/*
    * 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
    *
    *      http://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.
   */
  package org.apache.bcel.generic;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.Hashtable;
  import java.util.List;
  import java.util.Objects;
  import java.util.Stack;
  import java.util.stream.Collectors;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.classfile.AnnotationEntry;
  import org.apache.bcel.classfile.Annotations;
  import org.apache.bcel.classfile.Attribute;
  import org.apache.bcel.classfile.Code;
  import org.apache.bcel.classfile.CodeException;
  import org.apache.bcel.classfile.ExceptionTable;
  import org.apache.bcel.classfile.LineNumber;
  import org.apache.bcel.classfile.LineNumberTable;
  import org.apache.bcel.classfile.LocalVariable;
  import org.apache.bcel.classfile.LocalVariableTable;
  import org.apache.bcel.classfile.LocalVariableTypeTable;
  import org.apache.bcel.classfile.Method;
  import org.apache.bcel.classfile.ParameterAnnotationEntry;
  import org.apache.bcel.classfile.ParameterAnnotations;
  import org.apache.bcel.classfile.RuntimeVisibleParameterAnnotations;
  import org.apache.bcel.classfile.Utility;
  import org.apache.bcel.util.BCELComparator;
  import org.apache.commons.lang3.ArrayUtils;
  import org.apache.commons.lang3.stream.Streams;
  
  /**
   * Template class for building up a method. This is done by defining exception handlers, adding thrown exceptions, local
   * variables and attributes, whereas the 'LocalVariableTable' and 'LineNumberTable' attributes will be set automatically
   * for the code. Use stripAttributes() if you don't like this.
   *
   * While generating code it may be necessary to insert NOP operations. You can use the 'removeNOPs' method to get rid
   * off them. The resulting method object can be obtained via the 'getMethod()' method.
   *
   * @see InstructionList
   * @see Method
   */
  public class MethodGen extends FieldGenOrMethodGen {
  
      static final class BranchStack {
  
          private final Stack<BranchTarget> branchTargets = new Stack<>();
          private final Hashtable<InstructionHandle, BranchTarget> visitedTargets = new Hashtable<>();
  
          public BranchTarget pop() {
              if (!branchTargets.empty()) {
                  return branchTargets.pop();
              }
              return null;
          }
  
          public void push(final InstructionHandle target, final int stackDepth) {
              if (visited(target)) {
                  return;
              }
              branchTargets.push(visit(target, stackDepth));
          }
  
          private BranchTarget visit(final InstructionHandle target, final int stackDepth) {
              final BranchTarget bt = new BranchTarget(target, stackDepth);
              visitedTargets.put(target, bt);
              return bt;
          }
  
          private boolean visited(final InstructionHandle target) {
              return visitedTargets.get(target) != null;
          }
      }
  
      static final class BranchTarget {
  
          final InstructionHandle target;
          final int stackDepth;
  
          BranchTarget(final InstructionHandle target, final int stackDepth) {
              this.target = target;
             this.stackDepth = stackDepth;
         }
     }
 
     private static BCELComparator<FieldGenOrMethodGen> bcelComparator = new BCELComparator<FieldGenOrMethodGen>() {
 
         @Override
         public boolean equals(final FieldGenOrMethodGen a, final FieldGenOrMethodGen b) {
             return a == b || a != null && b != null && Objects.equals(a.getName(), b.getName()) && Objects.equals(a.getSignature(), b.getSignature());
         }
 
         @Override
         public int hashCode(final FieldGenOrMethodGen o) {
             return o != null ? Objects.hash(o.getSignature(), o.getName()) : 0;
         }
     };
 
     private static byte[] getByteCodes(final Method method) {
         final Code code = method.getCode();
         if (code == null) {
             throw new IllegalStateException(String.format("The method '%s' has no code.", method));
         }
         return code.getCode();
     }
 
     /**
      * @return Comparison strategy object.
      */
     public static BCELComparator<FieldGenOrMethodGen> getComparator() {
         return bcelComparator;
     }
 
