ClassWriter.java

/***
 * 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;

/**
 * A {@link ClassVisitor} that generates classes in bytecode form. More
 * precisely this visitor generates a byte array conforming to the Java class
 * file format. It can be used alone, to generate a Java class "from scratch",
 * or with one or more {@link ClassReader ClassReader} and adapter class visitor
 * to generate a modified class from one or more existing Java classes.
 * 
 * @author Eric Bruneton
 */
public class ClassWriter extends ClassVisitor {

    /**
     * Flag to automatically compute the maximum stack size and the maximum
     * number of local variables of methods. If this flag is set, then the
     * arguments of the {@link MethodVisitor#visitMaxs visitMaxs} method of the
     * {@link MethodVisitor} returned by the {@link #visitMethod visitMethod}
     * method will be ignored, and computed automatically from the signature and
     * the bytecode of each method.
     * 
     * @see #ClassWriter(int)
     */
    public static final int COMPUTE_MAXS = 1;

    /**
     * Flag to automatically compute the stack map frames of methods from
     * scratch. If this flag is set, then the calls to the
     * {@link MethodVisitor#visitFrame} method are ignored, and the stack map
     * frames are recomputed from the methods bytecode. The arguments of the
     * {@link MethodVisitor#visitMaxs visitMaxs} method are also ignored and
     * recomputed from the bytecode. In other words, computeFrames implies
     * computeMaxs.
     * 
     * @see #ClassWriter(int)
     */
    public static final int COMPUTE_FRAMES = 2;

    /**
     * Pseudo access flag to distinguish between the synthetic attribute and the
     * synthetic access flag.
     */
    static final int ACC_SYNTHETIC_ATTRIBUTE = 0x40000;

    /**
     * Factor to convert from ACC_SYNTHETIC_ATTRIBUTE to Opcode.ACC_SYNTHETIC.
     */
    static final int TO_ACC_SYNTHETIC = ACC_SYNTHETIC_ATTRIBUTE
            / Opcodes.ACC_SYNTHETIC;

    /**
     * The type of instructions without any argument.
     */
    static final int NOARG_INSN = 0;

    /**
     * The type of instructions with an signed byte argument.
     */
    static final int SBYTE_INSN = 1;

    /**
     * The type of instructions with an signed short argument.
     */
    static final int SHORT_INSN = 2;

    /**
     * The type of instructions with a local variable index argument.
     */
    static final int VAR_INSN = 3;

    /**
     * The type of instructions with an implicit local variable index argument.
     */
    static final int IMPLVAR_INSN = 4;

    /**
     * The type of instructions with a type descriptor argument.
     */
    static final int TYPE_INSN = 5;

    /**
     * The type of field and method invocations instructions.
     */
    static final int FIELDORMETH_INSN = 6;

    /**
     * The type of the INVOKEINTERFACE/INVOKEDYNAMIC instruction.
     */
    static final int ITFMETH_INSN = 7;

    /**
     * The type of the INVOKEDYNAMIC instruction.
     */
    static final int INDYMETH_INSN = 8;

    /**
     * The type of instructions with a 2 bytes bytecode offset label.
     */
    static final int LABEL_INSN = 9;

    /**
     * The type of instructions with a 4 bytes bytecode offset label.
     */
    static final int LABELW_INSN = 10;

    /**
     * The type of the LDC instruction.
     */
    static final int LDC_INSN = 11;

    /**
     * The type of the LDC_W and LDC2_W instructions.
     */
    static final int LDCW_INSN = 12;

    /**
     * The type of the IINC instruction.
     */
    static final int IINC_INSN = 13;

    /**
     * The type of the TABLESWITCH instruction.
     */
    static final int TABL_INSN = 14;

    /**
     * The type of the LOOKUPSWITCH instruction.
     */
    static final int LOOK_INSN = 15;

    /**
     * The type of the MULTIANEWARRAY instruction.
     */
    static final int MANA_INSN = 16;

    /**
     * The type of the WIDE instruction.
     */
    static final int WIDE_INSN = 17;

    /**
     * The instruction types of all JVM opcodes.
     */
    static final byte[] TYPE;

    /**
     * The type of CONSTANT_Class constant pool items.
     */
    static final int CLASS = 7;

    /**
     * The type of CONSTANT_Fieldref constant pool items.
     */
    static final int FIELD = 9;

    /**
     * The type of CONSTANT_Methodref constant pool items.
     */
    static final int METH = 10;

    /**
     * The type of CONSTANT_InterfaceMethodref constant pool items.
     */
    static final int IMETH = 11;

    /**
     * The type of CONSTANT_String constant pool items.
     */
    static final int STR = 8;

    /**
     * The type of CONSTANT_Integer constant pool items.
     */
    static final int INT = 3;

    /**
     * The type of CONSTANT_Float constant pool items.
     */
    static final int FLOAT = 4;

    /**
     * The type of CONSTANT_Long constant pool items.
     */
    static final int LONG = 5;

    /**
     * The type of CONSTANT_Double constant pool items.
     */
    static final int DOUBLE = 6;

    /**
     * The type of CONSTANT_NameAndType constant pool items.
     */
    static final int NAME_TYPE = 12;

    /**
     * The type of CONSTANT_Utf8 constant pool items.
     */
    static final int UTF8 = 1;

    /**
     * The type of CONSTANT_MethodType constant pool items.
     */
    static final int MTYPE = 16;

    /**
     * The type of CONSTANT_MethodHandle constant pool items.
     */
    static final int HANDLE = 15;

    /**
     * The type of CONSTANT_InvokeDynamic constant pool items.
     */
    static final int INDY = 18;

    /**
     * The base value for all CONSTANT_MethodHandle constant pool items.
     * Internally, ASM store the 9 variations of CONSTANT_MethodHandle into 9
     * different items.
     */
    static final int HANDLE_BASE = 20;

    /**
     * Normal type Item stored in the ClassWriter {@link ClassWriter#typeTable},
     * instead of the constant pool, in order to avoid clashes with normal
     * constant pool items in the ClassWriter constant pool's hash table.
     */
    static final int TYPE_NORMAL = 30;

    /**
     * Uninitialized type Item stored in the ClassWriter
     * {@link ClassWriter#typeTable}, instead of the constant pool, in order to
     * avoid clashes with normal constant pool items in the ClassWriter constant
     * pool's hash table.
     */
    static final int TYPE_UNINIT = 31;

    /**
     * Merged type Item stored in the ClassWriter {@link ClassWriter#typeTable},
     * instead of the constant pool, in order to avoid clashes with normal
     * constant pool items in the ClassWriter constant pool's hash table.
     */
    static final int TYPE_MERGED = 32;

