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// 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.
//! Integer and floating-point number formatting
// FIXME: #6220 Implement floating point formatting
#![allow(unsigned_negate)]
use collections::Collection;
use fmt;
use iter::DoubleEndedIterator;
use num::{Int, cast, zero};
use slice::{MutableSlice};
/// A type that represents a specific radix
#[doc(hidden)]
trait GenericRadix {
/// The number of digits.
fn base(&self) -> u8;
/// A radix-specific prefix string.
fn prefix(&self) -> &'static str { "" }
/// Converts an integer to corresponding radix digit.
fn digit(&self, x: u8) -> u8;
/// Format an integer using the radix using a formatter.
fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
// The radix can be as low as 2, so we need a buffer of at least 64
// characters for a base 2 number.
let mut buf = [0u8, ..64];
let base = cast(self.base()).unwrap();
let mut curr = buf.len();
let is_positive = x >= zero();
if is_positive {
// Accumulate each digit of the number from the least significant
// to the most significant figure.
for byte in buf.iter_mut().rev() {
let n = x % base; // Get the current place value.
x = x / base; // Deaccumulate the number.
*byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
curr -= 1;
if x == zero() { break; } // No more digits left to accumulate.
}
} else {
// Do the same as above, but accounting for two's complement.
for byte in buf.iter_mut().rev() {
let n = -(x % base); // Get the current place value.
x = x / base; // Deaccumulate the number.
*byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
curr -= 1;
if x == zero() { break; } // No more digits left to accumulate.
}
}
f.pad_integral(is_positive, self.prefix(), buf[curr..])
}
}
/// A binary (base 2) radix
#[deriving(Clone, PartialEq)]
struct Binary;
/// An octal (base 8) radix
#[deriving(Clone, PartialEq)]
struct Octal;
/// A decimal (base 10) radix
#[deriving(Clone, PartialEq)]
struct Decimal;
/// A hexadecimal (base 16) radix, formatted with lower-case characters
#[deriving(Clone, PartialEq)]
struct LowerHex;
/// A hexadecimal (base 16) radix, formatted with upper-case characters
#[deriving(Clone, PartialEq)]
pub struct UpperHex;
macro_rules! radix {
($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
impl GenericRadix for $T {
fn base(&self) -> u8 { $base }
fn prefix(&self) -> &'static str { $prefix }
fn digit(&self, x: u8) -> u8 {
match x {
$($x => $conv,)+
x => fail!("number not in the range 0..{}: {}", self.base() - 1, x),
}
}
}
}
}
radix!(Binary, 2, "0b", x @ 0 ... 2 => b'0' + x)
radix!(Octal, 8, "0o", x @ 0 ... 7 => b'0' + x)
radix!(Decimal, 10, "", x @ 0 ... 9 => b'0' + x)
radix!(LowerHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
x @ 10 ... 15 => b'a' + (x - 10))
radix!(UpperHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
x @ 10 ... 15 => b'A' + (x - 10))
/// A radix with in the range of `2..36`.
#[deriving(Clone, PartialEq)]
pub struct Radix {
base: u8,
}
impl Radix {
fn new(base: u8) -> Radix {
assert!(2 <= base && base <= 36, "the base must be in the range of 2..36: {}", base);
Radix { base: base }
}
}
impl GenericRadix for Radix {
fn base(&self) -> u8 { self.base }
fn digit(&self, x: u8) -> u8 {
match x {
x @ 0 ... 9 => b'0' + x,
x if x < self.base() => b'a' + (x - 10),
x => fail!("number not in the range 0..{}: {}", self.base() - 1, x),
}
}
}
/// A helper type for formatting radixes.
pub struct RadixFmt<T, R>(T, R);
/// Constructs a radix formatter in the range of `2..36`.
///
/// # Example
///
/// ```
/// use std::fmt::radix;
/// assert_eq!(format!("{}", radix(55i, 36)), "1j".to_string());
/// ```
pub fn radix<T>(x: T, base: u8) -> RadixFmt<T, Radix> {
RadixFmt(x, Radix::new(base))
}
macro_rules! radix_fmt {
($T:ty as $U:ty, $fmt:ident) => {
impl fmt::Show for RadixFmt<$T, Radix> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self { RadixFmt(ref x, radix) => radix.$fmt(*x as $U, f) }
}
}
}
}
macro_rules! int_base {
($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
impl fmt::$Trait for $T {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
$Radix.fmt_int(*self as $U, f)
}
}
}
}
macro_rules! integer {
($Int:ident, $Uint:ident) => {
int_base!(Show for $Int as $Int -> Decimal)
int_base!(Signed for $Int as $Int -> Decimal)
int_base!(Binary for $Int as $Uint -> Binary)
int_base!(Octal for $Int as $Uint -> Octal)
int_base!(LowerHex for $Int as $Uint -> LowerHex)
int_base!(UpperHex for $Int as $Uint -> UpperHex)
radix_fmt!($Int as $Int, fmt_int)
int_base!(Show for $Uint as $Uint -> Decimal)
int_base!(Unsigned for $Uint as $Uint -> Decimal)
int_base!(Binary for $Uint as $Uint -> Binary)
int_base!(Octal for $Uint as $Uint -> Octal)
int_base!(LowerHex for $Uint as $Uint -> LowerHex)
int_base!(UpperHex for $Uint as $Uint -> UpperHex)
radix_fmt!($Uint as $Uint, fmt_int)
}
}
integer!(int, uint)
integer!(i8, u8)
integer!(i16, u16)
integer!(i32, u32)
integer!(i64, u64)
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