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feat(corelib): OptionTrait boolean operators #6936

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merged 4 commits into from
Dec 28, 2024
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feat(corelib): OptionTrait boolean operators #6936

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6744e5f
feat(corelib): OptionTrait::ok_or_else (#6930)
julio4 Dec 26, 2024
359dee9
feat(corelib): OptionTrait boolean operators
julio4 Dec 26, 2024
643df42
Merge branch 'main' into feat/option_boolean_operators
julio4 Dec 26, 2024
741b9a9
Merge branch 'main' into feat/option_boolean_operators
julio4 Dec 27, 2024
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215 changes: 215 additions & 0 deletions corelib/src/option.cairo
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,52 @@
//! [`None`] values unchanged
//!
//! [`map`]: OptionTrait::map
//!
//! ## Boolean operators
//!
//! These methods treat the [`Option`] as a boolean value, where [`Some`]
//! acts like [`true`] and [`None`] acts like [`false`]. There are two
//! categories of these methods: ones that take an [`Option`] as input, and
//! ones that take a function as input (to be lazily evaluated).
//!
//! The [`and`], [`or`], and [`xor`] methods take another [`Option`] as
//! input, and produce an [`Option`] as output. Only the [`and`] method can
//! produce an [`Option<U>`] value having a different inner type `U` than
//! [`Option<T>`].
//!
//! | method | self | input | output |
//! |---------|-----------|-----------|-----------|
//! | [`and`] | `None` | (ignored) | `None` |
//! | [`and`] | `Some(x)` | `None` | `None` |
//! | [`and`] | `Some(x)` | `Some(y)` | `Some(y)` |
//! | [`or`] | `None` | `None` | `None` |
//! | [`or`] | `None` | `Some(y)` | `Some(y)` |
//! | [`or`] | `Some(x)` | (ignored) | `Some(x)` |
//! | [`xor`] | `None` | `None` | `None` |
//! | [`xor`] | `None` | `Some(y)` | `Some(y)` |
//! | [`xor`] | `Some(x)` | `None` | `Some(x)` |
//! | [`xor`] | `Some(x)` | `Some(y)` | `None` |
//!
//! [`and`]: OptionTrait::and
//! [`or`]: OptionTrait::or
//! [`xor`]: OptionTrait::xor
//!
//! The [`and_then`] and [`or_else`] methods take a function as input, and
//! only evaluate the function when they need to produce a new value. Only
//! the [`and_then`] method can produce an [`Option<U>`] value having a
//! different inner type `U` than [`Option<T>`].
//!
//! | method | self | function input | function result | output |
//! |--------------|-----------|----------------|-----------------|-----------|
//! | [`and_then`] | `None` | (not provided) | (not evaluated) | `None` |
//! | [`and_then`] | `Some(x)` | `x` | `None` | `None` |
//! | [`and_then`] | `Some(x)` | `x` | `Some(y)` | `Some(y)` |
//! | [`or_else`] | `None` | (not provided) | `None` | `None` |
//! | [`or_else`] | `None` | (not provided) | `Some(y)` | `Some(y)` |
//! | [`or_else`] | `Some(x)` | (not provided) | (not evaluated) | `Some(x)` |
//!
//! [`and_then`]: OptionTrait::and_then
//! [`or_else`]: OptionTrait::or_else

/// The `Option<T>` enum representing either `Some(value)` or `None`.
#[must_use]
Expand Down Expand Up @@ -216,6 +262,130 @@ pub trait OptionTrait<T> {
self: Option<T>, err: F,
) -> Result<T, E>;

/// Returns [`None`] if the option is [`None`], otherwise returns `optb`.
///
/// Arguments passed to `and` are eagerly evaluated; if you are passing the
/// result of a function call, it is recommended to use [`and_then`], which is
/// lazily evaluated.
///
/// [`and_then`]: OptionTrait::and_then
///
/// # Examples
///
/// ```
/// let x = Option::Some(2);
/// let y: Option<ByteArray> = Option::None;
/// assert_eq!(x.and(y), Option::None);
///
/// let x: Option<u32> = Option::None;
/// let y: Option<ByteArray> = Option::Some("foo");
/// assert_eq!(x.and(y), Option::None);
///
/// let x = Option::Some(2);
/// let y: Option<ByteArray> = Option::Some("foo");
/// assert_eq!(x.and(y), Option::Some("foo"));
///
/// let x: Option<u32> = Option::None;
/// let y: Option<ByteArray> = Option::None;
/// assert_eq!(x.and(y), Option::None);
/// ```
fn and<U, +Drop<T>, +Drop<U>>(self: Option<T>, optb: Option<U>) -> Option<U>;

