estring/src/core.rs

100 lines
2.2 KiB
Rust

//! Contains the ``EString`` type, as well as the basic implementation of conversions to
//! string types
//!
#[cfg(any(feature = "number", feature = "bool"))]
pub mod prim;
#[cfg(any(feature = "number", feature = "bool"))]
pub use prim::*;
#[cfg(feature = "vec")]
pub mod vec;
#[cfg(feature = "vec")]
pub use vec::*;
use crate::ParseError;
use std::convert::{Infallible, TryFrom};
/// Wrapper under String type.
#[derive(Debug, Default, PartialEq, Eq, Clone)]
pub struct EString(pub String);
impl EString {
/// Parses inner string by type annotations and returns result.
///
/// # Errors
///
/// Will return `Err` if estring cannot parse inner fragment
///
#[inline]
pub fn parse<T: TryFrom<EString>>(self) -> Result<T, ParseError> {
let orig = self.0.clone();
<T as TryFrom<EString>>::try_from(self).map_err(|_| ParseError(orig))
}
}
impl<T> From<T> for EString
where
T: std::fmt::Display,
{
#[inline]
fn from(val: T) -> Self {
Self(val.to_string())
}
}
impl std::ops::Deref for EString {
type Target = String;
#[inline]
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl TryFrom<EString> for String {
type Error = Infallible;
#[inline]
fn try_from(s: EString) -> Result<Self, Self::Error> {
Ok(s.0)
}
}
impl TryFrom<EString> for &'static str {
type Error = Infallible;
#[inline]
fn try_from(s: EString) -> Result<Self, Self::Error> {
Ok(Box::leak(s.0.into_boxed_str()))
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn should_deref_to_string() {
let estr = EString::from("hello");
assert_eq!(*estr, String::from("hello"));
}
#[test]
fn should_parse_into_itself() {
let estr = EString::from("hello");
match estr.parse::<EString>() {
Ok(res) => assert_eq!(res, EString::from("hello")),
_ => unreachable!(),
}
}
#[test]
fn should_parse_into_string() {
let estr = EString::from("hello");
match estr.parse::<String>() {
Ok(res) => assert_eq!(res, String::from("hello")),
_ => unreachable!(),
}
}
}