silk/usize

Pointer-width unsigned integers for lengths, indices, capacities, and allocation sizes.

When to use

Use usize for values that index target memory or describe its layout. Use a fixed-width integer for serialized data, protocols, and persistent identifiers whose range must not change between 32-bit and 64-bit targets.

Details

BITS and MAX follow the selected target. Ordinary arithmetic, narrowing conversions, division by zero, and invalid shift counts trap. checked* returns Option, wrapping* computes modulo the target width, and saturating* clamps at MIN or MAX.

ZERO and ONE provide typed values where an uncontextualized literal would be i32. Decimal parse uses the target's range, while toText allocates owned text.

Gotchas

A value valid as usize on a 64-bit target can be out of range on a 32-bit target.

Examples

Keep a count within the target range

import silk.option as Option

import silk.usize as usize

pub fn main() -> i32 {
  let next = usize.checkedAdd(usize.MAX, usize.ONE)
  let recovered = move next
    |> Option.unwrapOr<usize>(42)
  return usize.toI32(recovered)
}

Import as usize with import silk.usize.

Public declarations: 59.

MAX

pub const MAX: usize

The largest usize value for the compilation target.

Details

This is 4294967295 on a 32-bit target and 18446744073709551615 on a 64-bit target. Checked arithmetic rejects results above it.

MIN

pub const MIN: usize

The smallest usize value, which is zero at each pointer width.

BITS

pub const BITS: u32

The width of usize in bits, which is the compilation target's pointer width.

ZERO

pub const ZERO: usize

The usize zero value for a count without a typed context.

ONE

pub const ONE: usize

The usize value one for a step or count that has no other type context.

toU8

pub fn toU8(value: usize) -> u8

Converts value to u8. Traps if value is outside the u8 range. Use this function when an out-of-range value is a program error.

checkedToU8

pub fn checkedToU8(value: usize) -> Option<u8>

Converts value to u8, or returns None if value is outside the u8 range. Use this function when an out-of-range value is input data.

toU16

pub fn toU16(value: usize) -> u16

Converts value to u16. Traps if value is outside the u16 range. Use this function when an out-of-range value is a program error.

checkedToU16

pub fn checkedToU16(value: usize) -> Option<u16>

Converts value to u16, or returns None if value is outside the u16 range. Use this function when an out-of-range value is input data.

toU32

pub fn toU32(value: usize) -> u32

Converts value to u32. Traps if value is outside the u32 range. Use this function when an out-of-range value is a program error.

checkedToU32

pub fn checkedToU32(value: usize) -> Option<u32>

Converts value to u32, or returns None if value is outside the u32 range. Use this function when an out-of-range value is input data.

toU64

pub fn toU64(value: usize) -> u64

Converts value exactly to u64. Every usize value is representable.

checkedToU64

pub fn checkedToU64(value: usize) -> Option<u64>

Converts value exactly to u64 and returns Some. Every usize value is representable.

toUsize

pub fn toUsize(value: usize) -> usize

Returns value unchanged as usize. Use this function when generic conversion code can select usize as both source and destination.

checkedToUsize

pub fn checkedToUsize(value: usize) -> Option<usize>

Returns Some with value unchanged as usize. Use this function when generic checked-conversion code can select the same source and destination type.

toI8

pub fn toI8(value: usize) -> i8

Converts value to i8. Traps if value is outside the i8 range. Use this function when an out-of-range value is a program error.

checkedToI8

pub fn checkedToI8(value: usize) -> Option<i8>

Converts value to i8, or returns None if value is outside the i8 range. Use this function when an out-of-range value is input data.

toI16

pub fn toI16(value: usize) -> i16

Converts value to i16. Traps if value is outside the i16 range. Use this function when an out-of-range value is a program error.

checkedToI16

pub fn checkedToI16(value: usize) -> Option<i16>

Converts value to i16, or returns None if value is outside the i16 range. Use this function when an out-of-range value is input data.

toI32

pub fn toI32(value: usize) -> i32

Converts value to i32. Traps if value is outside the i32 range. Use this function when an out-of-range value is a program error.

checkedToI32

pub fn checkedToI32(value: usize) -> Option<i32>

Converts value to i32, or returns None if value is outside the i32 range. Use this function when an out-of-range value is input data.

toI64

pub fn toI64(value: usize) -> i64

Converts value to i64. Traps if value is outside the i64 range. Use this function when an out-of-range value is a program error.

checkedToI64

pub fn checkedToI64(value: usize) -> Option<i64>

Converts value to i64, or returns None if value is outside the i64 range. Use this function when an out-of-range value is input data.

toIsize

pub fn toIsize(value: usize) -> isize

Converts value to isize. Traps if value is outside the isize range. Use this function when an out-of-range value is a program error.

checkedToIsize

pub fn checkedToIsize(value: usize) -> Option<isize>

Converts value to isize, or returns None if value is outside the isize range. Use this function when an out-of-range value is input data.

toF32

pub fn toF32(value: usize) -> f32

Converts value to the nearest f32 value, with ties to even.

