1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/glue/nsDeque.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,610 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#include "nsDeque.h"
1.10 +#include "nsISupportsImpl.h"
1.11 +#include <string.h>
1.12 +#ifdef DEBUG_rickg
1.13 +#include <stdio.h>
1.14 +#endif
1.15 +
1.16 +/**
1.17 + * 07/02/2001 09:17p 509,104 clangref.pdf from openwatcom's site
1.18 + * Watcom C Language Reference Edition 11.0c
1.19 + * page 118 of 297
1.20 + *
1.21 + * The % symbol yields the remainder from the division of the first operand
1.22 + * by the second operand. The operands of % must have integral type.
1.23 + *
1.24 + * When both operands of % are positive, the result is a positive value
1.25 + * smaller than the second operand. When one or both operands is negative,
1.26 + * whether the result is positive or negative is implementation-defined.
1.27 + *
1.28 + */
1.29 +/* Ok, so first of all, C is underspecified. joy.
1.30 + * The following functions do not provide a correct implementation of modulus
1.31 + * They provide functionality for x>-y.
1.32 + * There are risks of 2*y being greater than max int, which is part of the
1.33 + * reason no multiplication is used and other operations are avoided.
1.34 + *
1.35 + * modasgn
1.36 + * @param x variable
1.37 + * @param y expression
1.38 + * approximately equivalent to x %= y
1.39 + *
1.40 + * modulus
1.41 + * @param x expression
1.42 + * @param y expression
1.43 + * approximately equivalent to x % y
1.44 + */
1.45 +#define modasgn(x,y) if (x<0) x+=y; x%=y
1.46 +#define modulus(x,y) ((x<0)?(x+y)%(y):(x)%(y))
1.47 +
1.48 +/**
1.49 + * Standard constructor
1.50 + * @param deallocator, called by Erase and ~nsDeque
1.51 + */
1.52 +nsDeque::nsDeque(nsDequeFunctor* aDeallocator) {
1.53 + MOZ_COUNT_CTOR(nsDeque);
1.54 + mDeallocator=aDeallocator;
1.55 + mOrigin=mSize=0;
1.56 + mData=mBuffer; // don't allocate space until you must
1.57 + mCapacity=sizeof(mBuffer)/sizeof(mBuffer[0]);
1.58 + memset(mData, 0, mCapacity*sizeof(mBuffer[0]));
1.59 +}
1.60 +
1.61 +/**
1.62 + * Destructor
1.63 + */
1.64 +nsDeque::~nsDeque() {
1.65 + MOZ_COUNT_DTOR(nsDeque);
1.66 +
1.67 +#ifdef DEBUG_rickg
1.68 + char buffer[30];
1.69 + printf("Capacity: %i\n", mCapacity);
1.70 +
1.71 + static int mCaps[15] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
1.72 + switch(mCapacity) {
1.73 + case 4: mCaps[0]++; break;
1.74 + case 8: mCaps[1]++; break;
1.75 + case 16: mCaps[2]++; break;
1.76 + case 32: mCaps[3]++; break;
1.77 + case 64: mCaps[4]++; break;
1.78 + case 128: mCaps[5]++; break;
1.79 + case 256: mCaps[6]++; break;
1.80 + case 512: mCaps[7]++; break;
1.81 + case 1024: mCaps[8]++; break;
1.82 + case 2048: mCaps[9]++; break;
1.83 + case 4096: mCaps[10]++; break;
1.84 + default:
1.85 + break;
1.86 + }
1.87 +#endif
1.88 +
1.89 + Erase();
1.90 + if (mData && (mData!=mBuffer)) {
1.91 + free(mData);
1.92 + }
1.93 + mData=0;
1.94 + SetDeallocator(0);
1.95 +}
1.96 +
1.97 +size_t nsDeque::SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
1.98 + size_t size = 0;
1.99 + if (mData != mBuffer) {
1.100 + size += aMallocSizeOf(mData);
1.101 + }
1.102 +
1.103 + if (mDeallocator) {
1.104 + size += aMallocSizeOf(mDeallocator);
1.105 + }
1.106 +
1.107 + return size;
1.108 +}
1.109 +
1.110 +size_t nsDeque::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
1.111 + return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
1.112 +}
1.113 +
1.114 +/**
1.115 + * Set the functor to be called by Erase()
1.116 + * The deque owns the functor.
