// 代码来自 https://github.com/rust-lang/rustlings
fn string_slice(arg: &str) {
    println!("{}", arg);
}
fn string(arg: String) {
    println!("{}", arg);
}

fn main() {
    string("red".to_string());
    string("rust is fun!".to_owned());
    string("nice weather".into());
    string(String::from("hi"));
    string(format!("Interpolation {}", "Station"));
    string("Happy Monday!".to_string().replace("Mon", "Tues"));
    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
    
    string_slice("blue");
    string_slice(&String::from("abc")[0..1]);
    string_slice(&"abc".to_string()[0..1]);
    string_slice("  hello there ".trim());
}

// 下面代码来自官方文档
// str.to_string
#[stable(feature = "str_to_string_specialization", since = "1.9.0")]
impl ToString for str {
    #[inline]
    fn to_string(&self) -> String {
        String::from(self)
    }
}

// str.to_owned()
#[stable(feature = "rust1", since = "1.0.0")]
impl ToOwned for str {
    type Owned = String;
    #[inline]
    fn to_owned(&self) -> String {
        unsafe { String::from_utf8_unchecked(self.as_bytes().to_owned()) }
    }
}

// str.into()
#[stable(feature = "rust1", since = "1.0.0")]
impl<T, U> Into<U> for T
where
    U: From<T>,
{
    fn into(self) -> U {
        U::from(self)
    }
}