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
19 use ops::{Div, Rem, Sub};
26 trait Int: Zero + PartialEq + PartialOrd + Div<Output=Self> + Rem<Output=Self> +
27 Sub<Output=Self> + Copy {
28 fn from_u8(u: u8) -> Self;
29 fn to_u8(&self) -> u8;
30 fn to_u32(&self) -> u32;
31 fn to_u64(&self) -> u64;
35 ($($t:ident)*) => ($(impl Int for $t {
36 fn from_u8(u: u8) -> $t { u as $t }
37 fn to_u8(&self) -> u8 { *self as u8 }
38 fn to_u32(&self) -> u32 { *self as u32 }
39 fn to_u64(&self) -> u64 { *self as u64 }
42 doit! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }
44 /// A type that represents a specific radix
47 /// The number of digits.
50 /// A radix-specific prefix string.
51 fn prefix(&self) -> &'static str {
55 /// Converts an integer to corresponding radix digit.
56 fn digit(&self, x: u8) -> u8;
58 /// Format an integer using the radix using a formatter.
59 fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
60 // The radix can be as low as 2, so we need a buffer of at least 64
61 // characters for a base 2 number.
63 let is_positive = x >= zero;
64 let mut buf = [0; 64];
65 let mut curr = buf.len();
66 let base = T::from_u8(self.base());
68 // Accumulate each digit of the number from the least significant
69 // to the most significant figure.
70 for byte in buf.iter_mut().rev() {
71 let n = x % base; // Get the current place value.
72 x = x / base; // Deaccumulate the number.
73 *byte = self.digit(n.to_u8()); // Store the digit in the buffer.
76 // No more digits left to accumulate.
81 // Do the same as above, but accounting for two's complement.
82 for byte in buf.iter_mut().rev() {
83 let n = zero - (x % base); // Get the current place value.
84 x = x / base; // Deaccumulate the number.
85 *byte = self.digit(n.to_u8()); // Store the digit in the buffer.
88 // No more digits left to accumulate.
93 let buf = unsafe { str::from_utf8_unchecked(&buf[curr..]) };
94 f.pad_integral(is_positive, self.prefix(), buf)
98 /// A binary (base 2) radix
99 #[derive(Clone, PartialEq)]
102 /// An octal (base 8) radix
103 #[derive(Clone, PartialEq)]
106 /// A decimal (base 10) radix
107 #[derive(Clone, PartialEq)]
110 /// A hexadecimal (base 16) radix, formatted with lower-case characters
111 #[derive(Clone, PartialEq)]
114 /// A hexadecimal (base 16) radix, formatted with upper-case characters
115 #[derive(Clone, PartialEq)]
119 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
120 impl GenericRadix for $T {
121 fn base(&self) -> u8 { $base }
122 fn prefix(&self) -> &'static str { $prefix }
123 fn digit(&self, x: u8) -> u8 {
126 x => panic!("number not in the range 0..{}: {}", self.base() - 1, x),
133 radix! { Binary, 2, "0b", x @ 0 ... 2 => b'0' + x }
134 radix! { Octal, 8, "0o", x @ 0 ... 7 => b'0' + x }
135 radix! { Decimal, 10, "", x @ 0 ... 9 => b'0' + x }
136 radix! { LowerHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
137 x @ 10 ... 15 => b'a' + (x - 10) }
138 radix! { UpperHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
139 x @ 10 ... 15 => b'A' + (x - 10) }
141 /// A radix with in the range of `2..36`.
142 #[derive(Clone, Copy, PartialEq)]
143 #[unstable(feature = "fmt_radix",
144 reason = "may be renamed or move to a different module",
151 fn new(base: u8) -> Radix {
152 assert!(2 <= base && base <= 36,
153 "the base must be in the range of 2..36: {}",
159 impl GenericRadix for Radix {
160 fn base(&self) -> u8 {
163 fn digit(&self, x: u8) -> u8 {
165 x @ 0 ... 9 => b'0' + x,
166 x if x < self.base() => b'a' + (x - 10),
167 x => panic!("number not in the range 0..{}: {}", self.base() - 1, x),
172 /// A helper type for formatting radixes.
173 #[unstable(feature = "fmt_radix",
174 reason = "may be renamed or move to a different module",
176 #[derive(Copy, Clone)]
177 pub struct RadixFmt<T, R>(T, R);
179 /// Constructs a radix formatter in the range of `2..36`.