     /**
      * Computes stack usage of an instruction list by performing control flow analysis.
      *
      * @return maximum stack depth used by method
      */
     public static int getMaxStack(final ConstantPoolGen cp, final InstructionList il, final CodeExceptionGen[] et) {
         final BranchStack branchTargets = new BranchStack();
         /*
          * Initially, populate the branch stack with the exception handlers, because these aren't (necessarily) branched to
          * explicitly. in each case, the stack will have depth 1, containing the exception object.
          */
         for (final CodeExceptionGen element : et) {
             final InstructionHandle handlerPc = element.getHandlerPC();
             if (handlerPc != null) {
                 branchTargets.push(handlerPc, 1);
             }
         }
         int stackDepth = 0;
         int maxStackDepth = 0;
         InstructionHandle ih = il.getStart();
         while (ih != null) {
             final Instruction instruction = ih.getInstruction();
             final short opcode = instruction.getOpcode();
             final int delta = instruction.produceStack(cp) - instruction.consumeStack(cp);
             stackDepth += delta;
             if (stackDepth > maxStackDepth) {
                 maxStackDepth = stackDepth;
             }
             // choose the next instruction based on whether current is a branch.
             if (instruction instanceof BranchInstruction) {
                 final BranchInstruction branch = (BranchInstruction) instruction;
                 if (instruction instanceof Select) {
                     // explore all of the select's targets. the default target is handled below.
                     final Select select = (Select) branch;
                     final InstructionHandle[] targets = select.getTargets();
                     for (final InstructionHandle target : targets) {
                         branchTargets.push(target, stackDepth);
                     }
                     // nothing to fall through to.
                     ih = null;
                 } else if (!(branch instanceof IfInstruction)) {
                     // if an instruction that comes back to following PC,
                     // push next instruction, with stack depth reduced by 1.
                     if (opcode == Const.JSR || opcode == Const.JSR_W) {
                         branchTargets.push(ih.getNext(), stackDepth - 1);
                     }
                     ih = null;
                 }
                 // for all branches, the target of the branch is pushed on the branch stack.
                 // conditional branches have a fall through case, selects don't, and
                 // jsr/jsr_w return to the next instruction.
                 branchTargets.push(branch.getTarget(), stackDepth);
             } else // check for instructions that terminate the method.
             if (opcode == Const.ATHROW || opcode == Const.RET || opcode >= Const.IRETURN && opcode <= Const.RETURN) {
                 ih = null;
             }
             // normal case, go to the next instruction.
             if (ih != null) {
                 ih = ih.getNext();
             }
             // if we have no more instructions, see if there are any deferred branches to explore.
             if (ih == null) {
                 final BranchTarget bt = branchTargets.pop();
                 if (bt != null) {
                     ih = bt.target;
                     stackDepth = bt.stackDepth;
                 }
             }
         }
         return maxStackDepth;
     }
 
     /**
      * @param comparator Comparison strategy object.
      */
     public static void setComparator(final BCELComparator<FieldGenOrMethodGen> comparator) {
         bcelComparator = comparator;
     }
 
     private String className;
     private Type[] argTypes;
     private String[] argNames;
     private int maxLocals;
     private int maxStack;
     private InstructionList il;
 
     private boolean stripAttributes;
     private LocalVariableTypeTable localVariableTypeTable;
     private final List<LocalVariableGen> variableList = new ArrayList<>();
 
     private final List<LineNumberGen> lineNumberList = new ArrayList<>();
 
     private final List<CodeExceptionGen> exceptionList = new ArrayList<>();
 
     private final List<String> throwsList = new ArrayList<>();
 
     private final List<Attribute> codeAttrsList = new ArrayList<>();
 
     private List<AnnotationEntryGen>[] paramAnnotations; // Array of lists containing AnnotationGen objects
 
     private boolean hasParameterAnnotations;
 
     private boolean haveUnpackedParameterAnnotations;
 
     private List<MethodObserver> observers;
 
     /**
      * Declare method. If the method is non-static the constructor automatically declares a local variable '$this' in slot
      * 0. The actual code is contained in the 'il' parameter, which may further manipulated by the user. But they must take
      * care not to remove any instruction (handles) that are still referenced from this object.
      *
      * For example one may not add a local variable and later remove the instructions it refers to without causing havoc. It
      * is safe however if you remove that local variable, too.
      *
      * @param accessFlags access qualifiers
      * @param returnType method type
      * @param argTypes argument types
      * @param argNames argument names (if this is null, default names will be provided for them)
      * @param methodName name of method
      * @param className class name containing this method (may be null, if you don't care)
      * @param il instruction list associated with this method, may be null only for abstract or native methods
      * @param cp constant pool
      */
     public MethodGen(final int accessFlags, final Type returnType, final Type[] argTypes, String[] argNames, final String methodName, final String className,
         final InstructionList il, final ConstantPoolGen cp) {
         super(accessFlags);
         setType(returnType);
         setArgumentTypes(argTypes);
         setArgumentNames(argNames);
         setName(methodName);
         setClassName(className);
         setInstructionList(il);
         setConstantPool(cp);
         final boolean abstract_ = isAbstract() || isNative();
         InstructionHandle start = null;
         final InstructionHandle end = null;
         if (!abstract_) {
             start = il.getStart();
             // end == null => live to end of method
             /*
              * Add local variables, namely the implicit 'this' and the arguments
              */
             if (!isStatic() && className != null) { // Instance method -> 'this' is local var 0
                 addLocalVariable("this", ObjectType.getInstance(className), start, end);
             }
         }
         if (argTypes != null) {
             final int size = argTypes.length;
             for (final Type argType : argTypes) {
                 if (Type.VOID == argType) {
                     throw new ClassGenException("'void' is an illegal argument type for a method");
                 }
             }
             if (argNames != null) { // Names for variables provided?
                 if (size != argNames.length) {
                     throw new ClassGenException("Mismatch in argument array lengths: " + size + " vs. " + argNames.length);
                 }
             } else { // Give them dummy names
                 argNames = new String[size];
                 for (int i = 0; i < size; i++) {
                     argNames[i] = "arg" + i;
                 }
                 setArgumentNames(argNames);
             }
             if (!abstract_) {
                 for (int i = 0; i < size; i++) {
                     addLocalVariable(argNames[i], argTypes[i], start, end);
                 }
             }
         }
     }
 