/// Returns [`None`] if the option is [`None`], otherwise calls `f` with the
/// wrapped value and returns the result.
///
/// Some languages call this operation flatmap.
///
/// # Examples
///
/// ```
/// use core::num::traits::CheckedMul;
///
/// let option: Option<ByteArray> = checked_mul(2_u32, 2_u32)
/// .and_then(|v| Option::Some(format!("{}", v)));
/// assert_eq!(option, Option::Some("4"));
///
/// let option: Option<ByteArray> = checked_mul(65536_u32, 65536_u32)
/// .and_then(|v| Option::Some(format!("{}", v)));
/// assert_eq!(option, Option::None); // overflowed!
///
/// let option: Option<ByteArray> = Option::<u32>::None
/// .and_then(|v| Option::Some(format!("{}", v)));
/// assert_eq!(option, Option::None);
/// ```
fn and_then<U, F, +Drop<F>, +core::ops::FnOnce<F, (T,)>[Output: Option<U>]>(
self: Option<T>, f: F,
) -> Option<U>;

/// Returns the option if it contains a value, otherwise returns `optb`.
///
/// Arguments passed to `or` are eagerly evaluated; if you are passing the
/// result of a function call, it is recommended to use [`or_else`], which is
/// lazily evaluated.
///
/// [`or_else`]: OptionTrait::or_else
///
/// # Examples
///
/// ```
/// let x = Option::Some(2);
/// let y = Option::None;
/// assert_eq!(x.or(y), Option::Some(2));
///
/// let x = Option::None;
/// let y = Option::Some(100);
/// assert_eq!(x.or(y), Option::Some(100));
///
/// let x = Option::Some(2);
/// let y = Option::Some(100);
/// assert_eq!(x.or(y), Option::Some(2));
///
/// let x: Option<u32> = Option::None;
/// let y = Option::None;
/// assert_eq!(x.or(y), Option::None);
/// ```
fn or<+Drop<T>>(self: Option<T>, optb: Option<T>) -> Option<T>;

/// Returns the option if it contains a value, otherwise calls `f` and
/// returns the result.
///
/// # Examples
///
/// ```
/// let nobody = || Option::<ByteArray>::None;
/// let vikings = || Option::<ByteArray>::Some("vikings");
///
/// assert_eq!(Option::Some("barbarians").or_else(vikings), Option::Some("barbarians"));
/// assert_eq!(Option::None.or_else(vikings), Option::Some("vikings"));
/// assert_eq!(Option::None.or_else(nobody), Option::None);
/// ```
fn or_else<F, +Drop<F>, +core::ops::FnOnce<F, ()>[Output: Option<T>]>(
self: Option<T>, f: F,
) -> Option<T>;

/// Returns [`Some`] if exactly one of `self`, `optb` is [`Some`], otherwise returns [`None`].
///
/// # Examples
///
/// ```
/// let x = Option::Some(2);
/// let y: Option<u32> = Option::None;
/// assert_eq!(x.xor(y), Option::Some(2));
///
/// let x: Option<u32> = Option::None;
/// let y = Option::Some(2);
/// assert_eq!(x.xor(y), Option::Some(2));
///
/// let x = Option::Some(2);
/// let y = Option::Some(2);
/// assert_eq!(x.xor(y), Option::None);
///
/// let x: Option<u32> = Option::None;
/// let y: Option<u32> = Option::None;
/// assert_eq!(x.xor(y), Option::None);
/// ```
fn xor<+Drop<T>>(self: Option<T>, optb: Option<T>) -> Option<T>;

/// Returns `true` if the `Option` is `Option::Some`, `false` otherwise.
///
/// # Examples
Expand Down Expand Up @@ -370,6 +540,51 @@ pub impl OptionTraitImpl<T> of OptionTrait<T> {
}
}

#[inline]
fn and<U, +Drop<T>, +Drop<U>>(self: Option<T>, optb: Option<U>) -> Option<U> {
match self {
Option::Some(_) => optb,
Option::None => Option::None,
}
}

