gecko-dev/layout/tables/SpanningCellSorter.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
// vim:cindent:ts=4:et:sw=4:
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla's table layout code.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2006
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Code to sort cells by their colspan, used by BasicTableLayoutStrategy.
*/
#include "nsIPresShell.h"
#include "pldhash.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 SpanningCellSorter {
public:
SpanningCellSorter(nsIPresShell *aPresShell);
~SpanningCellSorter();
struct Item {
PRInt32 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).
*/
PRBool AddCell(PRInt32 aColSpan, PRInt32 aRow, PRInt32 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(PRInt32 *aColSpan);
private:
nsIPresShell *mPresShell;
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];
PRInt32 SpanToIndex(PRInt32 aSpan) { return aSpan - ARRAY_BASE; }
PRInt32 IndexToSpan(PRInt32 aIndex) { return aIndex + ARRAY_BASE; }
PRBool UseArrayForSpan(PRInt32 aSpan) {
NS_ASSERTION(SpanToIndex(aSpan) >= 0, "cell without colspan");
return SpanToIndex(aSpan) < ARRAY_SIZE;
}
PLDHashTable mHashTable;
struct HashTableEntry : public PLDHashEntryHdr {
PRInt32 mColSpan;
Item *mItems;
};
static PLDHashTableOps HashTableOps;
PR_STATIC_CALLBACK(PLDHashNumber)
HashTableHashKey(PLDHashTable *table, const void *key);
PR_STATIC_CALLBACK(PRBool)
HashTableMatchEntry(PLDHashTable *table, const PLDHashEntryHdr *hdr,
const void *key);
PR_STATIC_CALLBACK(PLDHashOperator)
FillSortedArray(PLDHashTable *table, PLDHashEntryHdr *hdr,
PRUint32 number, void *arg);
static int SortArray(const void *a, const void *b, void *closure);
/* state used only during enumeration */
PRUint32 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) CPP_THROW_NEW { return nsnull; }
};