     /**
      * Instantiate from existing method.
      *
      * @param method method
      * @param className class name containing this method
      * @param cp constant pool
      */
     public MethodGen(final Method method, final String className, final ConstantPoolGen cp) {
         this(method.getAccessFlags(), Type.getReturnType(method.getSignature()), Type.getArgumentTypes(method.getSignature()),
             null /* may be overridden anyway */
             , method.getName(), className,
             (method.getAccessFlags() & (Const.ACC_ABSTRACT | Const.ACC_NATIVE)) == 0 ? new InstructionList(getByteCodes(method)) : null, cp);
         final Attribute[] attributes = method.getAttributes();
         for (final Attribute attribute : attributes) {
             Attribute a = attribute;
             if (a instanceof Code) {
                 final Code c = (Code) a;
                 setMaxStack(c.getMaxStack());
                 setMaxLocals(c.getMaxLocals());
                 final CodeException[] ces = c.getExceptionTable();
                 if (ces != null) {
                     for (final CodeException ce : ces) {
                         final int type = ce.getCatchType();
                         ObjectType cType = null;
                         if (type > 0) {
                             final String cen = method.getConstantPool().getConstantString(type, Const.CONSTANT_Class);
                             cType = ObjectType.getInstance(cen);
                         }
                         final int endPc = ce.getEndPC();
                         final int length = getByteCodes(method).length;
                         InstructionHandle end;
                         if (length == endPc) { // May happen, because end_pc is exclusive
                             end = il.getEnd();
                         } else {
                             end = il.findHandle(endPc);
                             end = end.getPrev(); // Make it inclusive
                         }
                         addExceptionHandler(il.findHandle(ce.getStartPC()), end, il.findHandle(ce.getHandlerPC()), cType);
                     }
                 }
                 final Attribute[] cAttributes = c.getAttributes();
                 for (final Attribute cAttribute : cAttributes) {
                     a = cAttribute;
                     if (a instanceof LineNumberTable) {
                         ((LineNumberTable) a).forEach(l -> {
                             final InstructionHandle ih = il.findHandle(l.getStartPC());
                             if (ih != null) {
                                 addLineNumber(ih, l.getLineNumber());
                             }
                         });
                     } else if (a instanceof LocalVariableTable) {
                         updateLocalVariableTable((LocalVariableTable) a);
                     } else if (a instanceof LocalVariableTypeTable) {
                         this.localVariableTypeTable = (LocalVariableTypeTable) a.copy(cp.getConstantPool());
                     } else {
                         addCodeAttribute(a);
                     }
                 }
             } else if (a instanceof ExceptionTable) {
                 Collections.addAll(throwsList, ((ExceptionTable) a).getExceptionNames());
             } else if (a instanceof Annotations) {
                 final Annotations runtimeAnnotations = (Annotations) a;
                 runtimeAnnotations.forEach(element -> addAnnotationEntry(new AnnotationEntryGen(element, cp, false)));
             } else {
                 addAttribute(a);
             }
         }
     }
 
     /**
      * @since 6.0
      */
     public void addAnnotationsAsAttribute(final ConstantPoolGen cp) {
         addAll(AnnotationEntryGen.getAnnotationAttributes(cp, super.getAnnotationEntries()));
     }
 
     /**
      * Add an attribute to the code. Currently, the JVM knows about the LineNumberTable, LocalVariableTable and StackMap
      * attributes, where the former two will be generated automatically and the latter is used for the MIDP only. Other
      * attributes will be ignored by the JVM but do no harm.
      *
      * @param a attribute to be added
      */
     public void addCodeAttribute(final Attribute a) {
         codeAttrsList.add(a);
     }
 
     /**
      * Add an exception possibly thrown by this method.
      *
      * @param className (fully qualified) name of exception
      */
     public void addException(final String className) {
         throwsList.add(className);
     }
 
     /**
      * Add an exception handler, i.e., specify region where a handler is active and an instruction where the actual handling
      * is done.
      *
      * @param startPc Start of region (inclusive)
      * @param endPc End of region (inclusive)
      * @param handlerPc Where handling is done
      * @param catchType class type of handled exception or null if any exception is handled
      * @return new exception handler object
      */
     public CodeExceptionGen addExceptionHandler(final InstructionHandle startPc, final InstructionHandle endPc, final InstructionHandle handlerPc,
         final ObjectType catchType) {
         if (startPc == null || endPc == null || handlerPc == null) {
             throw new ClassGenException("Exception handler target is null instruction");
         }
         final CodeExceptionGen c = new CodeExceptionGen(startPc, endPc, handlerPc, catchType);
         exceptionList.add(c);
         return c;
     }
 
