--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/xmlpatterns/expr/qevaluationcache.cpp Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,274 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtXmlPatterns module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/**
+ * @file
+ * @short This file is included by qevaluationcache_p.h.
+ * If you need includes in this file, put them in qevaluationcache_p.h, outside of the namespace.
+ */
+
+template<bool IsForGlobal>
+EvaluationCache<IsForGlobal>::EvaluationCache(const Expression::Ptr &op,
+ const VariableDeclaration::Ptr &varDecl,
+ const VariableSlotID aSlot) : SingleContainer(op)
+ , m_declaration(varDecl)
+ , m_varSlot(aSlot)
+{
+ Q_ASSERT(m_declaration);
+ Q_ASSERT(m_varSlot > -1);
+}
+
+template<bool IsForGlobal>
+DynamicContext::Ptr EvaluationCache<IsForGlobal>::topFocusContext(const DynamicContext::Ptr &context)
+{
+ DynamicContext::Ptr result(context);
+
+ while(true)
+ {
+ DynamicContext::Ptr candidate(result->previousContext());
+
+ /* We want the top focus, not GenericDynamicContext. */
+ if(candidate && candidate->focusIterator())
+ result = candidate;
+ else
+ return result;
+ }
+}
+
+template<bool IsForGlobal>
+Item EvaluationCache<IsForGlobal>::evaluateSingleton(const DynamicContext::Ptr &context) const
+{
+ ItemCacheCell &cell = IsForGlobal ? context->globalItemCacheCell(m_varSlot) : context->itemCacheCell(m_varSlot);
+
+ if(cell.cacheState == ItemCacheCell::Full)
+ return cell.cachedItem;
+ else
+ {
+ Q_ASSERT(cell.cacheState == ItemCacheCell::Empty);
+ cell.cachedItem = m_operand->evaluateSingleton(IsForGlobal ? topFocusContext(context) : context);
+ cell.cacheState = ItemCacheCell::Full;
+ return cell.cachedItem;
+ }
+}
+
+#if defined(Q_OS_IRIX) && defined(Q_CC_MIPS)
+/**
+ * @short Compile workaround for MIPSPro on IRIX.
+ *
+ * This function is never called.
+ *
+ * It's mere presence means the MIPSPro compiler can accept some other code below.
+ *
+ * I recommend Buddism.
+ */
+static inline Item::Iterator::Ptr workaroundIrixMIPSPro(const ItemSequenceCacheCell &cell)
+{
+ return Item::Iterator::Ptr(new ListIterator<Item, Item::List>(cell.cachedItems));
+}
+#endif
+
+template<bool IsForGlobal>
+Item::Iterator::Ptr EvaluationCache<IsForGlobal>::evaluateSequence(const DynamicContext::Ptr &context) const
+{
+ ItemSequenceCacheCell::Vector &cells = IsForGlobal ? context->globalItemSequenceCacheCells(m_varSlot) : context->itemSequenceCacheCells(m_varSlot);
+ ItemSequenceCacheCell &cell = cells[m_varSlot];
+
+
+ if(cell.inUse)
+ {
+ context->error(QtXmlPatterns::tr("Circularity detected"),
+ ReportContext::XTDE0640, this);
+ }
+
+ switch(cell.cacheState)
+ {
+ case ItemSequenceCacheCell::Full:
+ {
+ /**
+ * We don't use makeListIterator() here because the MIPSPro compiler can't handle it.
+ */
+ return Item::Iterator::Ptr(new ListIterator<Item, Item::List>(cell.cachedItems));
+ }
+ case ItemSequenceCacheCell::Empty:
+ {
+ cell.inUse = true;
+ cell.sourceIterator = m_operand->evaluateSequence(IsForGlobal ? topFocusContext(context) : context);
+ cell.cacheState = ItemSequenceCacheCell::PartiallyPopulated;
+ /* Fallthrough. */
+ }
+ case ItemSequenceCacheCell::PartiallyPopulated:
+ {
+ cell.inUse = false;
+ Q_ASSERT_X(cells.at(m_varSlot).sourceIterator, Q_FUNC_INFO,
+ "This trigger for a cache bug which hasn't yet been analyzed.");
+ return Item::Iterator::Ptr(new CachingIterator(cells, m_varSlot, IsForGlobal ? topFocusContext(context) : context));
+ }
+ default:
+ {
+ Q_ASSERT_X(false, Q_FUNC_INFO, "This path is not supposed to be run.");
+ return Item::Iterator::Ptr();
+ }
+ }
+}
+
+template<bool IsForGlobal>
+Expression::Ptr EvaluationCache<IsForGlobal>::typeCheck(const StaticContext::Ptr &context,
+ const SequenceType::Ptr &reqType)
+{
+ /* It's important that we do the typeCheck() before checking for the use of local variables,
+ * because ExpressionVariableReference can reference an expression that is a local variable,
+ * so it must rewrite itself to it operand before, and it does that in EvaluationCache::typeCheck(). */
+ const Expression::Ptr me(SingleContainer::typeCheck(context, reqType));
+
+ OperandsIterator it(me, OperandsIterator::ExcludeParent);
+ Expression::Ptr next(it.next());
+
+ /* If our operand or any sub operand gets its value from a for-loop, we cannot
+ * cache it since then our cache would be filled -- but not invalidated -- on the
+ * first for-iteration. Consider this query:
+ *
+ * <tt>for $i in expr
+ * let $v := $i/p
+ * return ($v, $v)</tt>
+ *
+ * An evaluation cache is inserted for the two operands in the return clause. However,
+ * $i changes for each iteration so the cache can only be active on a per-iteration basis,
+ * it it's possible(which it isn't).