    /**
     * The type of BootstrapMethods items. These items are stored in a special
     * class attribute named BootstrapMethods and not in the constant pool.
     */
    static final int BSM = 33;

    /**
     * The class reader from which this class writer was constructed, if any.
     */
    ClassReader cr;

    /**
     * Minor and major version numbers of the class to be generated.
     */
    int version;

    /**
     * Index of the next item to be added in the constant pool.
     */
    int index;

    /**
     * The constant pool of this class.
     */
    final ByteVector pool;

    /**
     * The constant pool's hash table data.
     */
    Item[] items;

    /**
     * The threshold of the constant pool's hash table.
     */
    int threshold;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    final Item key;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    final Item key2;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    final Item key3;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    final Item key4;

    /**
     * A type table used to temporarily store internal names that will not
     * necessarily be stored in the constant pool. This type table is used by
     * the control flow and data flow analysis algorithm used to compute stack
     * map frames from scratch. This array associates to each index <tt>i</tt>
     * the Item whose index is <tt>i</tt>. All Item objects stored in this array
     * are also stored in the {@link #items} hash table. These two arrays allow
     * to retrieve an Item from its index or, conversely, to get the index of an
     * Item from its value. Each Item stores an internal name in its
     * {@link Item#strVal1} field.
     */
    Item[] typeTable;

    /**
     * Number of elements in the {@link #typeTable} array.
     */
    private short typeCount;

    /**
     * The access flags of this class.
     */
    private int access;

    /**
     * The constant pool item that contains the internal name of this class.
     */
    private int name;

    /**
     * The internal name of this class.
     */
    String thisName;

    /**
     * The constant pool item that contains the signature of this class.
     */
    private int signature;

    /**
     * The constant pool item that contains the internal name of the super class
     * of this class.
     */
    private int superName;

    /**
     * Number of interfaces implemented or extended by this class or interface.
     */
    private int interfaceCount;

    /**
     * The interfaces implemented or extended by this class or interface. More
     * precisely, this array contains the indexes of the constant pool items
     * that contain the internal names of these interfaces.
     */
    private int[] interfaces;

    /**
     * The index of the constant pool item that contains the name of the source
     * file from which this class was compiled.
     */
    private int sourceFile;

    /**
     * The SourceDebug attribute of this class.
     */
    private ByteVector sourceDebug;

    /**
     * The constant pool item that contains the name of the enclosing class of
     * this class.
     */
    private int enclosingMethodOwner;

    /**
     * The constant pool item that contains the name and descriptor of the
     * enclosing method of this class.
     */
    private int enclosingMethod;

    /**
     * The runtime visible annotations of this class.
     */
    private AnnotationWriter anns;

    /**
     * The runtime invisible annotations of this class.
     */
    private AnnotationWriter ianns;

    /**
     * The runtime visible type annotations of this class.
     */
    private AnnotationWriter tanns;

    /**
     * The runtime invisible type annotations of this class.
     */
    private AnnotationWriter itanns;

    /**
     * The non standard attributes of this class.
     */
    private Attribute attrs;

    /**
     * The number of entries in the InnerClasses attribute.
     */
    private int innerClassesCount;

    /**
     * The InnerClasses attribute.
     */
    private ByteVector innerClasses;

    /**
     * The number of entries in the BootstrapMethods attribute.
     */
    int bootstrapMethodsCount;

    /**
     * The BootstrapMethods attribute.
     */
    ByteVector bootstrapMethods;

    /**
     * The fields of this class. These fields are stored in a linked list of
     * {@link FieldWriter} objects, linked to each other by their
     * {@link FieldWriter#fv} field. This field stores the first element of this
     * list.
     */
    FieldWriter firstField;

    /**
     * The fields of this class. These fields are stored in a linked list of
     * {@link FieldWriter} objects, linked to each other by their
     * {@link FieldWriter#fv} field. This field stores the last element of this
     * list.
     */
    FieldWriter lastField;

    /**
     * The methods of this class. These methods are stored in a linked list of
     * {@link MethodWriter} objects, linked to each other by their
     * {@link MethodWriter#mv} field. This field stores the first element of
     * this list.
     */
    MethodWriter firstMethod;

    /**
     * The methods of this class. These methods are stored in a linked list of
     * {@link MethodWriter} objects, linked to each other by their
     * {@link MethodWriter#mv} field. This field stores the last element of this
     * list.
     */
    MethodWriter lastMethod;

    /**
     * <tt>true</tt> if the maximum stack size and number of local variables
     * must be automatically computed.
     */
    private boolean computeMaxs;

    /**
     * <tt>true</tt> if the stack map frames must be recomputed from scratch.
     */
    private boolean computeFrames;

    /**
     * <tt>true</tt> if the stack map tables of this class are invalid. The
     * {@link MethodWriter#resizeInstructions} method cannot transform existing
     * stack map tables, and so produces potentially invalid classes when it is
     * executed. In this case the class is reread and rewritten with the
     * {@link #COMPUTE_FRAMES} option (the resizeInstructions method can resize
     * stack map tables when this option is used).
     */
    boolean invalidFrames;

    // ------------------------------------------------------------------------
    // Static initializer
    // ------------------------------------------------------------------------

    /**
     * Computes the instruction types of JVM opcodes.
     */
    static {
        int i;
        byte[] b = new byte[220];
        String s = "AAAAAAAAAAAAAAAABCLMMDDDDDEEEEEEEEEEEEEEEEEEEEAAAAAAAADD"
                + "DDDEEEEEEEEEEEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                + "AAAAAAAAAAAAAAAAANAAAAAAAAAAAAAAAAAAAAJJJJJJJJJJJJJJJJDOPAA"
                + "AAAAGGGGGGGHIFBFAAFFAARQJJKKJJJJJJJJJJJJJJJJJJ";
        for (i = 0; i < b.length; ++i) {
            b[i] = (byte) (s.charAt(i) - 'A');
        }
        TYPE = b;

