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Don't store right end of the interval in uniform_integer_distribution
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@ -46,12 +46,12 @@ class uniform_integer_distribution {
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using UnsignedIntegerType = Detail::make_unsigned_t<IntegerType>;
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// We store the left range bound converted to internal representation,
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// because it will be used in computation in the () operator.
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// Only the left bound is stored, and we store it converted to its
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// unsigned image. This avoids having to do the conversions inside
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// the operator(), at the cost of having to do the conversion in
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// the a() getter. The right bound is only needed in the b() getter,
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// so we recompute it there from other stored data.
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UnsignedIntegerType m_a;
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// After initialization, right bound is only used for the b() getter,
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// so we keep it in the original type.
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IntegerType m_b;
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// How many different values are there in [a, b]. a == b => 1, can be 0 for distribution over all values in the type.
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UnsignedIntegerType m_ab_distance;
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@ -64,11 +64,10 @@ class uniform_integer_distribution {
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// distribution will be reused many times and this is an optimization.
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UnsignedIntegerType m_rejection_threshold = 0;
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// Assumes m_b and m_a are already filled
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UnsignedIntegerType computeDistance() const {
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// This overflows and returns 0 if ua == 0 and ub == TYPE_MAX.
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UnsignedIntegerType computeDistance(IntegerType a, IntegerType b) const {
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// This overflows and returns 0 if a == 0 and b == TYPE_MAX.
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// We handle that later when generating the number.
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return transposeTo(m_b) - m_a + 1;
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return transposeTo(b) - transposeTo(a) + 1;
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}
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static UnsignedIntegerType computeRejectionThreshold(UnsignedIntegerType ab_distance) {
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@ -92,8 +91,7 @@ public:
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uniform_integer_distribution( IntegerType a, IntegerType b ):
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m_a( transposeTo(a) ),
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m_b( b ),
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m_ab_distance( computeDistance() ),
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m_ab_distance( computeDistance(a, b) ),
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m_rejection_threshold( computeRejectionThreshold(m_ab_distance) ) {
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assert( a <= b );
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}
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@ -118,7 +116,7 @@ public:
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}
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result_type a() const { return transposeBack(m_a); }
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result_type b() const { return m_b; }
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result_type b() const { return transposeBack(m_ab_distance + m_a - 1); }
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};
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} // end namespace Catch
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