diff -r 000000000000 -r 6474c204b198 xpcom/glue/nsDeque.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/glue/nsDeque.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,610 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDeque.h"
+#include "nsISupportsImpl.h"
+#include <string.h>
+#ifdef DEBUG_rickg
+#include <stdio.h>
+#endif
+
+/**
+ * 07/02/2001  09:17p 509,104 clangref.pdf from openwatcom's site
+ * Watcom C Language Reference Edition 11.0c
+ * page 118 of 297
+ *
+ * The % symbol yields the remainder from the division of the first operand
+ * by the second operand. The operands of % must have integral type.
+ *
+ * When both operands of % are positive, the result is a positive value
+ * smaller than the second operand. When one or both operands is negative,
+ * whether the result is positive or negative is implementation-defined.
+ *
+ */
+/* Ok, so first of all, C is underspecified. joy.
+ * The following functions do not provide a correct implementation of modulus
+ * They provide functionality for x>-y.
+ * There are risks of 2*y being greater than max int, which is part of the
+ * reason no multiplication is used and other operations are avoided.
+ *
+ * modasgn
+ * @param x variable
+ * @param y expression
+ * approximately equivalent to x %= y
+ *
+ * modulus
+ * @param x expression
+ * @param y expression
+ * approximately equivalent to x % y
+ */
+#define modasgn(x,y) if (x<0) x+=y; x%=y
+#define modulus(x,y) ((x<0)?(x+y)%(y):(x)%(y))
+
+/**
+ * Standard constructor
+ * @param deallocator, called by Erase and ~nsDeque
+ */
+nsDeque::nsDeque(nsDequeFunctor* aDeallocator) {
+  MOZ_COUNT_CTOR(nsDeque);
+  mDeallocator=aDeallocator;
+  mOrigin=mSize=0;
+  mData=mBuffer; // don't allocate space until you must
+  mCapacity=sizeof(mBuffer)/sizeof(mBuffer[0]);
+  memset(mData, 0, mCapacity*sizeof(mBuffer[0]));
+}
+
+/**
+ * Destructor
+ */
+nsDeque::~nsDeque() {
+  MOZ_COUNT_DTOR(nsDeque);
+
+#ifdef DEBUG_rickg
+  char buffer[30];
+  printf("Capacity: %i\n", mCapacity);
+
+  static int mCaps[15] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
+  switch(mCapacity) {
+    case 4:     mCaps[0]++; break;
+    case 8:     mCaps[1]++; break;
+    case 16:    mCaps[2]++; break;
+    case 32:    mCaps[3]++; break;
+    case 64:    mCaps[4]++; break;
+    case 128:   mCaps[5]++; break;
+    case 256:   mCaps[6]++; break;
+    case 512:   mCaps[7]++; break;
+    case 1024:  mCaps[8]++; break;
+    case 2048:  mCaps[9]++; break;
+    case 4096:  mCaps[10]++; break;
+    default:
+      break;
+  }
+#endif
+
+  Erase();
+  if (mData && (mData!=mBuffer)) {
+    free(mData);
+  }
+  mData=0;
+  SetDeallocator(0);
+}
+
+size_t nsDeque::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+  size_t size = 0;
+  if (mData != mBuffer) {
+    size += aMallocSizeOf(mData);
+  }
+
+  if (mDeallocator) {
+    size += aMallocSizeOf(mDeallocator);
+  }
+
+  return size;
+}
+
+size_t nsDeque::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+/**
+ * Set the functor to be called by Erase()
+ * The deque owns the functor.
+ *
+ * @param   aDeallocator functor object for use by Erase()
+ */
+void nsDeque::SetDeallocator(nsDequeFunctor* aDeallocator){
+  delete mDeallocator;
+  mDeallocator=aDeallocator;
+}
+
+/**
+ * Remove all items from container without destroying them.
