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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * 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 jdk.internal.org.objectweb.asm.tree;

import java.util.ListIterator;
import java.util.NoSuchElementException;
import jdk.internal.org.objectweb.asm.MethodVisitor;


A doubly linked list of AbstractInsnNode objects. This implementation is not thread
safe.

/**
 * A doubly linked list of {@link AbstractInsnNode} objects. <i>This implementation is not thread
 * safe</i>.
 */
public class InsnList {

    
The number of instructions in this list. 
/** The number of instructions in this list. */
    private int size;

    
The first instruction in this list. May be null. 
/** The first instruction in this list. May be {@literal null}. */
    private AbstractInsnNode firstInsn;

    
The last instruction in this list. May be null. 
/** The last instruction in this list. May be {@literal null}. */
    private AbstractInsnNode lastInsn;

    
A cache of the instructions of this list. This cache is used to improve the performance of the get method. 
/**
      * A cache of the instructions of this list. This cache is used to improve the performance of the
      * {@link #get} method.
      */
    AbstractInsnNode[] cache;

    
Returns the number of instructions in this list.

Returns:the number of instructions in this list.
/**
      * Returns the number of instructions in this list.
      *
      * @return the number of instructions in this list.
      */
    public int size() {
        return size;
    }

    
Returns the first instruction in this list.

Returns:the first instruction in this list, or null if the list is empty.
/**
      * Returns the first instruction in this list.
      *
      * @return the first instruction in this list, or {@literal null} if the list is empty.
      */
    public AbstractInsnNode getFirst() {
        return firstInsn;
    }

    
Returns the last instruction in this list.

Returns:the last instruction in this list, or null if the list is empty.
/**
      * Returns the last instruction in this list.
      *
      * @return the last instruction in this list, or {@literal null} if the list is empty.
      */
    public AbstractInsnNode getLast() {
        return lastInsn;
    }

    
Returns the instruction whose index is given. This method builds a cache of the instructions in
this list to avoid scanning the whole list each time it is called. Once the cache is built,
this method runs in constant time. This cache is invalidated by all the methods that modify the
list.

Params:
  • index – the index of the instruction that must be returned.
Throws:
Returns:the instruction whose index is given.
/**
      * Returns the instruction whose index is given. This method builds a cache of the instructions in
      * this list to avoid scanning the whole list each time it is called. Once the cache is built,
      * this method runs in constant time. This cache is invalidated by all the methods that modify the
      * list.
      *
      * @param index the index of the instruction that must be returned.
      * @return the instruction whose index is given.
      * @throws IndexOutOfBoundsException if (index &lt; 0 || index &gt;= size()).
      */
    public AbstractInsnNode get(final int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        if (cache == null) {
            cache = toArray();
        }
        return cache[index];
    }

    
Returns true if the given instruction belongs to this list. This method always scans the instructions of this list until it finds the given instruction or reaches the end of the list. 
Params:
  • insnNode – an instruction.
Returns:true if the given instruction belongs to this list.
/**
      * Returns {@literal true} if the given instruction belongs to this list. This method always scans
      * the instructions of this list until it finds the given instruction or reaches the end of the
      * list.
      *
      * @param insnNode an instruction.
      * @return {@literal true} if the given instruction belongs to this list.
      */
    public boolean contains(final AbstractInsnNode insnNode) {
        AbstractInsnNode currentInsn = firstInsn;
        while (currentInsn != null && currentInsn != insnNode) {
            currentInsn = currentInsn.nextInsn;
        }
        return currentInsn != null;
    }

    
Returns the index of the given instruction in this list. This method builds a cache of the
instruction indexes to avoid scanning the whole list each time it is called. Once the cache is
built, this method run in constant time. The cache is invalidated by all the methods that
modify the list.

