Quelle CachedTableAccessible.cpp Sprache: C

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* 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/. */

#include "CachedTableAccessible.h"

#include "AccIterator.h"
#include "HTMLTableAccessible.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/UniquePtr.h"
#include "nsAccUtils.h"
#include "nsIAccessiblePivot.h"
#include "Pivot.h"
#include "RemoteAccessible.h"

namespace mozilla::a11y {

// Used to search for table descendants relevant to table structure.
class TablePartRule : public PivotRule {
public:
  virtual uint16_t Match(Accessible* aAcc) override {
    role accRole = aAcc->Role();
    if (accRole == roles::CAPTION || aAcc->IsTableCell()) {
      return nsIAccessibleTraversalRule::FILTER_MATCH |
             nsIAccessibleTraversalRule::FILTER_IGNORE_SUBTREE;
    }
    if (aAcc->IsTableRow()) {
      return nsIAccessibleTraversalRule::FILTER_MATCH;
    }
    if (aAcc->IsTable() ||
        // Generic containers.
        accRole == roles::TEXT || accRole == roles::TEXT_CONTAINER ||
        accRole == roles::SECTION ||
        // Row groups.
        accRole == roles::ROWGROUP) {
      // Walk inside these, but don't match them.
      return nsIAccessibleTraversalRule::FILTER_IGNORE;
    }
    return nsIAccessibleTraversalRule::FILTER_IGNORE |
           nsIAccessibleTraversalRule::FILTER_IGNORE_SUBTREE;
  }
};

// The Accessible* keys should only be used for lookup. They should not be
// dereferenced.
using CachedTablesMap = nsTHashMap<Accessible*, CachedTableAccessible>;
// We use a global map rather than a map in each document for three reasons:
// 1. We don't have a common base class for local and remote documents.
// 2. It avoids wasting memory in a document that doesn't have any tables.
// 3. It allows the cache management to be encapsulated here in
// CachedTableAccessible.
static StaticAutoPtr<CachedTablesMap> sCachedTables;

/* static */
CachedTableAccessible* CachedTableAccessible::GetFrom(Accessible* aAcc) {
  MOZ_ASSERT(aAcc->IsTable());
  if (!sCachedTables) {
    sCachedTables = new CachedTablesMap();
    ClearOnShutdown(&sCachedTables);
  }
  return &sCachedTables->LookupOrInsertWith(
      aAcc, [&] { return CachedTableAccessible(aAcc); });
}

/* static */
void CachedTableAccessible::Invalidate(Accessible* aAcc) {
  if (!sCachedTables) {
    return;
  }

  if (Accessible* table = nsAccUtils::TableFor(aAcc)) {
    // Destroy the instance (if any). We'll create a new one the next time it
    // is requested.
    sCachedTables->Remove(table);
  }
}

