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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_DocumentFN_H

    53 #define Patternist_DocumentFN_H

    54 

    55 #include "qfunctioncall_p.h"

    56 

    57 QT_BEGIN_HEADER

    58 

    59 QT_BEGIN_NAMESPACE

    60 

    61 namespace QPatternist

    62 {

    63 

    64     /**

    65      * @short Implements XSL-T's function <tt>fn:document()</tt>.

    66      *

    67      * @c fn:document() has no evaluation functions, because it rewrites

    68      * itself to a set of expressions that is the implementation.

    69      *

    70      * The two-argument version:

    71      *

    72      * <tt>document($uris as item()*, $baseURINode as node()) as node()*</tt>

    73      *

    74      * is rewritten into:

    75      *

    76      * <tt>for $uri in distinct-values($uris)

    77      * return doc(resolve-uri($uri, base-uri($baseURINode)))</tt>

    78      *

    79      * and the single version argument:

    80      *

    81      * <tt>document($uris as item()*) as node()*</tt>

    82      *

    83      * is rewritten into:

    84      *

    85      * <tt>for $uri in distinct-values($uris)

    86      * return doc($uri)</tt>

    87      *

    88      * The distinct-values() call ensures the node deduplication and sorting,

    89      * although it fails in the case that URIs resolve/directs in some way to

    90      * the same document. Some of those cases can be solved by wrapping the

    91      * whole expression with a node deduplication(conceptually the-for-loop/.).

    92      * One advantage with distinct-values() over generating traditional node

    93      * sorting/deduplication code is that the latter contains node sorting

    94      * which is uecessary and can be hard to analyze away. distinct-values()

    95      * doesn't have this problem due to its narrower task..

    96      *

    97      * This works without problems, assuming XTRE1160 is not raised and that

    98      * the recover action instead is ignore. In the case XTRE1160 is raised,

    99      * one must cater for this.

   100      *

   101      * In addition to this, both signatures has its first argument changed to

   102      * type <tt>xs:string*</tt>, in order to generate atomization code.

   103      *

   104      * One notable thing is that the expression for $baseURINode, is moved

   105      * inside a loop, and will be evaluated repeatedly, unless moved out as

   106      * part of optimization.

   107      *

   108      * @ingroup Patternist_functions

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

   110      * @since 4.5

   111      */

   112     class DocumentFN : public FunctionCall

   113     {

   114     public:

   115         virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

   116                                           const SequenceType::Ptr &reqType);

   117     };

   118 }

   119 

   120 QT_END_NAMESPACE

   121 

   122 QT_END_HEADER

   123 

   124 #endif