1.117 + *
1.118 + * @param aDeallocator functor object for use by Erase()
1.119 + */
1.120 +void nsDeque::SetDeallocator(nsDequeFunctor* aDeallocator){
1.121 + delete mDeallocator;
1.122 + mDeallocator=aDeallocator;
1.123 +}
1.124 +
1.125 +/**
1.126 + * Remove all items from container without destroying them.
1.127 + */
1.128 +void nsDeque::Empty() {
1.129 + if (mSize && mData) {
1.130 + memset(mData, 0, mCapacity*sizeof(mData));
1.131 + }
1.132 + mSize=0;
1.133 + mOrigin=0;
1.134 +}
1.135 +
1.136 +/**
1.137 + * Remove and delete all items from container
1.138 + */
1.139 +void nsDeque::Erase() {
1.140 + if (mDeallocator && mSize) {
1.141 + ForEach(*mDeallocator);
1.142 + }
1.143 + Empty();
1.144 +}
1.145 +
1.146 +/**
1.147 + * This method quadruples the size of the deque
1.148 + * Elements in the deque are resequenced so that elements
1.149 + * in the deque are stored sequentially
1.150 + *
1.151 + * @return whether growing succeeded
1.152 + */
1.153 +bool nsDeque::GrowCapacity() {
1.154 + int32_t theNewSize=mCapacity<<2;
1.155 + NS_ASSERTION(theNewSize>mCapacity, "Overflow");
1.156 + if (theNewSize<=mCapacity)
1.157 + return false;
1.158 + void** temp=(void**)malloc(theNewSize * sizeof(void*));
1.159 + if (!temp)
1.160 + return false;
1.161 +
1.162 + //Here's the interesting part: You can't just move the elements
1.163 + //directly (in situ) from the old buffer to the new one.
1.164 + //Since capacity has changed, the old origin doesn't make
1.165 + //sense anymore. It's better to resequence the elements now.
1.166 +
1.167 + memcpy(temp, mData + mOrigin, sizeof(void*) * (mCapacity - mOrigin));
1.168 + memcpy(temp + (mCapacity - mOrigin), mData, sizeof(void*) * mOrigin);
1.169 +
1.170 + if (mData != mBuffer) {
1.171 + free(mData);
1.172 + }
1.173 +
1.174 + mCapacity=theNewSize;
1.175 + mOrigin=0; //now realign the origin...
1.176 + mData=temp;
1.177 +
1.178 + return true;
1.179 +}
1.180 +
1.181 +/**
1.182 + * This method adds an item to the end of the deque.
1.183 + * This operation has the potential to cause the
1.184 + * underlying buffer to resize.
1.185 + *
1.186 + * @param aItem: new item to be added to deque
1.187 + */
1.188 +bool nsDeque::Push(void* aItem, const fallible_t&) {
1.189 + if (mSize==mCapacity && !GrowCapacity()) {
1.190 + return false;
1.191 + }
1.192 + mData[modulus(mOrigin + mSize, mCapacity)]=aItem;
1.193 + mSize++;
1.194 + return true;
1.195 +}
1.196 +
1.197 +/**
1.198 + * This method adds an item to the front of the deque.
1.199 + * This operation has the potential to cause the
1.200 + * underlying buffer to resize.
1.201 + *
1.202 + * --Commments for GrowCapacity() case
1.203 + * We've grown and shifted which means that the old
1.204 + * final element in the deque is now the first element
1.205 + * in the deque. This is temporary.
1.206 + * We haven't inserted the new element at the front.
1.207 + *
1.208 + * To continue with the idea of having the front at zero
1.209 + * after a grow, we move the old final item (which through
1.210 + * the voodoo of mOrigin-- is now the first) to its final
1.211 + * position which is conveniently the old length.
