http://asm.objectweb.org/asm/: A very small and fast Java bytecode manipulation framework (ObjectWeb)
  • Eric Bruneton
  • Eugene Kuleshov
  • Remi Forax 
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;


An AnnotationVisitor that generates annotations in bytecode form. 
Author:Eric Bruneton, Eugene Kuleshov
/**
 * An {@link AnnotationVisitor} that generates annotations in bytecode form.
 * 
 * @author Eric Bruneton
 * @author Eugene Kuleshov
 */
final class AnnotationWriter extends AnnotationVisitor {

    
The class writer to which this annotation must be added.

/**
     * The class writer to which this annotation must be added.
     */
    private final ClassWriter cw;

    
The number of values in this annotation.

/**
     * The number of values in this annotation.
     */
    private int size;

    
true if values are named, false otherwise. Annotation
writers used for annotation default and annotation arrays use unnamed
values.

/**
     * <tt>true<tt> if values are named, <tt>false</tt> otherwise. Annotation
     * writers used for annotation default and annotation arrays use unnamed
     * values.
     */
    private final boolean named;

    
The annotation values in bytecode form. This byte vector only contains
the values themselves, i.e. the number of values must be stored as a
unsigned short just before these bytes.

/**
     * The annotation values in bytecode form. This byte vector only contains
     * the values themselves, i.e. the number of values must be stored as a
     * unsigned short just before these bytes.
     */
    private final ByteVector bv;

    
The byte vector to be used to store the number of values of this annotation. See bv. 
/**
     * The byte vector to be used to store the number of values of this
     * annotation. See {@link #bv}.
     */
    private final ByteVector parent;

    
Where the number of values of this annotation must be stored in parent. 
/**
     * Where the number of values of this annotation must be stored in
     * {@link #parent}.
     */
    private final int offset;

    
Next annotation writer. This field is used to store annotation lists.

/**
     * Next annotation writer. This field is used to store annotation lists.
     */
    AnnotationWriter next;

    
Previous annotation writer. This field is used to store annotation lists.

/**
     * Previous annotation writer. This field is used to store annotation lists.
     */
    AnnotationWriter prev;

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

    
Constructs a new AnnotationWriter. 
Params:
  • cw – 
           the class writer to which this annotation must be added.
  • named – 
           true if values are named, false otherwise.
  • bv – 
           where the annotation values must be stored.
  • parent – 
           where the number of annotation values must be stored.
  • offset – 
           where in parent the number of annotation values must
           be stored.
/**
     * Constructs a new {@link AnnotationWriter}.
     * 
     * @param cw
     *            the class writer to which this annotation must be added.
     * @param named
     *            <tt>true<tt> if values are named, <tt>false</tt> otherwise.
     * @param bv
     *            where the annotation values must be stored.
     * @param parent
     *            where the number of annotation values must be stored.
     * @param offset
     *            where in <tt>parent</tt> the number of annotation values must
     *            be stored.
     */
    AnnotationWriter(final ClassWriter cw, final boolean named,
            final ByteVector bv, final ByteVector parent, final int offset) {
        super(Opcodes.ASM5);
        this.cw = cw;
        this.named = named;
        this.bv = bv;
        this.parent = parent;
        this.offset = offset;
    }

    // ------------------------------------------------------------------------
    // Implementation of the AnnotationVisitor abstract class
    // ------------------------------------------------------------------------