+ */
+void nsDeque::Empty() {
+  if (mSize && mData) {
+    memset(mData, 0, mCapacity*sizeof(mData));
+  }
+  mSize=0;
+  mOrigin=0;
+}
+
+/**
+ * Remove and delete all items from container
+ */
+void nsDeque::Erase() {
+  if (mDeallocator && mSize) {
+    ForEach(*mDeallocator);
+  }
+  Empty();
+}
+
+/**
+ * This method quadruples the size of the deque
+ * Elements in the deque are resequenced so that elements
+ * in the deque are stored sequentially
+ *
+ * @return  whether growing succeeded
+ */
+bool nsDeque::GrowCapacity() {
+  int32_t theNewSize=mCapacity<<2;
+  NS_ASSERTION(theNewSize>mCapacity, "Overflow");
+  if (theNewSize<=mCapacity)
+    return false;
+  void** temp=(void**)malloc(theNewSize * sizeof(void*));
+  if (!temp)
+    return false;
+
+  //Here's the interesting part: You can't just move the elements
+  //directly (in situ) from the old buffer to the new one.
+  //Since capacity has changed, the old origin doesn't make
+  //sense anymore. It's better to resequence the elements now.
+
+  memcpy(temp, mData + mOrigin, sizeof(void*) * (mCapacity - mOrigin));
+  memcpy(temp + (mCapacity - mOrigin), mData, sizeof(void*) * mOrigin);
+
+  if (mData != mBuffer) {
+    free(mData);
+  }
+
+  mCapacity=theNewSize;
+  mOrigin=0; //now realign the origin...
+  mData=temp;
+
+  return true;
+}
+
+/**
+ * This method adds an item to the end of the deque.
+ * This operation has the potential to cause the
+ * underlying buffer to resize.
+ *
+ * @param   aItem: new item to be added to deque
+ */
+bool nsDeque::Push(void* aItem, const fallible_t&) {
+  if (mSize==mCapacity && !GrowCapacity()) {
+    return false;
+  }
+  mData[modulus(mOrigin + mSize, mCapacity)]=aItem;
+  mSize++;
+  return true;
+}
+
+/**
+ * This method adds an item to the front of the deque.
+ * This operation has the potential to cause the
+ * underlying buffer to resize.
+ *
+ * --Commments for GrowCapacity() case
+ * We've grown and shifted which means that the old
+ * final element in the deque is now the first element
+ * in the deque.  This is temporary.
+ * We haven't inserted the new element at the front.
+ *
+ * To continue with the idea of having the front at zero
+ * after a grow, we move the old final item (which through
+ * the voodoo of mOrigin-- is now the first) to its final
+ * position which is conveniently the old length.
+ *
+ * Note that this case only happens when the deque is full.
+ * [And that pieces of this magic only work if the deque is full.]
+ * picture:
+ *   [ABCDEFGH] @[mOrigin:3]:D.
+ * Task: PushFront("Z")
+ * shift mOrigin so, @[mOrigin:2]:C
+ * stretch and rearrange: (mOrigin:0)
+ *   [CDEFGHAB ________ ________ ________]
+ * copy: (The second C is currently out of bounds)
+ *   [CDEFGHAB C_______ ________ ________]
+ * later we will insert Z:
+ *   [ZDEFGHAB C_______ ________ ________]
+ * and increment size: 9. (C is no longer out of bounds)
+ * --
+ * @param   aItem: new item to be added to deque
+ */
+bool nsDeque::PushFront(void* aItem, const fallible_t&) {
+  mOrigin--;
+  modasgn(mOrigin,mCapacity);
+  if (mSize==mCapacity) {
+    if (!GrowCapacity()) {
+      return false;
+    }
+    /* Comments explaining this are above*/
+    mData[mSize]=mData[mOrigin];
+  }
+  mData[mOrigin]=aItem;
+  mSize++;
+  return true;
+}
+
+/**
+ * Remove and return the last item in the container.