        // code to generate the above string
        //
        // // SBYTE_INSN instructions
        // b[Constants.NEWARRAY] = SBYTE_INSN;
        // b[Constants.BIPUSH] = SBYTE_INSN;
        //
        // // SHORT_INSN instructions
        // b[Constants.SIPUSH] = SHORT_INSN;
        //
        // // (IMPL)VAR_INSN instructions
        // b[Constants.RET] = VAR_INSN;
        // for (i = Constants.ILOAD; i <= Constants.ALOAD; ++i) {
        // b[i] = VAR_INSN;
        // }
        // for (i = Constants.ISTORE; i <= Constants.ASTORE; ++i) {
        // b[i] = VAR_INSN;
        // }
        // for (i = 26; i <= 45; ++i) { // ILOAD_0 to ALOAD_3
        // b[i] = IMPLVAR_INSN;
        // }
        // for (i = 59; i <= 78; ++i) { // ISTORE_0 to ASTORE_3
        // b[i] = IMPLVAR_INSN;
        // }
        //
        // // TYPE_INSN instructions
        // b[Constants.NEW] = TYPE_INSN;
        // b[Constants.ANEWARRAY] = TYPE_INSN;
        // b[Constants.CHECKCAST] = TYPE_INSN;
        // b[Constants.INSTANCEOF] = TYPE_INSN;
        //
        // // (Set)FIELDORMETH_INSN instructions
        // for (i = Constants.GETSTATIC; i <= Constants.INVOKESTATIC; ++i) {
        // b[i] = FIELDORMETH_INSN;
        // }
        // b[Constants.INVOKEINTERFACE] = ITFMETH_INSN;
        // b[Constants.INVOKEDYNAMIC] = INDYMETH_INSN;
        //
        // // LABEL(W)_INSN instructions
        // for (i = Constants.IFEQ; i <= Constants.JSR; ++i) {
        // b[i] = LABEL_INSN;
        // }
        // b[Constants.IFNULL] = LABEL_INSN;
        // b[Constants.IFNONNULL] = LABEL_INSN;
        // b[200] = LABELW_INSN; // GOTO_W
        // b[201] = LABELW_INSN; // JSR_W
        // // temporary opcodes used internally by ASM - see Label and
        // MethodWriter
        // for (i = 202; i < 220; ++i) {
        // b[i] = LABEL_INSN;
        // }
        //
        // // LDC(_W) instructions
        // b[Constants.LDC] = LDC_INSN;
        // b[19] = LDCW_INSN; // LDC_W
        // b[20] = LDCW_INSN; // LDC2_W
        //
        // // special instructions
        // b[Constants.IINC] = IINC_INSN;
        // b[Constants.TABLESWITCH] = TABL_INSN;
        // b[Constants.LOOKUPSWITCH] = LOOK_INSN;
        // b[Constants.MULTIANEWARRAY] = MANA_INSN;
        // b[196] = WIDE_INSN; // WIDE
        //
        // for (i = 0; i < b.length; ++i) {
        // System.err.print((char)('A' + b[i]));
        // }
        // System.err.println();
    }

    // ------------------------------------------------------------------------
    // Constructor
    // ------------------------------------------------------------------------

    /**
     * Constructs a new {@link ClassWriter} object.
     * 
     * @param flags
     *            option flags that can be used to modify the default behavior
     *            of this class. See {@link #COMPUTE_MAXS},
     *            {@link #COMPUTE_FRAMES}.
     */
    public ClassWriter(final int flags) {
        super(Opcodes.ASM5);
        index = 1;
        pool = new ByteVector();
        items = new Item[256];
        threshold = (int) (0.75d * items.length);
        key = new Item();
        key2 = new Item();
        key3 = new Item();
        key4 = new Item();
        this.computeMaxs = (flags & COMPUTE_MAXS) != 0;
        this.computeFrames = (flags & COMPUTE_FRAMES) != 0;
    }

    /**
     * Constructs a new {@link ClassWriter} object and enables optimizations for
     * "mostly add" bytecode transformations. These optimizations are the
     * following:
     * 
     * <ul>
     * <li>The constant pool from the original class is copied as is in the new
     * class, which saves time. New constant pool entries will be added at the
     * end if necessary, but unused constant pool entries <i>won't be
     * removed</i>.</li>
     * <li>Methods that are not transformed are copied as is in the new class,
     * directly from the original class bytecode (i.e. without emitting visit
     * events for all the method instructions), which saves a <i>lot</i> of
     * time. Untransformed methods are detected by the fact that the
     * {@link ClassReader} receives {@link MethodVisitor} objects that come from
     * a {@link ClassWriter} (and not from any other {@link ClassVisitor}
     * instance).</li>
     * </ul>
     * 
     * @param classReader
     *            the {@link ClassReader} used to read the original class. It
     *            will be used to copy the entire constant pool from the
     *            original class and also to copy other fragments of original
     *            bytecode where applicable.
     * @param flags
     *            option flags that can be used to modify the default behavior
     *            of this class. <i>These option flags do not affect methods
     *            that are copied as is in the new class. This means that the
     *            maximum stack size nor the stack frames will be computed for
     *            these methods</i>. See {@link #COMPUTE_MAXS},
     *            {@link #COMPUTE_FRAMES}.
     */
    public ClassWriter(final ClassReader classReader, final int flags) {
        this(flags);
        classReader.copyPool(this);
        this.cr = classReader;
    }

    // ------------------------------------------------------------------------
    // Implementation of the ClassVisitor abstract class
    // ------------------------------------------------------------------------

    @Override
    public final void visit(final int version, final int access,
            final String name, final String signature, final String superName,
            final String[] interfaces) {
        this.version = version;
        this.access = access;
        this.name = newClass(name);
        thisName = name;
        if (ClassReader.SIGNATURES && signature != null) {
            this.signature = newUTF8(signature);
        }
        this.superName = superName == null ? 0 : newClass(superName);
        if (interfaces != null && interfaces.length > 0) {
            interfaceCount = interfaces.length;
            this.interfaces = new int[interfaceCount];
            for (int i = 0; i < interfaceCount; ++i) {
                this.interfaces[i] = newClass(interfaces[i]);
            }
        }
    }

    @Override
    public final void visitSource(final String file, final String debug) {
        if (file != null) {
            sourceFile = newUTF8(file);
        }
        if (debug != null) {
            sourceDebug = new ByteVector().encodeUTF8(debug, 0,
                    Integer.MAX_VALUE);
        }
    }

    @Override
    public final void visitOuterClass(final String owner, final String name,
            final String desc) {
        enclosingMethodOwner = newClass(owner);
        if (name != null && desc != null) {
            enclosingMethod = newNameType(name, desc);
        }
    }

    @Override
    public final AnnotationVisitor visitAnnotation(final String desc,
            final boolean visible) {
        if (!ClassReader.ANNOTATIONS) {
            return null;
        }
        ByteVector bv = new ByteVector();
        // write type, and reserve space for values count
        bv.putShort(newUTF8(desc)).putShort(0);
        AnnotationWriter aw = new AnnotationWriter(this, true, bv, bv, 2);
        if (visible) {
            aw.next = anns;
            anns = aw;
        } else {
            aw.next = ianns;
            ianns = aw;
        }
        return aw;
    }

