The OpenD Programming Language

opChecked

std checkedint

Defines binary operations with overflow checking for any two integral types. The result type obeys the language rules (even when they may be counterintuitive), and overflow is set if an overflow occurs (including inadvertent change of signedness, e.g. -1 is converted to uint). Conceptually the behavior is:

  1. Perform the operation in infinite precision
  2. If the infinite-precision result fits in the result type, return it and do not touch overflow
  3. Otherwise, set overflow to true and return an unspecified value

The implementation exploits properties of types and operations to minimize additional work.

typeof(mixin (x == "cmp" ? "0" : ("L() " ~ x ~ " R()")))
opChecked
(
string x
L
R
)
(
const L lhs
,
const R rhs
,
ref bool overflow
)
if (
isIntegral!L &&
isIntegral!R
)

Parameters

x

The binary operator involved, e.g. /

lhs L

The left-hand side of the operator

rhs R

The right-hand side of the operator

overflow bool

The overflow indicator (assigned true in case there's an error)

Return Value

Type: typeof(mixin (x == "cmp" ? "0" : ("L() " ~ x ~ " R()")))

The result of the operation, which is the same as the built-in operator

Examples

bool overflow;
assert(opChecked!"+"(const short(1), short(1), overflow) == 2 && !overflow);
assert(opChecked!"+"(1, 1, overflow) == 2 && !overflow);
assert(opChecked!"+"(1, 1u, overflow) == 2 && !overflow);
assert(opChecked!"+"(-1, 1u, overflow) == 0 && !overflow);
assert(opChecked!"+"(1u, -1, overflow) == 0 && !overflow);
bool overflow;
assert(opChecked!"-"(1, 1, overflow) == 0 && !overflow);
assert(opChecked!"-"(1, 1u, overflow) == 0 && !overflow);
assert(opChecked!"-"(1u, -1, overflow) == 2 && !overflow);
assert(opChecked!"-"(-1, 1u, overflow) == 0 && overflow);

Meta

Source

See Implementation

std checkedint functionsstructs
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