scala.tools.asm.tree.InsnList Maven / Gradle / Ivy
// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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package scala.tools.asm.tree;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import scala.tools.asm.MethodVisitor;
/**
* A doubly linked list of {@link AbstractInsnNode} objects. This implementation is not thread
* safe.
*/
public class InsnList implements Iterable {
/** The number of instructions in this list. */
private int size;
/** The first instruction in this list. May be {@literal null}. */
private AbstractInsnNode firstInsn;
/** 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
* {@link #get} method.
*/
AbstractInsnNode[] cache;
/**
* 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.
*
* @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.
*
* @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.
*
* @param index the index of the instruction that must be returned.
* @return the instruction whose index is given.
* @throws IndexOutOfBoundsException if (index < 0 || index >= size()).
*/
public AbstractInsnNode get(final int index) {
if (index < 0 || index >= size) {
throw new IndexOutOfBoundsException();
}
if (cache == null) {
cache = toArray();
}
return cache[index];
}
/**
* 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.
*
* @param insnNode an instruction of this list.
* @return 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 {@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.
*
* @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.
*
* @return an iterator over the instructions in this list.
*/
@Override
public ListIterator iterator() {
return iterator(0);
}
/**
* 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 iterator(final int index) {
return new InsnListIterator(index);
}
/**
* 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.
*
* @param oldInsnNode an instruction of this list.
* @param newInsnNode another instruction, which must not belong to any {@link InsnList}.
*/
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; // newInsnNode 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.
*
* @param insnNode an instruction, which must not belong to any {@link InsnList}.
*/
public void add(final AbstractInsnNode insnNode) {
if(insnNode.previousInsn != null || insnNode.nextInsn != null) {
// Adding an instruction that still refers to others (in the same or another InsnList) leads to hard to debug bugs.
// Initially everything may look ok (e.g. iteration follows `next` thus a stale `prev` isn't noticed).
// However, a stale link brings the doubly-linked into disarray e.g. upon removing an element,
// which results in the `next` of a stale `prev` being updated, among other failure scenarios.
// Better fail early.
throw new RuntimeException("Instruction " + insnNode + " already belongs to some InsnList.");
}
++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.
*
* @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.
*
* @param insnNode an instruction, which must not belong to any {@link InsnList}.
*/
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.
*
* @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.
*
* @param previousInsn an instruction of this list after which insnNode must be inserted.
* @param insnNode the instruction to be inserted, which must not belong to any {@link
* InsnList}.
*/
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.
*
* @param previousInsn an instruction of this list 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.
*
* @param nextInsn an instruction of this list before which insnNode must be inserted.
* @param insnNode the instruction to be inserted, which must not belong to any {@link
* InsnList}.
*/
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.
*
* @param nextInsn an instruction of this list 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.
*
* @param insnNode the instruction of this list 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.
*
* @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. */
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.
*/
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 < 0 || index > size()) {
throw new IndexOutOfBoundsException();
} else if (index == size()) {
nextInsn = null;
previousInsn = getLast();
} else {
AbstractInsnNode currentInsn = getFirst();
for (int i = 0; i < index; i++) {
currentInsn = currentInsn.nextInsn;
}
nextInsn = currentInsn;
previousInsn = currentInsn.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() {
if (previousInsn == null) {
throw new NoSuchElementException();
}
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();
}
}
}
}
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