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     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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     7 ** This file is part of the QtXmlPatterns module of the Qt Toolkit.

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    41 

    42 //

    43 //  W A R N I N G

    44 //  -------------

    45 //

    46 // This file is not part of the Qt API.  It exists purely as an

    47 // implementation detail.  This header file may change from version to

    48 // version without notice, or even be removed.

    49 //

    50 // We mean it.

    51 

    52 #ifndef Patternist_DynamicContext_H

    53 #define Patternist_DynamicContext_H

    54 

    55 #include "qautoptr_p.h"

    56 #include "qcachecells_p.h"

    57 #include "qexternalvariableloader_p.h"

    58 #include "qitem_p.h"

    59 #include "qnamepool_p.h"

    60 #include "qnodebuilder_p.h"

    61 #include "qprimitives_p.h"

    62 #include "qreportcontext_p.h"

    63 #include "qresourceloader_p.h"

    64 

    65 QT_BEGIN_HEADER

    66 

    67 QT_BEGIN_NAMESPACE

    68 

    69 class QDateTime;

    70 template<typename T> class QVector;

    71 

    72 namespace QPatternist

    73 {

    74     class DayTimeDuration;

    75     class Expression;

    76     class TemplateMode;

    77 

    78     /**

    79      * @short Carries information and facilities used at runtime, and hence

    80      * provides a state for that stage in a thread-safe manner.

    81      *

    82      * @see <a href="http://www.w3.org/TR/xquery/#eval_context">XQuery

    83      * 1.0: An XML Query Language, 2.1.2 Dynamic Context</a>

    84      * @see <a href="http://www.w3.org/TR/xquery/#id-dynamic-evaluation">XQuery

    85      * 1.0: An XML Query Language, 2.2.3.2 Dynamic Evaluation Phase</a>

    86      * @author Frans Englich <frans.englich@nokia.com>

    87      */

    88     class DynamicContext : public ReportContext

    89     {

    90     public:

    91         /**

    92          * @short Carries template parameters at runtime.

    93          *

    94          * The key is the name of the parameter, and the value the Expression

    95          * which supplies the value.

    96          */

    97         typedef QHash<QXmlName, QExplicitlySharedDataPointer<Expression> > TemplateParameterHash;

    98         typedef QExplicitlySharedDataPointer<DynamicContext> Ptr;

    99 

   100         virtual ~DynamicContext()

   101         {

   102         }

   103 

   104         /**

   105          * This function intentionally returns by reference.

   106          *

   107          * @see globalItemCacheCell()

   108          */

   109         virtual ItemCacheCell &itemCacheCell(const VariableSlotID slot) = 0;

   110 

   111         /**

   112          * This function intentionally returns by reference.

   113          *

   114          * @see globalItemSequenceCacheCells

   115          */

   116         virtual ItemSequenceCacheCell::Vector &itemSequenceCacheCells(const VariableSlotID slot) = 0;

   117 

   118         virtual xsInteger contextPosition() const = 0;

   119         virtual Item contextItem() const = 0;

   120         virtual xsInteger contextSize() = 0;

   121 

   122         virtual void setRangeVariable(const VariableSlotID slot,

   123                                       const Item &newValue) = 0;

   124         virtual Item rangeVariable(const VariableSlotID slot) const = 0;

   125         virtual void setExpressionVariable(const VariableSlotID slot,

   126                                            const QExplicitlySharedDataPointer<Expression> &newValue) = 0;

   127         virtual QExplicitlySharedDataPointer<Expression>

   128         expressionVariable(const VariableSlotID slot) const = 0;

   129 

   130         virtual Item::Iterator::Ptr positionIterator(const VariableSlotID slot) const = 0;

   131         virtual void setPositionIterator(const VariableSlotID slot,

   132                                          const Item::Iterator::Ptr &newValue) = 0;

   133 

   134         virtual void setFocusIterator(const Item::Iterator::Ptr &it) = 0;

   135         virtual Item::Iterator::Ptr focusIterator() const = 0;

