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use std::{
convert::TryFrom,
error, fmt,
num::{self, NonZeroI32},
str::FromStr,
};
pub(crate) const UNMAPPED: i32 = 0;
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct Position(NonZeroI32);
impl From<Position> for i32 {
fn from(position: Position) -> Self {
Self::from(position.0)
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ParseError {
Parse(num::ParseIntError),
Invalid(TryFromIntError),
}
impl error::Error for ParseError {}
impl fmt::Display for ParseError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Parse(e) => write!(f, "{}", e),
Self::Invalid(e) => write!(f, "{}", e),
}
}
}
impl FromStr for Position {
type Err = ParseError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let n: i32 = s.parse().map_err(ParseError::Parse)?;
Self::try_from(n).map_err(ParseError::Invalid)
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct TryFromIntError(i32);
impl error::Error for TryFromIntError {}
impl fmt::Display for TryFromIntError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "invalid value: {}", self.0)
}
}
impl TryFrom<i32> for Position {
type Error = TryFromIntError;
fn try_from(n: i32) -> Result<Self, Self::Error> {
if n < 0 {
Err(TryFromIntError(n))
} else {
NonZeroI32::new(n).map(Self).ok_or(TryFromIntError(n))
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_from_position_for_i32() -> Result<(), TryFromIntError> {
assert_eq!(i32::from(Position::try_from(8)?), 8);
assert_eq!(i32::from(Position::try_from(13)?), 13);
Ok(())
}
#[test]
fn test_from_str() -> Result<(), TryFromIntError> {
assert_eq!("13".parse(), Ok(Position::try_from(13)?));
assert!(matches!("".parse::<Position>(), Err(ParseError::Parse(_))));
assert!(matches!(
"noodles".parse::<Position>(),
Err(ParseError::Parse(_))
));
assert_eq!(
"0".parse::<Position>(),
Err(ParseError::Invalid(TryFromIntError(0)))
);
assert_eq!(
"-8".parse::<Position>(),
Err(ParseError::Invalid(TryFromIntError(-8)))
);
Ok(())
}
#[test]
fn test_try_from_i32_for_position() -> Result<(), num::TryFromIntError> {
assert_eq!(
Position::try_from(13),
Ok(Position(NonZeroI32::try_from(13)?))
);
assert_eq!(Position::try_from(0), Err(TryFromIntError(0)));
assert_eq!(Position::try_from(-8), Err(TryFromIntError(-8)));
Ok(())
}
}