Mercurial > lasercutter

     1 <html>

     2 <!--

     3  * ASM: a very small and fast Java bytecode manipulation framework

     4  * Copyright (c) 2000-2005 INRIA, France Telecom

     5  * All rights reserved.

     6  *

     7  * Redistribution and use in source and binary forms, with or without

     8  * modification, are permitted provided that the following conditions

     9  * are met:

    10  * 1. Redistributions of source code must retain the above copyright

    11  *    notice, this list of conditions and the following disclaimer.

    12  * 2. Redistributions in binary form must reproduce the above copyright

    13  *    notice, this list of conditions and the following disclaimer in the

    14  *    documentation and/or other materials provided with the distribution.

    15  * 3. Neither the name of the copyright holders nor the names of its

    16  *    contributors may be used to endorse or promote products derived from

    17  *    this software without specific prior written permission.

    18  *

    19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    20  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    22  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

    23  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF

    29  * THE POSSIBILITY OF SUCH DAMAGE.

    30 -->

    31 <body>

    32 Provides a small and fast bytecode manipulation framework.

    33 

    34 <p>

    35 	The <a href="http://www.objectweb.org/asm">ASM</a> framework is organized

    36 	around the {@link clojure.asm.ClassVisitor ClassVisitor},

    37 	{@link clojure.asm.FieldVisitor FieldVisitor} and

    38 	{@link clojure.asm.MethodVisitor MethodVisitor} interfaces, which allow

    39 	one to visit the fields and methods of a class, including the bytecode

    40 	instructions of each method.

    41 

    42 <p>

    43 	In addition to these main interfaces, ASM provides a {@link

    44 	clojure.asm.ClassReader ClassReader} class, that can parse an

    45 	existing class and make a given visitor visit it. ASM also provides

    46 	a {@link clojure.asm.ClassWriter ClassWriter} class, which is

    47 	a visitor that generates Java class files.

    48 

    49 <p>

    50 	In order to generate a class from scratch, only the {@link

    51 	clojure.asm.ClassWriter ClassWriter} class is necessary. Indeed,

    52 	in order to generate a class, one must just call its visit<i>XXX</i>

    53 	methods with the appropriate arguments to generate the desired fields

    54 	and methods. See the "helloworld" example in the ASM distribution for

    55 	more details about class generation.

    56 

    57 <p>

    58 	In order to modify existing classes, one must use a {@link

    59 	clojure.asm.ClassReader ClassReader} class to analyze

    60 	the original class, a class modifier, and a {@link clojure.asm.ClassWriter

    61 	ClassWriter} to construct the modified class. The class modifier

    62 	is just a {@link clojure.asm.ClassVisitor ClassVisitor}

    63 	that delegates most of the work to another {@link clojure.asm.ClassVisitor

    64 	ClassVisitor}, but that sometimes changes some parameter values,

    65 	or call additional methods, in order to implement the desired

    66 	modification process. In order to make it easier to implement such

    67 	class modifiers, ASM provides the {@link clojure.asm.ClassAdapter

    68 	ClassAdapter} and {@link clojure.asm.MethodAdapter MethodAdapter}

    69 	classes, which implement the {@link clojure.asm.ClassVisitor ClassVisitor}

    70 	and {@link clojure.asm.MethodVisitor MethodVisitor} interfaces by

    71 	delegating all work to other visitors. See the "adapt" example in the ASM

    72 	distribution for more details about class modification.

    73 

    74 <p>

    75 	The size of the core ASM library, <tt>asm.jar</tt>, is only 42KB, which is much

    76 	smaller than the size of the

    77 	<a href="http://jakarta.apache.org/bcel">BCEL</a> library (504KB), and than the

    78 	size of the

    79 	<a href="http://serp.sourceforge.net">SERP</a> library (150KB). ASM is also

    80 	much faster than these tools. Indeed the overhead of a load time class

    81 	transformation process is of the order of 60% with ASM, 700% or more with BCEL,

    82 	and 1100% or more with SERP (see the <tt>test/perf</tt> directory in the ASM

    83 	distribution)!

    84 

    85 	@since ASM 1.3

    86 </body>

    87 </html>
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 21 Aug 2010 06:25:44 -0400
parents
children