     /**
      * Give an instruction a line number corresponding to the source code line.
      *
      * @param ih instruction to tag
      * @return new line number object
      * @see LineNumber
      */
     public LineNumberGen addLineNumber(final InstructionHandle ih, final int srcLine) {
         final LineNumberGen l = new LineNumberGen(ih, srcLine);
         lineNumberList.add(l);
         return l;
     }
 
     /**
      * Adds a local variable to this method and assigns an index automatically.
      *
      * @param name variable name
      * @param type variable type
      * @param start from where the variable is valid, if this is null, it is valid from the start
      * @param end until where the variable is valid, if this is null, it is valid to the end
      * @return new local variable object
      * @see LocalVariable
      */
     public LocalVariableGen addLocalVariable(final String name, final Type type, final InstructionHandle start, final InstructionHandle end) {
         return addLocalVariable(name, type, maxLocals, start, end);
     }
 
     /**
      * Adds a local variable to this method.
      *
      * @param name variable name
      * @param type variable type
      * @param slot the index of the local variable, if type is long or double, the next available index is slot+2
      * @param start from where the variable is valid
      * @param end until where the variable is valid
      * @return new local variable object
      * @see LocalVariable
      */
     public LocalVariableGen addLocalVariable(final String name, final Type type, final int slot, final InstructionHandle start, final InstructionHandle end) {
         return addLocalVariable(name, type, slot, start, end, slot);
     }
 
     /**
      * Adds a local variable to this method.
      *
      * @param name variable name
      * @param type variable type
      * @param slot the index of the local variable, if type is long or double, the next available index is slot+2
      * @param start from where the variable is valid
      * @param end until where the variable is valid
      * @param origIndex the index of the local variable prior to any modifications
      * @return new local variable object
      * @see LocalVariable
      */
     public LocalVariableGen addLocalVariable(final String name, final Type type, final int slot, final InstructionHandle start, final InstructionHandle end,
         final int origIndex) {
         final byte t = type.getType();
         if (t != Const.T_ADDRESS) {
             final int add = type.getSize();
             if (slot + add > maxLocals) {
                 maxLocals = slot + add;
             }
             final LocalVariableGen l = new LocalVariableGen(slot, name, type, start, end, origIndex);
             int i;
             if ((i = variableList.indexOf(l)) >= 0) {
                 variableList.set(i, l);
             } else {
                 variableList.add(l);
             }
             return l;
         }
         throw new IllegalArgumentException("Can not use " + type + " as type for local variable");
     }
 
     /**
      * Add observer for this object.
      */
     public void addObserver(final MethodObserver o) {
         if (observers == null) {
             observers = new ArrayList<>();
         }
         observers.add(o);
     }
 
     public void addParameterAnnotation(final int parameterIndex, final AnnotationEntryGen annotation) {
         ensureExistingParameterAnnotationsUnpacked();
         if (!hasParameterAnnotations) {
             @SuppressWarnings("unchecked") // OK
             final List<AnnotationEntryGen>[] parmList = new List[argTypes.length];
             paramAnnotations = parmList;
             hasParameterAnnotations = true;
         }
         final List<AnnotationEntryGen> existingAnnotations = paramAnnotations[parameterIndex];
         if (existingAnnotations != null) {
             existingAnnotations.add(annotation);
         } else {
             final List<AnnotationEntryGen> l = new ArrayList<>();
             l.add(annotation);
             paramAnnotations[parameterIndex] = l;
         }
     }
 
     /**
      * @since 6.0
      */
     public void addParameterAnnotationsAsAttribute(final ConstantPoolGen cp) {
         if (!hasParameterAnnotations) {
             return;
         }
         final Attribute[] attrs = AnnotationEntryGen.getParameterAnnotationAttributes(cp, paramAnnotations);
         if (attrs != null) {
             addAll(attrs);
         }
     }
 
     private Attribute[] addRuntimeAnnotationsAsAttribute(final ConstantPoolGen cp) {
         final Attribute[] attrs = AnnotationEntryGen.getAnnotationAttributes(cp, super.getAnnotationEntries());
         addAll(attrs);
         return attrs;
     }
 
     private Attribute[] addRuntimeParameterAnnotationsAsAttribute(final ConstantPoolGen cp) {
         if (!hasParameterAnnotations) {
             return Attribute.EMPTY_ARRAY;
         }
         final Attribute[] attrs = AnnotationEntryGen.getParameterAnnotationAttributes(cp, paramAnnotations);
         addAll(attrs);
         return attrs;
     }
 
     private void adjustLocalVariableTypeTable(final LocalVariableTable lvt) {
         final LocalVariable[] lv = lvt.getLocalVariableTable();
         for (final LocalVariable element : localVariableTypeTable.getLocalVariableTypeTable()) {
             for (final LocalVariable l : lv) {
                 if (element.getName().equals(l.getName()) && element.getIndex() == l.getOrigIndex()) {
                     element.setLength(l.getLength());
                     element.setStartPC(l.getStartPC());
                     element.setIndex(l.getIndex());
                     break;
                 }
             }
         }
     }
 
