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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_SequenceFNs_H
#define Patternist_SequenceFNs_H
#include "qatomiccomparator_p.h"
#include "qcomparisonplatform_p.h"
#include "qliteral_p.h"
#include "qfunctioncall_p.h"
/**
* @file
* @short Contains classes implementing the functions found in
* <a href="http://www.w3.org/TR/xpath-functions/#general-seq-funcs">XQuery 1.0 and
* XPath 2.0 Functions and Operators, 15.1 General Functions and Operators on Sequences</a>.
*
* @todo document that some functions have both eval funcs implented.
*
* @ingroup Patternist_functions
*/
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
namespace QPatternist
{
/**
* @short Implements the function <tt>fn:boolean()</tt>.
*
* @see EBVExtractor
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
class BooleanFN : public FunctionCall
{
public:
virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;
/**
* If @p reqType is CommonSequenceTypes::EBV, the type check of
* the operand is returned. Hence, this removes redundant calls
* to <tt>fn:boolean()</tt>.
*/
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
};
/**
* @short Implements the function <tt>fn:index-of()</tt>.
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
class IndexOfFN : public FunctionCall,
public ComparisonPlatform<IndexOfFN, false>
{
public:
inline IndexOfFN() : ComparisonPlatform<IndexOfFN, false>()
{
}
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
inline AtomicComparator::Operator operatorID() const
{
return AtomicComparator::OperatorEqual;
}
};
/**
* @short Implements the functions <tt>fn:exists()</tt> and <tt>fn:empty()</tt>.
*
* Existence is a template value class. Appropriate implementations are achieved
* by instantiating it with either IDExistsFN or IDEmptyFN.
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
template<const Expression::ID Id>
class Existence : public FunctionCall
{
public:
virtual bool evaluateEBV(const DynamicContext::Ptr &context) const
{
if(Id == IDExistsFN)
return !m_operands.first()->evaluateSequence(context)->isEmpty();
else
return m_operands.first()->evaluateSequence(context)->isEmpty();
}
/**
* Attempts to rewrite to @c false or @c true by looking at the static
* cardinality of its operand.
*/
virtual Expression::Ptr compress(const StaticContext::Ptr &context)
{
// RVCT doesn't like using template parameter in trinary operator when the trinary operator result is
// passed directly into another constructor.
Q_ASSERT(Id == IDExistsFN || Id == IDEmptyFN);
const Expression::Ptr me(FunctionCall::compress(context));
if(me != this)
return me;
// RVCT doesn't like using template parameter in trinary operator when the trinary operator result is
// passed directly into another constructor.
Expression::ID tempId = Id;
const Cardinality myCard((tempId == IDExistsFN) ? Cardinality::oneOrMore() : Cardinality::empty());
const Cardinality card(m_operands.first()->staticType()->cardinality());
if(myCard.isMatch(card))
{ /* Since the dynamic type always is narrower than the static type or equal, and that the
static type is in scope, it means we will always be true. */
return wrapLiteral(CommonValues::BooleanTrue, context, this);
}
else
{
/* Is it even possible to hit? */
if(myCard.canMatch(card))
{
return me;
}
else
{ /* We can never hit. */
return wrapLiteral(CommonValues::BooleanFalse, context, this);
}
}
}
};
/**
* @short Implements the function <tt>fn:distinct-values()</tt>.
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
class DistinctValuesFN : public FunctionCall,
public ComparisonPlatform<IndexOfFN, false>
{
public:
inline DistinctValuesFN() : ComparisonPlatform<IndexOfFN, false>()
{
}
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
/**
* Performs necessary type checks, but also implements the optimization
* of rewriting to its operand if the operand's cardinality is zero-or-one
* or exactly-one.
*/
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
/**
* @returns a type whose item type is the type of the first operand, and
* a cardinality which is non-empty if the first operand's type is non-empty
* and allows exactly-one. The latter is needed for operands which has the
* cardinality 2+, since distinct-values possibly removes items from the
* source sequence.
*/
virtual SequenceType::Ptr staticType() const;
protected:
inline AtomicComparator::Operator operatorID() const
{
return AtomicComparator::OperatorEqual;
}
};
/**
* @short Implements the function <tt>fn:insert-before()</tt>.
*
* @todo docs, explain why evaluateSequence and evaluateSingleton is implemented
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
class InsertBeforeFN : public FunctionCall
{
public:
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
/**
* Implements the static enferences rules. The function's static item type
* is the union type of the first and third argument, and the cardinality is
* the cardinalities of the two operands added together. For example,
* insert-before((1, "str"), 1, xs:double(0)) has the static type xs:anyAtomicType+.
*
* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_insert_before">XQuery 1.0
* and XPath 2.0 Formal Semantics, 7.2.15 The fn:insert-before function</a>
*/
virtual SequenceType::Ptr staticType() const;
};
/**
* @short Implements the function <tt>fn:remove()</tt>.
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
class RemoveFN : public FunctionCall
{
public:
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
/**
* Implements the static enferences rules, "Since one item may be removed
* from the sequence, the resulting type is made optional:"
*
* <tt>statEnv |- (FN-URI,"remove")(Type, Type1) : prime(Type) * quantifier(Type)?</tt>
*
* However, because Patternist's type system is more fine grained than Formal Semantics,
* the sequence isn't made optional. Instead its minimum length is reduced with one.
*
* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_remove">XQuery 1.0
* and XPath 2.0 Formal Semantics, 7.2.11 The fn:remove function</a>
*/
virtual SequenceType::Ptr staticType() const;
};
/**
* @short Implements the function <tt>fn:reverse()</tt>.
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
*/
class ReverseFN : public FunctionCall
{
public:
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
/**
* Formally speaking, the type inference is:
*
@verbatim
statEnv |- (FN-URI,"reverse")(Type) : prime(Type) * quantifier(Type)
@endverbatim
*
* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_reverse">XQuery 1.0
* and XPath 2.0 Formal Semantics, 7.2.12 The fn:reverse function</a>
* @returns the static type of the function's first argument.
*/
virtual SequenceType::Ptr staticType() const;
};
/**
* @short Implements the function <tt>fn:subsequence()</tt>.
*
* @ingroup Patternist_functions
* @author Frans Englich <frans.englich@nokia.com>
* @todo Type inference can be made stronger for this function
*/
class SubsequenceFN : public FunctionCall
{
public:
SubsequenceFN();
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType);
/**
* This function implements rewrites the SubsequenceFN instance into an
* empty sequence if its third argument, the sequence length argument, is
* evaluated and is effectively equal or less than zero.
*/
virtual Expression::Ptr compress(const StaticContext::Ptr &context);
/**
* Partially implements the static type inference rules.
*
* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_subsequence">XQuery 1.0
* and XPath 2.0 Formal Semantics, 7.2.13 The fn:subsequence function</a>
*/
virtual SequenceType::Ptr staticType() const;
private:
bool m_hasTypeChecked;
};
}
QT_END_NAMESPACE
QT_END_HEADER
#endif