    @Override
    public void visit(final String name, final Object value) {
        ++size;
        if (named) {
            bv.putShort(cw.newUTF8(name));
        }
        if (value instanceof String) {
            bv.put12('s', cw.newUTF8((String) value));
        } else if (value instanceof Byte) {
            bv.put12('B', cw.newInteger(((Byte) value).byteValue()).index);
        } else if (value instanceof Boolean) {
            int v = ((Boolean) value).booleanValue() ? 1 : 0;
            bv.put12('Z', cw.newInteger(v).index);
        } else if (value instanceof Character) {
            bv.put12('C', cw.newInteger(((Character) value).charValue()).index);
        } else if (value instanceof Short) {
            bv.put12('S', cw.newInteger(((Short) value).shortValue()).index);
        } else if (value instanceof Type) {
            bv.put12('c', cw.newUTF8(((Type) value).getDescriptor()));
        } else if (value instanceof byte[]) {
            byte[] v = (byte[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('B', cw.newInteger(v[i]).index);
            }
        } else if (value instanceof boolean[]) {
            boolean[] v = (boolean[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('Z', cw.newInteger(v[i] ? 1 : 0).index);
            }
        } else if (value instanceof short[]) {
            short[] v = (short[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('S', cw.newInteger(v[i]).index);
            }
        } else if (value instanceof char[]) {
            char[] v = (char[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('C', cw.newInteger(v[i]).index);
            }
        } else if (value instanceof int[]) {
            int[] v = (int[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('I', cw.newInteger(v[i]).index);
            }
        } else if (value instanceof long[]) {
            long[] v = (long[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('J', cw.newLong(v[i]).index);
            }
        } else if (value instanceof float[]) {
            float[] v = (float[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('F', cw.newFloat(v[i]).index);
            }
        } else if (value instanceof double[]) {
            double[] v = (double[]) value;
            bv.put12('[', v.length);
            for (int i = 0; i < v.length; i++) {
                bv.put12('D', cw.newDouble(v[i]).index);
            }
        } else {
            Item i = cw.newConstItem(value);
            bv.put12(".s.IFJDCS".charAt(i.type), i.index);
        }
    }

    @Override
    public void visitEnum(final String name, final String desc,
            final String value) {
        ++size;
        if (named) {
            bv.putShort(cw.newUTF8(name));
        }
        bv.put12('e', cw.newUTF8(desc)).putShort(cw.newUTF8(value));
    }

    @Override
    public AnnotationVisitor visitAnnotation(final String name,
            final String desc) {
        ++size;
        if (named) {
            bv.putShort(cw.newUTF8(name));
        }
        // write tag and type, and reserve space for values count
        bv.put12('@', cw.newUTF8(desc)).putShort(0);
        return new AnnotationWriter(cw, true, bv, bv, bv.length - 2);
    }

    @Override
    public AnnotationVisitor visitArray(final String name) {
        ++size;
        if (named) {
            bv.putShort(cw.newUTF8(name));
        }
        // write tag, and reserve space for array size
        bv.put12('[', 0);
        return new AnnotationWriter(cw, false, bv, bv, bv.length - 2);
    }

    @Override
    public void visitEnd() {
        if (parent != null) {
            byte[] data = parent.data;
            data[offset] = (byte) (size >>> 8);
            data[offset + 1] = (byte) size;
        }
    }

    // ------------------------------------------------------------------------
    // Utility methods
    // ------------------------------------------------------------------------

    
Returns the size of this annotation writer list.

Returns:the size of this annotation writer list.
/**
     * Returns the size of this annotation writer list.
     * 
     * @return the size of this annotation writer list.
     */
    int getSize() {
        int size = 0;
        AnnotationWriter aw = this;
        while (aw != null) {
            size += aw.bv.length;
            aw = aw.next;
        }
        return size;
    }

    
Puts the annotations of this annotation writer list into the given byte
vector.

Params:
  • out – 
           where the annotations must be put.
/**
     * Puts the annotations of this annotation writer list into the given byte
     * vector.
     * 
     * @param out
     *            where the annotations must be put.
     */
    void put(final ByteVector out) {
        int n = 0;
        int size = 2;
        AnnotationWriter aw = this;
        AnnotationWriter last = null;
        while (aw != null) {
            ++n;
            size += aw.bv.length;
            aw.visitEnd(); // in case user forgot to call visitEnd
            aw.prev = last;
            last = aw;
            aw = aw.next;
        }
        out.putInt(size);
        out.putShort(n);
        aw = last;
        while (aw != null) {
            out.putByteArray(aw.bv.data, 0, aw.bv.length);
            aw = aw.prev;
        }
    }

    
Puts the given annotation lists into the given byte vector.

