catch2/internal/catch_evaluate.hpp

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/*
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* catch_evaluate.hpp
* Catch
*
* Created by Phil on 04/03/2011.
* Copyright 2011 Two Blue Cubes Ltd. All rights reserved.
*
* Distributed under the Boost Software License, Version 1.0. (See accompanying
* file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
*
*/
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#ifndef TWOBLUECUBES_CATCH_EVALUATE_HPP_INCLUDED
#define TWOBLUECUBES_CATCH_EVALUATE_HPP_INCLUDED
namespace Catch
{
namespace Internal
{
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enum Operator
{
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IsEqualTo,
IsNotEqualTo,
IsLessThan,
IsGreaterThan,
IsLessThanOrEqualTo,
IsGreaterThanOrEqualTo
};
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template<Operator Op>
struct OperatorTraits{ static const char* getName(){ return "*error - unknown operator*"; } };
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template<>
struct OperatorTraits<IsEqualTo>{ static const char* getName(){ return "=="; } };
template<>
struct OperatorTraits<IsNotEqualTo>{ static const char* getName(){ return "!="; } };
template<>
struct OperatorTraits<IsLessThan>{ static const char* getName(){ return "<"; } };
template<>
struct OperatorTraits<IsGreaterThan>{ static const char* getName(){ return ">"; } };
template<>
struct OperatorTraits<IsLessThanOrEqualTo>{ static const char* getName(){ return "<="; } };
template<>
struct OperatorTraits<IsGreaterThanOrEqualTo>{ static const char* getName(){ return ">="; } };
// Because we capture the LHS and RHS of a binary condition expression by reference, then
// compare the referenced values later, we may get compiler warnings when comparing unsigned
// integer types with integer literals (which are signed - int or long, specifically).
// To avoid this warning we filter out the problem cases as a set of overloads of the compare
// function. In those overloads we cast the unsigned type to its signed equivalent then
// perform the comparison. However we also have to handle the case where the signed value is
// negative. Comparing a negative value with an unsigned value (which will always be positive)
// has fixed logic per operator, so this is captured seperately as an enum value.
enum LostSign
{
None = 0,
LhsSignWasLost = 1,
RhsSignWasLost = 2
};
// So the compare overloads can be operator agnostic we convey the operator as a template
// enum, which is used to specialise an Evaluator for doing the comparison.
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template<typename T1, typename T2, Operator Op>
class Evaluator{};
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template<typename T1, typename T2>
struct Evaluator<T1, T2, IsEqualTo>
{
enum{ failsWhen = LhsSignWasLost | RhsSignWasLost };
static bool evaluate( const T1& lhs, const T2& rhs)
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{
return lhs == rhs;
}
};
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template<typename T1, typename T2>
struct Evaluator<T1, T2, IsNotEqualTo>
{
enum{ failsWhen = None };
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static bool evaluate( const T1& lhs, const T2& rhs )
{
return lhs != rhs;
}
};
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template<typename T1, typename T2>
struct Evaluator<T1, T2, IsLessThan>
{
enum{ failsWhen = RhsSignWasLost };
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static bool evaluate( const T1& lhs, const T2& rhs )
{
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return lhs < rhs;
}
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};
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsGreaterThan>
{
enum{ failsWhen = LhsSignWasLost };
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static bool evaluate( const T1& lhs, const T2& rhs )
{
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return lhs > rhs;
}
};
template<typename T1, typename T2>
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struct Evaluator<T1, T2, IsGreaterThanOrEqualTo>
{
enum{ failsWhen = LhsSignWasLost };
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static bool evaluate( const T1& lhs, const T2& rhs )
{
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return lhs >= rhs;
}
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};