1.212 + *
1.213 + * Note that this case only happens when the deque is full.
1.214 + * [And that pieces of this magic only work if the deque is full.]
1.215 + * picture:
1.216 + * [ABCDEFGH] @[mOrigin:3]:D.
1.217 + * Task: PushFront("Z")
1.218 + * shift mOrigin so, @[mOrigin:2]:C
1.219 + * stretch and rearrange: (mOrigin:0)
1.220 + * [CDEFGHAB ________ ________ ________]
1.221 + * copy: (The second C is currently out of bounds)
1.222 + * [CDEFGHAB C_______ ________ ________]
1.223 + * later we will insert Z:
1.224 + * [ZDEFGHAB C_______ ________ ________]
1.225 + * and increment size: 9. (C is no longer out of bounds)
1.226 + * --
1.227 + * @param aItem: new item to be added to deque
1.228 + */
1.229 +bool nsDeque::PushFront(void* aItem, const fallible_t&) {
1.230 + mOrigin--;
1.231 + modasgn(mOrigin,mCapacity);
1.232 + if (mSize==mCapacity) {
1.233 + if (!GrowCapacity()) {
1.234 + return false;
1.235 + }
1.236 + /* Comments explaining this are above*/
1.237 + mData[mSize]=mData[mOrigin];
1.238 + }
1.239 + mData[mOrigin]=aItem;
1.240 + mSize++;
1.241 + return true;
1.242 +}
1.243 +
1.244 +/**
1.245 + * Remove and return the last item in the container.
1.246 + *
1.247 + * @return ptr to last item in container
1.248 + */
1.249 +void* nsDeque::Pop() {
1.250 + void* result=0;
1.251 + if (mSize>0) {
1.252 + --mSize;
1.253 + int32_t offset=modulus(mSize + mOrigin, mCapacity);
1.254 + result=mData[offset];
1.255 + mData[offset]=0;
1.256 + if (!mSize) {
1.257 + mOrigin=0;
1.258 + }
1.259 + }
1.260 + return result;
1.261 +}
1.262 +
1.263 +/**
1.264 + * This method gets called you want to remove and return
1.265 + * the first member in the container.
1.266 + *
1.267 + * @return last item in container
1.268 + */
1.269 +void* nsDeque::PopFront() {
1.270 + void* result=0;
1.271 + if (mSize>0) {
1.272 + NS_ASSERTION(mOrigin < mCapacity, "Error: Bad origin");
1.273 + result=mData[mOrigin];
1.274 + mData[mOrigin++]=0; //zero it out for debugging purposes.
1.275 + mSize--;
1.276 + // Cycle around if we pop off the end
1.277 + // and reset origin if when we pop the last element
1.278 + if (mCapacity==mOrigin || !mSize) {
1.279 + mOrigin=0;
1.280 + }
1.281 + }
1.282 + return result;
1.283 +}
1.284 +
1.285 +/**
1.286 + * This method gets called you want to peek at the bottom
1.287 + * member without removing it.
1.288 + *
1.289 + * @return last item in container
1.290 + */
1.291 +void* nsDeque::Peek() {
1.292 + void* result=0;
1.293 + if (mSize>0) {
1.294 + result = mData[modulus(mSize - 1 + mOrigin, mCapacity)];
1.295 + }
1.296 + return result;
1.297 +}
1.298 +
1.299 +/**
1.300 + * This method gets called you want to peek at the topmost
1.301 + * member without removing it.
1.302 + *
1.303 + * @return last item in container
1.304 + */
1.305 +void* nsDeque::PeekFront() {
1.306 + void* result=0;
1.307 + if (mSize>0) {
1.308 + result=mData[mOrigin];
1.309 + }
1.310 + return result;
1.311 +}
1.312 +
1.313 +/**
1.314 + * Call this to retrieve the ith element from this container.
1.315 + * Keep in mind that accessing the underlying elements is
1.316 + * done in a relative fashion. Object 0 is not necessarily
1.317 + * the first element (the first element is at mOrigin).