Params:
  • insnNode – an instruction of this list.
Returns:the index of the given instruction in this list. The result of this method is
    undefined if the given instruction does not belong to this list. Use contains to test if an instruction belongs to an instruction list or not.
/**
      * Returns the index of the given instruction in this list. This method builds a cache of the
      * instruction indexes to avoid scanning the whole list each time it is called. Once the cache is
      * built, this method run in constant time. The cache is invalidated by all the methods that
      * modify the list.
      *
      * @param insnNode an instruction <i>of this list</i>.
      * @return the index of the given instruction in this list. <i>The result of this method is
      *     undefined if the given instruction does not belong to this list</i>. Use {@link #contains }
      *     to test if an instruction belongs to an instruction list or not.
      */
    public int indexOf(final AbstractInsnNode insnNode) {
        if (cache == null) {
            cache = toArray();
        }
        return insnNode.index;
    }

    
Makes the given visitor visit all the instructions in this list.

Params:
  • methodVisitor – the method visitor that must visit the instructions.
/**
      * Makes the given visitor visit all the instructions in this list.
      *
      * @param methodVisitor the method visitor that must visit the instructions.
      */
    public void accept(final MethodVisitor methodVisitor) {
        AbstractInsnNode currentInsn = firstInsn;
        while (currentInsn != null) {
            currentInsn.accept(methodVisitor);
            currentInsn = currentInsn.nextInsn;
        }
    }

    
Returns an iterator over the instructions in this list.

Returns:an iterator over the instructions in this list.
/**
      * Returns an iterator over the instructions in this list.
      *
      * @return an iterator over the instructions in this list.
      */
    public ListIterator<AbstractInsnNode> iterator() {
        return iterator(0);
    }

    
Returns an iterator over the instructions in this list.

Params:
  • index – index of instruction for the iterator to start at.
Returns:an iterator over the instructions in this list.
/**
      * Returns an iterator over the instructions in this list.
      *
      * @param index index of instruction for the iterator to start at.
      * @return an iterator over the instructions in this list.
      */
    @SuppressWarnings("unchecked")
    public ListIterator<AbstractInsnNode> iterator(final int index) {
        return new InsnListIterator(index);
    }

    
Returns an array containing all the instructions in this list.

Returns:an array containing all the instructions in this list.
/**
      * Returns an array containing all the instructions in this list.
      *
      * @return an array containing all the instructions in this list.
      */
    public AbstractInsnNode[] toArray() {
        int currentInsnIndex = 0;
        AbstractInsnNode currentInsn = firstInsn;
        AbstractInsnNode[] insnNodeArray = new AbstractInsnNode[size];
        while (currentInsn != null) {
            insnNodeArray[currentInsnIndex] = currentInsn;
            currentInsn.index = currentInsnIndex++;
            currentInsn = currentInsn.nextInsn;
        }
        return insnNodeArray;
    }

    
Replaces an instruction of this list with another instruction.

Params:
  • oldInsnNode – an instruction of this list.
  • newInsnNode – another instruction, which must not belong to any InsnList.
/**
      * Replaces an instruction of this list with another instruction.
      *
      * @param oldInsnNode an instruction <i>of this list</i>.
      * @param newInsnNode another instruction, <i>which must not belong to any {@link InsnList}</i>.
      */
    public void set(final AbstractInsnNode oldInsnNode, final AbstractInsnNode newInsnNode) {
        AbstractInsnNode nextInsn = oldInsnNode.nextInsn;
        newInsnNode.nextInsn = nextInsn;
        if (nextInsn != null) {
            nextInsn.previousInsn = newInsnNode;
        } else {
            lastInsn = newInsnNode;
        }
        AbstractInsnNode previousInsn = oldInsnNode.previousInsn;
        newInsnNode.previousInsn = previousInsn;
        if (previousInsn != null) {
            previousInsn.nextInsn = newInsnNode;
        } else {
            firstInsn = newInsnNode;
        }
        if (cache != null) {
            int index = oldInsnNode.index;
            cache[index] = newInsnNode;
            newInsnNode.index = index;
        } else {
            newInsnNode.index = 0; // newInnsnNode now belongs to an InsnList.
        }
        oldInsnNode.index = -1; // oldInsnNode no longer belongs to an InsnList.
        oldInsnNode.previousInsn = null;
        oldInsnNode.nextInsn = null;
    }

    
Adds the given instruction to the end of this list.

