54 lines
1.7 KiB
Rust
54 lines
1.7 KiB
Rust
|
// Copyright 2014 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.
|
||
|
|
|
||
|
|
//! Implementation of the `{:?}` format qualifier
|
||
|
|
//!
|
||
|
|
//! This module contains the `Poly` trait which is used to implement the `{:?}`
|
||
|
|
//! format expression in formatting macros. This trait is defined for all types
|
||
|
|
//! automatically, so it is likely not necessary to use this module manually
|
||
|
|
|
||
|
|
use std::fmt;
|
||
|
|
|
||
|
|
use repr;
|
||
|
|
|
||
|
|
/// Format trait for the `?` character
|
||
|
|
pub trait Poly {
|
||
|
|
/// Formats the value using the given formatter.
|
||
|
|
#[experimental]
|
||
|
|
fn fmt(&self, &mut fmt::Formatter) -> fmt::Result;
|
||
|
|
}
|
||
|
|
|
||
|
|
#[doc(hidden)]
|
||
|
|
pub fn secret_poly<T: Poly>(x: &T, fmt: &mut fmt::Formatter) -> fmt::Result {
|
||
|
|
// FIXME #11938 - UFCS would make us able call the this method
|
||
|
|
// directly Poly::fmt(x, fmt).
|
||
|
|
x.fmt(fmt)
|
||
|
|
}
|
||
|
|
|
||
|
|
impl<T> Poly for T {
|
||
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
||
|
|
match (f.width, f.precision) {
|
||
|
|
(None, None) => {
|
||
|
|
match repr::write_repr(f, self) {
|
||
|
|
Ok(()) => Ok(()),
|
||
|
|
Err(..) => Err(fmt::WriteError),
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// If we have a specified width for formatting, then we have to make
|
||
|
|
// this allocation of a new string
|
||
|
|
_ => {
|
||
|
|
let s = repr::repr_to_str(self);
|
||
|
|
f.pad(s.as_slice())
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|