     /**
      * @return deep copy of this method
      */
     public MethodGen copy(final String className, final ConstantPoolGen cp) {
         final Method m = ((MethodGen) clone()).getMethod();
         final MethodGen mg = new MethodGen(m, className, super.getConstantPool());
         if (super.getConstantPool() != cp) {
             mg.setConstantPool(cp);
             mg.getInstructionList().replaceConstantPool(super.getConstantPool(), cp);
         }
         return mg;
     }
 
     /**
      * Goes through the attributes on the method and identifies any that are RuntimeParameterAnnotations, extracting their
      * contents and storing them as parameter annotations. There are two kinds of parameter annotation - visible and
      * invisible. Once they have been unpacked, these attributes are deleted. (The annotations will be rebuilt as attributes
      * when someone builds a Method object out of this MethodGen object).
      */
     private void ensureExistingParameterAnnotationsUnpacked() {
         if (haveUnpackedParameterAnnotations) {
             return;
         }
         // Find attributes that contain parameter annotation data
         final Attribute[] attrs = getAttributes();
         ParameterAnnotations paramAnnVisAttr = null;
         ParameterAnnotations paramAnnInvisAttr = null;
         for (final Attribute attribute : attrs) {
             if (attribute instanceof ParameterAnnotations) {
                 // Initialize paramAnnotations
                 if (!hasParameterAnnotations) {
                     @SuppressWarnings("unchecked") // OK
                     final List<AnnotationEntryGen>[] parmList = new List[argTypes.length];
                     paramAnnotations = parmList;
                     Arrays.setAll(paramAnnotations, i -> new ArrayList<>());
                 }
                 hasParameterAnnotations = true;
                 final ParameterAnnotations rpa = (ParameterAnnotations) attribute;
                 if (rpa instanceof RuntimeVisibleParameterAnnotations) {
                     paramAnnVisAttr = rpa;
                 } else {
                     paramAnnInvisAttr = rpa;
                 }
                 final ParameterAnnotationEntry[] parameterAnnotationEntries = rpa.getParameterAnnotationEntries();
                 for (int j = 0; j < parameterAnnotationEntries.length; j++) {
                     // This returns Annotation[] ...
                     final ParameterAnnotationEntry immutableArray = rpa.getParameterAnnotationEntries()[j];
                     // ... which needs transforming into an AnnotationGen[] ...
                     final List<AnnotationEntryGen> mutable = makeMutableVersion(immutableArray.getAnnotationEntries());
                     // ... then add these to any we already know about
                     paramAnnotations[j].addAll(mutable);
                 }
             }
         }
         if (paramAnnVisAttr != null) {
             removeAttribute(paramAnnVisAttr);
         }
         if (paramAnnInvisAttr != null) {
             removeAttribute(paramAnnInvisAttr);
         }
         haveUnpackedParameterAnnotations = true;
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default two MethodGen objects are said to be equal when
      * their names and signatures are equal.
      *
      * @see Object#equals(Object)
      */
     @Override
     public boolean equals(final Object obj) {
         return obj instanceof FieldGenOrMethodGen && bcelComparator.equals(this, (FieldGenOrMethodGen) obj);
     }
 
     // J5TODO: Should paramAnnotations be an array of arrays? Rather than an array of lists, this
     // is more likely to suggest to the caller it is readonly (which a List does not).
     /**
      * Return a list of AnnotationGen objects representing parameter annotations
      *
      * @since 6.0
      */
     public List<AnnotationEntryGen> getAnnotationsOnParameter(final int i) {
         ensureExistingParameterAnnotationsUnpacked();
         if (!hasParameterAnnotations || i > argTypes.length) {
             return null;
         }
         return paramAnnotations[i];
     }
 
     public String getArgumentName(final int i) {
         return argNames[i];
     }
 
     public String[] getArgumentNames() {
         return argNames.clone();
     }
 
     public Type getArgumentType(final int i) {
         return argTypes[i];
     }
 
     public Type[] getArgumentTypes() {
         return argTypes.clone();
     }
 
     /**
      * @return class that contains this method
      */
     public String getClassName() {
         return className;
     }
 
     /**
      * @return all attributes of this method.
      */
     public Attribute[] getCodeAttributes() {
         return codeAttrsList.toArray(Attribute.EMPTY_ARRAY);
     }
 
     /**
      * @return code exceptions for 'Code' attribute
      */
     private CodeException[] getCodeExceptions() {
         final int size = exceptionList.size();
         final CodeException[] cExc = new CodeException[size];
         Arrays.setAll(cExc, i -> exceptionList.get(i).getCodeException(super.getConstantPool()));
         return cExc;
     }
 
