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Improved documentation. #258

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68 changes: 41 additions & 27 deletions src/cast.rs
Original file line number Diff line number Diff line change
Expand Up @@ -16,39 +16,39 @@ use core::{u128, u16, u32, u64, u8, usize};
/// even a large `f64` saturating to `f32` infinity.
pub trait ToPrimitive {
/// Converts the value of `self` to an `isize`. If the value cannot be
/// represented by an `isize`, then `None` is returned.
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How does removing the word "then" change the meaning of the sentence?

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It doesn't change the meaning. Seeing all those "then" removals listed, you may think it's something central. But I just changed it at one place for the more common phrasing, and then saw that the sentence was copied elsewhere, so I had to change these occurrences also.

The central piece of the PR is the addition of the lines that say See `Self` type or trait implementation for details. But since this is just a casual doc comment improvement, I don't think the additional "then" removals are a problem.

/// represented by an `isize`, `None` is returned.
#[inline]
fn to_isize(&self) -> Option<isize> {
self.to_i64().as_ref().and_then(ToPrimitive::to_isize)
}

/// Converts the value of `self` to an `i8`. If the value cannot be
/// represented by an `i8`, then `None` is returned.
/// represented by an `i8`, `None` is returned.
#[inline]
fn to_i8(&self) -> Option<i8> {
self.to_i64().as_ref().and_then(ToPrimitive::to_i8)
}

/// Converts the value of `self` to an `i16`. If the value cannot be
/// represented by an `i16`, then `None` is returned.
/// represented by an `i16`, `None` is returned.
#[inline]
fn to_i16(&self) -> Option<i16> {
self.to_i64().as_ref().and_then(ToPrimitive::to_i16)
}

/// Converts the value of `self` to an `i32`. If the value cannot be
/// represented by an `i32`, then `None` is returned.
/// represented by an `i32`, `None` is returned.
#[inline]
fn to_i32(&self) -> Option<i32> {
self.to_i64().as_ref().and_then(ToPrimitive::to_i32)
}

/// Converts the value of `self` to an `i64`. If the value cannot be
/// represented by an `i64`, then `None` is returned.
/// represented by an `i64`, `None` is returned.
fn to_i64(&self) -> Option<i64>;

/// Converts the value of `self` to an `i128`. If the value cannot be
/// represented by an `i128` (`i64` under the default implementation), then
/// represented by an `i128` (`i64` under the default implementation),
/// `None` is returned.
///
/// The default implementation converts through `to_i64()`. Types implementing
Expand All @@ -59,39 +59,39 @@ pub trait ToPrimitive {
}

/// Converts the value of `self` to a `usize`. If the value cannot be
/// represented by a `usize`, then `None` is returned.
/// represented by a `usize`, `None` is returned.
#[inline]
fn to_usize(&self) -> Option<usize> {
self.to_u64().as_ref().and_then(ToPrimitive::to_usize)
}

/// Converts the value of `self` to a `u8`. If the value cannot be
/// represented by a `u8`, then `None` is returned.
/// represented by a `u8`, `None` is returned.
#[inline]
fn to_u8(&self) -> Option<u8> {
self.to_u64().as_ref().and_then(ToPrimitive::to_u8)
}

/// Converts the value of `self` to a `u16`. If the value cannot be
/// represented by a `u16`, then `None` is returned.
/// represented by a `u16`, `None` is returned.
#[inline]
fn to_u16(&self) -> Option<u16> {
self.to_u64().as_ref().and_then(ToPrimitive::to_u16)
}

/// Converts the value of `self` to a `u32`. If the value cannot be
/// represented by a `u32`, then `None` is returned.
/// represented by a `u32`, `None` is returned.
#[inline]
fn to_u32(&self) -> Option<u32> {
self.to_u64().as_ref().and_then(ToPrimitive::to_u32)
}

/// Converts the value of `self` to a `u64`. If the value cannot be
/// represented by a `u64`, then `None` is returned.
/// represented by a `u64`, `None` is returned.
fn to_u64(&self) -> Option<u64>;

/// Converts the value of `self` to a `u128`. If the value cannot be
/// represented by a `u128` (`u64` under the default implementation), then
/// represented by a `u128` (`u64` under the default implementation),
/// `None` is returned.
///
/// The default implementation converts through `to_u64()`. Types implementing
Expand Down Expand Up @@ -394,39 +394,45 @@ impl_to_primitive_float!(f64);
/// even a large `f64` saturating to `f32` infinity.
pub trait FromPrimitive: Sized {
/// Converts an `isize` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_isize(n: isize) -> Option<Self> {
n.to_i64().and_then(FromPrimitive::from_i64)
}

/// Converts an `i8` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_i8(n: i8) -> Option<Self> {
FromPrimitive::from_i64(From::from(n))
}

/// Converts an `i16` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_i16(n: i16) -> Option<Self> {
FromPrimitive::from_i64(From::from(n))
}

/// Converts an `i32` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_i32(n: i32) -> Option<Self> {
FromPrimitive::from_i64(From::from(n))
}

/// Converts an `i64` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
fn from_i64(n: i64) -> Option<Self>;

/// Converts an `i128` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
///
/// The default implementation converts through `from_i64()`. Types implementing
/// this trait should override this method if they can represent a greater range.
Expand All @@ -436,39 +442,45 @@ pub trait FromPrimitive: Sized {
}

/// Converts a `usize` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_usize(n: usize) -> Option<Self> {
n.to_u64().and_then(FromPrimitive::from_u64)
}

/// Converts an `u8` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_u8(n: u8) -> Option<Self> {
FromPrimitive::from_u64(From::from(n))
}

/// Converts an `u16` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_u16(n: u16) -> Option<Self> {
FromPrimitive::from_u64(From::from(n))
}

/// Converts an `u32` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_u32(n: u32) -> Option<Self> {
FromPrimitive::from_u64(From::from(n))
}

/// Converts an `u64` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
fn from_u64(n: u64) -> Option<Self>;

/// Converts an `u128` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
///
/// The default implementation converts through `from_u64()`. Types implementing
/// this trait should override this method if they can represent a greater range.
Expand All @@ -478,14 +490,16 @@ pub trait FromPrimitive: Sized {
}

/// Converts a `f32` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
#[inline]
fn from_f32(n: f32) -> Option<Self> {
FromPrimitive::from_f64(From::from(n))
}

/// Converts a `f64` to return an optional value of this type. If the
/// value cannot be represented by this type, then `None` is returned.
/// value cannot be represented by this type, `None` is returned.
/// See `Self` type or trait implementation for details.
///
/// The default implementation tries to convert through `from_i64()`, and
/// failing that through `from_u64()`. Types implementing this trait should
Expand Down Expand Up @@ -661,7 +675,7 @@ pub fn cast<T: NumCast, U: NumCast>(n: T) -> Option<U> {
pub trait NumCast: Sized + ToPrimitive {
/// Creates a number from another value that can be converted into
/// a primitive via the `ToPrimitive` trait. If the source value cannot be
/// represented by the target type, then `None` is returned.
/// represented by the target type, `None` is returned.
///
/// A value can be represented by the target type when it lies within
/// the range of scalars supported by the target type.
Expand Down