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add try from methods #86

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3 changes: 2 additions & 1 deletion Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,8 @@ edition = "2018"
[package.metadata.docs.rs]
features = ["std", "num-bigint-std", "serde"]

[dependencies]
[dependencies.paste]
version = "1.0"
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Why is this dependency required?

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its for generating the call to the corresponding underlying impl ::[<from_ $name>]

                    fn try_from(n: $name) -> Result<Self, ()> {
                        <$into as FromPrimitive>::[<from_ $name>](n)
                            .map(Ratio::from_integer)
                            .ok_or(())
                    }


[dependencies.num-bigint]
optional = true
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9 changes: 9 additions & 0 deletions build.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,5 +4,14 @@ fn main() {
println!("cargo:rustc-cfg=has_int_exp_fmt");
}

let std = if ac.probe_sysroot_crate("std") {
"std"
} else {
"core"
};
if ac.probe_path(&format!("{}::convert::TryFrom", std)) {
autocfg::emit("has_try_from");
}

autocfg::rerun_path("build.rs");
}
84 changes: 84 additions & 0 deletions src/from.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,84 @@
use crate::{FromPrimitive, Ratio};

#[cfg(has_try_from)]
use crate::{approximate_float, approximate_float_unsigned};
#[cfg(has_try_from)]
use core::convert::TryFrom;

macro_rules! impl_try_from {
( $($name:ty),* => $into:ty ; $approx:ident) => {
$(
#[cfg(has_try_from)]
impl TryFrom<$name> for Ratio<$into> {
type Error = ();
paste::paste! {
fn try_from(n: $name) -> Result<Self, ()> {
<$into as FromPrimitive>::[<from_ $name>](n)
.map(Ratio::from_integer)
.ok_or(())
}
}
}
)*

#[cfg(has_try_from)]
impl TryFrom<f32> for Ratio<$into> {
type Error = ();
fn try_from(n: f32) -> Result<Self, ()> {
$approx(n, 10e-20, 30).ok_or(())
}
}

#[cfg(has_try_from)]
impl TryFrom<f64> for Ratio<$into> {
type Error = ();
fn try_from(n: f64) -> Result<Self, ()> {
$approx(n, 10e-20, 30).ok_or(())
}
}

};
}

impl_try_from!(i8, u16, i16, u32, i32, u64, i64, u128, i128 => u8 ; approximate_float_unsigned);
impl_try_from!(u8, u16, i16, u32, i32, u64, i64, u128, i128 => i8 ; approximate_float);

impl_try_from!(i16, u32, i32, u64, i64, u128, i128 => u16 ; approximate_float_unsigned);
impl_try_from!(u16, u32, i32, u64, i64, u128, i128 => i16 ; approximate_float);

impl_try_from!(i32, u64, i64, u128, i128 => u32 ; approximate_float_unsigned);
impl_try_from!(u32, u64, i64, u128, i128 => i32 ; approximate_float);

impl_try_from!(i64, u128, i128 => u64 ; approximate_float_unsigned);
impl_try_from!(u64, u128, i128 => i64 ; approximate_float);

impl_try_from!(i128 => u128 ; approximate_float_unsigned);
impl_try_from!(u128 => i128 ; approximate_float);

macro_rules! impl_from {
( $($name:ty),* => $into:ty) => {
$(
impl From<$name> for Ratio<$into> {
paste::paste! {
fn from(n: $name) -> Self {
<$into as FromPrimitive>::[< from_ $name>](n)
.map(Ratio::from_integer)
.unwrap()
}
}
}
)*
};
}

impl_from!(u8, u16, u32, u64 => u128);
impl_from!(u8, i8, u16, i16, u32, i32, u64, i64 => i128);

impl_from!(u8, u16, u32 => u64);
impl_from!(u8, i8, u16, i16, u32, i32 => i64);

impl_from!(u8, u16 => u32);
impl_from!(u8, i8, u16, i16 => i32);

impl_from!(u8 => u16);
impl_from!(u8, i8 => i16);
1 change: 1 addition & 0 deletions src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ use num_traits::{
Pow, Signed, Zero,
};

mod from;
mod pow;

/// Represents the ratio between two numbers.
Expand Down