationValues(v + 2, c, true,
                        mv.visitAnnotation(readUTF8(v, c), false));
            }
        }
        if (ANNOTATIONS && mpanns != 0) {
            readParameterAnnotations(mpanns, desc, c, true, mv);
        }
        if (ANNOTATIONS && impanns != 0) {
            readParameterAnnotations(impanns, desc, c, false, mv);
        }

        // visits the method attributes
        while (attributes != null) {
            Attribute attr = attributes.next;
            attributes.next = null;
            mv.visitAttribute(attributes);
            attributes = attr;
        }

        // visits the method code
        if (code != 0) {
            context.access = access;
            context.name = name;
            context.desc = desc;
            mv.visitCode();
            readCode(mv, context, code);
        }

        // visits the end of the method
        mv.visitEnd();

        return u;
    }

    
Reads the bytecode of a method and makes the given visitor visit it.
Params:
mv – 
           the visitor that must visit the method's code.
context – 
           information about the class being parsed.
u – 
           the start offset of the code attribute in the class file./**
     * Reads the bytecode of a method and makes the given visitor visit it.
     * 
     * @param mv
     *            the visitor that must visit the method's code.
     * @param context
     *            information about the class being parsed.
     * @param u
     *            the start offset of the code attribute in the class file.
     */
    private void readCode(final MethodVisitor mv, final Context context, int u) {
        // reads the header
        byte[] b = this.b;
        char[] c = context.buffer;
        int maxStack = readUnsignedShort(u);
        int maxLocals = readUnsignedShort(u + 2);
        int codeLength = readInt(u + 4);
        u += 8;

        // reads the bytecode to find the labels
        int codeStart = u;
        int codeEnd = u + codeLength;
        Label[] labels = new Label[codeLength + 2];
        readLabel(codeLength + 1, labels);
        while (u < codeEnd) {
            int offset = u - codeStart;
            int opcode = b[u] & 0xFF;
            switch (ClassWriter.TYPE[opcode]) {
            case ClassWriter.NOARG_INSN:
            case ClassWriter.IMPLVAR_INSN:
                u += 1;
                break;
            case ClassWriter.LABEL_INSN:
                readLabel(offset + readShort(u + 1), labels);
                u += 3;
                break;
            case ClassWriter.LABELW_INSN:
                readLabel(offset + readInt(u + 1), labels);
                u += 5;
                break;
            case ClassWriter.WIDE_INSN:
                opcode = b[u + 1] & 0xFF;
                if (opcode == Opcodes.IINC) {
                    u += 6;
                } else {
                    u += 4;
                }
                break;
            case ClassWriter.TABL_INSN:
                // skips 0 to 3 padding bytes
                u = u + 4 - (offset & 3);
                // reads instruction
                readLabel(offset + readInt(u), labels);
                for (int i = readInt(u + 8) - readInt(u + 4) + 1; i > 0; --i) {
                    readLabel(offset + readInt(u + 12), labels);
                    u += 4;
                }
                u += 12;
                break;
            case ClassWriter.LOOK_INSN:
                // skips 0 to 3 padding bytes
                u = u + 4 - (offset & 3);
                // reads instruction
                readLabel(offset + readInt(u), labels);
                for (int i = readInt(u + 4); i > 0; --i) {
                    readLabel(offset + readInt(u + 12), labels);
                    u += 8;
                }
                u += 8;
                break;
            case ClassWriter.VAR_INSN:
            case ClassWriter.SBYTE_INSN:
            case ClassWriter.LDC_INSN:
                u += 2;
                break;
            case ClassWriter.SHORT_INSN:
            case ClassWriter.LDCW_INSN:
            case ClassWriter.FIELDORMETH_INSN:
            case ClassWriter.TYPE_INSN:
            case ClassWriter.IINC_INSN:
                u += 3;
                break;
            case ClassWriter.ITFMETH_INSN:
            case ClassWriter.INDYMETH_INSN:
                u += 5;
                break;
            // case MANA_INSN:
            default:
                u += 4;
                break;
            }
        }

        // reads the try catch entries to find the labels, and also visits them
        for (int i = readUnsignedShort(u); i > 0; --i) {
            Label start = readLabel(readUnsignedShort(u + 2), labels);
            Label end = readLabel(readUnsignedShort(u + 4), labels);
            Label handler = readLabel(readUnsignedShort(u + 6), labels);
            String type = readUTF8(items[readUnsignedShort(u + 8)], c);
            mv.visitTryCatchBlock(start, end, handler, type);
            u += 8;
        }
        u += 2;

        // reads the code attributes
        int varTable = 0;
        int varTypeTable = 0;
        boolean zip = true;
        boolean unzip = (context.flags & EXPAND_FRAMES) != 0;
        int stackMap = 0;
        int stackMapSize = 0;
        int frameCount = 0;
        Context frame = null;
        Attribute attributes = null;

