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1 <html>
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2 <!--
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3 * ASM: a very small and fast Java bytecode manipulation framework
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4 * Copyright (c) 2000-2005 INRIA, France Telecom
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5 * All rights reserved.
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6 *
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7 * Redistribution and use in source and binary forms, with or without
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8 * modification, are permitted provided that the following conditions
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9 * are met:
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10 * 1. Redistributions of source code must retain the above copyright
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11 * notice, this list of conditions and the following disclaimer.
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12 * 2. Redistributions in binary form must reproduce the above copyright
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13 * notice, this list of conditions and the following disclaimer in the
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14 * documentation and/or other materials provided with the distribution.
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15 * 3. Neither the name of the copyright holders nor the names of its
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16 * contributors may be used to endorse or promote products derived from
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17 * this software without specific prior written permission.
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18 *
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19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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20 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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22 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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23 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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29 * THE POSSIBILITY OF SUCH DAMAGE.
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30 -->
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31 <body>
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32 Provides a small and fast bytecode manipulation framework.
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33
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34 <p>
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35 The <a href="http://www.objectweb.org/asm">ASM</a> framework is organized
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36 around the {@link clojure.asm.ClassVisitor ClassVisitor},
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37 {@link clojure.asm.FieldVisitor FieldVisitor} and
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38 {@link clojure.asm.MethodVisitor MethodVisitor} interfaces, which allow
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39 one to visit the fields and methods of a class, including the bytecode
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40 instructions of each method.
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41
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42 <p>
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43 In addition to these main interfaces, ASM provides a {@link
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44 clojure.asm.ClassReader ClassReader} class, that can parse an
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45 existing class and make a given visitor visit it. ASM also provides
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46 a {@link clojure.asm.ClassWriter ClassWriter} class, which is
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47 a visitor that generates Java class files.
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48
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49 <p>
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50 In order to generate a class from scratch, only the {@link
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51 clojure.asm.ClassWriter ClassWriter} class is necessary. Indeed,
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52 in order to generate a class, one must just call its visit<i>XXX</i>
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53 methods with the appropriate arguments to generate the desired fields
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54 and methods. See the "helloworld" example in the ASM distribution for
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55 more details about class generation.
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56
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57 <p>
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58 In order to modify existing classes, one must use a {@link
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59 clojure.asm.ClassReader ClassReader} class to analyze
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60 the original class, a class modifier, and a {@link clojure.asm.ClassWriter
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61 ClassWriter} to construct the modified class. The class modifier
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62 is just a {@link clojure.asm.ClassVisitor ClassVisitor}
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63 that delegates most of the work to another {@link clojure.asm.ClassVisitor
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64 ClassVisitor}, but that sometimes changes some parameter values,
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65 or call additional methods, in order to implement the desired
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66 modification process. In order to make it easier to implement such
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67 class modifiers, ASM provides the {@link clojure.asm.ClassAdapter
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68 ClassAdapter} and {@link clojure.asm.MethodAdapter MethodAdapter}
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69 classes, which implement the {@link clojure.asm.ClassVisitor ClassVisitor}
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70 and {@link clojure.asm.MethodVisitor MethodVisitor} interfaces by
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71 delegating all work to other visitors. See the "adapt" example in the ASM
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72 distribution for more details about class modification.
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73
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74 <p>
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75 The size of the core ASM library, <tt>asm.jar</tt>, is only 42KB, which is much
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76 smaller than the size of the
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77 <a href="http://jakarta.apache.org/bcel">BCEL</a> library (504KB), and than the
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78 size of the
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79 <a href="http://serp.sourceforge.net">SERP</a> library (150KB). ASM is also
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80 much faster than these tools. Indeed the overhead of a load time class
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81 transformation process is of the order of 60% with ASM, 700% or more with BCEL,
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82 and 1100% or more with SERP (see the <tt>test/perf</tt> directory in the ASM
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83 distribution)!
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84
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85 @since ASM 1.3
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86 </body>
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87 </html>
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