Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2             : // vim:cindent:ts=4:et:sw=4:
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #ifndef SpanningCellSorter_h
       8             : #define SpanningCellSorter_h
       9             : 
      10             : /*
      11             :  * Code to sort cells by their colspan, used by BasicTableLayoutStrategy.
      12             :  */
      13             : 
      14             : #include "PLDHashTable.h"
      15             : #include "nsDebug.h"
      16             : #include "StackArena.h"
      17             : 
      18             : /**
      19             :  * The SpanningCellSorter is responsible for accumulating lists of cells
      20             :  * with colspans so that those cells can later be enumerated, sorted
      21             :  * from lowest number of columns spanned to highest.  It does not use a
      22             :  * stable sort (in fact, it currently reverses).
      23             :  */
      24             : class MOZ_STACK_CLASS SpanningCellSorter {
      25             : public:
      26             :     SpanningCellSorter();
      27             :     ~SpanningCellSorter();
      28             : 
      29             :     struct Item {
      30             :         int32_t row, col;
      31             :         Item *next;
      32             :     };
      33             : 
      34             :     /**
      35             :      * Add a cell to the sorter.  Returns false on out of memory.
      36             :      * aColSpan is the number of columns spanned, and aRow/aCol are the
      37             :      * position of the cell in the table (for GetCellInfoAt).
      38             :      */
      39             :     bool AddCell(int32_t aColSpan, int32_t aRow, int32_t aCol);
      40             : 
      41             :     /**
      42             :      * Get the next *list* of cells.  Each list contains all the cells
      43             :      * for a colspan value, and the lists are given in order from lowest
      44             :      * to highest colspan.  The colspan value is filled in to *aColSpan.
      45             :      */
      46             :     Item* GetNext(int32_t *aColSpan);
      47             : private:
      48             : 
      49             :     enum State { ADDING, ENUMERATING_ARRAY, ENUMERATING_HASH, DONE };
      50             :     State mState;
      51             : 
      52             :     // store small colspans in an array for fast sorting and
      53             :     // enumeration, and large colspans in a hash table
      54             : 
      55             :     enum { ARRAY_BASE = 2 };
      56             :     enum { ARRAY_SIZE = 8 };
      57             :     Item *mArray[ARRAY_SIZE];
      58           0 :     int32_t SpanToIndex(int32_t aSpan) { return aSpan - ARRAY_BASE; }
      59           0 :     int32_t IndexToSpan(int32_t aIndex) { return aIndex + ARRAY_BASE; }
      60           0 :     bool UseArrayForSpan(int32_t aSpan) {
      61           0 :         NS_ASSERTION(SpanToIndex(aSpan) >= 0, "cell without colspan");
      62           0 :         return SpanToIndex(aSpan) < ARRAY_SIZE;
      63             :     }
      64             : 
      65             :     PLDHashTable mHashTable;
      66             :     struct HashTableEntry : public PLDHashEntryHdr {
      67             :         int32_t mColSpan;
      68             :         Item *mItems;
      69             :     };
      70             : 
      71             :     static const PLDHashTableOps HashTableOps;
      72             : 
      73             :     static PLDHashNumber HashTableHashKey(const void *key);
      74             :     static bool
      75             :         HashTableMatchEntry(const PLDHashEntryHdr *hdr, const void *key);
      76             : 
      77             :     static int SortArray(const void *a, const void *b, void *closure);
      78             : 
      79             :     /* state used only during enumeration */
      80             :     uint32_t mEnumerationIndex; // into mArray or mSortedHashTable
      81             :     HashTableEntry **mSortedHashTable;
      82             : 
      83             :     /*
      84             :      * operator new is forbidden since we use the pres shell's stack
      85             :      * memory, which much be pushed and popped at points matching a
      86             :      * push/pop on the C++ stack.
      87             :      */
      88             :     void* operator new(size_t sz) CPP_THROW_NEW { return nullptr; }
      89             : };
      90             : 
      91             : #endif