//! Implement Fallible String

//!

//! Thils file will ideally added to the fallible_collections library.

use alloc::collections::TryReserveError;

use alloc::string::String;

/// trait implementing all fallible methods on vec

pub(crate) trait FallibleString {

/// see with_capacity

fn try_with_capacity(capacity: usize) -> Result<String, TryReserveError>;

/// see push

fn try_push(&mut self, ch: char) -> Result<(), TryReserveError>;

/// see push_str

fn try_push_str(&mut self, string: &str) -> Result<(), TryReserveError>;

}

impl FallibleString for String {

#[inline]

fn try_with_capacity(capacity: usize) -> Result<String, TryReserveError> {

let mut s = String::new();

s.try_reserve(capacity)?;

Ok(s)

}

#[inline]

fn try_push(&mut self, ch: char) -> Result<(), TryReserveError> {

self.try_reserve(1)?;

self.push(ch);

Ok(())

}

#[inline]

fn try_push_str(&mut self, string: &str) -> Result<(), TryReserveError> {

self.try_reserve(string.len())?;

self.push_str(string);

Ok(())

}

}

/// TryString is a thin wrapper around String to provide support for fallible

/// allocation.

///

/// See the crate documentation for more.

#[derive(PartialEq)]

pub(crate) struct TryString {

inner: String,

}

impl From<TryString> for String {

fn from(s: TryString) -> String {

s.inner

}

}

impl core::convert::TryFrom<&str> for TryString {

type Error = TryReserveError;

#[inline]

fn try_from(value: &str) -> Result<Self, Self::Error> {

let mut inner = String::new();

inner.try_reserve(value.len())?;

inner.push_str(value);

Ok(TryString { inner })

}

}