rust/src/libcore/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 kinds::Copy;
use str;
use vec;

pub trait ToStr {
    pure fn to_str(&self) -> ~str;
}

impl ToStr for bool {
    #[inline(always)]
    pure fn to_str(&self) -> ~str { ::bool::to_str(*self) }
}
impl ToStr for () {
    #[inline(always)]
    pure fn to_str(&self) -> ~str { ~"()" }
}
impl ToStr for ~str {
    #[inline(always)]
    pure fn to_str(&self) -> ~str { copy *self }
}
impl ToStr for &str {
    #[inline(always)]
    pure fn to_str(&self) -> ~str { ::str::from_slice(*self) }
}
impl ToStr for @str {
    #[inline(always)]
    pure fn to_str(&self) -> ~str { ::str::from_slice(*self) }
}

// FIXME #4898: impl for one-tuples

impl<A:ToStr,B:ToStr> ToStr for (A, B) {
    #[inline(always)]
    pure fn to_str(&self) -> ~str {
        // FIXME(#4760): this causes an llvm assertion
        //let &(ref a, ref b) = self;
        match *self {
            (ref a, ref b) => {
                ~"(" + a.to_str() + ~", " + b.to_str() + ~")"
            }
        }
    }
}
impl<A:ToStr,B:ToStr,C:ToStr> ToStr for (A, B, C) {
    #[inline(always)]
    pure fn to_str(&self) -> ~str {
        // FIXME(#4760): this causes an llvm assertion
        //let &(ref a, ref b, ref c) = self;
        match *self {
            (ref a, ref b, ref c) => {
                fmt!("(%s, %s, %s)",
                    (*a).to_str(),
                    (*b).to_str(),
                    (*c).to_str()
                )
            }
        }
    }
}

impl<A:ToStr> ToStr for &[A] {
    #[inline(always)]
    pure fn to_str(&self) -> ~str {
        unsafe {
            // FIXME #4568
            // Bleh -- not really unsafe
            // push_str and push_char
            let mut acc = ~"[", first = true;
            for self.each |elt| {
                unsafe {
                    if first { first = false; }
                    else { str::push_str(&mut acc, ~", "); }
                    str::push_str(&mut acc, elt.to_str());
                }
            }
            str::push_char(&mut acc, ']');
            acc
        }
    }
}

impl<A:ToStr> ToStr for ~[A] {
    #[inline(always)]
    pure fn to_str(&self) -> ~str {
        unsafe {
            // FIXME #4568
            // Bleh -- not really unsafe
            // push_str and push_char
            let mut acc = ~"[", first = true;
            for self.each |elt| {
                unsafe {
                    if first { first = false; }
                    else { str::push_str(&mut acc, ~", "); }
                    str::push_str(&mut acc, elt.to_str());
                }
            }
            str::push_char(&mut acc, ']');
            acc
        }
    }
}

impl<A:ToStr> ToStr for @[A] {
    #[inline(always)]
    pure fn to_str(&self) -> ~str {
        unsafe {
            // FIXME #4568
            // Bleh -- not really unsafe
            // push_str and push_char
            let mut acc = ~"[", first = true;
            for self.each |elt| {
                unsafe {
                    if first { first = false; }
                    else { str::push_str(&mut acc, ~", "); }
                    str::push_str(&mut acc, elt.to_str());
                }
            }
            str::push_char(&mut acc, ']');
            acc
        }
    }
}

#[cfg(test)]
#[allow(non_implicitly_copyable_typarams)]
mod tests {
    #[test]
    fn test_simple_types() {
        assert 1i.to_str() == ~"1";
        assert (-1i).to_str() == ~"-1";
        assert 200u.to_str() == ~"200";
        assert 2u8.to_str() == ~"2";
        assert true.to_str() == ~"true";
        assert false.to_str() == ~"false";
        assert ().to_str() == ~"()";
        assert (~"hi").to_str() == ~"hi";
        assert (@"hi").to_str() == ~"hi";
    }

    #[test]
    fn test_tuple_types() {
        assert (1, 2).to_str() == ~"(1, 2)";
        assert (~"a", ~"b", false).to_str() == ~"(a, b, false)";
        assert ((), ((), 100)).to_str() == ~"((), ((), 100))";
    }

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