    @Override
    public final AnnotationVisitor visitTypeAnnotation(int typeRef,
            TypePath typePath, final String desc, final boolean visible) {
        if (!ClassReader.ANNOTATIONS) {
            return null;
        }
        ByteVector bv = new ByteVector();
        // write target_type and target_info
        AnnotationWriter.putTarget(typeRef, typePath, bv);
        // write type, and reserve space for values count
        bv.putShort(newUTF8(desc)).putShort(0);
        AnnotationWriter aw = new AnnotationWriter(this, true, bv, bv,
                bv.length - 2);
        if (visible) {
            aw.next = tanns;
            tanns = aw;
        } else {
            aw.next = itanns;
            itanns = aw;
        }
        return aw;
    }

    @Override
    public final void visitAttribute(final Attribute attr) {
        attr.next = attrs;
        attrs = attr;
    }

    @Override
    public final void visitInnerClass(final String name,
            final String outerName, final String innerName, final int access) {
        if (innerClasses == null) {
            innerClasses = new ByteVector();
        }
        // Sec. 4.7.6 of the JVMS states "Every CONSTANT_Class_info entry in the
        // constant_pool table which represents a class or interface C that is
        // not a package member must have exactly one corresponding entry in the
        // classes array". To avoid duplicates we keep track in the intVal field
        // of the Item of each CONSTANT_Class_info entry C whether an inner
        // class entry has already been added for C (this field is unused for
        // class entries, and changing its value does not change the hashcode
        // and equality tests). If so we store the index of this inner class
        // entry (plus one) in intVal. This hack allows duplicate detection in
        // O(1) time.
        Item nameItem = newClassItem(name);
        if (nameItem.intVal == 0) {
            ++innerClassesCount;
            innerClasses.putShort(nameItem.index);
            innerClasses.putShort(outerName == null ? 0 : newClass(outerName));
            innerClasses.putShort(innerName == null ? 0 : newUTF8(innerName));
            innerClasses.putShort(access);
            nameItem.intVal = innerClassesCount;
        } else {
            // Compare the inner classes entry nameItem.intVal - 1 with the
            // arguments of this method and throw an exception if there is a
            // difference?
        }
    }

    @Override
    public final FieldVisitor visitField(final int access, final String name,
            final String desc, final String signature, final Object value) {
        return new FieldWriter(this, access, name, desc, signature, value);
    }

    @Override
    public final MethodVisitor visitMethod(final int access, final String name,
            final String desc, final String signature, final String[] exceptions) {
        return new MethodWriter(this, access, name, desc, signature,
                exceptions, computeMaxs, computeFrames);
    }

    @Override
    public final void visitEnd() {
    }

    // ------------------------------------------------------------------------
    // Other public methods
    // ------------------------------------------------------------------------

    /**
     * Returns the bytecode of the class that was build with this class writer.
     * 
     * @return the bytecode of the class that was build with this class writer.
     */
    public byte[] toByteArray() {
        if (index > 0xFFFF) {
            throw new RuntimeException("Class file too large!");
        }
        // computes the real size of the bytecode of this class
        int size = 24 + 2 * interfaceCount;
        int nbFields = 0;
        FieldWriter fb = firstField;
        while (fb != null) {
            ++nbFields;
            size += fb.getSize();
            fb = (FieldWriter) fb.fv;
        }
        int nbMethods = 0;
        MethodWriter mb = firstMethod;
        while (mb != null) {
            ++nbMethods;
            size += mb.getSize();
            mb = (MethodWriter) mb.mv;
        }
        int attributeCount = 0;
        if (bootstrapMethods != null) {
            // we put it as first attribute in order to improve a bit
            // ClassReader.copyBootstrapMethods
            ++attributeCount;
            size += 8 + bootstrapMethods.length;
            newUTF8("BootstrapMethods");
        }
        if (ClassReader.SIGNATURES && signature != 0) {
            ++attributeCount;
            size += 8;
            newUTF8("Signature");
        }
        if (sourceFile != 0) {
            ++attributeCount;
            size += 8;
            newUTF8("SourceFile");
        }
        if (sourceDebug != null) {
            ++attributeCount;
            size += sourceDebug.length + 6;
            newUTF8("SourceDebugExtension");
        }
        if (enclosingMethodOwner != 0) {
            ++attributeCount;
            size += 10;
            newUTF8("EnclosingMethod");
        }
        if ((access & Opcodes.ACC_DEPRECATED) != 0) {
            ++attributeCount;
            size += 6;
            newUTF8("Deprecated");
        }
        if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
            if ((version & 0xFFFF) < Opcodes.V1_5
                    || (access & ACC_SYNTHETIC_ATTRIBUTE) != 0) {
                ++attributeCount;
                size += 6;
                newUTF8("Synthetic");
            }
        }
        if (innerClasses != null) {
            ++attributeCount;
            size += 8 + innerClasses.length;
            newUTF8("InnerClasses");
        }
        if (ClassReader.ANNOTATIONS && anns != null) {
            ++attributeCount;
            size += 8 + anns.getSize();
            newUTF8("RuntimeVisibleAnnotations");
        }
        if (ClassReader.ANNOTATIONS && ianns != null) {
            ++attributeCount;
            size += 8 + ianns.getSize();
            newUTF8("RuntimeInvisibleAnnotations");
        }
        if (ClassReader.ANNOTATIONS && tanns != null) {
            ++attributeCount;
            size += 8 + tanns.getSize();
            newUTF8("RuntimeVisibleTypeAnnotations");
        }
        if (ClassReader.ANNOTATIONS && itanns != null) {
            ++attributeCount;
            size += 8 + itanns.getSize();
            newUTF8("RuntimeInvisibleTypeAnnotations");
        }
        if (attrs != null) {
            attributeCount += attrs.getCount();
            size += attrs.getSize(this, null, 0, -1, -1);
        }
        size += pool.length;
        // allocates a byte vector of this size, in order to avoid unnecessary
        // arraycopy operations in the ByteVector.enlarge() method
        ByteVector out = new ByteVector(size);
        out.putInt(0xCAFEBABE).putInt(version);
        out.putShort(index).putByteArray(pool.data, 0, pool.length);
        int mask = Opcodes.ACC_DEPRECATED | ACC_SYNTHETIC_ATTRIBUTE
                | ((access & ACC_SYNTHETIC_ATTRIBUTE) / TO_ACC_SYNTHETIC);
        out.putShort(access & ~mask).putShort(name).putShort(superName);
        out.putShort(interfaceCount);
        for (int i = 0; i < interfaceCount; ++i) {
            out.putShort(interfaces[i]);
        }
        out.putShort(nbFields);
        fb = firstField;
        while (fb != null) {
            fb.put(out);
            fb = (FieldWriter) fb.fv;
        }
        out.putShort(nbMethods);
        mb = firstMethod;
        while (mb != null) {
            mb.put(out);
            mb = (MethodWriter) mb.mv;
        }
        out.putShort(attributeCount);
        if (bootstrapMethods != null) {
            out.putShort(newUTF8("BootstrapMethods"));
            out.putInt(bootstrapMethods.length + 2).putShort(
                    bootstrapMethodsCount);
            out.putByteArray(bootstrapMethods.data, 0, bootstrapMethods.length);
        }
        if (ClassReader.SIGNATURES && signature != 0) {
            out.putShort(newUTF8("Signature")).putInt(2).putShort(signature);
        }
        if (sourceFile != 0) {
            out.putShort(newUTF8("SourceFile")).putInt(2).putShort(sourceFile);
        }
        if (sourceDebug != null) {
            int len = sourceDebug.length;
            out.putShort(newUTF8("SourceDebugExtension")).putInt(len);
            out.putByteArray(sourceDebug.data, 0, len);
        }
        if (enclosingMethodOwner != 0) {
            out.putShort(newUTF8("EnclosingMethod")).putInt(4);
            out.putShort(enclosingMethodOwner).putShort(enclosingMethod);
        }
        if ((access & Opcodes.ACC_DEPRECATED) != 0) {
            out.putShort(newUTF8("Deprecated")).putInt(0);
        }
        if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
            if ((version & 0xFFFF) < Opcodes.V1_5
                    || (access & ACC_SYNTHETIC_ATTRIBUTE) != 0) {
                out.putShort(newUTF8("Synthetic")).putInt(0);
            }
        }
        if (innerClasses != null) {
            out.putShort(newUTF8("InnerClasses"));
            out.putInt(innerClasses.length + 2).putShort(innerClassesCount);
            out.putByteArray(innerClasses.data, 0, innerClasses.length);
        }
        if (ClassReader.ANNOTATIONS && anns != null) {
            out.putShort(newUTF8("RuntimeVisibleAnnotations"));
            anns.put(out);
        }
        if (ClassReader.ANNOTATIONS && ianns != null) {
            out.putShort(newUTF8("RuntimeInvisibleAnnotations"));
            ianns.put(out);
        }
        if (ClassReader.ANNOTATIONS && tanns != null) {
            out.putShort(newUTF8("RuntimeVisibleTypeAnnotations"));
            tanns.put(out);
        }
        if (ClassReader.ANNOTATIONS && itanns != null) {
            out.putShort(newUTF8("RuntimeInvisibleTypeAnnotations"));
            itanns.put(out);
        }
        if (attrs != null) {
            attrs.put(this, null, 0, -1, -1, out);
        }
        if (invalidFrames) {
            anns = null;
            ianns = null;
            attrs = null;
            innerClassesCount = 0;
            innerClasses = null;
            bootstrapMethodsCount = 0;
            bootstrapMethods = null;
            firstField = null;
            lastField = null;
            firstMethod = null;
            lastMethod = null;
            computeMaxs = false;
            computeFrames = true;
            invalidFrames = false;
            new ClassReader(out.data).accept(this, ClassReader.SKIP_FRAMES);
            return toByteArray();
        }
        return out.data;
    }