+ *
+ * @return  ptr to last item in container
+ */
+void* nsDeque::Pop() {
+  void* result=0;
+  if (mSize>0) {
+    --mSize;
+    int32_t offset=modulus(mSize + mOrigin, mCapacity);
+    result=mData[offset];
+    mData[offset]=0;
+    if (!mSize) {
+      mOrigin=0;
+    }
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to remove and return
+ * the first member in the container.
+ *
+ * @return  last item in container
+ */
+void* nsDeque::PopFront() {
+  void* result=0;
+  if (mSize>0) {
+    NS_ASSERTION(mOrigin < mCapacity, "Error: Bad origin");
+    result=mData[mOrigin];
+    mData[mOrigin++]=0;     //zero it out for debugging purposes.
+    mSize--;
+    // Cycle around if we pop off the end
+    // and reset origin if when we pop the last element
+    if (mCapacity==mOrigin || !mSize) {
+      mOrigin=0;
+    }
+  }
+  return result;
+}
+
+/**
+ * This method gets called you want to peek at the bottom
+ * member without removing it.
+ *
+ * @return  last item in container
+ */
+void* nsDeque::Peek() {
+  void* result=0;
+  if (mSize>0) {
+    result = mData[modulus(mSize - 1 + mOrigin, mCapacity)];
+  }
+  return result;
+} 
+
+/**
+ * This method gets called you want to peek at the topmost
+ * member without removing it.
+ *
+ * @return  last item in container
+ */
+void* nsDeque::PeekFront() {
+  void* result=0;
+  if (mSize>0) {
+    result=mData[mOrigin];
+  }
+  return result;
+}
+
+/**
+ * Call this to retrieve the ith element from this container.
+ * Keep in mind that accessing the underlying elements is
+ * done in a relative fashion. Object 0 is not necessarily
+ * the first element (the first element is at mOrigin).
+ *
+ * @param   aIndex : 0 relative offset of item you want
+ * @return  void* or null
+ */
+void* nsDeque::ObjectAt(int32_t aIndex) const {
+  void* result=0;
+  if ((aIndex>=0) && (aIndex<mSize)) {
+    result=mData[modulus(mOrigin + aIndex, mCapacity)];
+  }
+  return result;
+}
+
+void* nsDeque::RemoveObjectAt(int32_t aIndex) {
+  if ((aIndex<0) || (aIndex>=mSize)) {
+    return 0;
+  }
+  void* result=mData[modulus(mOrigin + aIndex, mCapacity)];
+
+  // "Shuffle down" all elements in the array by 1, overwritting the element
+  // being removed.
+  for (int32_t i=aIndex; i<mSize; i++) {
+    mData[modulus(mOrigin + i, mCapacity)] = mData[modulus(mOrigin + i + 1, mCapacity)];
+  }
+  mSize--;
+
+  return result;
+}
+
+/**
+ * Create and return an iterator pointing to
+ * the beginning of the queue. Note that this
+ * takes the circular buffer semantics into account.
+ *
+ * @return  new deque iterator, init'ed to 1st item
+ */
+nsDequeIterator nsDeque::Begin() const{
+  return nsDequeIterator(*this, 0);
+}
+
+/**
+ * Create and return an iterator pointing to
+ * the last item in the deque.
+ * Note that this takes the circular buffer semantics
+ * into account.
+ *
+ * @return  new deque iterator, init'ed to the last item
+ */
+nsDequeIterator nsDeque::End() const{
+  return nsDequeIterator(*this, mSize - 1);
+}
+
+void* nsDeque::Last() const {
+  return End().GetCurrent();
+}
+
+/**
+ * Call this method when you want to iterate all the
+ * members of the container, passing a functor along
+ * to call your code.