   136 

   137         virtual QExplicitlySharedDataPointer<DayTimeDuration> implicitTimezone() const = 0;

   138         virtual QDateTime currentDateTime() const = 0;

   139 

   140         virtual QAbstractXmlReceiver *outputReceiver() const = 0;

   141         virtual NodeBuilder::Ptr nodeBuilder(const QUrl &baseURI) const = 0;

   142         virtual ResourceLoader::Ptr resourceLoader() const = 0;

   143         virtual ExternalVariableLoader::Ptr externalVariableLoader() const = 0;

   144         virtual NamePool::Ptr namePool() const = 0;

   145 

   146         /**

   147          * @short Returns the item that @c fn:current() returns.

   148          *

   149          * Hence, this is not the focus, and very different from the focus.

   150          *

   151          * @see CurrentItemStore

   152          * @see CurrentFN

   153          */

   154         virtual Item currentItem() const = 0;

   155 

   156         DynamicContext::Ptr createFocus();

   157         DynamicContext::Ptr createStack();

   158         DynamicContext::Ptr createReceiverContext(QAbstractXmlReceiver *const receiver);

   159 

   160         /**

   161          * Whenever a tree gets built, this function is called. DynamicContext

   162          * has the responsibility of keeping a copy of @p nm, such that it

   163          * doesn't go out of scope, since no one else will reference @p nm.

   164          *

   165          * I think this is currently only used for temporary node trees. In

   166          * other cases they are stored in the ExternalResourceLoader.

   167          *

   168          * The caller guarantees that @p nm is not @c null.

   169          */

   170         virtual void addNodeModel(const QAbstractXmlNodeModel::Ptr &nm) = 0;

   171 

   172         /**

   173          * Same as itemCacheCell(), but is only used for global varibles. This

   174          * is needed because sometimes stack frames needs to be created for

   175          * other kinds of variables(such as in the case of user function

   176          * calls), while the global variable(s) needs to continue to use the

   177          * same cache, instead of one for each new stack frame, typically an

   178          * instance of StackContextBase.

   179          *

   180          * This has two effects:

   181          *

   182          * - It's an optimization. Instead of that a global variable gets evaluated each

   183          * time a user function is called, think recursive functions, it's done

   184          * only once.

   185          * - Query stability, hence affects things like node identity and

   186          * therefore conformance. Hence affects for instance what nodes a query

   187          * returns, since node identity affect node deduplication.

   188          */

   189         virtual ItemCacheCell &globalItemCacheCell(const VariableSlotID slot) = 0;

   190 

   191         /**

   192          * @short When a template is called, this member carries the template

   193          * parameters.

   194          *

   195          * Hence this is similar to the other variable stack functions such as

   196          * rangeVariable() and expressionVariable(), the difference being that

   197          * the order of template parameters as well as its arguments can appear

   198          * in arbitrary order. Hence the name is used to make the order

   199          * insignificant.

   200          */

   201         virtual TemplateParameterHash &templateParameterStore() = 0;

   202 

   203         /**

   204          * Same as itemSequenceCacheCells() but applies only for global

   205          * variables.

   206          *

   207          * @see globalItemCacheCell()

   208          */

   209         virtual ItemSequenceCacheCell::Vector &globalItemSequenceCacheCells(const VariableSlotID slot) = 0;

   210 

   211         /**

   212          * @short Returns the previous DynamicContext. If this context is the

   213          * top-level one, @c null is returned.

   214          */

   215         virtual DynamicContext::Ptr previousContext() const = 0;

   216 

   217         /**

   218          * @short Returns the current template mode that is in effect.

   219          *

   220          * If @c null is returned, it means that the default mode should be

   221          * used as the current mode.

   222          */

   223         virtual QExplicitlySharedDataPointer<TemplateMode> currentTemplateMode() const = 0;

   224     };

   225 }

   226 

   227 QT_END_NAMESPACE

   228 

   229 QT_END_HEADER

   230 

   231 #endif