src/examples/JasminVisitor.java - commons-bcel - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   https://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */

 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.nio.charset.StandardCharsets;
 import java.util.Date;
 import java.util.Hashtable;
 import java.util.StringTokenizer;

 import org.apache.bcel.Const;
 import org.apache.bcel.Repository;
 import org.apache.bcel.classfile.Attribute;
 import org.apache.bcel.classfile.ClassParser;
 import org.apache.bcel.classfile.Code;
 import org.apache.bcel.classfile.ConstantValue;
 import org.apache.bcel.classfile.Deprecated;
 import org.apache.bcel.classfile.ExceptionTable;
 import org.apache.bcel.classfile.Field;
 import org.apache.bcel.classfile.JavaClass;
 import org.apache.bcel.classfile.Method;
 import org.apache.bcel.classfile.Synthetic;
 import org.apache.bcel.classfile.Utility;
 import org.apache.bcel.generic.BranchHandle;
 import org.apache.bcel.generic.BranchInstruction;
 import org.apache.bcel.generic.CodeExceptionGen;
 import org.apache.bcel.generic.ConstantPoolGen;
 import org.apache.bcel.generic.Instruction;
 import org.apache.bcel.generic.InstructionHandle;
 import org.apache.bcel.generic.InstructionList;
 import org.apache.bcel.generic.LineNumberGen;
 import org.apache.bcel.generic.LocalVariableGen;
 import org.apache.bcel.generic.MethodGen;
 import org.apache.bcel.generic.ObjectType;
 import org.apache.bcel.generic.Select;
 import org.apache.bcel.generic.TABLESWITCH;

 /**
  * Disassemble Java class object into the <a href="https://jasmin.sourceforge.net"> Jasmin</a> format.
  */
 public class JasminVisitor extends org.apache.bcel.classfile.EmptyVisitor {
     public static void main(final String[] argv) throws Exception {
         JavaClass javaClass;

         if (argv.length == 0) {
             System.err.println("disassemble: No input files specified");
             return;
         }

         for (final String arg : argv) {
             if ((javaClass = Repository.lookupClass(arg)) == null) {
                 javaClass = new ClassParser(arg).parse();
             }

             String className = javaClass.getClassName();
             final int index = className.lastIndexOf('.');
             final String path = className.substring(0, index + 1).replace('.', File.separatorChar);
             className = className.substring(index + 1);

             if (!path.isEmpty()) {
                 final File file = new File(path);
                 if (!file.mkdirs()) {
                     System.err.println("Couldn't create directories for " + file);
                 }
             }

             final String name = path + className + ".j";
             try (FileOutputStream out = new FileOutputStream(name)) {
                 new JasminVisitor(javaClass, out).disassemble();
                 System.out.println("File dumped to: " + name);
             }
         }
     }

     private final JavaClass javaClass;
     private final PrintWriter printWriter;
     private final String className;

     private final ConstantPoolGen cp;

     private Method method;

     private Hashtable<InstructionHandle, String> map;

     public JasminVisitor(final JavaClass clazz, final OutputStream out) {
         this.javaClass = clazz;
         this.printWriter = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8)), false);
         this.className = clazz.getClassName();
         this.cp = new ConstantPoolGen(clazz.getConstantPool());
     }

     /**
      * Start traversal using DefaultVisitor pattern.
      */
     public void disassemble() {
         new org.apache.bcel.classfile.DescendingVisitor(javaClass, this).visit();
         printWriter.close();
     }

     private String get(final InstructionHandle ih) {
         final String str = new StringTokenizer(map.get(ih), "\n").nextToken();
         return str.substring(0, str.length() - 1);
     }

     /**
      * Unfortunately Jasmin expects ".end method" after each method. Thus we've to check for every of the method's
      * attributes if it's the last one and print ".end method" then.
      */
     private void printEndMethod(final Attribute attr) {
         final Attribute[] attributes = method.getAttributes();

         if (attr == attributes[attributes.length - 1]) {
             printWriter.println(".end method");
         }
     }

     private void put(final InstructionHandle ih, final String line) {
         final String str = map.get(ih);

         if (str == null) {
             map.put(ih, line);
         } else {
             if (line.startsWith("Label") || str.endsWith(line)) {
                 return;
             }

             map.put(ih, str + "\n" + line); // append
         }
     }

     @Override
     public void visitCode(final Code code) {
         int labelCounter = 0;

         printWriter.println(".limit stack " + code.getMaxStack());
         printWriter.println(".limit locals " + code.getMaxLocals());

         final MethodGen mg = new MethodGen(method, className, cp);
         final InstructionList il = mg.getInstructionList();
         final InstructionHandle[] ihs = il.getInstructionHandles();