+ *
+ * @param   aFunctor object to call for each member
+ * @return  *this
+ */
+void nsDeque::ForEach(nsDequeFunctor& aFunctor) const{
+  for (int32_t i=0; i<mSize; i++) {
+    aFunctor(ObjectAt(i));
+  }
+}
+
+/**
+ * Call this method when you want to iterate all the
+ * members of the container, calling the functor you 
+ * passed with each member. This process will interrupt
+ * if your function returns non 0 to this method.
+ *
+ * @param   aFunctor object to call for each member
+ * @return  first nonzero result of aFunctor or 0.
+ */
+const void* nsDeque::FirstThat(nsDequeFunctor& aFunctor) const{
+  for (int32_t i=0; i<mSize; i++) {
+    void* obj=aFunctor(ObjectAt(i));
+    if (obj) {
+      return obj;
+    }
+  }
+  return 0;
+}
+
+/******************************************************
+ * Here comes the nsDequeIterator class...
+ ******************************************************/
+
+/**
+ * DequeIterator is an object that knows how to iterate (forward and backward)
+ * through a Deque. Normally, you don't need to do this, but there are some special
+ * cases where it is pretty handy, so here you go.
+ *
+ * This is a standard dequeiterator constructor
+ *
+ * @param   aQueue is the deque object to be iterated
+ * @param   aIndex is the starting position for your iteration
+ */
+nsDequeIterator::nsDequeIterator(const nsDeque& aQueue, int aIndex)
+: mIndex(aIndex),
+  mDeque(aQueue)
+{
+}
+
+/**
+ * Create a copy of a DequeIterator
+ *
+ * @param   aCopy is another iterator to copy from
+ */
+nsDequeIterator::nsDequeIterator(const nsDequeIterator& aCopy)
+: mIndex(aCopy.mIndex),
+  mDeque(aCopy.mDeque)
+{
+}
+
+/**
+ * Moves iterator to first element in deque
+ * @return  *this
+ */
+nsDequeIterator& nsDequeIterator::First(){
+  mIndex=0;
+  return *this;
+}
+
+/**
+ * Standard assignment operator for dequeiterator
+ *
+ * @param   aCopy is an iterator to be copied from
+ * @return  *this
+ */
+nsDequeIterator& nsDequeIterator::operator=(const nsDequeIterator& aCopy) {
+  NS_ASSERTION(&mDeque==&aCopy.mDeque,"you can't change the deque that an interator is iterating over, sorry.");
+  mIndex=aCopy.mIndex;
+  return *this;
+}
+
+/**
+ * preform ! operation against to iterators to test for equivalence
+ * (or lack thereof)!
+ *
+ * @param   aIter is the object to be compared to
+ * @return  TRUE if NOT equal.
+ */
+bool nsDequeIterator::operator!=(nsDequeIterator& aIter) {
+  return bool(!this->operator==(aIter));
+}
+
+/**
+ * Compare two iterators for increasing order.
+ *
+ * @param   aIter is the other iterator to be compared to
+ * @return  TRUE if this object points to an element before
+ *          the element pointed to by aIter.
+ *          FALSE if this and aIter are not iterating over the same deque.
+ */
+bool nsDequeIterator::operator<(nsDequeIterator& aIter) {
+  return bool(((mIndex<aIter.mIndex) && (&mDeque==&aIter.mDeque)));
+}
+
+/**
+ * Compare two iterators for equivalence.
+ *
+ * @param   aIter is the other iterator to be compared to
+ * @return  TRUE if EQUAL
+ */
+bool nsDequeIterator::operator==(nsDequeIterator& aIter) {
+  return bool(((mIndex==aIter.mIndex) && (&mDeque==&aIter.mDeque)));
+}
+
+/**
+ * Compare two iterators for non strict decreasing order.
+ *
+ * @param   aIter is the other iterator to be compared to
+ * @return  TRUE if this object points to the same element, or
+ *          an element after the element pointed to by aIter.
+ *          FALSE if this and aIter are not iterating over the same deque.