Params:
  • insnNode – an instruction, which must not belong to any InsnList.
/**
      * Adds the given instruction to the end of this list.
      *
      * @param insnNode an instruction, <i>which must not belong to any {@link InsnList}</i>.
      */
    public void add(final AbstractInsnNode insnNode) {
        ++size;
        if (lastInsn == null) {
            firstInsn = insnNode;
            lastInsn = insnNode;
        } else {
            lastInsn.nextInsn = insnNode;
            insnNode.previousInsn = lastInsn;
        }
        lastInsn = insnNode;
        cache = null;
        insnNode.index = 0; // insnNode now belongs to an InsnList.
    }

    
Adds the given instructions to the end of this list.

Params:
  • insnList – an instruction list, which is cleared during the process. This list must be
    different from 'this'.
/**
      * Adds the given instructions to the end of this list.
      *
      * @param insnList an instruction list, which is cleared during the process. This list must be
      *     different from 'this'.
      */
    public void add(final InsnList insnList) {
        if (insnList.size == 0) {
            return;
        }
        size += insnList.size;
        if (lastInsn == null) {
            firstInsn = insnList.firstInsn;
            lastInsn = insnList.lastInsn;
        } else {
            AbstractInsnNode firstInsnListElement = insnList.firstInsn;
            lastInsn.nextInsn = firstInsnListElement;
            firstInsnListElement.previousInsn = lastInsn;
            lastInsn = insnList.lastInsn;
        }
        cache = null;
        insnList.removeAll(false);
    }

    
Inserts the given instruction at the beginning of this list.

Params:
  • insnNode – an instruction, which must not belong to any InsnList.
/**
      * Inserts the given instruction at the beginning of this list.
      *
      * @param insnNode an instruction, <i>which must not belong to any {@link InsnList}</i>.
      */
    public void insert(final AbstractInsnNode insnNode) {
        ++size;
        if (firstInsn == null) {
            firstInsn = insnNode;
            lastInsn = insnNode;
        } else {
            firstInsn.previousInsn = insnNode;
            insnNode.nextInsn = firstInsn;
        }
        firstInsn = insnNode;
        cache = null;
        insnNode.index = 0; // insnNode now belongs to an InsnList.
    }

    
Inserts the given instructions at the beginning of this list.

Params:
  • insnList – an instruction list, which is cleared during the process. This list must be
    different from 'this'.
/**
      * Inserts the given instructions at the beginning of this list.
      *
      * @param insnList an instruction list, which is cleared during the process. This list must be
      *     different from 'this'.
      */
    public void insert(final InsnList insnList) {
        if (insnList.size == 0) {
            return;
        }
        size += insnList.size;
        if (firstInsn == null) {
            firstInsn = insnList.firstInsn;
            lastInsn = insnList.lastInsn;
        } else {
            AbstractInsnNode lastInsnListElement = insnList.lastInsn;
            firstInsn.previousInsn = lastInsnListElement;
            lastInsnListElement.nextInsn = firstInsn;
            firstInsn = insnList.firstInsn;
        }
        cache = null;
        insnList.removeAll(false);
    }

    
Inserts the given instruction after the specified instruction.

Params:
  • previousInsn – an instruction of this list after which insnNode must be inserted.
  • insnNode – the instruction to be inserted, which must not belong to any InsnList.
/**
      * Inserts the given instruction after the specified instruction.
      *
      * @param previousInsn an instruction <i>of this list</i> after which insnNode must be inserted.
      * @param insnNode the instruction to be inserted, <i>which must not belong to any {@link
      *     InsnList}</i>.
      */
    public void insert(final AbstractInsnNode previousInsn, final AbstractInsnNode insnNode) {
        ++size;
        AbstractInsnNode nextInsn = previousInsn.nextInsn;
        if (nextInsn == null) {
            lastInsn = insnNode;
        } else {
            nextInsn.previousInsn = insnNode;
        }
        previousInsn.nextInsn = insnNode;
        insnNode.nextInsn = nextInsn;
        insnNode.previousInsn = previousInsn;
        cache = null;
        insnNode.index = 0; // insnNode now belongs to an InsnList.
    }

    
Inserts the given instructions after the specified instruction.