     /*
      * @return array of declared exception handlers
      */
     public CodeExceptionGen[] getExceptionHandlers() {
         return exceptionList.toArray(CodeExceptionGen.EMPTY_ARRAY);
     }
 
     /*
      * @return array of thrown exceptions
      */
     public String[] getExceptions() {
         return throwsList.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
     }
 
     /**
      * @return 'Exceptions' attribute of all the exceptions thrown by this method.
      */
     private ExceptionTable getExceptionTable(final ConstantPoolGen cp) {
         final int size = throwsList.size();
         final int[] ex = new int[size];
         Arrays.setAll(ex, i -> cp.addClass(throwsList.get(i)));
         return new ExceptionTable(cp.addUtf8("Exceptions"), 2 + 2 * size, ex, cp.getConstantPool());
     }
 
     public InstructionList getInstructionList() {
         return il;
     }
 
     /*
      * @return array of line numbers
      */
     public LineNumberGen[] getLineNumbers() {
         return lineNumberList.toArray(LineNumberGen.EMPTY_ARRAY);
     }
 
     /**
      * @return 'LineNumberTable' attribute of all the local variables of this method.
      */
     public LineNumberTable getLineNumberTable(final ConstantPoolGen cp) {
         final int size = lineNumberList.size();
         final LineNumber[] ln = new LineNumber[size];
         Arrays.setAll(ln, i -> lineNumberList.get(i).getLineNumber());
         return new LineNumberTable(cp.addUtf8("LineNumberTable"), 2 + ln.length * 4, ln, cp.getConstantPool());
     }
 
     /*
      * If the range of the variable has not been set yet, it will be set to be valid from the start to the end of the
      * instruction list.
      *
      * @return array of declared local variables sorted by index
      */
     public LocalVariableGen[] getLocalVariables() {
         final int size = variableList.size();
         final LocalVariableGen[] lg = new LocalVariableGen[size];
         variableList.toArray(lg);
         for (int i = 0; i < size; i++) {
             if (lg[i].getStart() == null && il != null) {
                 lg[i].setStart(il.getStart());
             }
             if (lg[i].getEnd() == null && il != null) {
                 lg[i].setEnd(il.getEnd());
             }
         }
         if (size > 1) {
             Arrays.sort(lg, Comparator.comparingInt(LocalVariableGen::getIndex));
         }
         return lg;
     }
 
     /**
      * @return 'LocalVariableTable' attribute of all the local variables of this method.
      */
     public LocalVariableTable getLocalVariableTable(final ConstantPoolGen cp) {
         final LocalVariableGen[] lg = getLocalVariables();
         final int size = lg.length;
         final LocalVariable[] lv = new LocalVariable[size];
         Arrays.setAll(lv, i -> lg[i].getLocalVariable(cp));
         return new LocalVariableTable(cp.addUtf8("LocalVariableTable"), 2 + lv.length * 10, lv, cp.getConstantPool());
     }
 
     /**
      * @return 'LocalVariableTypeTable' attribute of this method.
      */
     public LocalVariableTypeTable getLocalVariableTypeTable() {
         return localVariableTypeTable;
     }
 