toF64

pub fn toF64(value: usize) -> f64

Converts value to the nearest f64 value, with ties to even.

add

pub fn add(left: usize, right: usize) -> usize

Returns left + right and traps if the result is outside the usize range. Use this function when overflow is a program error.

subtract

pub fn subtract(left: usize, right: usize) -> usize

Returns left - right and traps if the result is outside the usize range. Use this function when overflow is a program error.

multiply

pub fn multiply(left: usize, right: usize) -> usize

Returns left * right and traps if the result is outside the usize range. Use this function when overflow is a program error.

divide

pub fn divide(left: usize, right: usize) -> usize

Returns left / right. Traps if right is zero. Use this function when a zero divisor is a program error.

remainder

pub fn remainder(left: usize, right: usize) -> usize

Returns the remainder of left / right. Traps if right is zero. Use this function when a zero divisor is a program error.

bitAnd

pub fn bitAnd(left: usize, right: usize) -> usize

Returns the bitwise AND of left and right.

bitOr

pub fn bitOr(left: usize, right: usize) -> usize

Returns the bitwise OR of left and right.

bitXor

pub fn bitXor(left: usize, right: usize) -> usize

Returns the bitwise exclusive OR of left and right.

bitNot

pub fn bitNot(value: usize) -> usize

Returns value with each bit inverted.

shiftLeft

pub fn shiftLeft(left: usize, right: usize) -> usize

Shifts left bits left by right positions. Traps if right is not less than BITS.

shiftRight

pub fn shiftRight(left: usize, right: usize) -> usize

Shifts left bits right by right positions and inserts zero bits. Traps if right is not less than BITS.

rotateLeft

pub fn rotateLeft(left: usize, right: usize) -> usize

Rotates the bits of left left by right positions.

rotateRight

pub fn rotateRight(left: usize, right: usize) -> usize

Rotates the bits of left right by right positions.

wrappingAdd

pub fn wrappingAdd(left: usize, right: usize) -> usize

Returns left + right, wrapped to the usize range. Use this function for deliberate modulo arithmetic.

wrappingSubtract

pub fn wrappingSubtract(left: usize, right: usize) -> usize

Returns left - right, wrapped to the usize range. Use this function for deliberate modulo arithmetic.

wrappingMultiply

pub fn wrappingMultiply(left: usize, right: usize) -> usize

Returns left * right, wrapped to the usize range. Use this function for deliberate modulo arithmetic.

saturatingAdd

pub fn saturatingAdd(left: usize, right: usize) -> usize

Returns left + right, clamped to MIN or MAX. Use this function when a boundary value is the required overflow result.

saturatingSubtract

pub fn saturatingSubtract(left: usize, right: usize) -> usize

Returns left - right, clamped to MIN or MAX. Use this function when a boundary value is the required overflow result.

saturatingMultiply

pub fn saturatingMultiply(left: usize, right: usize) -> usize

Returns left * right, clamped to MIN or MAX. Use this function when a boundary value is the required overflow result.

checkedAdd

pub fn checkedAdd(left: usize, right: usize) -> Option<usize>

Returns Some with left + right, or None if the result is outside the usize range. Use this function when overflow is input data.

checkedSubtract

pub fn checkedSubtract(left: usize, right: usize) -> Option<usize>

Returns Some with left - right, or None if the result is outside the usize range. Use this function when overflow is input data.

checkedMultiply

pub fn checkedMultiply(left: usize, right: usize) -> Option<usize>

Returns Some with left * right, or None if the result is outside the usize range. Use this function when overflow is input data.

checkedDivide

pub fn checkedDivide(left: usize, right: usize) -> Option<usize>

Returns Some with left / right, or None if right is zero. Use this function when a zero divisor is input data.

checkedRemainder

pub fn checkedRemainder(left: usize, right: usize) -> Option<usize>

Returns Some with the remainder, or None if right is zero. Use this function when a zero divisor is input data.

equals

pub fn equals(left: usize, right: usize) -> bool

Returns true when left and right are equal.

notEquals

pub fn notEquals(left: usize, right: usize) -> bool

Returns true when left and right are not equal.

lessThan

pub fn lessThan(left: usize, right: usize) -> bool

Returns true when left is less than right.

lessOrEqual

pub fn lessOrEqual(left: usize, right: usize) -> bool

Returns true when left is less than or equal to right.

greaterThan

pub fn greaterThan(left: usize, right: usize) -> bool

Returns true when left is greater than right.

greaterOrEqual

pub fn greaterOrEqual(left: usize, right: usize) -> bool

Returns true when left is greater than or equal to right.

toText

pub effect fn toText(value: usize) -> String ! OutOfMemoryError ? &mut Allocator

Renders the value as base-10 text in new owned storage. Allocation uses the required Allocator and can fail with OutOfMemoryError.

parse

pub fn parse(text: string) -> silk/result.Result<usize, silk/format.ParseError>

Reads the complete text as an unsigned decimal usize.

Details

A failure contains silk.format.NotANumber for empty text, a sign, a non-digit, or trailing bytes. It contains silk.format.OutOfRange outside the target's usize range.