#[inline]
fn and_then<U, F, +Drop<F>, +core::ops::FnOnce<F, (T,)>[Output: Option<U>]>(
self: Option<T>, f: F,
) -> Option<U> {
match self {
Option::Some(x) => f(x),
Option::None => Option::None,
}
}

#[inline]
fn or<+Drop<T>>(self: Option<T>, optb: Option<T>) -> Option<T> {
match self {
Option::Some(x) => Option::Some(x),
Option::None => optb,
}
}

#[inline]
fn or_else<F, +Drop<F>, +core::ops::FnOnce<F, ()>[Output: Option<T>]>(
self: Option<T>, f: F,
) -> Option<T> {
match self {
Option::Some(x) => Option::Some(x),
Option::None => f(),
}
}

#[inline]
fn xor<+Drop<T>>(self: Option<T>, optb: Option<T>) -> Option<T> {
match (self, optb) {
(Option::Some(x), Option::None) => Option::Some(x),
(Option::None, Option::Some(x)) => Option::Some(x),
_ => Option::None,
}
}

#[inline]
fn is_some(self: @Option<T>) -> bool {
match self {
Expand Down
82 changes: 82 additions & 0 deletions corelib/src/test/option_test.cairo
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,88 @@ fn test_option_none_ok_or_else() {
assert_eq!(option.ok_or_else( || 0), Result::Err(0));
}

#[test]
fn test_option_and() {
let x = Option::Some(2);
let y: Option<ByteArray> = Option::None;
assert_eq!(x.and(y), Option::None);

let x: Option<u32> = Option::None;
let y: Option<ByteArray> = Option::Some("foo");
assert_eq!(x.and(y), Option::None);

let x = Option::Some(2);
let y: Option<ByteArray> = Option::Some("foo");
assert_eq!(x.and(y), Option::Some("foo"));

let x: Option<u32> = Option::None;
let y: Option<ByteArray> = Option::None;
assert_eq!(x.and(y), Option::None);
}

#[test]
fn test_option_and_then() {
let checked_mul = core::num::traits::CheckedMul::checked_mul(2_u32, 2_u32);
let option: Option<ByteArray> = checked_mul.and_then(|v| Option::Some(format!("{}", v)));
assert_eq!(option, Option::Some("4"));

let checked_mul = core::num::traits::CheckedMul::checked_mul(65536_u32, 65536_u32);
let option: Option<ByteArray> = checked_mul.and_then(|v| Option::Some(format!("{}", v)));
assert_eq!(option, Option::None); // overflowed!

let option: Option<ByteArray> = Option::<u32>::None
.and_then(|v| Option::Some(format!("{}", v)));
assert_eq!(option, Option::None);
}

#[test]
fn test_option_or() {
let x = Option::Some(2);
let y = Option::None;
assert_eq!(x.or(y), Option::Some(2));

let x = Option::None;
let y = Option::Some(100);
assert_eq!(x.or(y), Option::Some(100));

let x = Option::Some(2);
let y = Option::Some(100);
assert_eq!(x.or(y), Option::Some(2));

let x: Option<u32> = Option::None;
let y = Option::None;
assert_eq!(x.or(y), Option::None);
}

#[test]
fn test_option_or_else() {
let nobody = || Option::<ByteArray>::None;
let vikings = || Option::<ByteArray>::Some("vikings");

assert_eq!(Option::Some("barbarians").or_else(vikings), Option::Some("barbarians"));
assert_eq!(Option::None.or_else(vikings), Option::Some("vikings"));
assert_eq!(Option::None.or_else(nobody), Option::None);
}

#[test]
fn test_option_xor() {
let x = Option::Some(2);
let y: Option<u32> = Option::None;
assert_eq!(x.xor(y), Option::Some(2));

let x: Option<u32> = Option::None;
let y = Option::Some(2);
assert_eq!(x.xor(y), Option::Some(2));

let x = Option::Some(2);
let y = Option::Some(2);
assert_eq!(x.xor(y), Option::None);

let x: Option<u32> = Option::None;
let y: Option<u32> = Option::None;
assert_eq!(x.xor(y), Option::None);
}

fn test_option_some_is_none_or() {
assert_eq!(Option::Some(2_u8).is_none_or(|x| x > 1), true);
assert_eq!(Option::Some(0_u8).is_none_or(|x| x > 1), false);
Expand Down
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