        for (int i = readUnsignedShort(u); i > 0; --i) {
            String attrName = readUTF8(u + 2, c);
            if ("LocalVariableTable".equals(attrName)) {
                if ((context.flags & SKIP_DEBUG) == 0) {
                    varTable = u + 8;
                    for (int j = readUnsignedShort(u + 8), v = u; j > 0; --j) {
                        int label = readUnsignedShort(v + 10);
                        if (labels[label] == null) {
                            readLabel(label, labels).status |= Label.DEBUG;
                        }
                        label += readUnsignedShort(v + 12);
                        if (labels[label] == null) {
                            readLabel(label, labels).status |= Label.DEBUG;
                        }
                        v += 10;
                    }
                }
            } else if ("LocalVariableTypeTable".equals(attrName)) {
                varTypeTable = u + 8;
            } else if ("LineNumberTable".equals(attrName)) {
                if ((context.flags & SKIP_DEBUG) == 0) {
                    for (int j = readUnsignedShort(u + 8), v = u; j > 0; --j) {
                        int label = readUnsignedShort(v + 10);
                        if (labels[label] == null) {
                            readLabel(label, labels).status |= Label.DEBUG;
                        }
                        labels[label].line = readUnsignedShort(v + 12);
                        v += 4;
                    }
                }
            } else if (FRAMES && "StackMapTable".equals(attrName)) {
                if ((context.flags & SKIP_FRAMES) == 0) {
                    stackMap = u + 10;
                    stackMapSize = readInt(u + 4);
                    frameCount = readUnsignedShort(u + 8);
                }
                /*
                 * here we do not extract the labels corresponding to the
                 * attribute content. This would require a full parsing of the
                 * attribute, which would need to be repeated in the second
                 * phase (see below). Instead the content of the attribute is
                 * read one frame at a time (i.e. after a frame has been
                 * visited, the next frame is read), and the labels it contains
                 * are also extracted one frame at a time. Thanks to the
                 * ordering of frames, having only a "one frame lookahead" is
                 * not a problem, i.e. it is not possible to see an offset
                 * smaller than the offset of the current insn and for which no
                 * Label exist.
                 */
                /*
                 * This is not true for UNINITIALIZED type offsets. We solve
                 * this by parsing the stack map table without a full decoding
                 * (see below).
                 */
            } else if (FRAMES && "StackMap".equals(attrName)) {
                if ((context.flags & SKIP_FRAMES) == 0) {
                    zip = false;
                    stackMap = u + 10;
                    stackMapSize = readInt(u + 4);
                    frameCount = readUnsignedShort(u + 8);
                }
                /*
                 * IMPORTANT! here we assume that the frames are ordered, as in
                 * the StackMapTable attribute, although this is not guaranteed
                 * by the attribute format.
                 */
            } else {
                for (int j = 0; j < context.attrs.length; ++j) {
                    if (context.attrs[j].type.equals(attrName)) {
                        Attribute attr = context.attrs[j].read(this, u + 8,
                                readInt(u + 4), c, codeStart - 8, labels);
                        if (attr != null) {
                            attr.next = attributes;
                            attributes = attr;
                        }
                    }
                }
            }
            u += 6 + readInt(u + 4);
        }
        u += 2;

        // generates the first (implicit) stack map frame
        if (FRAMES && stackMap != 0) {
            /*
             * for the first explicit frame the offset is not offset_delta + 1
             * but only offset_delta; setting the implicit frame offset to -1
             * allow the use of the "offset_delta + 1" rule in all cases
             */
            frame = context;
            frame.offset = -1;
            frame.mode = 0;
            frame.localCount = 0;
            frame.localDiff = 0;
            frame.stackCount = 0;
            frame.local = new Object[maxLocals];
            frame.stack = new Object[maxStack];
            if (unzip) {
                getImplicitFrame(context);
            }
            /*
             * Finds labels for UNINITIALIZED frame types. Instead of decoding
             * each element of the stack map table, we look for 3 consecutive
             * bytes that "look like" an UNINITIALIZED type (tag 8, offset
             * within code bounds, NEW instruction at this offset). We may find
             * false positives (i.e. not real UNINITIALIZED types), but this
             * should be rare, and the only consequence will be the creation of
             * an unneeded label. This is better than creating a label for each
             * NEW instruction, and faster than fully decoding the whole stack
             * map table.
             */
            for (int i = stackMap; i < stackMap + stackMapSize - 2; ++i) {
                if (b[i] == 8) { // UNINITIALIZED FRAME TYPE
                    int v = readUnsignedShort(i + 1);
                    if (v >= 0 && v < codeLength) {
                        if ((b[codeStart + v] & 0xFF) == Opcodes.NEW) {
                            readLabel(v, labels);
                        }
                    }
                }
            }
        }

        // visits the instructions
        u = codeStart;
        while (u < codeEnd) {
            int offset = u - codeStart;

            // visits the label and line number for this offset, if any
            Label l = labels[offset];
            if (l != null) {
                mv.visitLabel(l);
                if ((context.flags & SKIP_DEBUG) == 0 && l.line > 0) {
                    mv.visitLineNumber(l.line, l);
                }
            }

            // visits the frame for this offset, if any
            while (FRAMES && frame != null
                    && (frame.offset == offset || frame.offset == -1)) {
                // if there is a frame for this offset, makes the visitor visit
                // it, and reads the next frame if there is one.
                if (frame.offset != -1) {
                    if (!zip || unzip) {
                        mv.visitFrame(Opcodes.F_NEW, frame.localCount,
                                frame.local, frame.stackCount, frame.stack);
                    } else {
                        mv.visitFrame(frame.mode, frame.localDiff, frame.local,
                                frame.stackCount, frame.stack);
                    }
                }
                if (frameCount > 0) {
                    stackMap = readFrame(stackMap, zip, unzip, labels, frame);
                    --frameCount;
                } else {
                    frame = null;
                }
            }

