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_negate)]
17 use collections::Collection;
19 use iter::DoubleEndedIterator;
20 use num::{Int, cast, zero};
21 use slice::{ImmutableSlice, MutableSlice};
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 mut buf = [0u8, ..64];
40 let base = cast(self.base()).unwrap();
41 let mut curr = buf.len();
42 let is_positive = x >= zero();
44 // Accumulate each digit of the number from the least significant
45 // to the most significant figure.
46 for byte in buf.iter_mut().rev() {
47 let n = x % base; // Get the current place value.
48 x = x / base; // Deaccumulate the number.
49 *byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
51 if x == zero() { break; } // No more digits left to accumulate.
54 // Do the same as above, but accounting for two's complement.
55 for byte in buf.iter_mut().rev() {
56 let n = -(x % base); // Get the current place value.
57 x = x / base; // Deaccumulate the number.
58 *byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
60 if x == zero() { break; } // No more digits left to accumulate.
63 f.pad_integral(is_positive, self.prefix(), buf.slice_from(curr))
67 /// A binary (base 2) radix
68 #[deriving(Clone, PartialEq)]
71 /// An octal (base 8) radix
72 #[deriving(Clone, PartialEq)]
75 /// A decimal (base 10) radix
76 #[deriving(Clone, PartialEq)]
79 /// A hexadecimal (base 16) radix, formatted with lower-case characters
80 #[deriving(Clone, PartialEq)]
83 /// A hexadecimal (base 16) radix, formatted with upper-case characters
84 #[deriving(Clone, PartialEq)]
88 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
89 impl GenericRadix for $T {
90 fn base(&self) -> u8 { $base }
91 fn prefix(&self) -> &'static str { $prefix }
92 fn digit(&self, x: u8) -> u8 {
95 x => fail!("number not in the range 0..{}: {}", self.base() - 1, x),
102 radix!(Binary, 2, "0b", x @ 0 .. 2 => b'0' + x)
103 radix!(Octal, 8, "0o", x @ 0 .. 7 => b'0' + x)
104 radix!(Decimal, 10, "", x @ 0 .. 9 => b'0' + x)
105 radix!(LowerHex, 16, "0x", x @ 0 .. 9 => b'0' + x,
106 x @ 10 ..15 => b'a' + (x - 10))
107 radix!(UpperHex, 16, "0x", x @ 0 .. 9 => b'0' + x,
108 x @ 10 ..15 => b'A' + (x - 10))
110 /// A radix with in the range of `2..36`.
111 #[deriving(Clone, PartialEq)]
117 fn new(base: u8) -> Radix {
118 assert!(2 <= base && base <= 36, "the base must be in the range of 2..36: {}", base);
123 impl GenericRadix for Radix {
124 fn base(&self) -> u8 { self.base }
125 fn digit(&self, x: u8) -> u8 {
127 x @ 0 ..9 => b'0' + x,
128 x if x < self.base() => b'a' + (x - 10),
129 x => fail!("number not in the range 0..{}: {}", self.base() - 1, x),
134 /// A helper type for formatting radixes.
135 pub struct RadixFmt<T, R>(T, R);
137 /// Constructs a radix formatter in the range of `2..36`.
142 /// use std::fmt::radix;
143 /// assert_eq!(format!("{}", radix(55i, 36)), "1j".to_string());
145 pub fn radix<T>(x: T, base: u8) -> RadixFmt<T, Radix> {
146 RadixFmt(x, Radix::new(base))
149 macro_rules! radix_fmt {
150 ($T:ty as $U:ty, $fmt:ident) => {
151 impl fmt::Show for RadixFmt<$T, Radix> {
152 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
153 match *self { RadixFmt(ref x, radix) => radix.$fmt(*x as $U, f) }
158 macro_rules! int_base {
159 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
160 impl fmt::$Trait for $T {
161 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
162 $Radix.fmt_int(*self as $U, f)
167 macro_rules! integer {
168 ($Int:ident, $Uint:ident) => {
169 int_base!(Show for $Int as $Int -> Decimal)
170 int_base!(Signed for $Int as $Int -> Decimal)
171 int_base!(Binary for $Int as $Uint -> Binary)
172 int_base!(Octal for $Int as $Uint -> Octal)
173 int_base!(LowerHex for $Int as $Uint -> LowerHex)
174 int_base!(UpperHex for $Int as $Uint -> UpperHex)
175 radix_fmt!($Int as $Int, fmt_int)
177 int_base!(Show for $Uint as $Uint -> Decimal)
178 int_base!(Unsigned for $Uint as $Uint -> Decimal)
179 int_base!(Binary for $Uint as $Uint -> Binary)
180 int_base!(Octal for $Uint as $Uint -> Octal)
181 int_base!(LowerHex for $Uint as $Uint -> LowerHex)
182 int_base!(UpperHex for $Uint as $Uint -> UpperHex)
183 radix_fmt!($Uint as $Uint, fmt_int)