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Diffstat (limited to 'src/xmlpatterns/expr/qcastingplatform_p.h')
| -rw-r--r-- | src/xmlpatterns/expr/qcastingplatform_p.h | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/src/xmlpatterns/expr/qcastingplatform_p.h b/src/xmlpatterns/expr/qcastingplatform_p.h new file mode 100644 index 0000000..458e9eb --- /dev/null +++ b/src/xmlpatterns/expr/qcastingplatform_p.h @@ -0,0 +1,197 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (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 either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** 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 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +// +// 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_CastingPlatform_H +#define Patternist_CastingPlatform_H + +#include "qatomiccaster_p.h" +#include "qqnamevalue_p.h" +#include "qatomicstring_p.h" +#include "qvalidationerror_p.h" +#include "qatomiccasterlocator_p.h" +#include "qatomictype_p.h" +#include "qbuiltintypes_p.h" +#include "qcommonsequencetypes_p.h" +#include "qschematypefactory_p.h" +#include "qpatternistlocale_p.h" + +QT_BEGIN_HEADER + +QT_BEGIN_NAMESPACE + +namespace QPatternist +{ + /** + * @short Provides casting functionality for classes, such as CastAs or NumberFN, which + * needs to perform casting. + * + * Classes which need to perform casting can simply from this class and gain + * access to casting functinality wrapped in a convenient way. At the center of this + * class is the cast() function, which is used at runtime to perform the actual cast. + * + * The actual circumstances where casting is used, such as in the 'castable as' + * expression or the <tt>fn:number()</tt> function, often have other things to handle as well, + * error handling and cardinality checks for example. This class handles only casting + * and leaves the other case-specific details to the sub-class such that this class only + * do one thing well. + * + * This template class takes two parameters: + * - TSubClass This should be the class inheriting from CastingPlatform. + * - issueError if true, errors are issued via ReportContext, otherwise + * ValidationError instances are returned appropriately. + * + * The class inheriting CastingPlatform must implement the following function: + * @code + * ItemType::Ptr targetType() const + * @endcode + * + * that returns the type that should be cast to. The type must be an AtomicType. + * Typically, it is appropriate to declare this function @c inline. + * + * A sub-class calls prepareCasting() at compile time(such that CastingPlatform can attempt + * to lookup the proper AtomicCaster) and then it simply uses the cast() function at runtime. The + * function targetType() must be implemented such that CastingPlatform knows + * what type it shall cast to. + * + * @author Frans Englich <fenglich@trolltech.com> + * @ingroup Patternist_expressions + */ + template<typename TSubClass, const bool issueError> + class CastingPlatform + { + protected: + /** + * @note issueCastError() depends on the default value. + */ + inline CastingPlatform(const ReportContext::ErrorCode code = ReportContext::FORG0001) : m_errorCode(code) + { + } + + /** + * Attempts to cast @p sourceValue to targetType(), and returns + * the created value. Remember that prepareCasting() should have been + * called at compile time, otherwise this function will be slow. + * + * Error reporting is done in two ways. If a cast fails because + * of an error in lexical representation a ValidationError is returned. + * If the cause of failure is that the casting combination is invalid(such as + * when attempting to cast @c xs:date to @c xs:integer), a ValidationError + * is returned if @c false was passed in the template instantiation, + * an error is issued via @p context. + * + * @param sourceValue the value to cast. Must be non @c null. + * @param context the usual ReportContext, used for error reporting. + * @returns the new value which was the result of the cast. If the + * cast failed, an ValidationError is returned. + */ + Item cast(const Item &sourceValue, + const ReportContext::Ptr &context) const; + + /** + * This function should be called at compiled time, it attempts to determine + * what AtomicCaster that should be used when casting from @p sourceType to + * targetType(). If that is not possible, because the @p sourceType is + * @c xs:anyAtomicType for instance, the AtomicCaster lookup will done at + * runtime on a case-per-case basis. + * + * @returns @c true if the requested casting combination is valid or might be valid. + * If it is guranteed to be invalid, @c false is returned. + */ + bool prepareCasting(const ReportContext::Ptr &context, + const ItemType::Ptr &sourceType); + + /** + * Checks that the targetType() is a valid target type for <tt>castable as</tt> + * and <tt>cast as</tt>. For example, that it is not abstract. If the type is + * invalid, an error is raised via the @p context. Note that it is assumed the type + * is atomic. + */ + void checkTargetType(const ReportContext::Ptr &context) const; + + private: + inline Item castWithCaster(const Item &sourceValue, + const AtomicCaster::Ptr &caster, + const ReportContext::Ptr &context) const; + + /** + * Locates the caster for casting values of type @p sourceType to targetType(), if + * possible. + * + * @p castImpossible is not initialized. Initialize it to @c false. + */ + AtomicCaster::Ptr locateCaster(const ItemType::Ptr &sourceType, + const ReportContext::Ptr &context, + bool &castImpossible) const; + + inline ItemType::Ptr targetType() const + { + Q_ASSERT(static_cast<const TSubClass *>(this)->targetType()); + return static_cast<const TSubClass *>(this)->targetType(); + } + + void issueCastError(const Item &validationError, + const Item &sourceValue, + const ReportContext::Ptr &context) const; + + Q_DISABLE_COPY(CastingPlatform) + AtomicCaster::Ptr m_caster; + const ReportContext::ErrorCode m_errorCode; + }; + +#include "qcastingplatform.cpp" + +} + +QT_END_NAMESPACE + +QT_END_HEADER + +#endif |