            // visits the instruction at this offset
            int opcode = b[u] & 0xFF;
            switch (ClassWriter.TYPE[opcode]) {
            case ClassWriter.NOARG_INSN:
                mv.visitInsn(opcode);
                u += 1;
                break;
            case ClassWriter.IMPLVAR_INSN:
                if (opcode > Opcodes.ISTORE) {
                    opcode -= 59; // ISTORE_0
                    mv.visitVarInsn(Opcodes.ISTORE + (opcode >> 2),
                            opcode & 0x3);
                } else {
                    opcode -= 26; // ILOAD_0
                    mv.visitVarInsn(Opcodes.ILOAD + (opcode >> 2), opcode & 0x3);
                }
                u += 1;
                break;
            case ClassWriter.LABEL_INSN:
                mv.visitJumpInsn(opcode, labels[offset + readShort(u + 1)]);
                u += 3;
                break;
            case ClassWriter.LABELW_INSN:
                mv.visitJumpInsn(opcode - 33, labels[offset + readInt(u + 1)]);
                u += 5;
                break;
            case ClassWriter.WIDE_INSN:
                opcode = b[u + 1] & 0xFF;
                if (opcode == Opcodes.IINC) {
                    mv.visitIincInsn(readUnsignedShort(u + 2), readShort(u + 4));
                    u += 6;
                } else {
                    mv.visitVarInsn(opcode, readUnsignedShort(u + 2));
                    u += 4;
                }
                break;
            case ClassWriter.TABL_INSN: {
                // skips 0 to 3 padding bytes
                u = u + 4 - (offset & 3);
                // reads instruction
                int label = offset + readInt(u);
                int min = readInt(u + 4);
                int max = readInt(u + 8);
                Label[] table = new Label[max - min + 1];
                u += 12;
                for (int i = 0; i < table.length; ++i) {
                    table[i] = labels[offset + readInt(u)];
                    u += 4;
                }
                mv.visitTableSwitchInsn(min, max, labels[label], table);
                break;
            }
            case ClassWriter.LOOK_INSN: {
                // skips 0 to 3 padding bytes
                u = u + 4 - (offset & 3);
                // reads instruction
                int label = offset + readInt(u);
                int len = readInt(u + 4);
                int[] keys = new int[len];
                Label[] values = new Label[len];
                u += 8;
                for (int i = 0; i < len; ++i) {
                    keys[i] = readInt(u);
                    values[i] = labels[offset + readInt(u + 4)];
                    u += 8;
                }
                mv.visitLookupSwitchInsn(labels[label], keys, values);
                break;
            }
            case ClassWriter.VAR_INSN:
                mv.visitVarInsn(opcode, b[u + 1] & 0xFF);
                u += 2;
                break;
            case ClassWriter.SBYTE_INSN:
                mv.visitIntInsn(opcode, b[u + 1]);
                u += 2;
                break;
            case ClassWriter.SHORT_INSN:
                mv.visitIntInsn(opcode, readShort(u + 1));
                u += 3;
                break;
            case ClassWriter.LDC_INSN:
                mv.visitLdcInsn(readConst(b[u + 1] & 0xFF, c));
                u += 2;
                break;
            case ClassWriter.LDCW_INSN:
                mv.visitLdcInsn(readConst(readUnsignedShort(u + 1), c));
                u += 3;
                break;
            case ClassWriter.FIELDORMETH_INSN:
            case ClassWriter.ITFMETH_INSN: {
                int cpIndex = items[readUnsignedShort(u + 1)];
                String iowner = readClass(cpIndex, c);
                cpIndex = items[readUnsignedShort(cpIndex + 2)];
                String iname = readUTF8(cpIndex, c);
                String idesc = readUTF8(cpIndex + 2, c);
                if (opcode < Opcodes.INVOKEVIRTUAL) {
                    mv.visitFieldInsn(opcode, iowner, iname, idesc);
                } else {
                    mv.visitMethodInsn(opcode, iowner, iname, idesc);
                }
                if (opcode == Opcodes.INVOKEINTERFACE) {
                    u += 5;
                } else {
                    u += 3;
                }
                break;
            }
            case ClassWriter.INDYMETH_INSN: {
                int cpIndex = items[readUnsignedShort(u + 1)];
                int bsmIndex = context.bootstrapMethods[readUnsignedShort(cpIndex)];
                Handle bsm = (Handle) readConst(readUnsignedShort(bsmIndex), c);
                int bsmArgCount = readUnsignedShort(bsmIndex + 2);
                Object[] bsmArgs = new Object[bsmArgCount];
                bsmIndex += 4;
                for (int i = 0; i < bsmArgCount; i++) {
                    bsmArgs[i] = readConst(readUnsignedShort(bsmIndex), c);
                    bsmIndex += 2;
                }
                cpIndex = items[readUnsignedShort(cpIndex + 2)];
                String iname = readUTF8(cpIndex, c);
                String idesc = readUTF8(cpIndex + 2, c);
                mv.visitInvokeDynamicInsn(iname, idesc, bsm, bsmArgs);
                u += 5;
                break;
            }
            case ClassWriter.TYPE_INSN:
                mv.visitTypeInsn(opcode, readClass(u + 1, c));
                u += 3;
                break;
            case ClassWriter.IINC_INSN:
                mv.visitIincInsn(b[u + 1] & 0xFF, b[u + 2]);
                u += 3;
                break;
            // case MANA_INSN:
            default:
                mv.visitMultiANewArrayInsn(readClass(u + 1, c), b[u + 3] & 0xFF);
                u += 4;
                break;
            }
        }
        if (labels[codeLength] != null) {
            mv.visitLabel(labels[codeLength]);
        }

        // visits the local variable tables
        if ((context.flags & SKIP_DEBUG) == 0 && varTable != 0) {
            int[] typeTable = null;
            if (varTypeTable != 0) {
                u = varTypeTable + 2;
                typeTable = new int[readUnsignedShort(varTypeTable) * 3];
                for (int i = typeTable.length; i > 0;) {
                    typeTable[--i] = u + 6; // signature
                    typeTable[--i] = readUnsignedShort(u + 8); // index
                    typeTable[--i] = readUnsignedShort(u); // start
                    u += 10;
                }
            }
            u = varTable + 2;
            for (int i = readUnsignedShort(varTable); i > 0; --i) {
                int start = readUnsignedShort(u);
                int length = readUnsignedShort(u + 2);
                int index = readUnsignedShort(u + 8);
                String vsignature = null;
                if (typeTable != null) {
                    for (int j = 0; j < typeTable.length; j += 3) {
                        if (typeTable[j] == start && typeTable[j + 1] == index) {
                            vsignature = readUTF8(typeTable[j + 2], c);
                            break;
                        }
                    }
                }
                mv.visitLocalVariable(readUTF8(u + 4, c), readUTF8(u + 6, c),
                        vsignature, labels[start], labels[start + length],
                        index);
                u += 10;
            }
        }

        // visits the code attributes
        while (attributes != null) {
            Attribute attr = attributes.next;
            attributes.next = null;
            mv.visitAttribute(attributes);
            attributes = attr;
        }

        // visits the max stack and max locals values
        mv.visitMaxs(maxStack, maxLocals);
    }

