rust/src/libstd/to_str.rs

// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

/*!

The `ToStr` trait for converting to strings

*/

use option::{Some, None};
use str::OwnedStr;
use iter::Iterator;
use vec::ImmutableVector;

/// A generic trait for converting a value to a string
pub trait ToStr {
    /// Converts the value of `self` to an owned string
    fn to_str(&self) -> ~str;
}

/// Trait for converting a type to a string, consuming it in the process.
pub trait IntoStr {
    /// Consume and convert to a string.
    fn into_str(self) -> ~str;
}

impl ToStr for () {
    #[inline]
    fn to_str(&self) -> ~str { ~"()" }
}

impl<'a,A:ToStr> ToStr for &'a [A] {
    #[inline]
    fn to_str(&self) -> ~str {
        let mut acc = ~"[";
        let mut first = true;
        for elt in self.iter() {
            if first {
                first = false;
            }
            else {
                acc.push_str(", ");
            }
            acc.push_str(elt.to_str());
        }
        acc.push_char(']');
        acc
    }
}

impl<A:ToStr> ToStr for ~[A] {
    #[inline]
    fn to_str(&self) -> ~str {
        let mut acc = ~"[";
        let mut first = true;
        for elt in self.iter() {
            if first {
                first = false;
            }
            else {
                acc.push_str(", ");
            }
            acc.push_str(elt.to_str());
        }
        acc.push_char(']');
        acc
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_simple_types() {
        assert_eq!(1i.to_str(), ~"1");
        assert_eq!((-1i).to_str(), ~"-1");
        assert_eq!(200u.to_str(), ~"200");
        assert_eq!(2u8.to_str(), ~"2");
        assert_eq!(true.to_str(), ~"true");
        assert_eq!(false.to_str(), ~"false");
        assert_eq!(().to_str(), ~"()");
        assert_eq!((~"hi").to_str(), ~"hi");
    }

    #[test]
    fn test_vectors() {
        let x: ~[int] = ~[];
        assert_eq!(x.to_str(), ~"[]");
        assert_eq!((~[1]).to_str(), ~"[1]");
        assert_eq!((~[1, 2, 3]).to_str(), ~"[1, 2, 3]");
        assert!((~[~[], ~[1], ~[1, 1]]).to_str() ==
               ~"[[], [1], [1, 1]]");
    }
}