    // ------------------------------------------------------------------------
    // Utility methods: constant pool management
    // ------------------------------------------------------------------------

    /**
     * Adds a number or string constant to the constant pool of the class being
     * build. Does nothing if the constant pool already contains a similar item.
     * 
     * @param cst
     *            the value of the constant to be added to the constant pool.
     *            This parameter must be an {@link Integer}, a {@link Float}, a
     *            {@link Long}, a {@link Double}, a {@link String} or a
     *            {@link Type}.
     * @return a new or already existing constant item with the given value.
     */
    Item newConstItem(final Object cst) {
        if (cst instanceof Integer) {
            int val = ((Integer) cst).intValue();
            return newInteger(val);
        } else if (cst instanceof Byte) {
            int val = ((Byte) cst).intValue();
            return newInteger(val);
        } else if (cst instanceof Character) {
            int val = ((Character) cst).charValue();
            return newInteger(val);
        } else if (cst instanceof Short) {
            int val = ((Short) cst).intValue();
            return newInteger(val);
        } else if (cst instanceof Boolean) {
            int val = ((Boolean) cst).booleanValue() ? 1 : 0;
            return newInteger(val);
        } else if (cst instanceof Float) {
            float val = ((Float) cst).floatValue();
            return newFloat(val);
        } else if (cst instanceof Long) {
            long val = ((Long) cst).longValue();
            return newLong(val);
        } else if (cst instanceof Double) {
            double val = ((Double) cst).doubleValue();
            return newDouble(val);
        } else if (cst instanceof String) {
            return newString((String) cst);
        } else if (cst instanceof Type) {
            Type t = (Type) cst;
            int s = t.getSort();
            if (s == Type.OBJECT) {
                return newClassItem(t.getInternalName());
            } else if (s == Type.METHOD) {
                return newMethodTypeItem(t.getDescriptor());
            } else { // s == primitive type or array
                return newClassItem(t.getDescriptor());
            }
        } else if (cst instanceof Handle) {
            Handle h = (Handle) cst;
            return newHandleItem(h.tag, h.owner, h.name, h.desc, h.itf);
        } else {
            throw new IllegalArgumentException("value " + cst);
        }
    }

    /**
     * Adds a number or string constant to the constant pool of the class being
     * build. Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param cst
     *            the value of the constant to be added to the constant pool.
     *            This parameter must be an {@link Integer}, a {@link Float}, a
     *            {@link Long}, a {@link Double} or a {@link String}.
     * @return the index of a new or already existing constant item with the
     *         given value.
     */
    public int newConst(final Object cst) {
        return newConstItem(cst).index;
    }

    /**
     * Adds an UTF8 string to the constant pool of the class being build. Does
     * nothing if the constant pool already contains a similar item. <i>This
     * method is intended for {@link Attribute} sub classes, and is normally not
     * needed by class generators or adapters.</i>
     * 
     * @param value
     *            the String value.
     * @return the index of a new or already existing UTF8 item.
     */
    public int newUTF8(final String value) {
        key.set(UTF8, value, null, null);
        Item result = get(key);
        if (result == null) {
            pool.putByte(UTF8).putUTF8(value);
            result = new Item(index++, key);
            put(result);
        }
        return result.index;
    }

    /**
     * Adds a class reference to the constant pool of the class being build.
     * Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param value
     *            the internal name of the class.
     * @return a new or already existing class reference item.
     */
    Item newClassItem(final String value) {
        key2.set(CLASS, value, null, null);
        Item result = get(key2);
        if (result == null) {
            pool.put12(CLASS, newUTF8(value));
            result = new Item(index++, key2);
            put(result);
        }
        return result;
    }