    
Reads parameter annotations and makes the given visitor visit them.
Params:
v –  start offset in b of the annotations to be read.
desc – 
           the method descriptor.
buf –  buffer to be used to call readUTF8, readClass or 
           readConst.
visible – 
           true if the annotations to be read are visible at
           runtime.
mv – 
           the visitor that must visit the annotations./**
     * Reads parameter annotations and makes the given visitor visit them.
     * 
     * @param v
     *            start offset in {@link #b b} of the annotations to be read.
     * @param desc
     *            the method descriptor.
     * @param buf
     *            buffer to be used to call {@link #readUTF8 readUTF8},
     *            {@link #readClass(int,char[]) readClass} or {@link #readConst
     *            readConst}.
     * @param visible
     *            <tt>true</tt> if the annotations to be read are visible at
     *            runtime.
     * @param mv
     *            the visitor that must visit the annotations.
     */
    private void readParameterAnnotations(int v, final String desc,
            final char[] buf, final boolean visible, final MethodVisitor mv) {
        int i;
        int n = b[v++] & 0xFF;
        // workaround for a bug in javac (javac compiler generates a parameter
        // annotation array whose size is equal to the number of parameters in
        // the Java source file, while it should generate an array whose size is
        // equal to the number of parameters in the method descriptor - which
        // includes the synthetic parameters added by the compiler). This work-
        // around supposes that the synthetic parameters are the first ones.
        int synthetics = Type.getArgumentTypes(desc).length - n;
        AnnotationVisitor av;
        for (i = 0; i < synthetics; ++i) {
            // virtual annotation to detect synthetic parameters in MethodWriter
            av = mv.visitParameterAnnotation(i, "Ljava/lang/Synthetic;", false);
            if (av != null) {
                av.visitEnd();
            }
        }
        for (; i < n + synthetics; ++i) {
            int j = readUnsignedShort(v);
            v += 2;
            for (; j > 0; --j) {
                av = mv.visitParameterAnnotation(i, readUTF8(v, buf), visible);
                v = readAnnotationValues(v + 2, buf, true, av);
            }
        }
    }

    
Reads the values of an annotation and makes the given visitor visit them.
Params:
v –  the start offset in b of the values to be read (including the unsigned short that gives the number of values).
buf –  buffer to be used to call readUTF8, readClass or 
           readConst.
named – 
           if the annotation values are named or not.
av – 
           the visitor that must visit the values.
Returns:
the end offset of the annotation values./**
     * Reads the values of an annotation and makes the given visitor visit them.
     * 
     * @param v
     *            the start offset in {@link #b b} of the values to be read
     *            (including the unsigned short that gives the number of
     *            values).
     * @param buf
     *            buffer to be used to call {@link #readUTF8 readUTF8},
     *            {@link #readClass(int,char[]) readClass} or {@link #readConst
     *            readConst}.
     * @param named
     *            if the annotation values are named or not.
     * @param av
     *            the visitor that must visit the values.
     * @return the end offset of the annotation values.
     */
    private int readAnnotationValues(int v, final char[] buf,
            final boolean named, final AnnotationVisitor av) {
        int i = readUnsignedShort(v);
        v += 2;
        if (named) {
            for (; i > 0; --i) {
                v = readAnnotationValue(v + 2, buf, readUTF8(v, buf), av);
            }
        } else {
            for (; i > 0; --i) {
                v = readAnnotationValue(v, buf, null, av);
            }
        }
        if (av != null) {
            av.visitEnd();
        }
        return v;
    }

    
Reads a value of an annotation and makes the given visitor visit it.
Params:
v –  the start offset in b of the value to be read (not including the value name constant pool index).
buf –  buffer to be used to call readUTF8, readClass or 
           readConst.
name – 
           the name of the value to be read.
av – 
           the visitor that must visit the value.
Returns:
the end offset of the annotation value./**
     * Reads a value of an annotation and makes the given visitor visit it.
     * 
     * @param v
     *            the start offset in {@link #b b} of the value to be read
     *            (<i>not including the value name constant pool index</i>).
     * @param buf
     *            buffer to be used to call {@link #readUTF8 readUTF8},
     *            {@link #readClass(int,char[]) readClass} or {@link #readConst
     *            readConst}.
     * @param name
     *            the name of the value to be read.
     * @param av
     *            the visitor that must visit the value.
     * @return the end offset of the annotation value.
     */
    private int readAnnotationValue(int v, final char[] buf, final String name,
            final AnnotationVisitor av) {
        int i;
        if (av == null) {
            switch (b[v] & 0xFF) {
            case 'e': // enum_const_value
                return v + 5;
            case '@': // annotation_value
                return readAnnotationValues(v + 3, buf, true, null);
            case '[': // array_value
                return readAnnotationValues(v + 1, buf, false, null);
            default:
                return v + 3;
            }
        }
        switch (b[v++] & 0xFF) {
        case 'I': // pointer to CONSTANT_Integer
        case 'J': // pointer to CONSTANT_Long
        case 'F': // pointer to CONSTANT_Float
        case 'D': // pointer to CONSTANT_Double
            av.visit(name, readConst(readUnsignedShort(v), buf));
            v += 2;
            break;
        case 'B': // pointer to CONSTANT_Byte
            av.visit(name,
                    new Byte((byte) readInt(items[readUnsignedShort(v)])));
            v += 2;
            break;
        case 'Z': // pointer to CONSTANT_Boolean
            av.visit(name,
                    readInt(items[readUnsignedShort(v)]) == 0 ? Boolean.FALSE
                            : Boolean.TRUE);
            v += 2;
            break;
        case 'S': // pointer to CONSTANT_Short
            av.visit(name, new Short(
                    (short) readInt(items[readUnsignedShort(v)])));
            v += 2;
            break;
        case 'C': // pointer to CONSTANT_Char
            av.visit(name, new Character(
                    (char) readInt(items[readUnsignedShort(v)])));
            v += 2;
            break;
        case 's': // pointer to CONSTANT_Utf8
            av.visit(name, readUTF8(v, buf));
            v += 2;
            break;
        case 'e': // enum_const_value
            av.visitEnum(name, readUTF8(v, buf), readUTF8(v + 2, buf));
            v += 4;
            break;
        case 'c': // class_info
            av.visit(name, Type.getType(readUTF8(v, buf)));
            v += 2;
            break;
        case '@': // annotation_value
            v = readAnnotationValues(v + 2, buf, true,
                    av.visitAnnotation(name, readUTF8(v, buf)));
            break;
        case '[': // array_value
            int size = readUnsignedShort(v);
            v += 2;
            if (size == 0) {
                return readAnnotationValues(v - 2, buf, false,
                        av.visitArray(name));
            }
            switch (this.b[v++] & 0xFF) {
            case 'B':
                byte[] bv = new byte[size];
                for (i = 0; i < size; i++) {
                    bv[i] = (byte) readInt(items[readUnsignedShort(v)]);
                    v += 3;
                }
                av.visit(name, bv);
                --v;
                break;
            case 'Z':
                boolean[] zv = new boolean[size];
                for (i = 0; i < size; i++) {
                    zv[i] = readInt(items[readUnsignedShort(v)]) != 0;
                    v += 3;
                }
                av.visit(name, zv);
                --v;
                break;
            case 'S':
                short[] sv = new short[size];
                for (i = 0; i < size; i++) {
                    sv[i] = (short) readInt(items[readUnsignedShort(v)]);
                    v += 3;
                }
                av.visit(name, sv);
                --v;
                break;
            case 'C':
                char[] cv = new char[size];
                for (i = 0; i < size; i++) {
                    cv[i] = (char) readInt(items[readUnsignedShort(v)]);
                    v += 3;
                }
                av.visit(name, cv);
                --v;
                break;
            case 'I':
                int[] iv = new int[size];
                for (i = 0; i < size; i++) {
                    iv[i] = readInt(items[readUnsignedShort(v)]);
                    v += 3;
                }
                av.visit(name, iv);
                --v;
                break;
            case 'J':
                long[] lv = new long[size];
                for (i = 0; i < size; i++) {
                    lv[i] = readLong(items[readUnsignedShort(v)]);
                    v += 3;
                }
                av.visit(name, lv);
                --v;
                break;
            case 'F':
                float[] fv = new float[size];
                for (i = 0; i < size; i++) {
                    fv[i] = Float
                            .intBitsToFloat(readInt(items[readUnsignedShort(v)]));
                    v += 3;
                }
                av.visit(name, fv);
                --v;
                break;
            case 'D':
                double[] dv = new double[size];
                for (i = 0; i < size; i++) {
                    dv[i] = Double
                            .longBitsToDouble(readLong(items[readUnsignedShort(v)]));
                    v += 3;
                }
                av.visit(name, dv);
                --v;
                break;
            default:
                v = readAnnotationValues(v - 3, buf, false, av.visitArray(name));
            }
        }
        return v;
    }

