QPatternist::CppCastingHelper< TSubClass > Class Template Reference

Provides convenience methods for performing static casts between C++ classes. More...

#include <qcppcastinghelper_p.h>

Public Functions
template<typename TCastTarget >
const TCastTarget *	as () const
template<typename TCastTarget >
TCastTarget *	as ()

Protected Functions
	CppCastingHelper ()

Detailed Description

template<typename TSubClass>
class QPatternist::CppCastingHelper< TSubClass >

Provides convenience methods for performing static casts between C++ classes.

In Patternist, it is very common to do up-casts from Expression or Item, which typically involves writing messy code. Such an old-way cast looks like this:

static_cast<const MyClass *>(myInstance.data())->myClassMember()

CppCastingHelper provides the convenience method as() for this, which is functionally equivalent to the above code, but simpler:

myInstance->as<MyClass>()->myClassMember()

The as() function performs a static cast.

By using CppCastingHelper, this is achieved:

• Const correctness is automatically taken care of
• Less code to write
• When compiling in debug mode, the as() functions uses a dynamic_cast to verify that the static casts are properly done, such that sensible error messages are given when the casts are invalid. It also traps invalid casts which nevertheless happen to work on a particular platform/compiler/hardware architecture.

CppCastingHelper is a template class where the TSubClass parameter must be the class inheriting CppCastingHelper. See Item or Expression for demonstration.

Author

Frans Englich frans.nosp@m..eng.nosp@m.lich@.nosp@m.noki.nosp@m.a.com

Definition at line 97 of file qcppcastinghelper_p.h.

Constructors and Destructors

CppCastingHelper()

template<typename TSubClass>

QPatternist::CppCastingHelper< TSubClass >::CppCastingHelper ( )

inlineprotected

This constructor is protected because this class must be sub-classed.

Definition at line 153 of file qcppcastinghelper_p.h.

{}

Functions

as() [1/2]

template<typename TSubClass>

template<typename TCastTarget >

const TCastTarget* QPatternist::CppCastingHelper< TSubClass >::as ( ) const

inline

Casts this instance to:

const TCastTarget *

and returns the result.

When compiled in debug mode, this function perform a dynamic_cast, in order to check the correctness of the cast.

Definition at line 114 of file qcppcastinghelper_p.h.

Referenced by QPatternist::CastAs::castToQName(), QPatternist::XsdTypeChecker::checkConstrainingFacets(), QPatternist::XsdSchemaChecker::checkConstrainingFacets(), QPatternist::XsdTypeChecker::checkConstrainingFacetsBinary(), QPatternist::XsdTypeChecker::checkConstrainingFacetsBoolean(), QPatternist::XsdTypeChecker::checkConstrainingFacetsDateTime(), QPatternist::XsdTypeChecker::checkConstrainingFacetsDecimal(), QPatternist::XsdTypeChecker::checkConstrainingFacetsDouble(), QPatternist::XsdTypeChecker::checkConstrainingFacetsDuration(), QPatternist::XsdTypeChecker::checkConstrainingFacetsList(), QPatternist::XsdTypeChecker::checkConstrainingFacetsNotation(), QPatternist::XsdTypeChecker::checkConstrainingFacetsQName(), QPatternist::XsdTypeChecker::checkConstrainingFacetsSignedInteger(), QPatternist::XsdTypeChecker::checkConstrainingFacetsString(), QPatternist::XsdTypeChecker::checkConstrainingFacetsUnion(), QPatternist::XsdTypeChecker::checkConstrainingFacetsUnsignedInteger(), QPatternist::SubsequenceFN::compress(), QPatternist::GenericPredicate::create(), QPatternist::DeepEqualFN::evaluateEBV(), QPatternist::ComparisonIdentifier::matches(), QPatternist::IntegerIdentifier::matches(), QPatternist::XsdSchemaParser::parseComplexContent(), QPatternist::XsdSchemaParser::parseDefaultOpenContent(), QPatternist::XsdSchemaParser::parseFractionDigitsFacet(), QPatternist::XsdSchemaParser::parseGlobalComplexType(), QPatternist::XsdSchemaParser::parseGlobalElement(), QPatternist::XsdSchemaParser::parseLengthFacet(), QPatternist::XsdSchemaParser::parseLocalComplexType(), QPatternist::XsdSchemaParser::parseLocalElement(), QPatternist::XsdSchemaParser::parseMaxExclusiveFacet(), QPatternist::XsdSchemaParser::parseMaxInclusiveFacet(), QPatternist::XsdSchemaParser::parseMaxLengthFacet(), QPatternist::XsdSchemaParser::parseMinExclusiveFacet(), QPatternist::XsdSchemaParser::parseMinInclusiveFacet(), QPatternist::XsdSchemaParser::parseMinLengthFacet(), QPatternist::XsdSchemaParser::parseMinMaxConstraint(), QPatternist::XsdSchemaParser::parseTotalDigitsFacet(), QPatternist::XsdSchemaParser::parseWhiteSpaceFacet(), QPatternist::XsdSchemaResolver::resolveEnumerationFacetValues(), QPatternist::XSLT20CoreFunctions::retrieveExpression(), QPatternist::XPath10CoreFunctions::retrieveExpression(), QPatternist::XPath20CoreFunctions::retrieveExpression(), QPatternist::RangeExpression::staticType(), QPatternist::SubsequenceFN::staticType(), QPatternist::AtomicValue::toQt(), QPatternist::ElementConstructor::typeCheck(), QPatternist::XsdValidatingInstanceReader::validateElement(), and QPatternist::yyparse().

        {
#if defined(Patternist_DEBUG) && !defined(Q_CC_XLC)
/* At least on aix-xlc-64, the compiler cries when it sees dynamic_cast. */
            Q_ASSERT_X(dynamic_cast<const TCastTarget *>(static_cast<const TSubClass *>(this)),
                       Q_FUNC_INFO,
                       "The cast is invalid. This class does not inherit the cast target.");
#endif
            return static_cast<const TCastTarget *>(static_cast<const TSubClass *>(this));
        }

as() [2/2]

template<typename TSubClass>

template<typename TCastTarget >

TCastTarget* QPatternist::CppCastingHelper< TSubClass >::as ( )

inline

Casts this instance to:

TCastTarget *

and returns the result.

When compiled in debug mode, a dynamic_cast is attempted, in order to check the correctness of the cast.

Definition at line 138 of file qcppcastinghelper_p.h.

        {
#if defined(Patternist_DEBUG) && !defined(Q_CC_XLC)
/* At least on aix-xlc-64, the compiler cries when it sees dynamic_cast. */
            Q_ASSERT_X(dynamic_cast<TCastTarget *>(static_cast<TSubClass *>(this)),
                       Q_FUNC_INFO,
                       "The cast is invalid. This class does not inherit the cast target.");
#endif
            return static_cast<TCastTarget *>(static_cast<TSubClass *>(this));
        }

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The documentation for this class was generated from the following file:

• /src/xmlpatterns/utils/qcppcastinghelper_p.h