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Added special case logic for signed/ unsigned comparisons involving negative numbers and added test cases to cover them

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This commit is contained in:
Phil Nash 2011-03-15 22:22:19 +00:00
parent cc0ed3a988
commit f6758c2967
3 changed files with 115 additions and 23 deletions
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33
Test/ConditionTests.cpp
View File

@ -180,6 +180,39 @@ TEST_CASE( "./succeeding/conditions/int literals", "Comparisons with int literal
REQUIRE( 62270208023445 > ul );
}
// Because we have to do some conversions when comparing certain signed/ unsigned types (to avoid
// spurious warnings when comparing integer literals with unsigned integers), we have a set of tests
// here to confirm that the behaviour is correct at the boundaries
TEST_CASE( "./succeeding/conditions/unsigned-negative", "Comparisons between negative signed and unsigned ints, expected to succeed" )
{
using namespace Catch::Generators;
int negative = GENERATE( values( -1, -2, (std::numeric_limits<int>::min)() ) );
unsigned int ui = GENERATE( values( 0u, 1u, 2u, (std::numeric_limits<unsigned int>::max)() ) );
CHECK( ui > negative );
CHECK( negative < ui );
CHECK( ui >= negative );
CHECK( negative <= ui );
CHECK( ui != negative );
CHECK( negative != ui );
}
TEST_CASE( "./failing/conditions/unsigned-negative", "Comparisons between negative signed and unsigned ints, expected to fail" )
{
using namespace Catch::Generators;
int negative = GENERATE( values( -1, -2, (std::numeric_limits<int>::min)() ) );
unsigned int ui = GENERATE( values( 0u, 1u, 2u, (std::numeric_limits<unsigned int>::max)() ) );
CHECK( ui < negative );
CHECK( negative > ui );
CHECK( ui <= negative );
CHECK( negative >= ui );
CHECK( ui == negative );
CHECK( negative == ui );
}
// Not (!) tests
// The problem with the ! operator is that it has right-to-left associativity.
// This means we can't isolate it when we decompose. The simple REQUIRE( !false ) form, therefore,

18
internal/catch_capture.hpp
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@ -242,17 +242,17 @@ private:
}
///////////////////////////////////////////////////////////////////////////
template<Operator Op, typename T1, typename T2>
template<Internal::Operator Op, typename T1, typename T2>
MutableResultInfo& captureExpression
(
const T1& lhs,
const T2& rhs
)
{
setResultType( compare<Op>( lhs, rhs ) ? ResultWas::Ok : ResultWas::ExpressionFailed );
setResultType( Internal::compare<Op>( lhs, rhs ) ? ResultWas::Ok : ResultWas::ExpressionFailed );
m_lhs = toString( lhs );
m_rhs = toString( rhs );
m_op = OperatorTraits<Op>::getName();
m_op = Internal::OperatorTraits<Op>::getName();
return *this;
}
@ -282,7 +282,7 @@ public:
const RhsT& rhs
)
{
return m_result.captureExpression<IsEqualTo>( m_lhs, rhs );
return m_result.captureExpression<Internal::IsEqualTo>( m_lhs, rhs );
}
///////////////////////////////////////////////////////////////////////////
@ -292,7 +292,7 @@ public:
const RhsT& rhs
)
{
return m_result.captureExpression<IsNotEqualTo>( m_lhs, rhs );
return m_result.captureExpression<Internal::IsNotEqualTo>( m_lhs, rhs );
}
///////////////////////////////////////////////////////////////////////////
@ -302,7 +302,7 @@ public:
const RhsT& rhs
)
{
return m_result.captureExpression<IsLessThan>( m_lhs, rhs );
return m_result.captureExpression<Internal::IsLessThan>( m_lhs, rhs );
}
///////////////////////////////////////////////////////////////////////////
@ -312,7 +312,7 @@ public:
const RhsT& rhs
)
{
return m_result.captureExpression<IsGreaterThan>( m_lhs, rhs );
return m_result.captureExpression<Internal::IsGreaterThan>( m_lhs, rhs );
}
///////////////////////////////////////////////////////////////////////////
@ -322,7 +322,7 @@ public:
const RhsT& rhs
)
{
return m_result.captureExpression<IsLessThanOrEqualTo>( m_lhs, rhs );
return m_result.captureExpression<Internal::IsLessThanOrEqualTo>( m_lhs, rhs );
}
///////////////////////////////////////////////////////////////////////////
@ -332,7 +332,7 @@ public:
const RhsT& rhs
)
{
return m_result.captureExpression<IsGreaterThanOrEqualTo>( m_lhs, rhs );
return m_result.captureExpression<Internal::IsGreaterThanOrEqualTo>( m_lhs, rhs );
}
///////////////////////////////////////////////////////////////////////////