    
Computes the implicit frame of the method currently being parsed (as defined in the given Context) and stores it in the given context. 
Params:
frame – 
           information about the class being parsed./**
     * Computes the implicit frame of the method currently being parsed (as
     * defined in the given {@link Context}) and stores it in the given context.
     * 
     * @param frame
     *            information about the class being parsed.
     */
    private void getImplicitFrame(final Context frame) {
        String desc = frame.desc;
        Object[] locals = frame.local;
        int local = 0;
        if ((frame.access & Opcodes.ACC_STATIC) == 0) {
            if ("<init>".equals(frame.name)) {
                locals[local++] = Opcodes.UNINITIALIZED_THIS;
            } else {
                locals[local++] = readClass(header + 2, frame.buffer);
            }
        }
        int i = 1;
        loop: while (true) {
            int j = i;
            switch (desc.charAt(i++)) {
            case 'Z':
            case 'C':
            case 'B':
            case 'S':
            case 'I':
                locals[local++] = Opcodes.INTEGER;
                break;
            case 'F':
                locals[local++] = Opcodes.FLOAT;
                break;
            case 'J':
                locals[local++] = Opcodes.LONG;
                break;
            case 'D':
                locals[local++] = Opcodes.DOUBLE;
                break;
            case '[':
                while (desc.charAt(i) == '[') {
                    ++i;
                }
                if (desc.charAt(i) == 'L') {
                    ++i;
                    while (desc.charAt(i) != ';') {
                        ++i;
                    }
                }
                locals[local++] = desc.substring(j, ++i);
                break;
            case 'L':
                while (desc.charAt(i) != ';') {
                    ++i;
                }
                locals[local++] = desc.substring(j + 1, i++);
                break;
            default:
                break loop;
            }
        }
        frame.localCount = local;
    }

    
Reads a stack map frame and stores the result in the given Context object. 
Params:
stackMap – 
           the start offset of a stack map frame in the class file.
zip – 
           if the stack map frame at stackMap is compressed or not.
unzip – 
           if the stack map frame must be uncompressed.
labels – 
           the labels of the method currently being parsed, indexed by
           their offset. A new label for the parsed stack map frame is
           stored in this array if it does not already exist.
frame – 
           where the parsed stack map frame must be stored.
Returns:
the offset of the first byte following the parsed frame./**
     * Reads a stack map frame and stores the result in the given
     * {@link Context} object.
     * 
     * @param stackMap
     *            the start offset of a stack map frame in the class file.
     * @param zip
     *            if the stack map frame at stackMap is compressed or not.
     * @param unzip
     *            if the stack map frame must be uncompressed.
     * @param labels
     *            the labels of the method currently being parsed, indexed by
     *            their offset. A new label for the parsed stack map frame is
     *            stored in this array if it does not already exist.
     * @param frame
     *            where the parsed stack map frame must be stored.
     * @return the offset of the first byte following the parsed frame.
     */
    private int readFrame(int stackMap, boolean zip, boolean unzip,
            Label[] labels, Context frame) {
        char[] c = frame.buffer;
        int tag;
        int delta;
        if (zip) {
            tag = b[stackMap++] & 0xFF;
        } else {
            tag = MethodWriter.FULL_FRAME;
            frame.offset = -1;
        }
        frame.localDiff = 0;
        if (tag < MethodWriter.SAME_LOCALS_1_STACK_ITEM_FRAME) {
            delta = tag;
            frame.mode = Opcodes.F_SAME;
            frame.stackCount = 0;
        } else if (tag < MethodWriter.RESERVED) {
            delta = tag - MethodWriter.SAME_LOCALS_1_STACK_ITEM_FRAME;
            stackMap = readFrameType(frame.stack, 0, stackMap, c, labels);
            frame.mode = Opcodes.F_SAME1;
            frame.stackCount = 1;
        } else {
            delta = readUnsignedShort(stackMap);
            stackMap += 2;
            if (tag == MethodWriter.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
                stackMap = readFrameType(frame.stack, 0, stackMap, c, labels);
                frame.mode = Opcodes.F_SAME1;
                frame.stackCount = 1;
            } else if (tag >= MethodWriter.CHOP_FRAME
                    && tag < MethodWriter.SAME_FRAME_EXTENDED) {
                frame.mode = Opcodes.F_CHOP;
                frame.localDiff = MethodWriter.SAME_FRAME_EXTENDED - tag;
                frame.localCount -= frame.localDiff;
                frame.stackCount = 0;
            } else if (tag == MethodWriter.SAME_FRAME_EXTENDED) {
                frame.mode = Opcodes.F_SAME;
                frame.stackCount = 0;
            } else if (tag < MethodWriter.FULL_FRAME) {
                int local = unzip ? frame.localCount : 0;
                for (int i = tag - MethodWriter.SAME_FRAME_EXTENDED; i > 0; i--) {
                    stackMap = readFrameType(frame.local, local++, stackMap, c,
                            labels);
                }
                frame.mode = Opcodes.F_APPEND;
                frame.localDiff = tag - MethodWriter.SAME_FRAME_EXTENDED;
                frame.localCount += frame.localDiff;
                frame.stackCount = 0;
            } else { // if (tag == FULL_FRAME) {
                frame.mode = Opcodes.F_FULL;
                int n = readUnsignedShort(stackMap);
                stackMap += 2;
                frame.localDiff = n;
                frame.localCount = n;
                for (int local = 0; n > 0; n--) {
                    stackMap = readFrameType(frame.local, local++, stackMap, c,
                            labels);
                }
                n = readUnsignedShort(stackMap);
                stackMap += 2;
                frame.stackCount = n;
                for (int stack = 0; n > 0; n--) {
                    stackMap = readFrameType(frame.stack, stack++, stackMap, c,
                            labels);
                }
            }
        }
        frame.offset += delta + 1;
        readLabel(frame.offset, labels);
        return stackMap;
    }

