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 { "" }
53 /// Converts an integer to corresponding radix digit.
54 fn digit(&self, x: u8) -> u8;
56 /// Format an integer using the radix using a formatter.
57 fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
58 // The radix can be as low as 2, so we need a buffer of at least 64
59 // characters for a base 2 number.
61 let is_positive = x >= zero;
62 let mut buf = [0; 64];
63 let mut curr = buf.len();
64 let base = T::from_u8(self.base());
66 // Accumulate each digit of the number from the least significant
67 // to the most significant figure.
68 for byte in buf.iter_mut().rev() {
69 let n = x % base; // Get the current place value.
70 x = x / base; // Deaccumulate the number.
71 *byte = self.digit(n.to_u8()); // Store the digit in the buffer.
73 if x == zero { break }; // No more digits left to accumulate.
76 // Do the same as above, but accounting for two's complement.
77 for byte in buf.iter_mut().rev() {
78 let n = zero - (x % base); // Get the current place value.
79 x = x / base; // Deaccumulate the number.
80 *byte = self.digit(n.to_u8()); // Store the digit in the buffer.
82 if x == zero { break }; // No more digits left to accumulate.
85 let buf = unsafe { str::from_utf8_unchecked(&buf[curr..]) };
86 f.pad_integral(is_positive, self.prefix(), buf)
90 /// A binary (base 2) radix
91 #[derive(Clone, PartialEq)]
94 /// An octal (base 8) radix
95 #[derive(Clone, PartialEq)]
98 /// A decimal (base 10) radix
99 #[derive(Clone, PartialEq)]
102 /// A hexadecimal (base 16) radix, formatted with lower-case characters
103 #[derive(Clone, PartialEq)]
106 /// A hexadecimal (base 16) radix, formatted with upper-case characters
107 #[derive(Clone, PartialEq)]
111 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
112 impl GenericRadix for $T {
113 fn base(&self) -> u8 { $base }
114 fn prefix(&self) -> &'static str { $prefix }
115 fn digit(&self, x: u8) -> u8 {
118 x => panic!("number not in the range 0..{}: {}", self.base() - 1, x),
125 radix! { Binary, 2, "0b", x @ 0 ... 2 => b'0' + x }
126 radix! { Octal, 8, "0o", x @ 0 ... 7 => b'0' + x }
127 radix! { Decimal, 10, "", x @ 0 ... 9 => b'0' + x }
128 radix! { LowerHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
129 x @ 10 ... 15 => b'a' + (x - 10) }
130 radix! { UpperHex, 16, "0x", x @ 0 ... 9 => b'0' + x,
131 x @ 10 ... 15 => b'A' + (x - 10) }
133 /// A radix with in the range of `2..36`.
134 #[derive(Clone, Copy, PartialEq)]
135 #[unstable(feature = "fmt_radix",
136 reason = "may be renamed or move to a different module",
143 fn new(base: u8) -> Radix {
144 assert!(2 <= base && base <= 36, "the base must be in the range of 2..36: {}", base);
149 impl GenericRadix for Radix {
150 fn base(&self) -> u8 { self.base }
151 fn digit(&self, x: u8) -> u8 {
153 x @ 0 ... 9 => b'0' + x,
154 x if x < self.base() => b'a' + (x - 10),
155 x => panic!("number not in the range 0..{}: {}", self.base() - 1, x),
160 /// A helper type for formatting radixes.
161 #[unstable(feature = "fmt_radix",
162 reason = "may be renamed or move to a different module",
164 #[derive(Copy, Clone)]
165 pub struct RadixFmt<T, R>(T, R);
167 /// Constructs a radix formatter in the range of `2..36`.