87
internal/catch_evaluate.hpp
View File

@ -14,6 +14,8 @@
#define TWOBLUECUBES_CATCH_EVALUATE_HPP_INCLUDED
namespace Catch
{
namespace Internal
{
enum Operator
{
@ -46,13 +48,32 @@ namespace Catch
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.
template<typename T1, typename T2, Operator Op>
class Evaluator{};
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsEqualTo>
{
static bool evaluate( const T1& lhs, const T2& rhs )
enum{ failsWhen = LhsSignWasLost | RhsSignWasLost };
static bool evaluate( const T1& lhs, const T2& rhs)
{
return lhs == rhs;
}
@ -60,6 +81,8 @@ namespace Catch
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsNotEqualTo>
{
enum{ failsWhen = None };
static bool evaluate( const T1& lhs, const T2& rhs )
{
return lhs != rhs;
@ -68,6 +91,8 @@ namespace Catch
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsLessThan>
{
enum{ failsWhen = RhsSignWasLost };
static bool evaluate( const T1& lhs, const T2& rhs )
{
return lhs < rhs;
@ -76,6 +101,8 @@ namespace Catch
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsGreaterThan>
{
enum{ failsWhen = LhsSignWasLost };
static bool evaluate( const T1& lhs, const T2& rhs )
{
return lhs > rhs;
@ -84,6 +111,8 @@ namespace Catch
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsGreaterThanOrEqualTo>
{
enum{ failsWhen = LhsSignWasLost };
static bool evaluate( const T1& lhs, const T2& rhs )
{
return lhs >= rhs;
@ -92,12 +121,40 @@ namespace Catch
template<typename T1, typename T2>
struct Evaluator<T1, T2, IsLessThanOrEqualTo>
{
enum{ failsWhen = RhsSignWasLost };
static bool evaluate( const T1& lhs, const T2& rhs )
{
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
template<Operator Op, typename T1, typename T2>
bool compare( const T1& lhs, const T2& rhs )
{
@ -107,58 +164,60 @@ namespace Catch
// unsigned X to int
template<Operator Op> bool compare( unsigned int lhs, int rhs )
{
return Evaluator<unsigned int, unsigned int, Op>::evaluate( lhs, static_cast<unsigned int>( rhs ) );
return applyEvaluator<Op>( lhs, static_cast<unsigned int>( rhs ), testRhsSign( rhs ) );
}
template<Operator Op> bool compare( unsigned long lhs, int rhs )
{
return Evaluator<unsigned long, unsigned int, Op>::evaluate( lhs, static_cast<unsigned int>( rhs ) );
return applyEvaluator<Op>( lhs, static_cast<unsigned int>( rhs ), testRhsSign( rhs ) );
}
template<Operator Op> bool compare( unsigned char lhs, int rhs )
{
return Evaluator<unsigned char, unsigned int, Op>::evaluate( lhs, static_cast<unsigned int>( rhs ) );
return applyEvaluator<Op>( lhs, static_cast<unsigned int>( rhs ), testRhsSign( rhs ) );
}
// unsigned X to long
template<Operator Op> bool compare( unsigned int lhs, long rhs )
{
return Evaluator<unsigned int, unsigned long, Op>::evaluate( lhs, static_cast<unsigned long>( rhs ) );
return applyEvaluator<Op>( lhs, static_cast<unsigned long>( rhs ), testRhsSign( rhs ) );
}
template<Operator Op> bool compare( unsigned long lhs, long rhs )
{
return Evaluator<unsigned long, unsigned long, Op>::evaluate( lhs, static_cast<unsigned long>( rhs ) );
return applyEvaluator<Op>( lhs, static_cast<unsigned long>( rhs ), testRhsSign( rhs ) );
}
template<Operator Op> bool compare( unsigned char lhs, long rhs )
{
return Evaluator<unsigned char, unsigned long, Op>::evaluate( lhs, static_cast<unsigned long>( rhs ) );
return applyEvaluator<Op>( lhs, static_cast<unsigned long>( rhs ), testRhsSign( rhs ) );
}
// int to unsigned X
template<Operator Op> bool compare( int lhs, unsigned int rhs )
{
return Evaluator<unsigned int, unsigned int, Op>::evaluate( static_cast<unsigned int>( lhs ), rhs );
return applyEvaluator<Op>( static_cast<unsigned int>( lhs ), rhs, testLhsSign( lhs ) );
}
template<Operator Op> bool compare( int lhs, unsigned long rhs )
{
return Evaluator<unsigned int, unsigned long, Op>::evaluate( static_cast<unsigned int>( lhs ), rhs );
return applyEvaluator<Op>( static_cast<unsigned int>( lhs ), rhs, testLhsSign( lhs ) );
}
template<Operator Op> bool compare( int lhs, unsigned char rhs )
{
return Evaluator<unsigned int, unsigned char, Op>::evaluate( static_cast<unsigned int>( lhs ), rhs );
return applyEvaluator<Op>( static_cast<unsigned int>( lhs ), rhs, testLhsSign( lhs ) );
}
// long to unsigned X
template<Operator Op> bool compare( long lhs, unsigned int rhs )
{
return Evaluator<unsigned long, unsigned int, Op>::evaluate( static_cast<unsigned long>( lhs ), rhs );
return applyEvaluator<Op>( static_cast<unsigned long>( lhs ), rhs, testLhsSign( lhs ) );
}
template<Operator Op> bool compare( long lhs, unsigned long rhs )
{
return Evaluator<unsigned long, unsigned long, Op>::evaluate( static_cast<unsigned long>( lhs ), rhs );
return applyEvaluator<Op>( static_cast<unsigned long>( lhs ), rhs, testLhsSign( lhs ) );
}
template<Operator Op> bool compare( long lhs, unsigned char rhs )
{
return Evaluator<unsigned long, unsigned char, Op>::evaluate( static_cast<unsigned long>( lhs ), rhs );
return applyEvaluator<Op>( static_cast<unsigned long>( lhs ), rhs, testLhsSign( lhs ) );
}
}
} // end of namespace Internal
} // end of namespace Catch
#endif // TWOBLUECUBES_CATCH_EVALUATE_HPP_INCLUDED