    
Reads a stack map frame type and stores it at the given index in the
given array.
Params:
frame – 
           the array where the parsed type must be stored.
index – 
           the index in 'frame' where the parsed type must be stored.
v – 
           the start offset of the stack map frame type to read.
buf – 
           a buffer to read strings.
labels – 
           the labels of the method currently being parsed, indexed by
           their offset. If the parsed type is an Uninitialized type, a
           new label for the corresponding NEW instruction is stored in
           this array if it does not already exist.
Returns:
the offset of the first byte after the parsed type./**
     * Reads a stack map frame type and stores it at the given index in the
     * given array.
     * 
     * @param frame
     *            the array where the parsed type must be stored.
     * @param index
     *            the index in 'frame' where the parsed type must be stored.
     * @param v
     *            the start offset of the stack map frame type to read.
     * @param buf
     *            a buffer to read strings.
     * @param labels
     *            the labels of the method currently being parsed, indexed by
     *            their offset. If the parsed type is an Uninitialized type, a
     *            new label for the corresponding NEW instruction is stored in
     *            this array if it does not already exist.
     * @return the offset of the first byte after the parsed type.
     */
    private int readFrameType(final Object[] frame, final int index, int v,
            final char[] buf, final Label[] labels) {
        int type = b[v++] & 0xFF;
        switch (type) {
        case 0:
            frame[index] = Opcodes.TOP;
            break;
        case 1:
            frame[index] = Opcodes.INTEGER;
            break;
        case 2:
            frame[index] = Opcodes.FLOAT;
            break;
        case 3:
            frame[index] = Opcodes.DOUBLE;
            break;
        case 4:
            frame[index] = Opcodes.LONG;
            break;
        case 5:
            frame[index] = Opcodes.NULL;
            break;
        case 6:
            frame[index] = Opcodes.UNINITIALIZED_THIS;
            break;
        case 7: // Object
            frame[index] = readClass(v, buf);
            v += 2;
            break;
        default: // Uninitialized
            frame[index] = readLabel(readUnsignedShort(v), labels);
            v += 2;
        }
        return v;
    }

    
Returns the label corresponding to the given offset. The default
implementation of this method creates a label for the given offset if it
has not been already created.
Params:
offset – 
           a bytecode offset in a method.
labels – 
           the already created labels, indexed by their offset. If a
           label already exists for offset this method must not create a
           new one. Otherwise it must store the new label in this array.
Returns:
a non null Label, which must be equal to labels[offset]./**
     * Returns the label corresponding to the given offset. The default
     * implementation of this method creates a label for the given offset if it
     * has not been already created.
     * 
     * @param offset
     *            a bytecode offset in a method.
     * @param labels
     *            the already created labels, indexed by their offset. If a
     *            label already exists for offset this method must not create a
     *            new one. Otherwise it must store the new label in this array.
     * @return a non null Label, which must be equal to labels[offset].
     */
    protected Label readLabel(int offset, Label[] labels) {
        if (labels[offset] == null) {
            labels[offset] = new Label();
        }
        return labels[offset];
    }

    
Returns the start index of the attribute_info structure of this class.
Returns:
the start index of the attribute_info structure of this class./**
     * Returns the start index of the attribute_info structure of this class.
     * 
     * @return the start index of the attribute_info structure of this class.
     */
    private int getAttributes() {
        // skips the header
        int u = header + 8 + readUnsignedShort(header + 6) * 2;
        // skips fields and methods
        for (int i = readUnsignedShort(u); i > 0; --i) {
            for (int j = readUnsignedShort(u + 8); j > 0; --j) {
                u += 6 + readInt(u + 12);
            }
            u += 8;
        }
        u += 2;
        for (int i = readUnsignedShort(u); i > 0; --i) {
            for (int j = readUnsignedShort(u + 8); j > 0; --j) {
                u += 6 + readInt(u + 12);
            }
            u += 8;
        }
        // the attribute_info structure starts just after the methods
        return u + 2;
    }

