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Struct std.checkedint.WithNaN

Hook that reserves a special value as a "Not a Number" representative. For signed integrals, the reserved value is T.min. For signed integrals, the reserved value is T.max.

struct WithNaN ;

The default value of a Checked!(X, WithNaN) is its NaN value, so care must be taken that all variables are explicitly initialized. Any arithmetic and logic operation involving at least on NaN becomes NaN itself. All of a == b, a < b, a > b, a <= b, a >= b yield false if at least one of a and b is NaN.

Methods

NameDescription
hookOpBinary (lhs, rhs) Defines hooks for binary operators +, -, *, /, %, ^^, &, |, ^, <<, >>, and >>> for cases where a Checked object is the left-hand side operand. If lhs == WithNaN.defaultValue!Lhs, returns WithNaN.defaultValue!(typeof(lhs + rhs)) without evaluating the operand. Otherwise, evaluates the operand. If evaluation does not overflow, returns the result. Otherwise, returns WithNaN.defaultValue!(typeof(lhs + rhs)).
hookOpBinaryRight (lhs, rhs) Defines hooks for binary operators +, -, *, /, %, ^^, &, |, ^, <<, >>, and >>> for cases where a Checked object is the right-hand side operand. If rhs == WithNaN.defaultValue!Rhs, returns WithNaN.defaultValue!(typeof(lhs + rhs)) without evaluating the operand. Otherwise, evaluates the operand. If evaluation does not overflow, returns the result. Otherwise, returns WithNaN.defaultValue!(typeof(lhs + rhs)).
hookOpCast (rhs) If rhs is WithNaN.defaultValue!Rhs, returns WithNaN.defaultValue!Lhs. Otherwise, returns cast(Lhs) rhs.
hookOpCmp (lhs, rhs) If lhs == WithNaN.defaultValue!Lhs, returns double.init. Otherwise, has the same semantics as the default comparison.
hookOpEquals (lhs, rhs) Returns false if lhs == WithNaN.defaultValue!Lhs, lhs == rhs otherwise.
hookOpOpAssign (lhs, rhs) Defines hooks for binary operators +=, -=, *=, /=, %=, ^^=, &=, |=, ^=, <<=, >>=, and >>>= for cases where a Checked object is the left-hand side operand. If lhs == WithNaN.defaultValue!Lhs, no action is carried. Otherwise, evaluates the operand. If evaluation does not overflow and fits in Lhs without loss of information or change of sign, sets lhs to the result. Otherwise, sets lhs to WithNaN.defaultValue!Lhs.
hookOpUnary (v) Defines hooks for unary operators -, ~, ++, and --.

Example

auto x1 = Checked!(int, WithNaN)();
assert(x1.isNaN);
writeln(x1.get); // int.min
assert(x1 != x1);
assert(!(x1 < x1));
assert(!(x1 > x1));
assert(!(x1 == x1));
++x1;
assert(x1.isNaN);
writeln(x1.get); // int.min
--x1;
assert(x1.isNaN);
writeln(x1.get); // int.min
x1 = 42;
assert(!x1.isNaN);
writeln(x1); // x1
assert(x1 <= x1);
assert(x1 >= x1);
static assert(x1.min == int.min + 1);
x1 += long(int.max);

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