Checked

Checked integral type wraps an integral T and customizes its behavior with the help of a Hook type. The type wrapped must be one of the predefined integrals (unqualified), or another instance of Checked.

struct Checked (

Hook = Abort

) if (

isIntegral!T ||

is(T == Checked!(U, H),

)

) {

template among(values...) via import std.algorithm.comparison : among;;

template stateSize(T) via import std.experimental.allocator.common : stateSize;;

struct FormatSpec(Char) via import std.format.spec : FormatSpec;;

enum bool isInputRange(R, E); via import std.range.primitives : isInputRange, ElementType;;

template ElementType(R) via import std.range.primitives : isInputRange, ElementType;;

eponymoustemplate hasMember(T, string name) via import std.traits : hasMember, isSomeChar;;

template isSomeChar(T) via import std.traits : hasMember, isSomeChar;;

alias Representation = T;

static if(stateSize!Hook > 0)

Hook hook;

auto get();

static if(hasMember!(Hook, "min"))

enum Checked!(T, Hook) min;

static if(!(hasMember!(Hook, "min")))

enum Checked!(T, Hook) min;

static if(hasMember!(Hook, "max"))

enum Checked!(T, Hook) max;

static if(!(hasMember!(Hook, "max")))

enum Checked!(T, Hook) max;

this(U rhs);

Checked opAssign(U rhs);

this(Range str);

U opCast();

bool opEquals(U rhs);

size_t toHash();

void toString(Writer sink, FormatSpec!Char fmt);

auto opCmp(U rhs);

auto opCmp(Checked!(U, Hook1) rhs);

auto opUnary();

Checked opUnary();

auto opBinary(Rhs rhs);

auto opBinary(Checked!(U, Hook1) rhs);

auto opBinaryRight(Lhs lhs);

Checked opOpAssign(Rhs rhs);

}

Constructors

this this(U rhs): Constructor taking a value properly convertible to the underlying type. U may be either an integral that can be converted to T without a loss, or another Checked instance whose representation may be in turn converted to T without a loss.
this this(Range str): Construct from a decimal string. The conversion follows the same rules as std.conv.to converting a string to the wrapped T type.

Members

Aliases

Representation alias Representation = T: The type of the integral subject to checking.

Functions

get auto get()
opAssign Checked opAssign(U rhs): Assignment operator. Has the same constraints as the constructor.
opBinary auto opBinary(Rhs rhs)
auto opBinary(Checked!(U, Hook1) rhs): Defines binary operators +, -, *, /, %, ^^, &, |, ^, <<, >>, and >>>. If Hook defines hookOpBinary, opBinary forwards to Checked!(typeof(hook.hookOpBinary!op(get, rhs)), Hook)(hook.hookOpBinary!op(get, rhs)).
opBinaryRight auto opBinaryRight(Lhs lhs): Defines binary operators +, -, *, /, %, ^^, &, |, ^, <<, >>, and >>> for the case when a built-in numeric or Boolean type is on the left-hand side, and a Checked instance is on the right-hand side.
opCast U opCast(): Casting operator to integral, bool, or floating point type.
opCmp auto opCmp(U rhs)
auto opCmp(Checked!(U, Hook1) rhs): Compares this against rhs for ordering. If Hook defines hookOpCmp, the function forwards to hook.hookOpCmp(get, rhs). Otherwise, the result of the built-in comparison operation is returned.
opEquals bool opEquals(U rhs): Compares this against rhs for equality.
opOpAssign Checked opOpAssign(Rhs rhs): Defines operators +=, -=, *=, /=, %=, ^^=, &=, |=, ^=, <<=, >>=, and >>>=.
opUnary auto opUnary()
Checked opUnary(): Defines unary operators +, -, ~, ++, and --. Unary + is not overridable and always has built-in behavior (returns this). For the others, if Hook defines hookOpUnary, opUnary forwards to Checked!(typeof(hook.hookOpUnary!op(get)), Hook)(hook.hookOpUnary!op(get)).
toHash size_t toHash(): Generates a hash for this. If Hook defines hookToHash, the call immediately returns hook.hookToHash(payload). If Hook does not implement hookToHash, but it has state, a hash will be generated for the Hook using the built-in function and it will be xored with the hash of the payload.
toString void toString(Writer sink, FormatSpec!Char fmt): Writes a string representation of this to a sink.

Variables

hook Hook hook;: hook is a member variable if it has state, or an alias for Hook otherwise.
max enum Checked!(T, Hook) max;: Defines the minimum and maximum. These values are hookable by defining Hook.min and/or Hook.max.
min enum Checked!(T, Hook) min;: Defines the minimum and maximum. These values are hookable by defining Hook.min and/or Hook.max.

Parameters

T: type that is wrapped in the Checked type
Hook: hook type that customizes the behavior of the Checked type

Examples

// Hook that ignores all problems.
static struct Ignore
{
    @nogc nothrow pure @safe static:
    Dst onBadCast(Dst, Src)(Src src) { return cast(Dst) src; }
    Lhs onLowerBound(Rhs, T)(Rhs rhs, T bound) { return cast(T) rhs; }
    T onUpperBound(Rhs, T)(Rhs rhs, T bound) { return cast(T) rhs; }
    bool hookOpEquals(Lhs, Rhs)(Lhs lhs, Rhs rhs) { return lhs == rhs; }
    int hookOpCmp(Lhs, Rhs)(Lhs lhs, Rhs rhs) { return (lhs > rhs) - (lhs < rhs); }
    typeof(~Lhs()) onOverflow(string x, Lhs)(ref Lhs lhs) { return mixin(x ~ "lhs"); }
    typeof(Lhs() + Rhs()) onOverflow(string x, Lhs, Rhs)(Lhs lhs, Rhs rhs)
    {
        static if (x == "/")
            return typeof(lhs / rhs).min;
        else
            return mixin("lhs" ~ x ~ "rhs");
    }
}

auto x = Checked!(int, Ignore)(5) + 7;

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