1.318 + *
1.319 + * @param aIndex : 0 relative offset of item you want
1.320 + * @return void* or null
1.321 + */
1.322 +void* nsDeque::ObjectAt(int32_t aIndex) const {
1.323 + void* result=0;
1.324 + if ((aIndex>=0) && (aIndex<mSize)) {
1.325 + result=mData[modulus(mOrigin + aIndex, mCapacity)];
1.326 + }
1.327 + return result;
1.328 +}
1.329 +
1.330 +void* nsDeque::RemoveObjectAt(int32_t aIndex) {
1.331 + if ((aIndex<0) || (aIndex>=mSize)) {
1.332 + return 0;
1.333 + }
1.334 + void* result=mData[modulus(mOrigin + aIndex, mCapacity)];
1.335 +
1.336 + // "Shuffle down" all elements in the array by 1, overwritting the element
1.337 + // being removed.
1.338 + for (int32_t i=aIndex; i<mSize; i++) {
1.339 + mData[modulus(mOrigin + i, mCapacity)] = mData[modulus(mOrigin + i + 1, mCapacity)];
1.340 + }
1.341 + mSize--;
1.342 +
1.343 + return result;
1.344 +}
1.345 +
1.346 +/**
1.347 + * Create and return an iterator pointing to
1.348 + * the beginning of the queue. Note that this
1.349 + * takes the circular buffer semantics into account.
1.350 + *
1.351 + * @return new deque iterator, init'ed to 1st item
1.352 + */
1.353 +nsDequeIterator nsDeque::Begin() const{
1.354 + return nsDequeIterator(*this, 0);
1.355 +}
1.356 +
1.357 +/**
1.358 + * Create and return an iterator pointing to
1.359 + * the last item in the deque.
1.360 + * Note that this takes the circular buffer semantics
1.361 + * into account.
1.362 + *
1.363 + * @return new deque iterator, init'ed to the last item
1.364 + */
1.365 +nsDequeIterator nsDeque::End() const{
1.366 + return nsDequeIterator(*this, mSize - 1);
1.367 +}
1.368 +
1.369 +void* nsDeque::Last() const {
1.370 + return End().GetCurrent();
1.371 +}
1.372 +
1.373 +/**
1.374 + * Call this method when you want to iterate all the
1.375 + * members of the container, passing a functor along
1.376 + * to call your code.
1.377 + *
1.378 + * @param aFunctor object to call for each member
1.379 + * @return *this
1.380 + */
1.381 +void nsDeque::ForEach(nsDequeFunctor& aFunctor) const{
1.382 + for (int32_t i=0; i<mSize; i++) {
1.383 + aFunctor(ObjectAt(i));
1.384 + }
1.385 +}
1.386 +
1.387 +/**
1.388 + * Call this method when you want to iterate all the
1.389 + * members of the container, calling the functor you
1.390 + * passed with each member. This process will interrupt
1.391 + * if your function returns non 0 to this method.
1.392 + *
1.393 + * @param aFunctor object to call for each member
1.394 + * @return first nonzero result of aFunctor or 0.
1.395 + */
1.396 +const void* nsDeque::FirstThat(nsDequeFunctor& aFunctor) const{
1.397 + for (int32_t i=0; i<mSize; i++) {
1.398 + void* obj=aFunctor(ObjectAt(i));
1.399 + if (obj) {
1.400 + return obj;
1.401 + }
1.402 + }
1.403 + return 0;
1.404 +}
1.405 +
1.406 +/******************************************************
1.407 + * Here comes the nsDequeIterator class...
1.408 + ******************************************************/
1.409 +
1.410 +/**
1.411 + * DequeIterator is an object that knows how to iterate (forward and backward)
1.412 + * through a Deque. Normally, you don't need to do this, but there are some special
1.413 + * cases where it is pretty handy, so here you go.