+ *
+ * This means that for some queries we don't cache what we really should, and hence evaluate
+ * in a sub-optimal way, since this DependsOnLocalVariable don't communicate whether it references
+ * a loop that affects us. The correct fix for this would be to let ForExpression reset the
+ * relevant caches only, but we don't know which ones that are. */
+ while(next)
+ {
+ if(next->has(DependsOnLocalVariable))
+ return m_operand->typeCheck(context, reqType);
+
+ next = it.next();
+ }
+
+ return me;
+}
+
+template<bool IsForGlobal>
+Expression::Ptr EvaluationCache<IsForGlobal>::compress(const StaticContext::Ptr &context)
+{
+ const Expression::Ptr me(SingleContainer::compress(context));
+
+ if(me != this)
+ return me;
+
+ if(m_operand->is(IDRangeVariableReference))
+ return m_operand;
+
+ if(m_declaration->usedByMany())
+ {
+ /* If it's only an atomic value an EvaluationCache is overkill. However,
+ * it's still needed for functions like fn:current-time() that must adhere to
+ * query stability. */
+ const Properties props(m_operand->properties());
+
+ if(props.testFlag(EvaluationCacheRedundant) ||
+ ((props.testFlag(IsEvaluated)) &&
+ !props.testFlag(DisableElimination) &&
+ CommonSequenceTypes::ExactlyOneAtomicType->matches(m_operand->staticType())))
+ {
+ return m_operand;
+ }
+ else
+ return me;
+ }
+ else
+ {
+ /* If we're only used once, there's no need for an EvaluationCache. */
+ return m_operand;
+ }
+}
+
+template<bool IsForGlobal>
+SequenceType::Ptr EvaluationCache<IsForGlobal>::staticType() const
+{
+ return m_operand->staticType();
+}
+
+template<bool IsForGlobal>
+SequenceType::List EvaluationCache<IsForGlobal>::expectedOperandTypes() const
+{
+ /* Remember that EvaluationCache::typeCheck() will be called from multiple locations,
+ * which potentially have different type requirements. For instance, one wants a node,
+ * and another requires atomization and casting.
+ *
+ * Returning ZeroOrMoreItems is safe here because staticType() returns the operand's type
+ * and therefore the convertors like Atomizer will be parents to us, and hence only affect
+ * the relevant path.
+ *
+ * ZeroOrMoreItems also make sense logically since we're actually only used where the
+ * variable references reference us. */
+ SequenceType::List result;
+ result.append(CommonSequenceTypes::ZeroOrMoreItems);
+
+ return result;
+}
+
+template<bool IsForGlobal>
+Expression::Properties EvaluationCache<IsForGlobal>::properties() const
+{
+ /* We cannot return the operand's properties unconditionally, because some
+ * doesn't hold for this Expression.
+ *
+ * However, some of the properties must propagate through, which are the ones being OR'd here.
+ */
+ return m_operand->properties() & (DisableElimination | IsEvaluated | DisableTypingDeduction);
+}
+
+template<bool IsForGlobal>
+ExpressionVisitorResult::Ptr
+EvaluationCache<IsForGlobal>::accept(const ExpressionVisitor::Ptr &visitor) const
+{
+ return visitor->visit(this);
+}
+
+template<bool IsForGlobal>
+const SourceLocationReflection *EvaluationCache<IsForGlobal>::actualReflection() const
+{
+ return m_operand->actualReflection();
+}
+