         /*
          * Pass 1: Give all referenced instruction handles a symbolic name, for example a label.
          */
         map = new Hashtable<>();

         for (final InstructionHandle ih1 : ihs) {
             if (ih1 instanceof BranchHandle) {
                 final BranchInstruction bi = (BranchInstruction) ih1.getInstruction();

                 if (bi instanceof Select) { // Special cases LOOKUPSWITCH and TABLESWITCH
                     for (final InstructionHandle target : ((Select) bi).getTargets()) {
                         put(target, "Label" + labelCounter++ + ":");
                     }
                 }

                 final InstructionHandle ih = bi.getTarget();
                 put(ih, "Label" + labelCounter++ + ":");
             }
         }

         final LocalVariableGen[] lvs = mg.getLocalVariables();
         for (final LocalVariableGen lv : lvs) {
             InstructionHandle ih = lv.getStart();
             put(ih, "Label" + labelCounter++ + ":");
             ih = lv.getEnd();
             put(ih, "Label" + labelCounter++ + ":");
         }

         final CodeExceptionGen[] ehs = mg.getExceptionHandlers();
         for (final CodeExceptionGen c : ehs) {
             InstructionHandle ih = c.getStartPC();

             put(ih, "Label" + labelCounter++ + ":");
             ih = c.getEndPC();
             put(ih, "Label" + labelCounter++ + ":");
             ih = c.getHandlerPC();
             put(ih, "Label" + labelCounter++ + ":");
         }

         final LineNumberGen[] lns = mg.getLineNumbers();
         for (final LineNumberGen ln : lns) {
             final InstructionHandle ih = ln.getInstruction();
             put(ih, ".line " + ln.getSourceLine());
         }

         // Pass 2: Output code.
         for (final LocalVariableGen l : lvs) {
             printWriter.println(
                 ".var " + l.getIndex() + " is " + l.getName() + " " + l.getType().getSignature() + " from " + get(l.getStart()) + " to " + get(l.getEnd()));
         }

         printWriter.print("\n");

         for (InstructionHandle ih : ihs) {
             final Instruction inst = ih.getInstruction();
             String str = map.get(ih);

             if (str != null) {
                 printWriter.println(str);
             }

             if (inst instanceof BranchInstruction) {
                 if (inst instanceof Select) { // Special cases LOOKUPSWITCH and TABLESWITCH
                     final Select s = (Select) inst;
                     final int[] matchs = s.getMatchs();
                     final InstructionHandle[] targets = s.getTargets();

                     if (s instanceof TABLESWITCH) {
                         printWriter.println("\ttableswitch " + matchs[0] + " " + matchs[matchs.length - 1]);

                         for (final InstructionHandle target : targets) {
                             printWriter.println("\t\t" + get(target));
                         }

                     } else { // LOOKUPSWITCH
                         printWriter.println("\tlookupswitch ");

                         for (int j = 0; j < targets.length; j++) {
                             printWriter.println("\t\t" + matchs[j] + " : " + get(targets[j]));
                         }
                     }

                     printWriter.println("\t\tdefault: " + get(s.getTarget())); // Applies for both
                 } else {
                     final BranchInstruction bi = (BranchInstruction) inst;
                     ih = bi.getTarget();
                     str = get(ih);
                     printWriter.println("\t" + Const.getOpcodeName(bi.getOpcode()) + " " + str);
                 }
             } else {
                 printWriter.println("\t" + inst.toString(cp.getConstantPool()));
             }
         }

         printWriter.print("\n");

         for (final CodeExceptionGen c : ehs) {
             final ObjectType caught = c.getCatchType();
             final String className = caught == null ? // catch any exception, used when compiling finally
                 "all" : Utility.packageToPath(caught.getClassName());

             printWriter.println(".catch " + className + " from " + get(c.getStartPC()) + " to " + get(c.getEndPC()) + " using " + get(c.getHandlerPC()));
         }

         printEndMethod(code);
     }

     @Override
     public void visitConstantValue(final ConstantValue cv) {
         printWriter.println(" = " + cv);
     }