Params:
  • previousInsn – an instruction of this list after which the instructions must be
    inserted.
  • insnList – the instruction list to be inserted, which is cleared during the process. This
    list must be different from 'this'.
/**
      * Inserts the given instructions after the specified instruction.
      *
      * @param previousInsn an instruction <i>of this list</i> after which the instructions must be
      *     inserted.
      * @param insnList the instruction list to be inserted, which is cleared during the process. This
      *     list must be different from 'this'.
      */
    public void insert(final AbstractInsnNode previousInsn, final InsnList insnList) {
        if (insnList.size == 0) {
            return;
        }
        size += insnList.size;
        AbstractInsnNode firstInsnListElement = insnList.firstInsn;
        AbstractInsnNode lastInsnListElement = insnList.lastInsn;
        AbstractInsnNode nextInsn = previousInsn.nextInsn;
        if (nextInsn == null) {
            lastInsn = lastInsnListElement;
        } else {
            nextInsn.previousInsn = lastInsnListElement;
        }
        previousInsn.nextInsn = firstInsnListElement;
        lastInsnListElement.nextInsn = nextInsn;
        firstInsnListElement.previousInsn = previousInsn;
        cache = null;
        insnList.removeAll(false);
    }

    
Inserts the given instruction before the specified instruction.

Params:
  • nextInsn – an instruction of this list before which insnNode must be inserted.
  • insnNode – the instruction to be inserted, which must not belong to any InsnList.
/**
      * Inserts the given instruction before the specified instruction.
      *
      * @param nextInsn an instruction <i>of this list</i> before which insnNode must be inserted.
      * @param insnNode the instruction to be inserted, <i>which must not belong to any {@link
      *     InsnList}</i>.
      */
    public void insertBefore(final AbstractInsnNode nextInsn, final AbstractInsnNode insnNode) {
        ++size;
        AbstractInsnNode previousInsn = nextInsn.previousInsn;
        if (previousInsn == null) {
            firstInsn = insnNode;
        } else {
            previousInsn.nextInsn = insnNode;
        }
        nextInsn.previousInsn = insnNode;
        insnNode.nextInsn = nextInsn;
        insnNode.previousInsn = previousInsn;
        cache = null;
        insnNode.index = 0; // insnNode now belongs to an InsnList.
    }

    
Inserts the given instructions before the specified instruction.

Params:
  • nextInsn – an instruction of this list before which the instructions must be
    inserted.
  • insnList – the instruction list to be inserted, which is cleared during the process. This
    list must be different from 'this'.
/**
      * Inserts the given instructions before the specified instruction.
      *
      * @param nextInsn an instruction <i>of this list</i> before which the instructions must be
      *     inserted.
      * @param insnList the instruction list to be inserted, which is cleared during the process. This
      *     list must be different from 'this'.
      */
    public void insertBefore(final AbstractInsnNode nextInsn, final InsnList insnList) {
        if (insnList.size == 0) {
            return;
        }
        size += insnList.size;
        AbstractInsnNode firstInsnListElement = insnList.firstInsn;
        AbstractInsnNode lastInsnListElement = insnList.lastInsn;
        AbstractInsnNode previousInsn = nextInsn.previousInsn;
        if (previousInsn == null) {
            firstInsn = firstInsnListElement;
        } else {
            previousInsn.nextInsn = firstInsnListElement;
        }
        nextInsn.previousInsn = lastInsnListElement;
        lastInsnListElement.nextInsn = nextInsn;
        firstInsnListElement.previousInsn = previousInsn;
        cache = null;
        insnList.removeAll(false);
    }

    
Removes the given instruction from this list.

Params:
  • insnNode – the instruction of this list that must be removed.
/**
      * Removes the given instruction from this list.
      *
      * @param insnNode the instruction <i>of this list</i> that must be removed.
      */
    public void remove(final AbstractInsnNode insnNode) {
        --size;
        AbstractInsnNode nextInsn = insnNode.nextInsn;
        AbstractInsnNode previousInsn = insnNode.previousInsn;
        if (nextInsn == null) {
            if (previousInsn == null) {
                firstInsn = null;
                lastInsn = null;
            } else {
                previousInsn.nextInsn = null;
                lastInsn = previousInsn;
            }
        } else {
            if (previousInsn == null) {
                firstInsn = nextInsn;
                nextInsn.previousInsn = null;
            } else {
                previousInsn.nextInsn = nextInsn;
                nextInsn.previousInsn = previousInsn;
            }
        }
        cache = null;
        insnNode.index = -1; // insnNode no longer belongs to an InsnList.
        insnNode.previousInsn = null;
        insnNode.nextInsn = null;
    }

    
Removes all the instructions of this list.