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsLessThanOrEqualTo>
{
enum{ failsWhen = RhsSignWasLost };
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static bool evaluate( const T1& lhs, const T2& rhs )
{
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return lhs <= rhs;
}
};
// All the special case signed/ unsigned overloads of compare forward to this function,
// which, for negative numbers checks the special case fixed logic, otherwise forwards on
// to the specialised Evaluator for the operator enum
template<Operator Op, typename T1, typename T2>
bool applyEvaluator( const T1& lhs, const T2& rhs, LostSign lostSign )
{
typedef Evaluator<T1, T2, Op> EvaluatorType;
return lostSign == None
? EvaluatorType::evaluate( lhs, rhs )
: ( EvaluatorType::failsWhen & lostSign ) != lostSign;
}
template<typename T>
LostSign testLhsSign( T lhs )
{
return lhs < 0 ? LhsSignWasLost : None;
}
template<typename T>
LostSign testRhsSign( T rhs )
{
return rhs < 0 ? RhsSignWasLost : None;
}
// "base" overload
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template<Operator Op, typename T1, typename T2>
bool compare( const T1& lhs, const T2& rhs )
{
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return Evaluator<T1, T2, Op>::evaluate( lhs, rhs );
}
// unsigned X to int
template<Operator Op> bool compare( unsigned int lhs, int rhs )
{
return applyEvaluator<Op>( lhs, static_cast<unsigned int>( rhs ), testRhsSign( rhs ) );
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}
template<Operator Op> bool compare( unsigned long lhs, int rhs )
{
return applyEvaluator<Op>( lhs, static_cast<unsigned int>( rhs ), testRhsSign( rhs ) );
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}
template<Operator Op> bool compare( unsigned char lhs, int rhs )
{
return applyEvaluator<Op>( lhs, static_cast<unsigned int>( rhs ), testRhsSign( rhs ) );
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}
// unsigned X to long
template<Operator Op> bool compare( unsigned int lhs, long rhs )
{
return applyEvaluator<Op>( lhs, static_cast<unsigned long>( rhs ), testRhsSign( rhs ) );
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}
template<Operator Op> bool compare( unsigned long lhs, long rhs )
{
return applyEvaluator<Op>( lhs, static_cast<unsigned long>( rhs ), testRhsSign( rhs ) );
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}
template<Operator Op> bool compare( unsigned char lhs, long rhs )
{
return applyEvaluator<Op>( lhs, static_cast<unsigned long>( rhs ), testRhsSign( rhs ) );
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}
// int to unsigned X
template<Operator Op> bool compare( int lhs, unsigned int rhs )
{
return applyEvaluator<Op>( static_cast<unsigned int>( lhs ), rhs, testLhsSign( lhs ) );
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}
template<Operator Op> bool compare( int lhs, unsigned long rhs )
{
return applyEvaluator<Op>( static_cast<unsigned int>( lhs ), rhs, testLhsSign( lhs ) );
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}
template<Operator Op> bool compare( int lhs, unsigned char rhs )
{
return applyEvaluator<Op>( static_cast<unsigned int>( lhs ), rhs, testLhsSign( lhs ) );
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}
// long to unsigned X
template<Operator Op> bool compare( long lhs, unsigned int rhs )
{
return applyEvaluator<Op>( static_cast<unsigned long>( lhs ), rhs, testLhsSign( lhs ) );
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}
template<Operator Op> bool compare( long lhs, unsigned long rhs )
{
return applyEvaluator<Op>( static_cast<unsigned long>( lhs ), rhs, testLhsSign( lhs ) );
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}
template<Operator Op> bool compare( long lhs, unsigned char rhs )
{
return applyEvaluator<Op>( static_cast<unsigned long>( lhs ), rhs, testLhsSign( lhs ) );
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}
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template<Operator Op, typename T>
bool compare( long lhs, const T* rhs )
{
return Evaluator<T*, T*, Op>::evaluate( reinterpret_cast<T*>( NULL ), rhs );
}
template<Operator Op, typename T>
bool compare( long lhs, T* rhs )
{
return Evaluator<T*, T*, Op>::evaluate( reinterpret_cast<T*>( lhs ), rhs );
}
} // end of namespace Internal
} // end of namespace Catch
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#endif // TWOBLUECUBES_CATCH_EVALUATE_HPP_INCLUDED