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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_CastingPlatform_H |
| #define Patternist_CastingPlatform_H |
| |
| #include "qatomiccasterlocator_p.h" |
| #include "qatomiccaster_p.h" |
| #include "qatomicstring_p.h" |
| #include "qatomictype_p.h" |
| #include "qbuiltintypes_p.h" |
| #include "qcommonsequencetypes_p.h" |
| #include "qpatternistlocale_p.h" |
| #include "qqnamevalue_p.h" |
| #include "qschematypefactory_p.h" |
| #include "qstaticcontext_p.h" |
| #include "qvalidationerror_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. |
| * |
| * @see ValueFactory |
| * @author Frans Englich <frans.englich@nokia.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. |
| */ |
| static AtomicCaster::Ptr locateCaster(const ItemType::Ptr &sourceType, |
| const ReportContext::Ptr &context, |
| bool &castImpossible, |
| const SourceLocationReflection *const location, |
| const ItemType::Ptr &targetType); |
| private: |
| inline Item castWithCaster(const Item &sourceValue, |
| const AtomicCaster::Ptr &caster, |
| const DynamicContext::Ptr &context) 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 |
