1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Integer and floating-point number formatting
13 // FIXME: #6220 Implement floating point formatting
15 #![allow(unsigned_negation)]
18 use iter::DoubleEndedIteratorExt;
21 use slice::SlicePrelude;
23 /// A type that represents a specific radix
26 /// The number of digits.
29 /// A radix-specific prefix string.
30 fn prefix(&self) -> &'static str { "" }
32 /// Converts an integer to corresponding radix digit.
33 fn digit(&self, x: u8) -> u8;
35 /// Format an integer using the radix using a formatter.
36 fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
37 // The radix can be as low as 2, so we need a buffer of at least 64
38 // characters for a base 2 number.
39 let zero = Int::zero();
40 let is_positive = x >= zero;
41 let mut buf = [0u8, ..64];
42 let mut curr = buf.len();
43 let base = cast(self.base()).unwrap();
45 // Accumulate each digit of the number from the least significant
46 // to the most significant figure.
47 for byte in buf.iter_mut().rev() {
48 let n = x % base; // Get the current place value.
49 x = x / base; // Deaccumulate the number.
50 *byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
52 if x == zero { break }; // No more digits left to accumulate.
55 // Do the same as above, but accounting for two's complement.
56 for byte in buf.iter_mut().rev() {
57 let n = zero - (x % base); // Get the current place value.
58 x = x / base; // Deaccumulate the number.
59 *byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
61 if x == zero { break }; // No more digits left to accumulate.
64 f.pad_integral(is_positive, self.prefix(), buf[curr..])
68 /// A binary (base 2) radix
69 #[deriving(Clone, PartialEq)]
72 /// An octal (base 8) radix
73 #[deriving(Clone, PartialEq)]
76 /// A decimal (base 10) radix
77 #[deriving(Clone, PartialEq)]
80 /// A hexadecimal (base 16) radix, formatted with lower-case characters
81 #[deriving(Clone, PartialEq)]
84 /// A hexadecimal (base 16) radix, formatted with upper-case characters
85 #[deriving(Clone, PartialEq)]
89 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
90 impl GenericRadix for $T {
91 fn base(&self) -> u8 { $base }
92 fn prefix(&self) -> &'static str { $prefix }
93 fn digit(&self, x: u8) -> u8 {
96 x => panic!("number not in the range 0..{}: {}", self.base() - 1, x),
103 radix!(Binary, 2, "0b", x @ 0 ... 2 => b'0' + x)
104 radix!(Octal, 8, "0o", x @ 0 ... 7 => b'0' + x)
105 radix!(Decimal, 10, "", x @ 0 ... 9 => b'0' + x)
106 radix!(LowerHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
107 x @ 10 ... 15 => b'a' + (x - 10))
108 radix!(UpperHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
109 x @ 10 ... 15 => b'A' + (x - 10))
111 /// A radix with in the range of `2..36`.
112 #[deriving(Clone, PartialEq)]
113 #[unstable = "may be renamed or move to a different module"]
118 impl Copy for Radix {}
121 fn new(base: u8) -> Radix {
122 assert!(2 <= base && base <= 36, "the base must be in the range of 2..36: {}", base);
127 impl GenericRadix for Radix {
128 fn base(&self) -> u8 { self.base }
129 fn digit(&self, x: u8) -> u8 {
131 x @ 0 ... 9 => b'0' + x,
132 x if x < self.base() => b'a' + (x - 10),
133 x => panic!("number not in the range 0..{}: {}", self.base() - 1, x),
138 /// A helper type for formatting radixes.
139 #[unstable = "may be renamed or move to a different module"]
140 pub struct RadixFmt<T, R>(T, R);
142 impl<T,R> Copy for RadixFmt<T,R> where T: Copy, R: Copy {}
144 /// Constructs a radix formatter in the range of `2..36`.
149 /// use std::fmt::radix;
150 /// assert_eq!(format!("{}", radix(55i, 36)), "1j".to_string());
152 #[unstable = "may be renamed or move to a different module"]
153 pub fn radix<T>(x: T, base: u8) -> RadixFmt<T, Radix> {
154 RadixFmt(x, Radix::new(base))
157 macro_rules! radix_fmt {
158 ($T:ty as $U:ty, $fmt:ident) => {
159 impl fmt::Show for RadixFmt<$T, Radix> {
160 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
161 match *self { RadixFmt(ref x, radix) => radix.$fmt(*x as $U, f) }
166 macro_rules! int_base {
167 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
168 impl fmt::$Trait for $T {
169 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
170 $Radix.fmt_int(*self as $U, f)
175 macro_rules! integer {
176 ($Int:ident, $Uint:ident) => {
177 int_base!(Show for $Int as $Int -> Decimal)
178 int_base!(Binary for $Int as $Uint -> Binary)
179 int_base!(Octal for $Int as $Uint -> Octal)
180 int_base!(LowerHex for $Int as $Uint -> LowerHex)
181 int_base!(UpperHex for $Int as $Uint -> UpperHex)
182 radix_fmt!($Int as $Int, fmt_int)
184 int_base!(Show for $Uint as $Uint -> Decimal)
185 int_base!(Binary for $Uint as $Uint -> Binary)
186 int_base!(Octal for $Uint as $Uint -> Octal)
187 int_base!(LowerHex for $Uint as $Uint -> LowerHex)
188 int_base!(UpperHex for $Uint as $Uint -> UpperHex)
189 radix_fmt!($Uint as $Uint, fmt_int)