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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