Core Lib Documentation: Zeroable module (#6722)

Co-authored-by: enitrat <[email protected]>

corelib/src/zeroable.cairo

@@ -1,23 +1,30 @@
-// === Zeroable ===
+//! Types and traits for handling non-zero values and zero checking operations.
+//!
+//! This module provides the [`NonZero`] wrapper type which guarantees that a value is never
+//! zero.
+//! The [`Zeroable`] trait is meant for internal use only. The public-facing equivalent is the
+//! [`Zero`] trait.
+//!
+//! [`Zero`]: core::num::traits::zero::Zero
 
 /// A trait for types that have a concept of zero and can be compared to zero.
 ///
 /// This trait is useful for numeric types or any type that has an additive identity element.
 pub(crate) trait Zeroable<T> {
-    /// Returns the additive identity element of Self, 0.
+    /// Returns the additive identity element of `self`, 0.
     ///
-    /// This method should return a value that, when added to any other value of type T,
+    /// This method should return a value that, when added to any other value of type `T`,
     /// does not change that value.
     ///
     /// # Examples
     ///
     /// ```
-    /// assert_eq!(Zeroable::<i32>::zero(), 0);
+    /// assert!(Zeroable::<i32>::zero() == 0);
     /// ```
     #[must_use]
     fn zero() -> T;
 
-    /// Returns whether self is equal to 0, the additive identity element.
+    /// Returns whether `self` is equal to 0, the additive identity element.
     ///
     /// # Examples
     ///
@@ -28,7 +35,7 @@ pub(crate) trait Zeroable<T> {
     #[must_use]
     fn is_zero(self: T) -> bool;
 
-    /// Returns whether self is not equal to 0, the additive identity element.
+    /// Returns whether `self` is not equal to 0, the additive identity element.
     ///
     /// This method is the logical inverse of `is_zero()`.
     ///
@@ -48,18 +55,15 @@ pub(crate) mod zero_based {
     pub(crate) impl ZeroableImpl<
         T, impl ZeroImpl: crate::num::traits::Zero<T>, +Drop<T>, +Copy<T>,
     > of super::Zeroable<T> {
-        /// Returns the zero value for the type.
         fn zero() -> T {
             ZeroImpl::zero()
         }
 
-        /// Checks if the value is zero.
         #[inline]
         fn is_zero(self: T) -> bool {
             ZeroImpl::is_zero(@self)
         }
 
-        /// Checks if the value is non-zero.
         #[inline]
         fn is_non_zero(self: T) -> bool {
             ZeroImpl::is_non_zero(@self)
@@ -69,13 +73,13 @@ pub(crate) mod zero_based {
 
 pub(crate) impl Felt252Zeroable = zero_based::ZeroableImpl<felt252>;
 
-// === NonZero ===
 
 /// A wrapper type for non-zero values of type T.
 ///
 /// This type guarantees that the wrapped value is never zero.
 #[derive(Copy, Drop)]
 pub extern type NonZero<T>;
+
 impl NonZeroNeg<T, +Neg<T>, +TryInto<T, NonZero<T>>> of Neg<NonZero<T>> {
     fn neg(a: NonZero<T>) -> NonZero<T> {
         // TODO(orizi): Optimize using bounded integers.
@@ -89,26 +93,20 @@ impl NonZeroNeg<T, +Neg<T>, +TryInto<T, NonZero<T>>> of Neg<NonZero<T>> {
 pub(crate) enum IsZeroResult<T> {
     /// Indicates that the value is zero.
     Zero,
-    /// Indicates that the value is non-zero, wrapping it in a NonZero<T>.
+    /// Indicates that the value is non-zero, wrapping it in a `NonZero<T>`.
     NonZero: NonZero<T>,
 }
 
-/// Unwraps a NonZero<T> to retrieve the underlying value of type T.
+/// Unwraps a `NonZero<T>` to retrieve the underlying value of type `T`.
 extern fn unwrap_non_zero<T>(a: NonZero<T>) -> T nopanic;
 
-/// Implements the `Into` trait for converting NonZero<T> to T.
 pub(crate) impl NonZeroIntoImpl<T> of Into<NonZero<T>, T> {
-    /// Converts a NonZero<T> to T.
     fn into(self: NonZero<T>) -> T nopanic {
         unwrap_non_zero(self)
     }
 }
 
-/// Implements the `Into` trait for converting IsZeroResult<T> to bool.
 impl IsZeroResultIntoBool<T, +Drop<T>> of Into<IsZeroResult<T>, bool> {
-    /// Converts an IsZeroResult<T> to a boolean.
-    ///
-    /// Returns true if the result is Zero, false otherwise.
     fn into(self: IsZeroResult<T>) -> bool {
         match self {
             IsZeroResult::Zero => true,
@@ -117,17 +115,14 @@ impl IsZeroResultIntoBool<T, +Drop<T>> of Into<IsZeroResult<T>, bool> {
     }
 }
 
-/// Implements the `PartialEq` trait for NonZero<T>.
 impl NonZeroPartialEq<T, +PartialEq<T>, +Copy<T>, +Drop<T>> of PartialEq<NonZero<T>> {
-    /// Checks if two NonZero<T> values are equal.
     #[inline]
     fn eq(lhs: @NonZero<T>, rhs: @NonZero<T>) -> bool {
         let lhs: T = (*lhs).into();
         let rhs: T = (*rhs).into();
         lhs == rhs
     }
 
-    /// Checks if two NonZero<T> values are not equal.
     #[inline]
     fn ne(lhs: @NonZero<T>, rhs: @NonZero<T>) -> bool {
         let lhs: T = (*lhs).into();
@@ -136,17 +131,12 @@ impl NonZeroPartialEq<T, +PartialEq<T>, +Copy<T>, +Drop<T>> of PartialEq<NonZero
     }
 }
 
-/// Implements the `Serde` trait for NonZero<T>.
 impl NonZeroSerde<T, +Serde<T>, +Copy<T>, +Drop<T>, +TryInto<T, NonZero<T>>> of Serde<NonZero<T>> {
-    /// Serializes a NonZero<T> value.
     fn serialize(self: @NonZero<T>, ref output: Array<felt252>) {
         let value: T = (*self).into();
         value.serialize(ref output);
     }
 
-    /// Deserializes a NonZero<T> value.
-    ///
-    /// Returns None if deserialization fails or if the deserialized value is zero.
     fn deserialize(ref serialized: Span<felt252>) -> Option<NonZero<T>> {
         Serde::<T>::deserialize(ref serialized)?.try_into()
     }