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9e14278425
We use stable sorting here as we want the order to not change unless really needed. Depends on D181890 Differential Revision: https://phabricator.services.mozilla.com/D181891
91 lines
2.8 KiB
C++
91 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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// vim:cindent:ts=4:et:sw=4:
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef SpanningCellSorter_h
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#define SpanningCellSorter_h
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/*
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* Code to sort cells by their colspan, used by BasicTableLayoutStrategy.
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*/
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#include "PLDHashTable.h"
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#include "nsDebug.h"
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#include "nsTArray.h"
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#include "StackArena.h"
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/**
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* The SpanningCellSorter is responsible for accumulating lists of cells
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* with colspans so that those cells can later be enumerated, sorted
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* from lowest number of columns spanned to highest. It does not use a
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* stable sort (in fact, it currently reverses).
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*/
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class MOZ_STACK_CLASS SpanningCellSorter {
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public:
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SpanningCellSorter();
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~SpanningCellSorter();
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struct Item {
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int32_t row, col;
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Item* next;
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};
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/**
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* Add a cell to the sorter. Returns false on out of memory.
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* aColSpan is the number of columns spanned, and aRow/aCol are the
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* position of the cell in the table (for GetCellInfoAt).
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*/
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bool AddCell(int32_t aColSpan, int32_t aRow, int32_t aCol);
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/**
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* Get the next *list* of cells. Each list contains all the cells
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* for a colspan value, and the lists are given in order from lowest
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* to highest colspan. The colspan value is filled in to *aColSpan.
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*/
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Item* GetNext(int32_t* aColSpan);
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private:
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enum State { ADDING, ENUMERATING_ARRAY, ENUMERATING_HASH, DONE };
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State mState;
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// store small colspans in an array for fast sorting and
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// enumeration, and large colspans in a hash table
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enum { ARRAY_BASE = 2 };
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enum { ARRAY_SIZE = 8 };
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Item* mArray[ARRAY_SIZE];
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int32_t SpanToIndex(int32_t aSpan) { return aSpan - ARRAY_BASE; }
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int32_t IndexToSpan(int32_t aIndex) { return aIndex + ARRAY_BASE; }
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bool UseArrayForSpan(int32_t aSpan) {
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NS_ASSERTION(SpanToIndex(aSpan) >= 0, "cell without colspan");
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return SpanToIndex(aSpan) < ARRAY_SIZE;
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}
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PLDHashTable mHashTable;
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struct HashTableEntry : public PLDHashEntryHdr {
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int32_t mColSpan;
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Item* mItems;
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};
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static const PLDHashTableOps HashTableOps;
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static PLDHashNumber HashTableHashKey(const void* key);
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static bool HashTableMatchEntry(const PLDHashEntryHdr* hdr, const void* key);
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static int CompareHashTableEntry(HashTableEntry* a, HashTableEntry* b);
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/* state used only during enumeration */
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uint32_t mEnumerationIndex; // into mArray or mSortedHashTable
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nsTArray<HashTableEntry*> mSortedHashTable;
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/*
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* operator new is forbidden since we use the pres shell's stack
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* memory, which much be pushed and popped at points matching a
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* push/pop on the C++ stack.
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*/
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void* operator new(size_t sz) noexcept(true) { return nullptr; }
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};
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#endif
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