    /**
     * Adds a class reference to the constant pool of the class being build.
     * Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param value
     *            the internal name of the class.
     * @return the index of a new or already existing class reference item.
     */
    public int newClass(final String value) {
        return newClassItem(value).index;
    }

    /**
     * Adds a method type reference to the constant pool of the class being
     * build. Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param methodDesc
     *            method descriptor of the method type.
     * @return a new or already existing method type reference item.
     */
    Item newMethodTypeItem(final String methodDesc) {
        key2.set(MTYPE, methodDesc, null, null);
        Item result = get(key2);
        if (result == null) {
            pool.put12(MTYPE, newUTF8(methodDesc));
            result = new Item(index++, key2);
            put(result);
        }
        return result;
    }

    /**
     * Adds a method type reference to the constant pool of the class being
     * build. Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param methodDesc
     *            method descriptor of the method type.
     * @return the index of a new or already existing method type reference
     *         item.
     */
    public int newMethodType(final String methodDesc) {
        return newMethodTypeItem(methodDesc).index;
    }

    /**
     * Adds a handle to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item. <i>This method is
     * intended for {@link Attribute} sub classes, and is normally not needed by
     * class generators or adapters.</i>
     * 
     * @param tag
     *            the kind of this handle. Must be {@link Opcodes#H_GETFIELD},
     *            {@link Opcodes#H_GETSTATIC}, {@link Opcodes#H_PUTFIELD},
     *            {@link Opcodes#H_PUTSTATIC}, {@link Opcodes#H_INVOKEVIRTUAL},
     *            {@link Opcodes#H_INVOKESTATIC},
     *            {@link Opcodes#H_INVOKESPECIAL},
     *            {@link Opcodes#H_NEWINVOKESPECIAL} or
     *            {@link Opcodes#H_INVOKEINTERFACE}.
     * @param owner
     *            the internal name of the field or method owner class.
     * @param name
     *            the name of the field or method.
     * @param desc
     *            the descriptor of the field or method.
     * @param itf
     *            true if the owner is an interface.
     * @return a new or an already existing method type reference item.
     */
    Item newHandleItem(final int tag, final String owner, final String name,
            final String desc, final boolean itf) {
        key4.set(HANDLE_BASE + tag, owner, name, desc);
        Item result = get(key4);
        if (result == null) {
            if (tag <= Opcodes.H_PUTSTATIC) {
                put112(HANDLE, tag, newField(owner, name, desc));
            } else {
                put112(HANDLE,
                        tag,
                        newMethod(owner, name, desc, itf));
            }
            result = new Item(index++, key4);
            put(result);
        }
        return result;
    }

    /**
     * Adds a handle to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item. <i>This method is
     * intended for {@link Attribute} sub classes, and is normally not needed by
     * class generators or adapters.</i>
     * 
     * @param tag
     *            the kind of this handle. Must be {@link Opcodes#H_GETFIELD},
     *            {@link Opcodes#H_GETSTATIC}, {@link Opcodes#H_PUTFIELD},
     *            {@link Opcodes#H_PUTSTATIC}, {@link Opcodes#H_INVOKEVIRTUAL},
     *            {@link Opcodes#H_INVOKESTATIC},
     *            {@link Opcodes#H_INVOKESPECIAL},
     *            {@link Opcodes#H_NEWINVOKESPECIAL} or
     *            {@link Opcodes#H_INVOKEINTERFACE}.
     * @param owner
     *            the internal name of the field or method owner class.
     * @param name
     *            the name of the field or method.
     * @param desc
     *            the descriptor of the field or method.
     * @return the index of a new or already existing method type reference
     *         item.
     *         
     * @deprecated this method is superseded by
     *             {@link #newHandle(int, String, String, String, boolean)}.
     */
    @Deprecated
    public int newHandle(final int tag, final String owner, final String name,
            final String desc) {
        return newHandle(tag, owner, name, desc, tag == Opcodes.H_INVOKEINTERFACE);
    }

    /**
     * Adds a handle to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item. <i>This method is
     * intended for {@link Attribute} sub classes, and is normally not needed by
     * class generators or adapters.</i>
     * 
     * @param tag
     *            the kind of this handle. Must be {@link Opcodes#H_GETFIELD},
     *            {@link Opcodes#H_GETSTATIC}, {@link Opcodes#H_PUTFIELD},
     *            {@link Opcodes#H_PUTSTATIC}, {@link Opcodes#H_INVOKEVIRTUAL},
     *            {@link Opcodes#H_INVOKESTATIC},
     *            {@link Opcodes#H_INVOKESPECIAL},
     *            {@link Opcodes#H_NEWINVOKESPECIAL} or
     *            {@link Opcodes#H_INVOKEINTERFACE}.
     * @param owner
     *            the internal name of the field or method owner class.
     * @param name
     *            the name of the field or method.
     * @param desc
     *            the descriptor of the field or method.
     * @param itf
     *            true if the owner is an interface.
     * @return the index of a new or already existing method type reference
     *         item.
     */
    public int newHandle(final int tag, final String owner, final String name,
            final String desc, final boolean itf) {
        return newHandleItem(tag, owner, name, desc, itf).index;
    }
    
    /**
     * Adds an invokedynamic reference to the constant pool of the class being
     * build. Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param name
     *            name of the invoked method.
     * @param desc
     *            descriptor of the invoke method.
     * @param bsm
     *            the bootstrap method.
     * @param bsmArgs
     *            the bootstrap method constant arguments.
     * 
     * @return a new or an already existing invokedynamic type reference item.
     */
    Item newInvokeDynamicItem(final String name, final String desc,
            final Handle bsm, final Object... bsmArgs) {
        // cache for performance
        ByteVector bootstrapMethods = this.bootstrapMethods;
        if (bootstrapMethods == null) {
            bootstrapMethods = this.bootstrapMethods = new ByteVector();
        }

        int position = bootstrapMethods.length; // record current position

        int hashCode = bsm.hashCode();
        bootstrapMethods.putShort(newHandle(bsm.tag, bsm.owner, bsm.name,
                bsm.desc, bsm.isInterface()));

        int argsLength = bsmArgs.length;
        bootstrapMethods.putShort(argsLength);

        for (int i = 0; i < argsLength; i++) {
            Object bsmArg = bsmArgs[i];
            hashCode ^= bsmArg.hashCode();
            bootstrapMethods.putShort(newConst(bsmArg));
        }

        byte[] data = bootstrapMethods.data;
        int length = (1 + 1 + argsLength) << 1; // (bsm + argCount + arguments)
        hashCode &= 0x7FFFFFFF;
        Item result = items[hashCode % items.length];
        loop: while (result != null) {
            if (result.type != BSM || result.hashCode != hashCode) {
                result = result.next;
                continue;
            }