184 /// #![feature(fmt_radix)]
186 /// use std::fmt::radix;
187 /// assert_eq!(format!("{}", radix(55, 36)), "1j".to_string());
189 #[unstable(feature = "fmt_radix",
190 reason = "may be renamed or move to a different module",
192 pub fn radix<T>(x: T, base: u8) -> RadixFmt<T, Radix> {
193 RadixFmt(x, Radix::new(base))
196 macro_rules! radix_fmt {
197 ($T:ty as $U:ty, $fmt:ident) => {
198 #[stable(feature = "rust1", since = "1.0.0")]
199 impl fmt::Debug for RadixFmt<$T, Radix> {
200 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
201 fmt::Display::fmt(self, f)
204 #[stable(feature = "rust1", since = "1.0.0")]
205 impl fmt::Display for RadixFmt<$T, Radix> {
206 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
207 match *self { RadixFmt(ref x, radix) => radix.$fmt(*x as $U, f) }
213 macro_rules! int_base {
214 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
215 #[stable(feature = "rust1", since = "1.0.0")]
216 impl fmt::$Trait for $T {
217 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
218 $Radix.fmt_int(*self as $U, f)
226 #[stable(feature = "rust1", since = "1.0.0")]
227 impl fmt::Debug for $T {
228 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
229 fmt::Display::fmt(self, f)
235 macro_rules! integer {
236 ($Int:ident, $Uint:ident) => {
237 int_base! { Binary for $Int as $Uint -> Binary }
238 int_base! { Octal for $Int as $Uint -> Octal }
239 int_base! { LowerHex for $Int as $Uint -> LowerHex }
240 int_base! { UpperHex for $Int as $Uint -> UpperHex }
241 radix_fmt! { $Int as $Int, fmt_int }
244 int_base! { Binary for $Uint as $Uint -> Binary }
245 int_base! { Octal for $Uint as $Uint -> Octal }
246 int_base! { LowerHex for $Uint as $Uint -> LowerHex }
247 int_base! { UpperHex for $Uint as $Uint -> UpperHex }
248 radix_fmt! { $Uint as $Uint, fmt_int }
252 integer! { isize, usize }
254 integer! { i16, u16 }
255 integer! { i32, u32 }
256 integer! { i64, u64 }
258 const DEC_DIGITS_LUT: &'static[u8] =
259 b"0001020304050607080910111213141516171819\
260 2021222324252627282930313233343536373839\
261 4041424344454647484950515253545556575859\
262 6061626364656667686970717273747576777879\
263 8081828384858687888990919293949596979899";
265 macro_rules! impl_Display {
266 ($($t:ident),*: $conv_fn:ident) => ($(
267 impl fmt::Display for $t {
268 #[allow(unused_comparisons)]
269 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
270 let is_positive = *self >= 0;
271 let mut n = if is_positive {
274 // convert the negative num to positive by summing 1 to it's 2 complement
275 (!self.$conv_fn()).wrapping_add(1)
277 let mut buf: [u8; 20] = unsafe { mem::uninitialized() };
278 let mut curr = buf.len() as isize;
279 let buf_ptr = buf.as_mut_ptr();
280 let lut_ptr = DEC_DIGITS_LUT.as_ptr();
283 // eagerly decode 4 characters at a time
284 if <$t>::max_value() as u64 >= 10000 {
286 let rem = (n % 10000) as isize;
289 let d1 = (rem / 100) << 1;
290 let d2 = (rem % 100) << 1;
292 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
293 ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
297 // if we reach here numbers are <= 9999, so at most 4 chars long
298 let mut n = n as isize; // possibly reduce 64bit math
300 // decode 2 more chars, if > 2 chars
302 let d1 = (n % 100) << 1;
305 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
308 // decode last 1 or 2 chars
311 *buf_ptr.offset(curr) = (n as u8) + 48;
315 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
319 let buf_slice = unsafe {
320 str::from_utf8_unchecked(
321 slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize))
323 f.pad_integral(is_positive, "", buf_slice)
328 impl_Display!(i8, u8, i16, u16, i32, u32: to_u32);
329 impl_Display!(i64, u64: to_u64);
330 #[cfg(target_pointer_width = "32")]
331 impl_Display!(isize, usize: to_u32);
332 #[cfg(target_pointer_width = "64")]
333 impl_Display!(isize, usize: to_u64);