     public int getMaxLocals() {
         return maxLocals;
     }
 
     public int getMaxStack() {
         return maxStack;
     }
 
     /**
      * Gets method object. Never forget to call setMaxStack() or setMaxStack(max), respectively, before calling this method
      * (the same applies for max locals).
      *
      * @return method object
      */
     public Method getMethod() {
         final String signature = getSignature();
         final ConstantPoolGen cp = super.getConstantPool();
         final int nameIndex = cp.addUtf8(super.getName());
         final int signatureIndex = cp.addUtf8(signature);
         /*
          * Also updates positions of instructions, i.e., their indices
          */
         final byte[] byteCode = il != null ? il.getByteCode() : null;
         LineNumberTable lnt = null;
         LocalVariableTable lvt = null;
         /*
          * Create LocalVariableTable and LineNumberTable attributes (for debuggers, e.g.)
          */
         if (!variableList.isEmpty() && !stripAttributes) {
             updateLocalVariableTable(getLocalVariableTable(cp));
             addCodeAttribute(lvt = getLocalVariableTable(cp));
         }
         if (localVariableTypeTable != null) {
             // LocalVariable length in LocalVariableTypeTable is not updated automatically. It's a difference with
             // LocalVariableTable.
             if (lvt != null) {
                 adjustLocalVariableTypeTable(lvt);
             }
             addCodeAttribute(localVariableTypeTable);
         }
         if (!lineNumberList.isEmpty() && !stripAttributes) {
             addCodeAttribute(lnt = getLineNumberTable(cp));
         }
         final Attribute[] codeAttrs = getCodeAttributes();
         /*
          * Each attribute causes 6 additional header bytes
          */
         int attrsLen = 0;
         for (final Attribute codeAttr : codeAttrs) {
             attrsLen += codeAttr.getLength() + 6;
         }
         final CodeException[] cExc = getCodeExceptions();
         final int excLen = cExc.length * 8; // Every entry takes 8 bytes
         Code code = null;
         if (byteCode != null && !isAbstract() && !isNative()) {
             // Remove any stale code attribute
             final Attribute[] attributes = getAttributes();
             for (final Attribute a : attributes) {
                 if (a instanceof Code) {
                     removeAttribute(a);
                 }
             }
             code = new Code(cp.addUtf8("Code"), 8 + byteCode.length + // prologue byte code
                 2 + excLen + // exceptions
                 2 + attrsLen, // attributes
                 maxStack, maxLocals, byteCode, cExc, codeAttrs, cp.getConstantPool());
             addAttribute(code);
         }
         final Attribute[] annotations = addRuntimeAnnotationsAsAttribute(cp);
         final Attribute[] parameterAnnotations = addRuntimeParameterAnnotationsAsAttribute(cp);
         ExceptionTable et = null;
         if (!throwsList.isEmpty()) {
             addAttribute(et = getExceptionTable(cp));
             // Add 'Exceptions' if there are "throws" clauses
         }
         final Method m = new Method(super.getAccessFlags(), nameIndex, signatureIndex, getAttributes(), cp.getConstantPool());
         // Undo effects of adding attributes
         if (lvt != null) {
             removeCodeAttribute(lvt);
         }
         if (localVariableTypeTable != null) {
             removeCodeAttribute(localVariableTypeTable);
         }
         if (lnt != null) {
             removeCodeAttribute(lnt);
         }
         if (code != null) {
             removeAttribute(code);
         }
         if (et != null) {
             removeAttribute(et);
         }
         removeRuntimeAttributes(annotations);
         removeRuntimeAttributes(parameterAnnotations);
         return m;
     }
 
     public Type getReturnType() {
         return getType();
     }
 
     @Override
     public String getSignature() {
         return Type.getMethodSignature(super.getType(), argTypes);
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default return the hash code of the method's name XOR
      * signature.
      *
      * @see Object#hashCode()
      */
     @Override
     public int hashCode() {
         return bcelComparator.hashCode(this);
     }
 
     private List<AnnotationEntryGen> makeMutableVersion(final AnnotationEntry[] mutableArray) {
         return Streams.of(mutableArray).map(ae -> new AnnotationEntryGen(ae, getConstantPool(), false)).collect(Collectors.toList());
     }
 
     /**
      * Remove a code attribute.
      */
     public void removeCodeAttribute(final Attribute a) {
         codeAttrsList.remove(a);
     }
 
     /**
      * Remove all code attributes.
      */
     public void removeCodeAttributes() {
         localVariableTypeTable = null;
         codeAttrsList.clear();
     }
 
     /**
      * Remove an exception.
      */
     public void removeException(final String c) {
         throwsList.remove(c);
     }
 
     /**
      * Remove an exception handler.
      */
     public void removeExceptionHandler(final CodeExceptionGen c) {
         exceptionList.remove(c);
     }
 
     /**
      * Remove all line numbers.
      */
     public void removeExceptionHandlers() {
         exceptionList.clear();
     }
 
     /**
      * Remove all exceptions.
      */
     public void removeExceptions() {
         throwsList.clear();
     }
 
     /**
      * Remove a line number.
      */
     public void removeLineNumber(final LineNumberGen l) {
         lineNumberList.remove(l);
     }
 
     /**
      * Remove all line numbers.
      */
     public void removeLineNumbers() {
         lineNumberList.clear();
     }
 
     /**
      * Remove a local variable, its slot will not be reused, if you do not use addLocalVariable with an explicit index
      * argument.
      */
     public void removeLocalVariable(final LocalVariableGen l) {
         l.dispose();
         variableList.remove(l);
     }
 
     /**
      * Remove all local variables.
      */
     public void removeLocalVariables() {
         variableList.forEach(LocalVariableGen::dispose);
         variableList.clear();
     }
 
     /**
      * Remove the LocalVariableTypeTable
      */
     public void removeLocalVariableTypeTable() {
         localVariableTypeTable = null;
     }
 
     /**
      * Remove all NOPs from the instruction list (if possible) and update every object referring to them, i.e., branch
      * instructions, local variables and exception handlers.
      */
     public void removeNOPs() {
         if (il != null) {
             InstructionHandle next;
             /*
              * Check branch instructions.
              */
             for (InstructionHandle ih = il.getStart(); ih != null; ih = next) {
                 next = ih.getNext();
                 if (next != null && ih.getInstruction() instanceof NOP) {
                     try {
                         il.delete(ih);
                     } catch (final TargetLostException e) {
                         for (final InstructionHandle target : e.getTargets()) {
                             for (final InstructionTargeter targeter : target.getTargeters()) {
                                 targeter.updateTarget(target, next);
                             }
                         }
                     }
                 }
             }
         }
     }
 