            // because the data encode the size of the argument
            // we don't need to test if these size are equals
            int resultPosition = result.intVal;
            for (int p = 0; p < length; p++) {
                if (data[position + p] != data[resultPosition + p]) {
                    result = result.next;
                    continue loop;
                }
            }
            break;
        }

        int bootstrapMethodIndex;
        if (result != null) {
            bootstrapMethodIndex = result.index;
            bootstrapMethods.length = position; // revert to old position
        } else {
            bootstrapMethodIndex = bootstrapMethodsCount++;
            result = new Item(bootstrapMethodIndex);
            result.set(position, hashCode);
            put(result);
        }

        // now, create the InvokeDynamic constant
        key3.set(name, desc, bootstrapMethodIndex);
        result = get(key3);
        if (result == null) {
            put122(INDY, bootstrapMethodIndex, newNameType(name, desc));
            result = new Item(index++, key3);
            put(result);
        }
        return result;
    }

    /**
     * Adds an invokedynamic reference to the constant pool of the class being
     * build. Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param name
     *            name of the invoked method.
     * @param desc
     *            descriptor of the invoke method.
     * @param bsm
     *            the bootstrap method.
     * @param bsmArgs
     *            the bootstrap method constant arguments.
     * 
     * @return the index of a new or already existing invokedynamic reference
     *         item.
     */
    public int newInvokeDynamic(final String name, final String desc,
            final Handle bsm, final Object... bsmArgs) {
        return newInvokeDynamicItem(name, desc, bsm, bsmArgs).index;
    }

    /**
     * Adds a field reference to the constant pool of the class being build.
     * Does nothing if the constant pool already contains a similar item.
     * 
     * @param owner
     *            the internal name of the field's owner class.
     * @param name
     *            the field's name.
     * @param desc
     *            the field's descriptor.
     * @return a new or already existing field reference item.
     */
    Item newFieldItem(final String owner, final String name, final String desc) {
        key3.set(FIELD, owner, name, desc);
        Item result = get(key3);
        if (result == null) {
            put122(FIELD, newClass(owner), newNameType(name, desc));
            result = new Item(index++, key3);
            put(result);
        }
        return result;
    }

    /**
     * Adds a field reference to the constant pool of the class being build.
     * Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param owner
     *            the internal name of the field's owner class.
     * @param name
     *            the field's name.
     * @param desc
     *            the field's descriptor.
     * @return the index of a new or already existing field reference item.
     */
    public int newField(final String owner, final String name, final String desc) {
        return newFieldItem(owner, name, desc).index;
    }

    /**
     * Adds a method reference to the constant pool of the class being build.
     * Does nothing if the constant pool already contains a similar item.
     * 
     * @param owner
     *            the internal name of the method's owner class.
     * @param name
     *            the method's name.
     * @param desc
     *            the method's descriptor.
     * @param itf
     *            <tt>true</tt> if <tt>owner</tt> is an interface.
     * @return a new or already existing method reference item.
     */
    Item newMethodItem(final String owner, final String name,
            final String desc, final boolean itf) {
        int type = itf ? IMETH : METH;
        key3.set(type, owner, name, desc);
        Item result = get(key3);
        if (result == null) {
            put122(type, newClass(owner), newNameType(name, desc));
            result = new Item(index++, key3);
            put(result);
        }
        return result;
    }

    /**
     * Adds a method reference to the constant pool of the class being build.
     * Does nothing if the constant pool already contains a similar item.
     * <i>This method is intended for {@link Attribute} sub classes, and is
     * normally not needed by class generators or adapters.</i>
     * 
     * @param owner
     *            the internal name of the method's owner class.
     * @param name
     *            the method's name.
     * @param desc
     *            the method's descriptor.
     * @param itf
     *            <tt>true</tt> if <tt>owner</tt> is an interface.
     * @return the index of a new or already existing method reference item.
     */
    public int newMethod(final String owner, final String name,
            final String desc, final boolean itf) {
        return newMethodItem(owner, name, desc, itf).index;
    }

    /**
     * Adds an integer to the constant pool of the class being build. Does
     * nothing if the constant pool already contains a similar item.
     * 
     * @param value
     *            the int value.
     * @return a new or already existing int item.
     */
    Item newInteger(final int value) {
        key.set(value);
        Item result = get(key);
        if (result == null) {
            pool.putByte(INT).putInt(value);
            result = new Item(index++, key);
            put(result);
        }
        return result;
    }

    /**
     * Adds a float to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item.
     * 
     * @param value
     *            the float value.
     * @return a new or already existing float item.
     */
    Item newFloat(final float value) {
        key.set(value);
        Item result = get(key);
        if (result == null) {
            pool.putByte(FLOAT).putInt(key.intVal);
            result = new Item(index++, key);
            put(result);
        }
        return result;
    }

    /**
     * Adds a long to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item.
     * 
     * @param value
     *            the long value.
     * @return a new or already existing long item.
     */
    Item newLong(final long value) {
        key.set(value);
        Item result = get(key);
        if (result == null) {
            pool.putByte(LONG).putLong(value);
            result = new Item(index, key);
            index += 2;
            put(result);
        }
        return result;
    }

    /**
     * Adds a double to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item.
     * 
     * @param value
     *            the double value.
     * @return a new or already existing double item.
     */
    Item newDouble(final double value) {
        key.set(value);
        Item result = get(key);
        if (result == null) {
            pool.putByte(DOUBLE).putLong(key.longVal);
            result = new Item(index, key);
            index += 2;
            put(result);
        }
        return result;
    }

    /**
     * Adds a string to the constant pool of the class being build. Does nothing
     * if the constant pool already contains a similar item.
     * 
     * @param value
     *            the String value.
     * @return a new or already existing string item.
     */
    private Item newString(final String value) {
        key2.set(STR, value, null, null);
        Item result = get(key2);
        if (result == null) {
            pool.put12(STR, newUTF8(value));
            result = new Item(index++, key2);
            put(result);
        }
        return result;
    }

    /**
     * Adds a name and type to the constant pool of the class being build. Does
     * nothing if the constant pool already contains a similar item. <i>This
     * method is intended for {@link Attribute} sub classes, and is normally not
     * needed by class generators or adapters.</i>
     * 
     * @param name
     *            a name.
     * @param desc
     *            a type descriptor.
     * @return the index of a new or already existing name and type item.
     */
    public int newNameType(final String name, final String desc) {
        return newNameTypeItem(name, desc).index;
    }

