The Tor Browser: xpcom/glue/nsDeque.cpp@6474c204b198 (annotated)

xpcom/glue/nsDeque.cpp@6474c204b198 (annotated)

xpcom/glue/nsDeque.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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);
 }

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xpcom/glue/nsDeque.cpp@6474c204b198 (annotated)

xpcom/glue/nsDeque.cpp