Params:
  • panns – 
           an array of annotation writer lists.
  • off – 
           index of the first annotation to be written.
  • out – 
           where the annotations must be put.
/**
     * Puts the given annotation lists into the given byte vector.
     * 
     * @param panns
     *            an array of annotation writer lists.
     * @param off
     *            index of the first annotation to be written.
     * @param out
     *            where the annotations must be put.
     */
    static void put(final AnnotationWriter[] panns, final int off,
            final ByteVector out) {
        int size = 1 + 2 * (panns.length - off);
        for (int i = off; i < panns.length; ++i) {
            size += panns[i] == null ? 0 : panns[i].getSize();
        }
        out.putInt(size).putByte(panns.length - off);
        for (int i = off; i < panns.length; ++i) {
            AnnotationWriter aw = panns[i];
            AnnotationWriter last = null;
            int n = 0;
            while (aw != null) {
                ++n;
                aw.visitEnd(); // in case user forgot to call visitEnd
                aw.prev = last;
                last = aw;
                aw = aw.next;
            }
            out.putShort(n);
            aw = last;
            while (aw != null) {
                out.putByteArray(aw.bv.data, 0, aw.bv.length);
                aw = aw.prev;
            }
        }
    }

    
Puts the given type reference and type path into the given bytevector.
LOCAL_VARIABLE and RESOURCE_VARIABLE target types are not supported.

Params:
  • typeRef –  a reference to the annotated type. See TypeReference.
  • typePath – 
           the path to the annotated type argument, wildcard bound, array
           element type, or static inner type within 'typeRef'. May be
           null if the annotation targets 'typeRef' as a whole.
  • out – 
           where the type reference and type path must be put.
/**
     * Puts the given type reference and type path into the given bytevector.
     * LOCAL_VARIABLE and RESOURCE_VARIABLE target types are not supported.
     * 
     * @param typeRef
     *            a reference to the annotated type. See {@link TypeReference}.
     * @param typePath
     *            the path to the annotated type argument, wildcard bound, array
     *            element type, or static inner type within 'typeRef'. May be
     *            <tt>null</tt> if the annotation targets 'typeRef' as a whole.
     * @param out
     *            where the type reference and type path must be put.
     */
    static void putTarget(int typeRef, TypePath typePath, ByteVector out) {
        switch (typeRef >>> 24) {
        case 0x00: // CLASS_TYPE_PARAMETER
        case 0x01: // METHOD_TYPE_PARAMETER
        case 0x16: // METHOD_FORMAL_PARAMETER
            out.putShort(typeRef >>> 16);
            break;
        case 0x13: // FIELD
        case 0x14: // METHOD_RETURN
        case 0x15: // METHOD_RECEIVER
            out.putByte(typeRef >>> 24);
            break;
        case 0x47: // CAST
        case 0x48: // CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT
        case 0x49: // METHOD_INVOCATION_TYPE_ARGUMENT
        case 0x4A: // CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT
        case 0x4B: // METHOD_REFERENCE_TYPE_ARGUMENT
            out.putInt(typeRef);
            break;
        // case 0x10: // CLASS_EXTENDS
        // case 0x11: // CLASS_TYPE_PARAMETER_BOUND
        // case 0x12: // METHOD_TYPE_PARAMETER_BOUND
        // case 0x17: // THROWS
        // case 0x42: // EXCEPTION_PARAMETER
        // case 0x43: // INSTANCEOF
        // case 0x44: // NEW
        // case 0x45: // CONSTRUCTOR_REFERENCE
        // case 0x46: // METHOD_REFERENCE
        default:
            out.put12(typeRef >>> 24, (typeRef & 0xFFFF00) >> 8);
            break;
        }
        if (typePath == null) {
            out.putByte(0);
        } else {
            int length = typePath.b[typePath.offset] * 2 + 1;
            out.putByteArray(typePath.b, typePath.offset, length);
        }
    }
}