source: trunk/src/xmlpatterns/functions/qdocumentfn_p.h@ 846

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//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.

#ifndef Patternist_DocumentFN_H
#define Patternist_DocumentFN_H

#include "qfunctioncall_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{

    /**
     * @short Implements XSL-T's function <tt>fn:document()</tt>.
     *
     * @c fn:document() has no evaluation functions, because it rewrites
     * itself to a set of expressions that is the implementation.
     *
     * The two-argument version:
     *
     * <tt>document($uris as item()*, $baseURINode as node()) as node()*</tt>
     *
     * is rewritten into:
     *
     * <tt>for $uri in distinct-values($uris)
     * return doc(resolve-uri($uri, base-uri($baseURINode)))</tt>
     *
     * and the single version argument:
     *
     * <tt>document($uris as item()*) as node()*</tt>
     *
     * is rewritten into:
     *
     * <tt>for $uri in distinct-values($uris)
     * return doc($uri)</tt>
     *
     * The distinct-values() call ensures the node deduplication and sorting,
     * although it fails in the case that URIs resolve/directs in some way to
     * the same document. Some of those cases can be solved by wrapping the
     * whole expression with a node deduplication(conceptually the-for-loop/.).
     * One advantage with distinct-values() over generating traditional node
     * sorting/deduplication code is that the latter contains node sorting
     * which is uecessary and can be hard to analyze away. distinct-values()
     * doesn't have this problem due to its narrower task..
     *
     * This works without problems, assuming XTRE1160 is not raised and that
     * the recover action instead is ignore. In the case XTRE1160 is raised,
     * one must cater for this.
     *
     * In addition to this, both signatures has its first argument changed to
     * type <tt>xs:string*</tt>, in order to generate atomization code.
     *
     * One notable thing is that the expression for $baseURINode, is moved
     * inside a loop, and will be evaluated repeatedly, unless moved out as
     * part of optimization.
     *
     * @ingroup Patternist_functions
     * @author Frans Englich <[email protected]>
     * @since 4.5
     */
    class DocumentFN : public FunctionCall
    {
    public:
        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
                                          const SequenceType::Ptr &reqType);
    };
}

QT_END_NAMESPACE

QT_END_HEADER

#endif