CachedTableAccessible::CachedTableAccessible(Accessible* aAcc) : mAcc(aAcc) {
  MOZ_ASSERT(mAcc);
  // Build the cache. The cache can only be built once per instance. When it's
  // invalidated, we just throw away the instance and create a new one when
  // the cache is next needed.
  int32_t rowIdx = -1;
  uint32_t colIdx = 0;
  // Maps a column index to the cell index of its previous implicit column
  // header.
  nsTHashMap<uint32_t, uint32_t> prevColHeaders;
  Pivot pivot(mAcc);
  TablePartRule rule;
  for (Accessible* part = pivot.Next(mAcc, rule); part;
       part = pivot.Next(part, rule)) {
    role partRole = part->Role();
    if (partRole == roles::CAPTION) {
      // If there are multiple captions, use the first.
      if (!mCaptionAccID) {
        mCaptionAccID = part->ID();
      }
      continue;
    }
    if (part->IsTableRow()) {
      ++rowIdx;
      colIdx = 0;
      // This might be an empty row, so ensure a row here, as our row count is
      // based on the length of mRowColToCellIdx.
      EnsureRow(rowIdx);
      continue;
    }
    MOZ_ASSERT(part->IsTableCell());
    if (rowIdx == -1) {
      // We haven't created a row yet, so this cell must be outside a row.
      continue;
    }
    // Check for a cell spanning multiple rows which already occupies this
    // position. Keep incrementing until we find a vacant position.
    for (;;) {
      EnsureRowCol(rowIdx, colIdx);
      if (mRowColToCellIdx[rowIdx][colIdx] == kNoCellIdx) {
        // This position is not occupied.
        break;
      }
      // This position is occupied.
      ++colIdx;
    }
    // Create the cell.
    uint32_t cellIdx = mCells.Length();
    auto prevColHeader = prevColHeaders.MaybeGet(colIdx);
    auto cell = mCells.AppendElement(
        CachedTableCellAccessible(part->ID(), part, rowIdx, colIdx,
                                  prevColHeader ? *prevColHeader : kNoCellIdx));
    mAccToCellIdx.InsertOrUpdate(part, cellIdx);
    // Update our row/col map.
    // This cell might span multiple rows and/or columns. In that case, we need
    // to occupy multiple coordinates in the row/col map.
    uint32_t lastRowForCell =
        static_cast<uint32_t>(rowIdx) + cell->RowExtent() - 1;
    MOZ_ASSERT(lastRowForCell >= static_cast<uint32_t>(rowIdx));
    uint32_t lastColForCell = colIdx + cell->ColExtent() - 1;
    MOZ_ASSERT(lastColForCell >= colIdx);
    for (uint32_t spannedRow = static_cast<uint32_t>(rowIdx);
         spannedRow <= lastRowForCell; ++spannedRow) {
      for (uint32_t spannedCol = colIdx; spannedCol <= lastColForCell;
           ++spannedCol) {
        EnsureRowCol(spannedRow, spannedCol);
        auto& rowCol = mRowColToCellIdx[spannedRow][spannedCol];
        // If a cell already occupies this position, it overlaps with this one;
        // e.g. r1..2c2 and r2c1..2. In that case, we want to prefer the first
        // cell.
        if (rowCol == kNoCellIdx) {
          rowCol = cellIdx;
        }
      }
    }
    if (partRole == roles::COLUMNHEADER) {
      for (uint32_t spannedCol = colIdx; spannedCol <= lastColForCell;
           ++spannedCol) {
        prevColHeaders.InsertOrUpdate(spannedCol, cellIdx);
      }
    }
    // Increment for the next cell.
    colIdx = lastColForCell + 1;
  }
}

void CachedTableAccessible::EnsureRow(uint32_t aRowIdx) {
  if (mRowColToCellIdx.Length() <= aRowIdx) {
    mRowColToCellIdx.AppendElements(aRowIdx - mRowColToCellIdx.Length() + 1);
  }
  MOZ_ASSERT(mRowColToCellIdx.Length() > aRowIdx);
}

void CachedTableAccessible::EnsureRowCol(uint32_t aRowIdx, uint32_t aColIdx) {
  EnsureRow(aRowIdx);
  auto& row = mRowColToCellIdx[aRowIdx];
  if (mColCount <= aColIdx) {
    mColCount = aColIdx + 1;
  }
  row.SetCapacity(mColCount);
  for (uint32_t newCol = row.Length(); newCol <= aColIdx; ++newCol) {
    // An entry doesn't yet exist for this column in this row.
    row.AppendElement(kNoCellIdx);
  }
  MOZ_ASSERT(row.Length() > aColIdx);
}

Accessible* CachedTableAccessible::Caption() const {
  if (mCaptionAccID) {
    Accessible* caption = nsAccUtils::GetAccessibleByID(
        nsAccUtils::DocumentFor(mAcc), mCaptionAccID);
    MOZ_ASSERT(caption, "Dead caption Accessible!");
    MOZ_ASSERT(caption->Role() == roles::CAPTION, "Caption has wrong role");
    return caption;
  }
  return nullptr;
}

void CachedTableAccessible::Summary(nsString& aSummary) {
  if (Caption()) {
    // If there's a caption, we map caption to Name and summary to Description.
    mAcc->Description(aSummary);
  } else {
    // If there's no caption, we map summary to Name.
    mAcc->Name(aSummary);
  }
}

Accessible* CachedTableAccessible::CellAt(uint32_t aRowIdx, uint32_t aColIdx) {
  int32_t cellIdx = CellIndexAt(aRowIdx, aColIdx);
  if (cellIdx == -1) {
    return nullptr;
  }
  return mCells[cellIdx].Acc(mAcc);
}

bool CachedTableAccessible::IsProbablyLayoutTable() {
  if (RemoteAccessible* remoteAcc = mAcc->AsRemote()) {
    return remoteAcc->TableIsProbablyForLayout();
  }
  if (auto* localTable = HTMLTableAccessible::GetFrom(mAcc->AsLocal())) {
    return localTable->IsProbablyLayoutTable();
  }
  return false;
}