Params:
  • mark – if the instructions must be marked as no longer belonging to any InsnList.
/**
      * Removes all the instructions of this list.
      *
      * @param mark if the instructions must be marked as no longer belonging to any {@link InsnList}.
      */
    void removeAll(final boolean mark) {
        if (mark) {
            AbstractInsnNode currentInsn = firstInsn;
            while (currentInsn != null) {
                AbstractInsnNode next = currentInsn.nextInsn;
                currentInsn.index = -1; // currentInsn no longer belongs to an InsnList.
                currentInsn.previousInsn = null;
                currentInsn.nextInsn = null;
                currentInsn = next;
            }
        }
        size = 0;
        firstInsn = null;
        lastInsn = null;
        cache = null;
    }

    
Removes all the instructions of this list. 
/** Removes all the instructions of this list. */
    public void clear() {
        removeAll(false);
    }

    
Resets all the labels in the instruction list. This method should be called before reusing an
instruction list between several ClassWriters.

/**
      * Resets all the labels in the instruction list. This method should be called before reusing an
      * instruction list between several <code>ClassWriter</code>s.
      */
    public void resetLabels() {
        AbstractInsnNode currentInsn = firstInsn;
        while (currentInsn != null) {
            if (currentInsn instanceof LabelNode) {
                ((LabelNode) currentInsn).resetLabel();
            }
            currentInsn = currentInsn.nextInsn;
        }
    }

    // Note: this class is not generified because it would create bridges.
    @SuppressWarnings("rawtypes")
    private final class InsnListIterator implements ListIterator {

        AbstractInsnNode nextInsn;

        AbstractInsnNode previousInsn;

        AbstractInsnNode remove;

        InsnListIterator(final int index) {
            if (index == size()) {
                nextInsn = null;
                previousInsn = getLast();
            } else {
                nextInsn = get(index);
                previousInsn = nextInsn.previousInsn;
            }
        }

        @Override
        public boolean hasNext() {
            return nextInsn != null;
        }

        @Override
        public Object next() {
            if (nextInsn == null) {
                throw new NoSuchElementException();
            }
            AbstractInsnNode result = nextInsn;
            previousInsn = result;
            nextInsn = result.nextInsn;
            remove = result;
            return result;
        }

        @Override
        public void remove() {
            if (remove != null) {
                if (remove == nextInsn) {
                    nextInsn = nextInsn.nextInsn;
                } else {
                    previousInsn = previousInsn.previousInsn;
                }
                InsnList.this.remove(remove);
                remove = null;
            } else {
                throw new IllegalStateException();
            }
        }

        @Override
        public boolean hasPrevious() {
            return previousInsn != null;
        }

        @Override
        public Object previous() {
            AbstractInsnNode result = previousInsn;
            nextInsn = result;
            previousInsn = result.previousInsn;
            remove = result;
            return result;
        }

        @Override
        public int nextIndex() {
            if (nextInsn == null) {
                return size();
            }
            if (cache == null) {
                cache = toArray();
            }
            return nextInsn.index;
        }

        @Override
        public int previousIndex() {
            if (previousInsn == null) {
                return -1;
            }
            if (cache == null) {
                cache = toArray();
            }
            return previousInsn.index;
        }

        @Override
        public void add(final Object o) {
            if (nextInsn != null) {
                InsnList.this.insertBefore(nextInsn, (AbstractInsnNode) o);
            } else if (previousInsn != null) {
                InsnList.this.insert(previousInsn, (AbstractInsnNode) o);
            } else {
                InsnList.this.add((AbstractInsnNode) o);
            }
            previousInsn = (AbstractInsnNode) o;
            remove = null;
        }

        @Override
        public void set(final Object o) {
            if (remove != null) {
                InsnList.this.set(remove, (AbstractInsnNode) o);
                if (remove == previousInsn) {
                    previousInsn = (AbstractInsnNode) o;
                } else {
                    nextInsn = (AbstractInsnNode) o;
                }
            } else {
                throw new IllegalStateException();
            }
        }
    }
}