    
Reads an attribute in b. 
Params:
attrs –  prototypes of the attributes that must be parsed during the visit of the class. Any attribute whose type is not equal to the type of one the prototypes is ignored (i.e. an empty Attribute instance is returned).
type – 
           the type of the attribute.
off –  index of the first byte of the attribute's content in b. The 6 attribute header bytes, containing the type and the length of the attribute, are not taken into account here (they have already been read).
len – 
           the length of the attribute's content.
buf –  buffer to be used to call readUTF8, readClass or 
           readConst.
codeOff –  index of the first byte of code's attribute content in b, or -1 if the attribute to be read is not a code attribute. The 6 attribute header bytes, containing the type and the length of the attribute, are not taken into account here.
labels – 
           the labels of the method's code, or null if the
           attribute to be read is not a code attribute.
Returns:
the attribute that has been read, or null to skip this
        attribute./**
     * Reads an attribute in {@link #b b}.
     * 
     * @param attrs
     *            prototypes of the attributes that must be parsed during the
     *            visit of the class. Any attribute whose type is not equal to
     *            the type of one the prototypes is ignored (i.e. an empty
     *            {@link Attribute} instance is returned).
     * @param type
     *            the type of the attribute.
     * @param off
     *            index of the first byte of the attribute's content in
     *            {@link #b b}. The 6 attribute header bytes, containing the
     *            type and the length of the attribute, are not taken into
     *            account here (they have already been read).
     * @param len
     *            the length of the attribute's content.
     * @param buf
     *            buffer to be used to call {@link #readUTF8 readUTF8},
     *            {@link #readClass(int,char[]) readClass} or {@link #readConst
     *            readConst}.
     * @param codeOff
     *            index of the first byte of code's attribute content in
     *            {@link #b b}, or -1 if the attribute to be read is not a code
     *            attribute. The 6 attribute header bytes, containing the type
     *            and the length of the attribute, are not taken into account
     *            here.
     * @param labels
     *            the labels of the method's code, or <tt>null</tt> if the
     *            attribute to be read is not a code attribute.
     * @return the attribute that has been read, or <tt>null</tt> to skip this
     *         attribute.
     */
    private Attribute readAttribute(final Attribute[] attrs, final String type,
            final int off, final int len, final char[] buf, final int codeOff,
            final Label[] labels) {
        for (int i = 0; i < attrs.length; ++i) {
            if (attrs[i].type.equals(type)) {
                return attrs[i].read(this, off, len, buf, codeOff, labels);
            }
        }
        return new Attribute(type).read(this, off, len, null, -1, null);
    }

    // ------------------------------------------------------------------------
    // Utility methods: low level parsing
    // ------------------------------------------------------------------------

    
Returns the number of constant pool items in b. 
Returns:
the number of constant pool items in b./**
     * Returns the number of constant pool items in {@link #b b}.
     * 
     * @return the number of constant pool items in {@link #b b}.
     */
    public int getItemCount() {
        return items.length;
    }

    
Returns the start index of the constant pool item in b, plus one. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
item – 
           the index a constant pool item.
Returns:
the start index of the constant pool item in b, plus one./**
     * Returns the start index of the constant pool item in {@link #b b}, plus
     * one. <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param item
     *            the index a constant pool item.
     * @return the start index of the constant pool item in {@link #b b}, plus
     *         one.
     */
    public int getItem(final int item) {
        return items[item];
    }

    
Returns the maximum length of the strings contained in the constant pool
of the class.
Returns:
the maximum length of the strings contained in the constant pool
        of the class./**
     * Returns the maximum length of the strings contained in the constant pool
     * of the class.
     * 
     * @return the maximum length of the strings contained in the constant pool
     *         of the class.
     */
    public int getMaxStringLength() {
        return maxStringLength;
    }

    
Reads a byte value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of the value to be read in b.
Returns:
the read value./**
     * Reads a byte value in {@link #b b}. <i>This method is intended for
     * {@link Attribute} sub classes, and is normally not needed by class
     * generators or adapters.</i>
     * 
     * @param index
     *            the start index of the value to be read in {@link #b b}.
     * @return the read value.
     */
    public int readByte(final int index) {
        return b[index] & 0xFF;
    }

    
Reads an unsigned short value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of the value to be read in b.
Returns:
the read value./**
     * Reads an unsigned short value in {@link #b b}. <i>This method is intended
     * for {@link Attribute} sub classes, and is normally not needed by class
     * generators or adapters.</i>
     * 
     * @param index
     *            the start index of the value to be read in {@link #b b}.
     * @return the read value.
     */
    public int readUnsignedShort(final int index) {
        byte[] b = this.b;
        return ((b[index] & 0xFF) << 8) | (b[index + 1] & 0xFF);
    }

    
Reads a signed short value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of the value to be read in b.
Returns:
the read value./**
     * Reads a signed short value in {@link #b b}. <i>This method is intended
     * for {@link Attribute} sub classes, and is normally not needed by class
     * generators or adapters.</i>
     * 
     * @param index
     *            the start index of the value to be read in {@link #b b}.
     * @return the read value.
     */
    public short readShort(final int index) {
        byte[] b = this.b;
        return (short) (((b[index] & 0xFF) << 8) | (b[index + 1] & 0xFF));
    }

    
Reads a signed int value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of the value to be read in b.
Returns:
the read value./**
     * Reads a signed int value in {@link #b b}. <i>This method is intended for
     * {@link Attribute} sub classes, and is normally not needed by class
     * generators or adapters.</i>
     * 
     * @param index
     *            the start index of the value to be read in {@link #b b}.
     * @return the read value.
     */
    public int readInt(final int index) {
        byte[] b = this.b;
        return ((b[index] & 0xFF) << 24) | ((b[index + 1] & 0xFF) << 16)
                | ((b[index + 2] & 0xFF) << 8) | (b[index + 3] & 0xFF);
    }

    
Reads a signed long value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of the value to be read in b.
Returns:
the read value./**
     * Reads a signed long value in {@link #b b}. <i>This method is intended for
     * {@link Attribute} sub classes, and is normally not needed by class
     * generators or adapters.</i>
     * 
     * @param index
     *            the start index of the value to be read in {@link #b b}.
     * @return the read value.
     */
    public long readLong(final int index) {
        long l1 = readInt(index);
        long l0 = readInt(index + 4) & 0xFFFFFFFFL;
        return (l1 << 32) | l0;
    }