/* static */
CachedTableCellAccessible* CachedTableCellAccessible::GetFrom(
    Accessible* aAcc) {
  MOZ_ASSERT(aAcc->IsTableCell());
  for (Accessible* parent = aAcc; parent; parent = parent->Parent()) {
    if (parent->IsDoc()) {
      break;  // Never cross document boundaries.
    }
    TableAccessible* table = parent->AsTable();
    if (!table) {
      continue;
    }
    if (LocalAccessible* local = parent->AsLocal()) {
      nsIContent* content = local->GetContent();
      if (content && content->IsXULElement()) {
        // XUL tables don't use CachedTableAccessible.
        break;
      }
    }
    // Non-XUL tables only use CachedTableAccessible.
    auto* cachedTable = static_cast<CachedTableAccessible*>(table);
    if (auto cellIdx = cachedTable->mAccToCellIdx.Lookup(aAcc)) {
      return &cachedTable->mCells[*cellIdx];
    }
    // We found a table, but it doesn't know about this cell. This can happen
    // if a cell is outside of a row due to authoring error. We must not search
    // ancestor tables, since this cell's data is not valid there and vice
    // versa.
    break;
  }
  return nullptr;
}

Accessible* CachedTableCellAccessible::Acc(Accessible* aTableAcc) const {
  Accessible* acc =
      nsAccUtils::GetAccessibleByID(nsAccUtils::DocumentFor(aTableAcc), mAccID);
  MOZ_DIAGNOSTIC_ASSERT(acc == mAcc, "Cell's cached mAcc is dead!");
  return acc;
}

TableAccessible* CachedTableCellAccessible::Table() const {
  for (const Accessible* acc = mAcc; acc; acc = acc->Parent()) {
    // Since the caller has this cell, the table is already created, so it's
    // okay to ignore the const restriction here.
    if (TableAccessible* table = const_cast<Accessible*>(acc)->AsTable()) {
      return table;
    }
  }
  return nullptr;
}

uint32_t CachedTableCellAccessible::ColExtent() const {
  if (RemoteAccessible* remoteAcc = mAcc->AsRemote()) {
    if (RequestDomainsIfInactive(CacheDomain::Table)) {
      return 1;
    }
    if (remoteAcc->mCachedFields) {
      if (auto colSpan = remoteAcc->mCachedFields->GetAttribute<int32_t>(
              CacheKey::ColSpan)) {
        MOZ_ASSERT(*colSpan > 0);
        return *colSpan;
      }
    }
  } else if (auto* cell = HTMLTableCellAccessible::GetFrom(mAcc->AsLocal())) {
    // For HTML table cells, we must use the HTMLTableCellAccessible
    // GetColExtent method rather than using the DOM attributes directly.
    // This is because of things like rowspan="0" which depend on knowing
    // about thead, tbody, etc., which is info we don't have in the a11y tree.
    uint32_t colExtent = cell->ColExtent();
    MOZ_ASSERT(colExtent > 0);
    if (colExtent > 0) {
      return colExtent;
    }
  }
  return 1;
}

uint32_t CachedTableCellAccessible::RowExtent() const {
  if (RemoteAccessible* remoteAcc = mAcc->AsRemote()) {
    if (RequestDomainsIfInactive(CacheDomain::Table)) {
      return 1;
    }
    if (remoteAcc->mCachedFields) {
      if (auto rowSpan = remoteAcc->mCachedFields->GetAttribute<int32_t>(
              CacheKey::RowSpan)) {
        MOZ_ASSERT(*rowSpan > 0);
        return *rowSpan;
      }
    }
  } else if (auto* cell = HTMLTableCellAccessible::GetFrom(mAcc->AsLocal())) {
    // For HTML table cells, we must use the HTMLTableCellAccessible
    // GetRowExtent method rather than using the DOM attributes directly.
    // This is because of things like rowspan="0" which depend on knowing
    // about thead, tbody, etc., which is info we don't have in the a11y tree.
    uint32_t rowExtent = cell->RowExtent();
    MOZ_ASSERT(rowExtent > 0);
    if (rowExtent > 0) {
      return rowExtent;
    }
  }
  return 1;
}