     @Override
     public void visitDeprecated(final Deprecated attribute) {
         printEndMethod(attribute);
     }

     @Override
     public void visitExceptionTable(final ExceptionTable e) {
         for (final String name : e.getExceptionNames()) {
             printWriter.println(".throws " + Utility.packageToPath(name));
         }

         printEndMethod(e);
     }

     @Override
     public void visitField(final Field field) {
         printWriter.print(".field " + Utility.accessToString(field.getAccessFlags()) + " \"" + field.getName() + "\"" + field.getSignature());
         if (field.getAttributes().length == 0) {
             printWriter.print("\n");
         }
     }

     @Override
     public void visitJavaClass(final JavaClass clazz) {
         printWriter.println(";; Produced by JasminVisitor (BCEL)");
         printWriter.println(";; https://commons.apache.org/bcel/");
         printWriter.println(";; " + new Date() + "\n");

         printWriter.println(".source " + clazz.getSourceFileName());
         printWriter.println("." + Utility.classOrInterface(clazz.getAccessFlags()) + " " + Utility.accessToString(clazz.getAccessFlags(), true) + " "
             + Utility.packageToPath(clazz.getClassName()));
         printWriter.println(".super " + Utility.packageToPath(clazz.getSuperclassName()));

         for (final String iface : clazz.getInterfaceNames()) {
             printWriter.println(".implements " + Utility.packageToPath(iface));
         }

         printWriter.print("\n");
     }

     @Override
     public void visitMethod(final Method visitMethod) {
         this.method = visitMethod; // Remember for use in subsequent visitXXX calls

         printWriter.println("\n.method " + Utility.accessToString(method.getAccessFlags()) + " " + method.getName() + method.getSignature());

         final Attribute[] attributes = method.getAttributes();
         if (attributes == null || attributes.length == 0) {
             printWriter.println(".end method");
         }
     }

     @Override
     public void visitSynthetic(final Synthetic attribute) {
         if (method != null) {
             printEndMethod(attribute);
         }
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* https://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/

	import java.io.BufferedWriter;
	import java.io.File;
	import java.io.FileOutputStream;
	import java.io.OutputStream;
	import java.io.OutputStreamWriter;
	import java.io.PrintWriter;
	import java.nio.charset.StandardCharsets;
	import java.util.Date;
	import java.util.Hashtable;
	import java.util.StringTokenizer;

	import org.apache.bcel.Const;
	import org.apache.bcel.Repository;
	import org.apache.bcel.classfile.Attribute;
	import org.apache.bcel.classfile.ClassParser;
	import org.apache.bcel.classfile.Code;
	import org.apache.bcel.classfile.ConstantValue;
	import org.apache.bcel.classfile.Deprecated;
	import org.apache.bcel.classfile.ExceptionTable;
	import org.apache.bcel.classfile.Field;
	import org.apache.bcel.classfile.JavaClass;
	import org.apache.bcel.classfile.Method;
	import org.apache.bcel.classfile.Synthetic;
	import org.apache.bcel.classfile.Utility;
	import org.apache.bcel.generic.BranchHandle;
	import org.apache.bcel.generic.BranchInstruction;
	import org.apache.bcel.generic.CodeExceptionGen;
	import org.apache.bcel.generic.ConstantPoolGen;
	import org.apache.bcel.generic.Instruction;
	import org.apache.bcel.generic.InstructionHandle;
	import org.apache.bcel.generic.InstructionList;
	import org.apache.bcel.generic.LineNumberGen;
	import org.apache.bcel.generic.LocalVariableGen;
	import org.apache.bcel.generic.MethodGen;
	import org.apache.bcel.generic.ObjectType;
	import org.apache.bcel.generic.Select;
	import org.apache.bcel.generic.TABLESWITCH;

	/**
	* Disassemble Java class object into the <a href="https://jasmin.sourceforge.net"> Jasmin</a> format.
	*/
	public class JasminVisitor extends org.apache.bcel.classfile.EmptyVisitor {
	public static void main(final String[] argv) throws Exception {
	JavaClass javaClass;

	if (argv.length == 0) {
	System.err.println("disassemble: No input files specified");
	return;
	}

	for (final String arg : argv) {
	if ((javaClass = Repository.lookupClass(arg)) == null) {
	javaClass = new ClassParser(arg).parse();
	}

