michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: // vim:cindent:ts=4:et:sw=4:
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef SpanningCellSorter_h
michael@0: #define SpanningCellSorter_h
michael@0: 
michael@0: /*
michael@0:  * Code to sort cells by their colspan, used by BasicTableLayoutStrategy.
michael@0:  */
michael@0: 
michael@0: #include "pldhash.h"
michael@0: #include "nsDebug.h"
michael@0: #include "StackArena.h"
michael@0: 
michael@0: class nsIPresShell;
michael@0: 
michael@0: /**
michael@0:  * The SpanningCellSorter is responsible for accumulating lists of cells
michael@0:  * with colspans so that those cells can later be enumerated, sorted
michael@0:  * from lowest number of columns spanned to highest.  It does not use a
michael@0:  * stable sort (in fact, it currently reverses).
michael@0:  */
michael@0: class MOZ_STACK_CLASS SpanningCellSorter {
michael@0: public:
michael@0:     SpanningCellSorter();
michael@0:     ~SpanningCellSorter();
michael@0: 
michael@0:     struct Item {
michael@0:         int32_t row, col;
michael@0:         Item *next;
michael@0:     };
michael@0: 
michael@0:     /**
michael@0:      * Add a cell to the sorter.  Returns false on out of memory.
michael@0:      * aColSpan is the number of columns spanned, and aRow/aCol are the
michael@0:      * position of the cell in the table (for GetCellInfoAt).
michael@0:      */
michael@0:     bool AddCell(int32_t aColSpan, int32_t aRow, int32_t aCol);
michael@0: 
michael@0:     /**
michael@0:      * Get the next *list* of cells.  Each list contains all the cells
michael@0:      * for a colspan value, and the lists are given in order from lowest
michael@0:      * to highest colspan.  The colspan value is filled in to *aColSpan.
michael@0:      */
michael@0:     Item* GetNext(int32_t *aColSpan);
michael@0: private:
michael@0: 
michael@0:     enum State { ADDING, ENUMERATING_ARRAY, ENUMERATING_HASH, DONE };
michael@0:     State mState;
michael@0: 
michael@0:     // store small colspans in an array for fast sorting and
michael@0:     // enumeration, and large colspans in a hash table
michael@0: 
michael@0:     enum { ARRAY_BASE = 2 };
michael@0:     enum { ARRAY_SIZE = 8 };
michael@0:     Item *mArray[ARRAY_SIZE];
michael@0:     int32_t SpanToIndex(int32_t aSpan) { return aSpan - ARRAY_BASE; }
michael@0:     int32_t IndexToSpan(int32_t aIndex) { return aIndex + ARRAY_BASE; }
michael@0:     bool UseArrayForSpan(int32_t aSpan) {
michael@0:         NS_ASSERTION(SpanToIndex(aSpan) >= 0, "cell without colspan");
michael@0:         return SpanToIndex(aSpan) < ARRAY_SIZE;
michael@0:     }
michael@0: 
michael@0:     PLDHashTable mHashTable;
michael@0:     struct HashTableEntry : public PLDHashEntryHdr {
michael@0:         int32_t mColSpan;
michael@0:         Item *mItems;
michael@0:     };
michael@0: 
michael@0:     static const PLDHashTableOps HashTableOps;
michael@0: 
michael@0:     static PLDHashNumber
michael@0:         HashTableHashKey(PLDHashTable *table, const void *key);
michael@0:     static bool
michael@0:         HashTableMatchEntry(PLDHashTable *table, const PLDHashEntryHdr *hdr,
michael@0:                             const void *key);
michael@0: 
michael@0:     static PLDHashOperator
michael@0:         FillSortedArray(PLDHashTable *table, PLDHashEntryHdr *hdr,
michael@0:                         uint32_t number, void *arg);
michael@0: 
michael@0:     static int SortArray(const void *a, const void *b, void *closure);
michael@0: 
michael@0:     /* state used only during enumeration */
michael@0:     uint32_t mEnumerationIndex; // into mArray or mSortedHashTable
michael@0:     HashTableEntry **mSortedHashTable;
michael@0: 
michael@0:     /*
michael@0:      * operator new is forbidden since we use the pres shell's stack
michael@0:      * memory, which much be pushed and popped at points matching a
michael@0:      * push/pop on the C++ stack.
michael@0:      */
michael@0:     void* operator new(size_t sz) CPP_THROW_NEW { return nullptr; }
michael@0: };
michael@0: 
michael@0: #endif