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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=4:et:sw=4:
/* 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/. */
#ifndef SpanningCellSorter_h
#define SpanningCellSorter_h
/*
* Code to sort cells by their colspan, used by BasicTableLayoutStrategy.
*/
#include "PLDHashTable.h"
#include "nsDebug.h"
#include "StackArena.h"
/**
* The SpanningCellSorter is responsible for accumulating lists of cells
* with colspans so that those cells can later be enumerated, sorted
* from lowest number of columns spanned to highest. It does not use a
* stable sort (in fact, it currently reverses).
*/
class MOZ_STACK_CLASS SpanningCellSorter {
public:
SpanningCellSorter();
~SpanningCellSorter();
struct Item {
int32_t row, col;
Item* next;
};
/**
* Add a cell to the sorter. Returns false on out of memory.
* aColSpan is the number of columns spanned, and aRow/aCol are the
* position of the cell in the table (for GetCellInfoAt).
*/
bool AddCell(int32_t aColSpan, int32_t aRow, int32_t aCol);
/**
* Get the next *list* of cells. Each list contains all the cells
* for a colspan value, and the lists are given in order from lowest
* to highest colspan. The colspan value is filled in to *aColSpan.
*/
Item* GetNext(int32_t* aColSpan);
private:
enum State { ADDING, ENUMERATING_ARRAY, ENUMERATING_HASH, DONE };
State mState;
// store small colspans in an array for fast sorting and
// enumeration, and large colspans in a hash table
enum { ARRAY_BASE = 2 };
enum { ARRAY_SIZE = 8 };
Item* mArray[ARRAY_SIZE];
int32_t SpanToIndex(int32_t aSpan) { return aSpan - ARRAY_BASE; }
int32_t IndexToSpan(int32_t aIndex) { return aIndex + ARRAY_BASE; }
bool UseArrayForSpan(int32_t aSpan) {
NS_ASSERTION(SpanToIndex(aSpan) >= 0, "cell without colspan");
return SpanToIndex(aSpan) < ARRAY_SIZE;
}
PLDHashTable mHashTable;
struct HashTableEntry : public PLDHashEntryHdr {
int32_t mColSpan;
Item* mItems;
};
static const PLDHashTableOps HashTableOps;
static PLDHashNumber HashTableHashKey(const void* key);
static bool HashTableMatchEntry(const PLDHashEntryHdr* hdr, const void* key);
static int SortArray(const void* a, const void* b, void* closure);
/* state used only during enumeration */
uint32_t mEnumerationIndex; // into mArray or mSortedHashTable
HashTableEntry** mSortedHashTable;
/*
* operator new is forbidden since we use the pres shell's stack
* memory, which much be pushed and popped at points matching a
* push/pop on the C++ stack.
*/
void* operator new(size_t sz) noexcept(true) { return nullptr; }
};
#endif