	String className = javaClass.getClassName();
	final int index = className.lastIndexOf('.');
	final String path = className.substring(0, index + 1).replace('.', File.separatorChar);
	className = className.substring(index + 1);

	if (!path.isEmpty()) {
	final File file = new File(path);
	if (!file.mkdirs()) {
	System.err.println("Couldn't create directories for " + file);
	}
	}

	final String name = path + className + ".j";
	try (FileOutputStream out = new FileOutputStream(name)) {
	new JasminVisitor(javaClass, out).disassemble();
	System.out.println("File dumped to: " + name);
	}
	}
	}

	private final JavaClass javaClass;
	private final PrintWriter printWriter;
	private final String className;

	private final ConstantPoolGen cp;

	private Method method;

	private Hashtable<InstructionHandle, String> map;

	public JasminVisitor(final JavaClass clazz, final OutputStream out) {
	this.javaClass = clazz;
	this.printWriter = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8)), false);
	this.className = clazz.getClassName();
	this.cp = new ConstantPoolGen(clazz.getConstantPool());
	}

	/**
	* Start traversal using DefaultVisitor pattern.
	*/
	public void disassemble() {
	new org.apache.bcel.classfile.DescendingVisitor(javaClass, this).visit();
	printWriter.close();
	}

	private String get(final InstructionHandle ih) {
	final String str = new StringTokenizer(map.get(ih), "\n").nextToken();
	return str.substring(0, str.length() - 1);
	}

	/**
	* Unfortunately Jasmin expects ".end method" after each method. Thus we've to check for every of the method's
	* attributes if it's the last one and print ".end method" then.
	*/
	private void printEndMethod(final Attribute attr) {
	final Attribute[] attributes = method.getAttributes();

	if (attr == attributes[attributes.length - 1]) {
	printWriter.println(".end method");
	}
	}

	private void put(final InstructionHandle ih, final String line) {
	final String str = map.get(ih);

	if (str == null) {
	map.put(ih, line);
	} else {
	if (line.startsWith("Label") \|\| str.endsWith(line)) {
	return;
	}

	map.put(ih, str + "\n" + line); // append
	}
	}

	@Override
	public void visitCode(final Code code) {
	int labelCounter = 0;

	printWriter.println(".limit stack " + code.getMaxStack());
	printWriter.println(".limit locals " + code.getMaxLocals());

	final MethodGen mg = new MethodGen(method, className, cp);
	final InstructionList il = mg.getInstructionList();
	final InstructionHandle[] ihs = il.getInstructionHandles();

	/*
	* Pass 1: Give all referenced instruction handles a symbolic name, for example a label.
	*/
	map = new Hashtable<>();

	for (final InstructionHandle ih1 : ihs) {
	if (ih1 instanceof BranchHandle) {
	final BranchInstruction bi = (BranchInstruction) ih1.getInstruction();

	if (bi instanceof Select) { // Special cases LOOKUPSWITCH and TABLESWITCH
	for (final InstructionHandle target : ((Select) bi).getTargets()) {
	put(target, "Label" + labelCounter++ + ":");
	}
	}

	final InstructionHandle ih = bi.getTarget();
	put(ih, "Label" + labelCounter++ + ":");
	}
	}

	final LocalVariableGen[] lvs = mg.getLocalVariables();
	for (final LocalVariableGen lv : lvs) {
	InstructionHandle ih = lv.getStart();
	put(ih, "Label" + labelCounter++ + ":");
	ih = lv.getEnd();
	put(ih, "Label" + labelCounter++ + ":");
	}

	final CodeExceptionGen[] ehs = mg.getExceptionHandlers();
	for (final CodeExceptionGen c : ehs) {
	InstructionHandle ih = c.getStartPC();

	put(ih, "Label" + labelCounter++ + ":");
	ih = c.getEndPC();
	put(ih, "Label" + labelCounter++ + ":");
	ih = c.getHandlerPC();
	put(ih, "Label" + labelCounter++ + ":");
	}

	final LineNumberGen[] lns = mg.getLineNumbers();
	for (final LineNumberGen ln : lns) {
	final InstructionHandle ih = ln.getInstruction();
	put(ih, ".line " + ln.getSourceLine());
	}

