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


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);
        }
    }
}