1.414 + *
1.415 + * This is a standard dequeiterator constructor
1.416 + *
1.417 + * @param aQueue is the deque object to be iterated
1.418 + * @param aIndex is the starting position for your iteration
1.419 + */
1.420 +nsDequeIterator::nsDequeIterator(const nsDeque& aQueue, int aIndex)
1.421 +: mIndex(aIndex),
1.422 + mDeque(aQueue)
1.423 +{
1.424 +}
1.425 +
1.426 +/**
1.427 + * Create a copy of a DequeIterator
1.428 + *
1.429 + * @param aCopy is another iterator to copy from
1.430 + */
1.431 +nsDequeIterator::nsDequeIterator(const nsDequeIterator& aCopy)
1.432 +: mIndex(aCopy.mIndex),
1.433 + mDeque(aCopy.mDeque)
1.434 +{
1.435 +}
1.436 +
1.437 +/**
1.438 + * Moves iterator to first element in deque
1.439 + * @return *this
1.440 + */
1.441 +nsDequeIterator& nsDequeIterator::First(){
1.442 + mIndex=0;
1.443 + return *this;
1.444 +}
1.445 +
1.446 +/**
1.447 + * Standard assignment operator for dequeiterator
1.448 + *
1.449 + * @param aCopy is an iterator to be copied from
1.450 + * @return *this
1.451 + */
1.452 +nsDequeIterator& nsDequeIterator::operator=(const nsDequeIterator& aCopy) {
1.453 + NS_ASSERTION(&mDeque==&aCopy.mDeque,"you can't change the deque that an interator is iterating over, sorry.");
1.454 + mIndex=aCopy.mIndex;
1.455 + return *this;
1.456 +}
1.457 +
1.458 +/**
1.459 + * preform ! operation against to iterators to test for equivalence
1.460 + * (or lack thereof)!
1.461 + *
1.462 + * @param aIter is the object to be compared to
1.463 + * @return TRUE if NOT equal.
1.464 + */
1.465 +bool nsDequeIterator::operator!=(nsDequeIterator& aIter) {
1.466 + return bool(!this->operator==(aIter));
1.467 +}
1.468 +
1.469 +/**
1.470 + * Compare two iterators for increasing order.
1.471 + *
1.472 + * @param aIter is the other iterator to be compared to
1.473 + * @return TRUE if this object points to an element before
1.474 + * the element pointed to by aIter.
1.475 + * FALSE if this and aIter are not iterating over the same deque.
1.476 + */
1.477 +bool nsDequeIterator::operator<(nsDequeIterator& aIter) {
1.478 + return bool(((mIndex<aIter.mIndex) && (&mDeque==&aIter.mDeque)));
1.479 +}
1.480 +
1.481 +/**
1.482 + * Compare two iterators for equivalence.
1.483 + *
1.484 + * @param aIter is the other iterator to be compared to
1.485 + * @return TRUE if EQUAL
1.486 + */
1.487 +bool nsDequeIterator::operator==(nsDequeIterator& aIter) {
1.488 + return bool(((mIndex==aIter.mIndex) && (&mDeque==&aIter.mDeque)));
1.489 +}
1.490 +
1.491 +/**
1.492 + * Compare two iterators for non strict decreasing order.
1.493 + *
1.494 + * @param aIter is the other iterator to be compared to
1.495 + * @return TRUE if this object points to the same element, or
1.496 + * an element after the element pointed to by aIter.
1.497 + * FALSE if this and aIter are not iterating over the same deque.
1.498 + */
1.499 +bool nsDequeIterator::operator>=(nsDequeIterator& aIter) {
1.500 + return bool(((mIndex>=aIter.mIndex) && (&mDeque==&aIter.mDeque)));
1.501 +}
1.502 +
1.503 +/**
1.504 + * Pre-increment operator
1.505 + *
1.506 + * @return object at post-incremented index
1.507 + */
1.508 +void* nsDequeIterator::operator++() {
1.509 + NS_ASSERTION(mIndex<mDeque.mSize,
1.510 + "You have reached the end of the Internet."\
1.511 + "You have seen everything there is to see. Please go back. Now."