	// Pass 2: Output code.
	for (final LocalVariableGen l : lvs) {
	printWriter.println(
	".var " + l.getIndex() + " is " + l.getName() + " " + l.getType().getSignature() + " from " + get(l.getStart()) + " to " + get(l.getEnd()));
	}

	printWriter.print("\n");

	for (InstructionHandle ih : ihs) {
	final Instruction inst = ih.getInstruction();
	String str = map.get(ih);

	if (str != null) {
	printWriter.println(str);
	}

	if (inst instanceof BranchInstruction) {
	if (inst instanceof Select) { // Special cases LOOKUPSWITCH and TABLESWITCH
	final Select s = (Select) inst;
	final int[] matchs = s.getMatchs();
	final InstructionHandle[] targets = s.getTargets();

	if (s instanceof TABLESWITCH) {
	printWriter.println("\ttableswitch " + matchs[0] + " " + matchs[matchs.length - 1]);

	for (final InstructionHandle target : targets) {
	printWriter.println("\t\t" + get(target));
	}

	} else { // LOOKUPSWITCH
	printWriter.println("\tlookupswitch ");

	for (int j = 0; j < targets.length; j++) {
	printWriter.println("\t\t" + matchs[j] + " : " + get(targets[j]));
	}
	}

	printWriter.println("\t\tdefault: " + get(s.getTarget())); // Applies for both
	} else {
	final BranchInstruction bi = (BranchInstruction) inst;
	ih = bi.getTarget();
	str = get(ih);
	printWriter.println("\t" + Const.getOpcodeName(bi.getOpcode()) + " " + str);
	}
	} else {
	printWriter.println("\t" + inst.toString(cp.getConstantPool()));
	}
	}

	printWriter.print("\n");

	for (final CodeExceptionGen c : ehs) {
	final ObjectType caught = c.getCatchType();
	final String className = caught == null ? // catch any exception, used when compiling finally
	"all" : Utility.packageToPath(caught.getClassName());

	printWriter.println(".catch " + className + " from " + get(c.getStartPC()) + " to " + get(c.getEndPC()) + " using " + get(c.getHandlerPC()));
	}

	printEndMethod(code);
	}

	@Override
	public void visitConstantValue(final ConstantValue cv) {
	printWriter.println(" = " + cv);
	}

	@Override
	public void visitDeprecated(final Deprecated attribute) {
	printEndMethod(attribute);
	}

	@Override
	public void visitExceptionTable(final ExceptionTable e) {
	for (final String name : e.getExceptionNames()) {
	printWriter.println(".throws " + Utility.packageToPath(name));
	}

	printEndMethod(e);
	}

	@Override
	public void visitField(final Field field) {
	printWriter.print(".field " + Utility.accessToString(field.getAccessFlags()) + " \"" + field.getName() + "\"" + field.getSignature());
	if (field.getAttributes().length == 0) {
	printWriter.print("\n");
	}
	}

	@Override
	public void visitJavaClass(final JavaClass clazz) {
	printWriter.println(";; Produced by JasminVisitor (BCEL)");
	printWriter.println(";; https://commons.apache.org/bcel/");
	printWriter.println(";; " + new Date() + "\n");

	printWriter.println(".source " + clazz.getSourceFileName());
	printWriter.println("." + Utility.classOrInterface(clazz.getAccessFlags()) + " " + Utility.accessToString(clazz.getAccessFlags(), true) + " "
	+ Utility.packageToPath(clazz.getClassName()));
	printWriter.println(".super " + Utility.packageToPath(clazz.getSuperclassName()));

	for (final String iface : clazz.getInterfaceNames()) {
	printWriter.println(".implements " + Utility.packageToPath(iface));
	}

	printWriter.print("\n");
	}

	@Override
	public void visitMethod(final Method visitMethod) {
	this.method = visitMethod; // Remember for use in subsequent visitXXX calls

	printWriter.println("\n.method " + Utility.accessToString(method.getAccessFlags()) + " " + method.getName() + method.getSignature());

	final Attribute[] attributes = method.getAttributes();
	if (attributes == null \|\| attributes.length == 0) {
	printWriter.println(".end method");
	}
	}

	@Override
	public void visitSynthetic(final Synthetic attribute) {
	if (method != null) {
	printEndMethod(attribute);
	}
	}
	}