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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_TypeChecker_H
#define Patternist_TypeChecker_H
#include "qstaticcontext_p.h"
#include "qexpression_p.h"
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
namespace QPatternist
{
/**
* @short Contains functions that applies Function Conversion Rules and other
* kinds of compile-time type checking tasks.
*
* @ingroup Patternist_types
* @author Frans Englich <frans.englich@nokia.com>
*/
class TypeChecker
{
public:
enum Option
{
/**
* @short When set, the function conversion rules are applied.
*
* For instance, this is type promotion and conversions from @c
* xs:untypedAtomic to @c xs:date. This is done for function calls,
* but not when binding an expression to a variable.
*/
AutomaticallyConvert = 1,
/**
* @short Whether the focus should be checked or not.
*
* Sometimes the focus is unknown at the time
* applyFunctionConversion() is called, and therefore it is
* of interest to post pone the check to later on.
*/
CheckFocus = 2,
/**
* When applyFunctionConversion() is passed AutomaticallyConvert
* and promotion is required, such as from @c xs:integer to
* @c xs:float, there will be no conversion performed, with the
* assumption that the receiver will call Numeric::toFloat() or
* similar.
*
* However, when GeneratePromotion is set, code will be generated
* that performs this conversion regardless of what any receiver
* do.
*
* This is useful in the case where one Expression only pipes the
* result of another. The only known case of that as of this
* writing is when UserFunctionCallsite evaluates its body.
*/
GeneratePromotion
};
typedef QFlags<Option> Options;
/**
* @short Builds a pipeline of artificial AST nodes that ensures @p operand
* conforms to the type @p reqType by applying the Function
* Conversion Rules.
*
* This new Expression is returned, or, if no conversions were necessary,
* @p operand as it is.
*
* applyFunctionConversion() also performs various checks, such as if
* @p operand needs the focus and that the focus is defined in the
* @p context. These checks are largely guided by @p operand's
* Expression::properties().
*
* @see <a href="http://www.w3.org/TR/xpath20/\#id-function-calls">XML Path
* Language (XPath) 2.0, 3.1.5 Function Calls</a>, more specifically the
* Function Conversion Rules
*/
static Expression::Ptr
applyFunctionConversion(const Expression::Ptr &operand,
const SequenceType::Ptr &reqType,
const StaticContext::Ptr &context,
const ReportContext::ErrorCode code = ReportContext::XPTY0004,
const Options = Options(AutomaticallyConvert | CheckFocus));
private:
static inline Expression::Ptr typeCheck(Expression *const op,
const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
/**
* @short Implements the type checking and promotion part of the Function Conversion Rules.
*/
static Expression::Ptr verifyType(const Expression::Ptr &operand,
const SequenceType::Ptr &reqSeqType,
const StaticContext::Ptr &context,
const ReportContext::ErrorCode code,
const Options options);
/**
* Determines whether type promotion is possible from one type to another. False
* is returned when a promotion is not possible or if a promotion is not needed(as when
* the types are identical), since that can be considered to not be type promotion.
*
* @returns @c true if @p fromType can be promoted to @p toType.
* @see <a href="http://www.w3.org/TR/xpath20/#promotion">XML Path Language
* (XPath) 2.0, B.1 Type Promotion</a>
*/
static bool promotionPossible(const ItemType::Ptr &fromType,
const ItemType::Ptr &toType,
const StaticContext::Ptr &context);
/**
* @short Centralizes a message-string to reduce work for translators
* and increase consistency.
*/
static inline QString wrongType(const NamePool::Ptr &np,
const ItemType::Ptr &reqType,
const ItemType::Ptr &opType);
/**
* No implementation is provided for this constructor. This class
* is not supposed to be instantiated.
*/
inline TypeChecker();
Q_DISABLE_COPY(TypeChecker)
};
}
QT_END_NAMESPACE
QT_END_HEADER
#endif