     /**
      * Remove observer for this object.
      */
     public void removeObserver(final MethodObserver o) {
         if (observers != null) {
             observers.remove(o);
         }
     }
 
     /**
      * Would prefer to make this private, but need a way to test if client is using BCEL version 6.5.0 or later that
      * contains fix for BCEL-329.
      *
      * @since 6.5.0
      */
     public void removeRuntimeAttributes(final Attribute[] attributes) {
         Streams.of(attributes).forEach(this::removeAttribute);
     }
 
     public void setArgumentName(final int i, final String name) {
         argNames[i] = name;
     }
 
     public void setArgumentNames(final String[] argNames) {
         this.argNames = ArrayUtils.nullToEmpty(argNames);
     }
 
     public void setArgumentType(final int i, final Type type) {
         argTypes[i] = type;
     }
 
     public void setArgumentTypes(final Type[] argTypes) {
         this.argTypes = argTypes != null ? argTypes : Type.NO_ARGS;
     }
 
     public void setClassName(final String className) { // TODO could be package-protected?
         this.className = className;
     }
 
     public void setInstructionList(final InstructionList il) { // TODO could be package-protected?
         this.il = il;
     }
 
     /**
      * Compute maximum number of local variables.
      */
     public void setMaxLocals() { // TODO could be package-protected? (some tests would need repackaging)
         if (il != null) {
             int max = isStatic() ? 0 : 1;
             for (final Type argType : argTypes) {
                 max += argType.getSize();
             }
             for (InstructionHandle ih = il.getStart(); ih != null; ih = ih.getNext()) {
                 final Instruction ins = ih.getInstruction();
                 if (ins instanceof LocalVariableInstruction || ins instanceof RET || ins instanceof IINC) {
                     final int index = ((IndexedInstruction) ins).getIndex() + ((TypedInstruction) ins).getType(super.getConstantPool()).getSize();
                     if (index > max) {
                         max = index;
                     }
                 }
             }
             maxLocals = max;
         } else {
             maxLocals = 0;
         }
     }
 
     /**
      * Sets maximum number of local variables.
      */
     public void setMaxLocals(final int m) {
         maxLocals = m;
     }
 
     /**
      * Computes max. stack size by performing control flow analysis.
      */
     public void setMaxStack() { // TODO could be package-protected? (some tests would need repackaging)
         if (il != null) {
             maxStack = getMaxStack(super.getConstantPool(), il, getExceptionHandlers());
         } else {
             maxStack = 0;
         }
     }
 
     /**
      * Sets maximum stack size for this method.
      */
     public void setMaxStack(final int m) { // TODO could be package-protected?
         maxStack = m;
     }
 
     public void setReturnType(final Type returnType) {
         setType(returnType);
     }
 
     /**
      * Do not/Do produce attributes code attributesLineNumberTable and LocalVariableTable, like javac -O
      */
     public void stripAttributes(final boolean flag) {
         stripAttributes = flag;
     }
 
     /**
      * Return string representation close to declaration format, 'public static void main(String[]) throws IOException',
      * e.g.
      *
      * @return String representation of the method.
      */
     @Override
     public final String toString() {
         final String access = Utility.accessToString(super.getAccessFlags());
         String signature = Type.getMethodSignature(super.getType(), argTypes);
         signature = Utility.methodSignatureToString(signature, super.getName(), access, true, getLocalVariableTable(super.getConstantPool()));
         final StringBuilder buf = new StringBuilder(signature);
         for (final Attribute a : getAttributes()) {
             if (!(a instanceof Code || a instanceof ExceptionTable)) {
                 buf.append(" [").append(a).append("]");
             }
         }
 
         if (!throwsList.isEmpty()) {
             for (final String throwsDescriptor : throwsList) {
                 buf.append("\n\t\tthrows ").append(throwsDescriptor);
             }
         }
         return buf.toString();
     }
 
     /**
      * Call notify() method on all observers. This method is not called automatically whenever the state has changed, but
      * has to be called by the user after they have finished editing the object.
      */
     public void update() {
         if (observers != null) {
             for (final MethodObserver observer : observers) {
                 observer.notify(this);
             }
         }
     }
 
     private void updateLocalVariableTable(final LocalVariableTable a) {
         removeLocalVariables();
         for (final LocalVariable l : a.getLocalVariableTable()) {
             InstructionHandle start = il.findHandle(l.getStartPC());
             final InstructionHandle end = il.findHandle(l.getStartPC() + l.getLength());
             // Repair malformed handles
             if (null == start) {
                 start = il.getStart();
             }
             // end == null => live to end of method
             // Since we are recreating the LocalVaraible, we must
             // propagate the orig_index to new copy.
             addLocalVariable(l.getName(), Type.getType(l.getSignature()), l.getIndex(), start, end, l.getOrigIndex());
         }
     }
 }