172 /// #![feature(fmt_radix)]
174 /// use std::fmt::radix;
175 /// assert_eq!(format!("{}", radix(55, 36)), "1j".to_string());
177 #[unstable(feature = "fmt_radix",
178 reason = "may be renamed or move to a different module",
180 pub fn radix<T>(x: T, base: u8) -> RadixFmt<T, Radix> {
181 RadixFmt(x, Radix::new(base))
184 macro_rules! radix_fmt {
185 ($T:ty as $U:ty, $fmt:ident) => {
186 #[stable(feature = "rust1", since = "1.0.0")]
187 impl fmt::Debug for RadixFmt<$T, Radix> {
188 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
189 fmt::Display::fmt(self, f)
192 #[stable(feature = "rust1", since = "1.0.0")]
193 impl fmt::Display for RadixFmt<$T, Radix> {
194 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
195 match *self { RadixFmt(ref x, radix) => radix.$fmt(*x as $U, f) }
201 macro_rules! int_base {
202 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
203 #[stable(feature = "rust1", since = "1.0.0")]
204 impl fmt::$Trait for $T {
205 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
206 $Radix.fmt_int(*self as $U, f)
214 #[stable(feature = "rust1", since = "1.0.0")]
215 impl fmt::Debug for $T {
216 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
217 fmt::Display::fmt(self, f)
223 macro_rules! integer {
224 ($Int:ident, $Uint:ident) => {
225 int_base! { Binary for $Int as $Uint -> Binary }
226 int_base! { Octal for $Int as $Uint -> Octal }
227 int_base! { LowerHex for $Int as $Uint -> LowerHex }
228 int_base! { UpperHex for $Int as $Uint -> UpperHex }
229 radix_fmt! { $Int as $Int, fmt_int }
232 int_base! { Binary for $Uint as $Uint -> Binary }
233 int_base! { Octal for $Uint as $Uint -> Octal }
234 int_base! { LowerHex for $Uint as $Uint -> LowerHex }
235 int_base! { UpperHex for $Uint as $Uint -> UpperHex }
236 radix_fmt! { $Uint as $Uint, fmt_int }
240 integer! { isize, usize }
242 integer! { i16, u16 }
243 integer! { i32, u32 }
244 integer! { i64, u64 }
246 const DEC_DIGITS_LUT: &'static[u8] =
247 b"0001020304050607080910111213141516171819\
248 2021222324252627282930313233343536373839\
249 4041424344454647484950515253545556575859\
250 6061626364656667686970717273747576777879\
251 8081828384858687888990919293949596979899";
253 macro_rules! impl_Display {
254 ($($t:ident),*: $conv_fn:ident) => ($(
255 impl fmt::Display for $t {
256 #[allow(unused_comparisons)]
257 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
258 let is_positive = *self >= 0;
259 let mut n = if is_positive {
262 // convert the negative num to positive by summing 1 to it's 2 complement
263 (!self.$conv_fn()).wrapping_add(1)
265 let mut buf: [u8; 20] = unsafe { mem::uninitialized() };
266 let mut curr = buf.len() as isize;
267 let buf_ptr = buf.as_mut_ptr();
268 let lut_ptr = DEC_DIGITS_LUT.as_ptr();
271 // eagerly decode 4 characters at a time
272 if <$t>::max_value() as u64 >= 10000 {
274 let rem = (n % 10000) as isize;
277 let d1 = (rem / 100) << 1;
278 let d2 = (rem % 100) << 1;
280 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
281 ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
285 // if we reach here numbers are <= 9999, so at most 4 chars long
286 let mut n = n as isize; // possibly reduce 64bit math
288 // decode 2 more chars, if > 2 chars
290 let d1 = (n % 100) << 1;
293 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
296 // decode last 1 or 2 chars
299 *buf_ptr.offset(curr) = (n as u8) + 48;
303 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
307 let buf_slice = unsafe {
308 str::from_utf8_unchecked(
309 slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize))
311 f.pad_integral(is_positive, "", buf_slice)
316 impl_Display!(i8, u8, i16, u16, i32, u32: to_u32);
317 impl_Display!(i64, u64: to_u64);
318 #[cfg(target_pointer_width = "32")]
319 impl_Display!(isize, usize: to_u32);
320 #[cfg(target_pointer_width = "64")]
321 impl_Display!(isize, usize: to_u64);