UniquePtr<AccIterable> CachedTableCellAccessible::GetExplicitHeadersIterator() {
  if (RemoteAccessible* remoteAcc = mAcc->AsRemote()) {
    if (RequestDomainsIfInactive(CacheDomain::Table)) {
      return nullptr;
    }
    if (remoteAcc->mCachedFields) {
      if (auto headers =
              remoteAcc->mCachedFields->GetAttribute<nsTArray<uint64_t>>(
                  CacheKey::CellHeaders)) {
        return MakeUnique<RemoteAccIterator>(*headers, remoteAcc->Document());
      }
    }
  } else if (LocalAccessible* localAcc = mAcc->AsLocal()) {
    return MakeUnique<AssociatedElementsIterator>(
        localAcc->Document(), localAcc->GetContent(), nsGkAtoms::headers);
  }
  return nullptr;
}

void CachedTableCellAccessible::ColHeaderCells(nsTArray<Accessible*>* aCells) {
  auto* table = static_cast<CachedTableAccessible*>(Table());
  if (!table) {
    return;
  }
  if (mAcc->IsRemote() && RequestDomainsIfInactive(CacheDomain::Table)) {
    return;
  }
  if (auto iter = GetExplicitHeadersIterator()) {
    while (Accessible* header = iter->Next()) {
      role headerRole = header->Role();
      if (headerRole == roles::COLUMNHEADER) {
        aCells->AppendElement(header);
      } else if (headerRole != roles::ROWHEADER) {
        // Treat this cell as a column header only if it's in the same column.
        if (auto cellIdx = table->mAccToCellIdx.Lookup(header)) {
          CachedTableCellAccessible& cell = table->mCells[*cellIdx];
          if (cell.ColIdx() == ColIdx()) {
            aCells->AppendElement(header);
          }
        }
      }
    }
    if (!aCells->IsEmpty()) {
      return;
    }
  }
  Accessible* doc = nsAccUtils::DocumentFor(table->AsAccessible());
  // Each cell stores its previous implicit column header, effectively forming a
  // linked list. We traverse that to get all the headers.
  CachedTableCellAccessible* cell = this;
  for (;;) {
    if (cell->mPrevColHeaderCellIdx == kNoCellIdx) {
      break;  // No more headers.
    }
    cell = &table->mCells[cell->mPrevColHeaderCellIdx];
    Accessible* cellAcc = nsAccUtils::GetAccessibleByID(doc, cell->mAccID);
    aCells->AppendElement(cellAcc);
  }
}

void CachedTableCellAccessible::RowHeaderCells(nsTArray<Accessible*>* aCells) {
  auto* table = static_cast<CachedTableAccessible*>(Table());
  if (!table) {
    return;
  }
  if (auto iter = GetExplicitHeadersIterator()) {
    while (Accessible* header = iter->Next()) {
      role headerRole = header->Role();
      if (headerRole == roles::ROWHEADER) {
        aCells->AppendElement(header);
      } else if (headerRole != roles::COLUMNHEADER) {
        // Treat this cell as a row header only if it's in the same row.
        if (auto cellIdx = table->mAccToCellIdx.Lookup(header)) {
          CachedTableCellAccessible& cell = table->mCells[*cellIdx];
          if (cell.RowIdx() == RowIdx()) {
            aCells->AppendElement(header);
          }
        }
      }
    }
    if (!aCells->IsEmpty()) {
      return;
    }
  }
  Accessible* doc = nsAccUtils::DocumentFor(table->AsAccessible());
  // We don't cache implicit row headers because there are usually not that many
  // cells per row. Get all the row headers on the row before this cell.
  uint32_t row = RowIdx();
  uint32_t thisCol = ColIdx();
  for (uint32_t col = thisCol - 1; col < thisCol; --col) {
    int32_t cellIdx = table->CellIndexAt(row, col);
    if (cellIdx == -1) {
      continue;
    }
    CachedTableCellAccessible& cell = table->mCells[cellIdx];
    Accessible* cellAcc = nsAccUtils::GetAccessibleByID(doc, cell.mAccID);
    MOZ_ASSERT(cellAcc);
    // cell might span multiple columns. We don't want to visit it multiple
    // times, so ensure col is set to cell's starting column.
    col = cell.ColIdx();
    if (cellAcc->Role() != roles::ROWHEADER) {
      continue;
    }
    aCells->AppendElement(cellAcc);
  }
}

bool CachedTableCellAccessible::Selected() {
  return mAcc->State() & states::SELECTED;
}

}  // namespace mozilla::a11y

quality87%

¤ Dauer der Verarbeitung: 0.17 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.