1.512 + );
1.513 +#ifndef TIMELESS_LIGHTWEIGHT
1.514 + if (mIndex>=mDeque.mSize) return 0;
1.515 +#endif
1.516 + return mDeque.ObjectAt(++mIndex);
1.517 +}
1.518 +
1.519 +/**
1.520 + * Post-increment operator
1.521 + *
1.522 + * @param param is ignored
1.523 + * @return object at pre-incremented index
1.524 + */
1.525 +void* nsDequeIterator::operator++(int) {
1.526 + NS_ASSERTION(mIndex<=mDeque.mSize,
1.527 + "You have already reached the end of the Internet."\
1.528 + "You have seen everything there is to see. Please go back. Now."
1.529 + );
1.530 +#ifndef TIMELESS_LIGHTWEIGHT
1.531 + if (mIndex>mDeque.mSize) return 0;
1.532 +#endif
1.533 + return mDeque.ObjectAt(mIndex++);
1.534 +}
1.535 +
1.536 +/**
1.537 + * Pre-decrement operator
1.538 + *
1.539 + * @return object at pre-decremented index
1.540 + */
1.541 +void* nsDequeIterator::operator--() {
1.542 + NS_ASSERTION(mIndex>=0,
1.543 + "You have reached the beginning of the Internet."\
1.544 + "You have seen everything there is to see. Please go forward. Now."
1.545 + );
1.546 +#ifndef TIMELESS_LIGHTWEIGHT
1.547 + if (mIndex<0) return 0;
1.548 +#endif
1.549 + return mDeque.ObjectAt(--mIndex);
1.550 +}
1.551 +
1.552 +/**
1.553 + * Post-decrement operator
1.554 + *
1.555 + * @param param is ignored
1.556 + * @return object at post-decremented index
1.557 + */
1.558 +void* nsDequeIterator::operator--(int) {
1.559 + NS_ASSERTION(mIndex>=0,
1.560 + "You have already reached the beginning of the Internet."\
1.561 + "You have seen everything there is to see. Please go forward. Now."
1.562 + );
1.563 +#ifndef TIMELESS_LIGHTWEIGHT
1.564 + if (mIndex<0) return 0;
1.565 +#endif
1.566 + return mDeque.ObjectAt(mIndex--);
1.567 +}
1.568 +
1.569 +/**
1.570 + * Dereference operator
1.571 + * Note that the iterator floats, so you don't need to do:
1.572 + * <code>++iter; aDeque.PopFront();</code>
1.573 + * Unless you actually want your iterator to jump 2 spaces.
1.574 + *
1.575 + * Picture: [1 2I 3 4]
1.576 + * PopFront()
1.577 + * Picture: [2 3I 4]
1.578 + * Note that I still happily points to object at the second index
1.579 + *
1.580 + * @return object at ith index
1.581 + */
1.582 +void* nsDequeIterator::GetCurrent() {
1.583 + NS_ASSERTION(mIndex<mDeque.mSize&&mIndex>=0,"Current is out of bounds");
1.584 +#ifndef TIMELESS_LIGHTWEIGHT
1.585 + if (mIndex>=mDeque.mSize||mIndex<0) return 0;
1.586 +#endif
1.587 + return mDeque.ObjectAt(mIndex);
1.588 +}
1.589 +
1.590 +/**
1.591 + * Call this method when you want to iterate all the
1.592 + * members of the container, passing a functor along
1.593 + * to call your code.
1.594 + *
1.595 + * @param aFunctor object to call for each member
1.596 + * @return *this
1.597 + */
1.598 +void nsDequeIterator::ForEach(nsDequeFunctor& aFunctor) const{
1.599 + mDeque.ForEach(aFunctor);
1.600 +}
1.601 +
1.602 +/**
1.603 + * Call this method when you want to iterate all the
1.604 + * members of the container, calling the functor you
1.605 + * passed with each member. This process will interrupt
1.606 + * if your function returns non 0 to this method.
1.607 + *
1.608 + * @param aFunctor object to call for each member
1.609 + * @return first nonzero result of aFunctor or 0.
1.610 + */
1.611 +const void* nsDequeIterator::FirstThat(nsDequeFunctor& aFunctor) const{
1.612 + return mDeque.FirstThat(aFunctor);
1.613 +}