    /**
     * Adds a name and type to the constant pool of the class being build. Does
     * nothing if the constant pool already contains a similar item.
     * 
     * @param name
     *            a name.
     * @param desc
     *            a type descriptor.
     * @return a new or already existing name and type item.
     */
    Item newNameTypeItem(final String name, final String desc) {
        key2.set(NAME_TYPE, name, desc, null);
        Item result = get(key2);
        if (result == null) {
            put122(NAME_TYPE, newUTF8(name), newUTF8(desc));
            result = new Item(index++, key2);
            put(result);
        }
        return result;
    }

    /**
     * Adds the given internal name to {@link #typeTable} and returns its index.
     * Does nothing if the type table already contains this internal name.
     * 
     * @param type
     *            the internal name to be added to the type table.
     * @return the index of this internal name in the type table.
     */
    int addType(final String type) {
        key.set(TYPE_NORMAL, type, null, null);
        Item result = get(key);
        if (result == null) {
            result = addType(key);
        }
        return result.index;
    }

    /**
     * Adds the given "uninitialized" type to {@link #typeTable} and returns its
     * index. This method is used for UNINITIALIZED types, made of an internal
     * name and a bytecode offset.
     * 
     * @param type
     *            the internal name to be added to the type table.
     * @param offset
     *            the bytecode offset of the NEW instruction that created this
     *            UNINITIALIZED type value.
     * @return the index of this internal name in the type table.
     */
    int addUninitializedType(final String type, final int offset) {
        key.type = TYPE_UNINIT;
        key.intVal = offset;
        key.strVal1 = type;
        key.hashCode = 0x7FFFFFFF & (TYPE_UNINIT + type.hashCode() + offset);
        Item result = get(key);
        if (result == null) {
            result = addType(key);
        }
        return result.index;
    }

    /**
     * Adds the given Item to {@link #typeTable}.
     * 
     * @param item
     *            the value to be added to the type table.
     * @return the added Item, which a new Item instance with the same value as
     *         the given Item.
     */
    private Item addType(final Item item) {
        ++typeCount;
        Item result = new Item(typeCount, key);
        put(result);
        if (typeTable == null) {
            typeTable = new Item[16];
        }
        if (typeCount == typeTable.length) {
            Item[] newTable = new Item[2 * typeTable.length];
            System.arraycopy(typeTable, 0, newTable, 0, typeTable.length);
            typeTable = newTable;
        }
        typeTable[typeCount] = result;
        return result;
    }

    /**
     * Returns the index of the common super type of the two given types. This
     * method calls {@link #getCommonSuperClass} and caches the result in the
     * {@link #items} hash table to speedup future calls with the same
     * parameters.
     * 
     * @param type1
     *            index of an internal name in {@link #typeTable}.
     * @param type2
     *            index of an internal name in {@link #typeTable}.
     * @return the index of the common super type of the two given types.
     */
    int getMergedType(final int type1, final int type2) {
        key2.type = TYPE_MERGED;
        key2.longVal = type1 | (((long) type2) << 32);
        key2.hashCode = 0x7FFFFFFF & (TYPE_MERGED + type1 + type2);
        Item result = get(key2);
        if (result == null) {
            String t = typeTable[type1].strVal1;
            String u = typeTable[type2].strVal1;
            key2.intVal = addType(getCommonSuperClass(t, u));
            result = new Item((short) 0, key2);
            put(result);
        }
        return result.intVal;
    }

    /**
     * Returns the common super type of the two given types. The default
     * implementation of this method <i>loads</i> the two given classes and uses
     * the java.lang.Class methods to find the common super class. It can be
     * overridden to compute this common super type in other ways, in particular
     * without actually loading any class, or to take into account the class
     * that is currently being generated by this ClassWriter, which can of
     * course not be loaded since it is under construction.
     * 
     * @param type1
     *            the internal name of a class.
     * @param type2
     *            the internal name of another class.
     * @return the internal name of the common super class of the two given
     *         classes.
     */
    protected String getCommonSuperClass(final String type1, final String type2) {
        Class<?> c, d;
        ClassLoader classLoader = getClass().getClassLoader();
        try {
            c = Class.forName(type1.replace('/', '.'), false, classLoader);
            d = Class.forName(type2.replace('/', '.'), false, classLoader);
        } catch (Exception e) {
            throw new RuntimeException(e.toString());
        }
        if (c.isAssignableFrom(d)) {
            return type1;
        }
        if (d.isAssignableFrom(c)) {
            return type2;
        }
        if (c.isInterface() || d.isInterface()) {
            return "java/lang/Object";
        } else {
            do {
                c = c.getSuperclass();
            } while (!c.isAssignableFrom(d));
            return c.getName().replace('.', '/');
        }
    }

    /**
     * Returns the constant pool's hash table item which is equal to the given
     * item.
     * 
     * @param key
     *            a constant pool item.
     * @return the constant pool's hash table item which is equal to the given
     *         item, or <tt>null</tt> if there is no such item.
     */
    private Item get(final Item key) {
        Item i = items[key.hashCode % items.length];
        while (i != null && (i.type != key.type || !key.isEqualTo(i))) {
            i = i.next;
        }
        return i;
    }

    /**
     * Puts the given item in the constant pool's hash table. The hash table
     * <i>must</i> not already contains this item.
     * 
     * @param i
     *            the item to be added to the constant pool's hash table.
     */
    private void put(final Item i) {
        if (index + typeCount > threshold) {
            int ll = items.length;
            int nl = ll * 2 + 1;
            Item[] newItems = new Item[nl];
            for (int l = ll - 1; l >= 0; --l) {
                Item j = items[l];
                while (j != null) {
                    int index = j.hashCode % newItems.length;
                    Item k = j.next;
                    j.next = newItems[index];
                    newItems[index] = j;
                    j = k;
                }
            }
            items = newItems;
            threshold = (int) (nl * 0.75);
        }
        int index = i.hashCode % items.length;
        i.next = items[index];
        items[index] = i;
    }

    /**
     * Puts one byte and two shorts into the constant pool.
     * 
     * @param b
     *            a byte.
     * @param s1
     *            a short.
     * @param s2
     *            another short.
     */
    private void put122(final int b, final int s1, final int s2) {
        pool.put12(b, s1).putShort(s2);
    }

    /**
     * Puts two bytes and one short into the constant pool.
     * 
     * @param b1
     *            a byte.
     * @param b2
     *            another byte.
     * @param s
     *            a short.
     */
    private void put112(final int b1, final int b2, final int s) {
        pool.put11(b1, b2).putShort(s);
    }
}