Struct OneBasedUsize 

pub struct OneBasedUsize(/* private fields */);

Represents 1-based index of usize.

To describe configuration by humans, often 1-based index is easier than 0-based to understand. On the other hand, 0-based index is easier to use in the programming. Also, it’s quite hard to track if the index is 0-based or 1-based. OneBasedUsize provides ergonomics to handle user provided 1-baed index safely.

 // Creates from 1-based index
 let v = OneBasedUsize::from_one_based(5).unwrap();
 assert_eq!(v.as_zero_based(), 4);

 // Creates from 0-based index
 let v = OneBasedUsize::from_zero_based(0).unwrap();
 assert_eq!(v.as_one_based().get(), 1);

Implementations

impl OneBasedUsize

pub const BITS: u32 = 64u32

The size of this one-based integer type in bits.

This value is equal to usize::BITS.

pub const MIN: Self

The smallest value that can be represented by this one-based integer type, from_one_based(1).

pub const MAX: Self

The largest value that can be represented by this one-based integer type, equal to from_one_based(usize::MAX).

pub const fn from_one_based(v: usize) -> Option<Self>

Creates a one-based integer from 1-based index value. Returns None if the given index is zero.

Note you can define a constant easily given Option::unwrap() or Option::expect() are also const.

 const ONE_BASED_TEN: OneBasedUsize = OneBasedUsize::from_one_based(10).expect("10 is non zero");
assert_eq!(ONE_BASED_TEN.as_zero_based(), 9);

pub const unsafe fn from_one_based_unchecked(v: usize) -> Self

Creates a one-based integer from 1-based index value without check.

Safety

Input must be greater than zero.

pub const fn from_one_based_nonzero(v: NonZeroUsize) -> Self

Creates a one-based integer from non-zero 1-based index value.

Given the underlying value is guaranteed to be non-zero, this will always succeed.

pub const fn from_zero_based(v: usize) -> Option<Self>

Creates a one-based integer from 0-based index value. Returns None if the given index is MAX value, as that would cause overflow when converted to 1-based.

pub const unsafe fn from_zero_based_unchecked(v: usize) -> Self

Creates a one-based integer from 0-based index value without check.

Safety

This function results in undefined behavior when v == usize::MAX.

// This should cause undefined behavior
unsafe {
     OneBasedUsize::from_zero_based_unchecked(usize::MAX);
}

pub const fn as_zero_based(self) -> usize

Returns regular 0-based index.

pub const fn as_one_based(self) -> NonZeroUsize

Returns 1-based index.

pub const fn checked_add(self, other: usize) -> Option<Self>

Adds an unsigned integer to a one-based integer value. Checks for overflow and returns None on overflow.

let one = OneBasedUsize::from_zero_based(1).unwrap();
let two = OneBasedUsize::from_zero_based(2).unwrap();
let max = OneBasedUsize::MAX;

assert_eq!(Some(two), one.checked_add(1));
assert_eq!(None, max.checked_add(1));

pub const fn saturating_add(self, other: usize) -> Self

Adds an unsigned integer to a one-based integer value. Returns Self::MAX on overflow.

let one = OneBasedUsize::from_zero_based(1).unwrap();
let two = OneBasedUsize::from_zero_based(2).unwrap();
let max = OneBasedUsize::MAX;

assert_eq!(two, one.saturating_add(1));
assert_eq!(max, max.saturating_add(1));

Trait Implementations

impl Clone for OneBasedUsize

fn clone(&self) -> OneBasedUsize

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for OneBasedUsize

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for OneBasedUsize

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromStr for OneBasedUsize

type Err = ParseIntError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Ord for OneBasedUsize

fn cmp(&self, other: &OneBasedUsize) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for OneBasedUsize

fn eq(&self, other: &OneBasedUsize) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for OneBasedUsize

fn partial_cmp(&self, other: &OneBasedUsize) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl TryFrom<OneBasedU128> for OneBasedUsize

fn try_from(value: OneBasedU128) -> Result<Self, Self::Error>

Attempts to convert OneBasedU128 to OneBasedUsize.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedU16> for OneBasedUsize

fn try_from(value: OneBasedU16) -> Result<Self, Self::Error>

Attempts to convert OneBasedU16 to OneBasedUsize.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedU32> for OneBasedUsize

fn try_from(value: OneBasedU32) -> Result<Self, Self::Error>

Attempts to convert OneBasedU32 to OneBasedUsize.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedU64> for OneBasedUsize

fn try_from(value: OneBasedU64) -> Result<Self, Self::Error>

Attempts to convert OneBasedU64 to OneBasedUsize.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedU8> for OneBasedUsize

fn try_from(value: OneBasedU8) -> Result<Self, Self::Error>

Attempts to convert OneBasedU8 to OneBasedUsize.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedUsize> for OneBasedU128

fn try_from(value: OneBasedUsize) -> Result<Self, Self::Error>

Attempts to convert OneBasedUsize to OneBasedU128.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedUsize> for OneBasedU16

fn try_from(value: OneBasedUsize) -> Result<Self, Self::Error>

Attempts to convert OneBasedUsize to OneBasedU16.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedUsize> for OneBasedU32

fn try_from(value: OneBasedUsize) -> Result<Self, Self::Error>

Attempts to convert OneBasedUsize to OneBasedU32.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedUsize> for OneBasedU64

fn try_from(value: OneBasedUsize) -> Result<Self, Self::Error>

Attempts to convert OneBasedUsize to OneBasedU64.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl TryFrom<OneBasedUsize> for OneBasedU8

fn try_from(value: OneBasedUsize) -> Result<Self, Self::Error>

Attempts to convert OneBasedUsize to OneBasedU8.

type Error = TryFromIntError

The type returned in the event of a conversion error.

impl Copy for OneBasedUsize

impl Eq for OneBasedUsize

impl StructuralPartialEq for OneBasedUsize