    
Reads an UTF8 string constant pool item in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of an unsigned short value in b, whose value is the index of an UTF8 constant pool item.
buf – 
           buffer to be used to read the item. This buffer must be
           sufficiently large. It is not automatically resized.
Returns:
the String corresponding to the specified UTF8 item./**
     * Reads an UTF8 string constant pool item in {@link #b b}. <i>This method
     * is intended for {@link Attribute} sub classes, and is normally not needed
     * by class generators or adapters.</i>
     * 
     * @param index
     *            the start index of an unsigned short value in {@link #b b},
     *            whose value is the index of an UTF8 constant pool item.
     * @param buf
     *            buffer to be used to read the item. This buffer must be
     *            sufficiently large. It is not automatically resized.
     * @return the String corresponding to the specified UTF8 item.
     */
    public String readUTF8(int index, final char[] buf) {
        int item = readUnsignedShort(index);
        if (index == 0 || item == 0) {
            return null;
        }
        String s = strings[item];
        if (s != null) {
            return s;
        }
        index = items[item];
        return strings[item] = readUTF(index + 2, readUnsignedShort(index), buf);
    }

    
Reads UTF8 string in b. 
Params:
index – 
           start offset of the UTF8 string to be read.
utfLen – 
           length of the UTF8 string to be read.
buf – 
           buffer to be used to read the string. This buffer must be
           sufficiently large. It is not automatically resized.
Returns:
the String corresponding to the specified UTF8 string./**
     * Reads UTF8 string in {@link #b b}.
     * 
     * @param index
     *            start offset of the UTF8 string to be read.
     * @param utfLen
     *            length of the UTF8 string to be read.
     * @param buf
     *            buffer to be used to read the string. This buffer must be
     *            sufficiently large. It is not automatically resized.
     * @return the String corresponding to the specified UTF8 string.
     */
    private String readUTF(int index, final int utfLen, final char[] buf) {
        int endIndex = index + utfLen;
        byte[] b = this.b;
        int strLen = 0;
        int c;
        int st = 0;
        char cc = 0;
        while (index < endIndex) {
            c = b[index++];
            switch (st) {
            case 0:
                c = c & 0xFF;
                if (c < 0x80) { // 0xxxxxxx
                    buf[strLen++] = (char) c;
                } else if (c < 0xE0 && c > 0xBF) { // 110x xxxx 10xx xxxx
                    cc = (char) (c & 0x1F);
                    st = 1;
                } else { // 1110 xxxx 10xx xxxx 10xx xxxx
                    cc = (char) (c & 0x0F);
                    st = 2;
                }
                break;

            case 1: // byte 2 of 2-byte char or byte 3 of 3-byte char
                buf[strLen++] = (char) ((cc << 6) | (c & 0x3F));
                st = 0;
                break;

            case 2: // byte 2 of 3-byte char
                cc = (char) ((cc << 6) | (c & 0x3F));
                st = 1;
                break;
            }
        }
        return new String(buf, 0, strLen);
    }

    
Reads a class constant pool item in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
index –  the start index of an unsigned short value in b, whose value is the index of a class constant pool item.
buf – 
           buffer to be used to read the item. This buffer must be
           sufficiently large. It is not automatically resized.
Returns:
the String corresponding to the specified class item./**
     * Reads a class constant pool item in {@link #b b}. <i>This method is
     * intended for {@link Attribute} sub classes, and is normally not needed by
     * class generators or adapters.</i>
     * 
     * @param index
     *            the start index of an unsigned short value in {@link #b b},
     *            whose value is the index of a class constant pool item.
     * @param buf
     *            buffer to be used to read the item. This buffer must be
     *            sufficiently large. It is not automatically resized.
     * @return the String corresponding to the specified class item.
     */
    public String readClass(final int index, final char[] buf) {
        // computes the start index of the CONSTANT_Class item in b
        // and reads the CONSTANT_Utf8 item designated by
        // the first two bytes of this CONSTANT_Class item
        return readUTF8(items[readUnsignedShort(index)], buf);
    }

    
Reads a numeric or string constant pool item in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
Params:
item – 
           the index of a constant pool item.
buf – 
           buffer to be used to read the item. This buffer must be
           sufficiently large. It is not automatically resized.
Returns:
the Integer, Float, Long, Double, String, Type or Handle corresponding to the given constant pool item./**
     * Reads a numeric or string constant pool item in {@link #b b}. <i>This
     * method is intended for {@link Attribute} sub classes, and is normally not
     * needed by class generators or adapters.</i>
     * 
     * @param item
     *            the index of a constant pool item.
     * @param buf
     *            buffer to be used to read the item. This buffer must be
     *            sufficiently large. It is not automatically resized.
     * @return the {@link Integer}, {@link Float}, {@link Long}, {@link Double},
     *         {@link String}, {@link Type} or {@link Handle} corresponding to
     *         the given constant pool item.
     */
    public Object readConst(final int item, final char[] buf) {
        int index = items[item];
        switch (b[index - 1]) {
        case ClassWriter.INT:
            return new Integer(readInt(index));
        case ClassWriter.FLOAT:
            return new Float(Float.intBitsToFloat(readInt(index)));
        case ClassWriter.LONG:
            return new Long(readLong(index));
        case ClassWriter.DOUBLE:
            return new Double(Double.longBitsToDouble(readLong(index)));
        case ClassWriter.CLASS:
            return Type.getObjectType(readUTF8(index, buf));
        case ClassWriter.STR:
            return readUTF8(index, buf);
        case ClassWriter.MTYPE:
            return Type.getMethodType(readUTF8(index, buf));
        default: // case ClassWriter.HANDLE_BASE + [1..9]:
            int tag = readByte(index);
            int[] items = this.items;
            int cpIndex = items[readUnsignedShort(index + 1)];
            String owner = readClass(cpIndex, buf);
            cpIndex = items[readUnsignedShort(cpIndex + 2)];
            String name = readUTF8(cpIndex, buf);
            String desc = readUTF8(cpIndex + 2, buf);
            return new Handle(tag, owner, name, desc);
        }
    }
}