+ */
+bool nsDequeIterator::operator>=(nsDequeIterator& aIter) {
+  return bool(((mIndex>=aIter.mIndex) && (&mDeque==&aIter.mDeque)));
+}
+
+/**
+ * Pre-increment operator
+ *
+ * @return  object at post-incremented index
+ */
+void* nsDequeIterator::operator++() {
+  NS_ASSERTION(mIndex<mDeque.mSize,
+    "You have reached the end of the Internet."\
+    "You have seen everything there is to see. Please go back. Now."
+  );
+#ifndef TIMELESS_LIGHTWEIGHT
+  if (mIndex>=mDeque.mSize) return 0;
+#endif
+  return mDeque.ObjectAt(++mIndex);
+}
+
+/**
+ * Post-increment operator
+ *
+ * @param   param is ignored
+ * @return  object at pre-incremented index
+ */
+void* nsDequeIterator::operator++(int) {
+  NS_ASSERTION(mIndex<=mDeque.mSize,
+    "You have already reached the end of the Internet."\
+    "You have seen everything there is to see. Please go back. Now."
+  );
+#ifndef TIMELESS_LIGHTWEIGHT
+  if (mIndex>mDeque.mSize) return 0;
+#endif
+  return mDeque.ObjectAt(mIndex++);
+}
+
+/**
+ * Pre-decrement operator
+ *
+ * @return  object at pre-decremented index
+ */
+void* nsDequeIterator::operator--() {
+  NS_ASSERTION(mIndex>=0,
+    "You have reached the beginning of the Internet."\
+    "You have seen everything there is to see. Please go forward. Now."
+  );
+#ifndef TIMELESS_LIGHTWEIGHT
+  if (mIndex<0) return 0;
+#endif
+  return mDeque.ObjectAt(--mIndex);
+}
+
+/**
+ * Post-decrement operator
+ *
+ * @param   param is ignored
+ * @return  object at post-decremented index
+ */
+void* nsDequeIterator::operator--(int) {
+  NS_ASSERTION(mIndex>=0,
+    "You have already reached the beginning of the Internet."\
+    "You have seen everything there is to see. Please go forward. Now."
+  );
+#ifndef TIMELESS_LIGHTWEIGHT
+  if (mIndex<0) return 0;
+#endif
+  return mDeque.ObjectAt(mIndex--);
+}
+
+/**
+ * Dereference operator
+ * Note that the iterator floats, so you don't need to do:
+ * <code>++iter; aDeque.PopFront();</code>
+ * Unless you actually want your iterator to jump 2 spaces.
+ *
+ * Picture: [1 2I 3 4]
+ * PopFront()
+ * Picture: [2 3I 4]
+ * Note that I still happily points to object at the second index
+ *
+ * @return  object at ith index
+ */
+void* nsDequeIterator::GetCurrent() {
+  NS_ASSERTION(mIndex<mDeque.mSize&&mIndex>=0,"Current is out of bounds");
+#ifndef TIMELESS_LIGHTWEIGHT
+  if (mIndex>=mDeque.mSize||mIndex<0) return 0;
+#endif
+  return mDeque.ObjectAt(mIndex);
+}
+
+/**
+ * Call this method when you want to iterate all the
+ * members of the container, passing a functor along
+ * to call your code.
+ *
+ * @param   aFunctor object to call for each member
+ * @return  *this
+ */
+void nsDequeIterator::ForEach(nsDequeFunctor& aFunctor) const{
+  mDeque.ForEach(aFunctor);
+}
+
+/**
+ * Call this method when you want to iterate all the
+ * members of the container, calling the functor you 
+ * passed with each member. This process will interrupt
+ * if your function returns non 0 to this method.
+ *
+ * @param   aFunctor object to call for each member
+ * @return  first nonzero result of aFunctor or 0.
+ */
+const void* nsDequeIterator::FirstThat(nsDequeFunctor& aFunctor) const{
+  return mDeque.FirstThat(aFunctor);
+}