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fix min/max variadic fold #1

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fix min/max variadic fold #1

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8 changes: 4 additions & 4 deletions src/stdfunctions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,16 +15,16 @@ float sign( float x )
template <typename... Args>
float minv( float arg0, Args... args )
{
float r;
( ( r = std::min( arg0, args ) ), ... );
float r = arg0;
( ( r = std::min( r, args ) ), ... );
return r;
}

template <typename... Args>
float maxv( float arg0, Args... args )
{
float r;
( ( r = std::max( arg0, args ) ), ... );
float r = arg0;
( ( r = std::max( r, args ) ), ... );
return r;
}

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21 changes: 21 additions & 0 deletions tests/functions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -191,3 +191,24 @@ TEST( Functions, CanUseStandardFunctions )
ASSERT_EQ( 1, TestEval( "cos(0)" ) );
ASSERT_EQ( 3, TestEval( "max(1, 2, 3)" ) );
}

TEST( Functions, MinMaxFoldThroughAccumulator )
{
// Smallest/largest is neither the first nor the last argument: a
// buggy fold that compares each tail element against arg0 (rather
// than folding through the running result) would return the wrong
// answer here.
ASSERT_EQ( 3, TestEval( "min(5, 3, 7)" ) );
ASSERT_EQ( 9, TestEval( "max(1, 9, 4)" ) );
ASSERT_EQ( 1, TestEval( "min(5, 1, 5, 5, 5)" ) );
ASSERT_EQ( 9, TestEval( "max(2, 9, 2, 2, 2)" ) );
}

TEST( Functions, MinMaxSingleArgument )
{
// One-arg form: a fold over an empty parameter pack must still
// produce a defined result equal to that single argument.
ASSERT_EQ( 7, TestEval( "min(7)" ) );
ASSERT_EQ( 7, TestEval( "max(7)" ) );
ASSERT_EQ( -3, TestEval( "min(-3)" ) );
}