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
17 use ops::{Div, Rem, Sub};
24 trait Int: PartialEq + PartialOrd + Div<Output=Self> + Rem<Output=Self> +
25 Sub<Output=Self> + Copy {
27 fn from_u8(u: u8) -> Self;
28 fn to_u8(&self) -> u8;
29 fn to_u16(&self) -> u16;
30 fn to_u32(&self) -> u32;
31 fn to_u64(&self) -> u64;
32 fn to_u128(&self) -> u128;
36 ($($t:ident)*) => ($(impl Int for $t {
38 fn from_u8(u: u8) -> $t { u as $t }
39 fn to_u8(&self) -> u8 { *self as u8 }
40 fn to_u16(&self) -> u16 { *self as u16 }
41 fn to_u32(&self) -> u32 { *self as u32 }
42 fn to_u64(&self) -> u64 { *self as u64 }
43 fn to_u128(&self) -> u128 { *self as u128 }
46 doit! { i8 i16 i32 i64 i128 isize u8 u16 u32 u64 u128 usize }
48 /// A type that represents a specific radix
51 /// The number of digits.
54 /// A radix-specific prefix string.
55 const PREFIX: &'static str;
57 /// Converts an integer to corresponding radix digit.
58 fn digit(x: u8) -> u8;
60 /// Format an integer using the radix using a formatter.
61 fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
62 // The radix can be as low as 2, so we need a buffer of at least 128
63 // characters for a base 2 number.
65 let is_nonnegative = x >= zero;
66 let mut buf: [u8; 128] = unsafe { mem::uninitialized() };
67 let mut curr = buf.len();
68 let base = T::from_u8(Self::BASE);
70 // Accumulate each digit of the number from the least significant
71 // to the most significant figure.
72 for byte in buf.iter_mut().rev() {
73 let n = x % base; // Get the current place value.
74 x = x / base; // Deaccumulate the number.
75 *byte = Self::digit(n.to_u8()); // Store the digit in the buffer.
78 // No more digits left to accumulate.
83 // Do the same as above, but accounting for two's complement.
84 for byte in buf.iter_mut().rev() {
85 let n = zero - (x % base); // Get the current place value.
86 x = x / base; // Deaccumulate the number.
87 *byte = Self::digit(n.to_u8()); // Store the digit in the buffer.
90 // No more digits left to accumulate.
95 let buf = unsafe { str::from_utf8_unchecked(&buf[curr..]) };
96 f.pad_integral(is_nonnegative, Self::PREFIX, buf)
100 /// A binary (base 2) radix
101 #[derive(Clone, PartialEq)]
104 /// An octal (base 8) radix
105 #[derive(Clone, PartialEq)]
108 /// A hexadecimal (base 16) radix, formatted with lower-case characters
109 #[derive(Clone, PartialEq)]
112 /// A hexadecimal (base 16) radix, formatted with upper-case characters
113 #[derive(Clone, PartialEq)]
117 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
118 impl GenericRadix for $T {
119 const BASE: u8 = $base;
120 const PREFIX: &'static str = $prefix;
121 fn digit(x: u8) -> u8 {
124 x => panic!("number not in the range 0..={}: {}", Self::BASE - 1, x),
131 radix! { Binary, 2, "0b", x @ 0 ..= 1 => b'0' + x }
132 radix! { Octal, 8, "0o", x @ 0 ..= 7 => b'0' + x }
133 radix! { LowerHex, 16, "0x", x @ 0 ..= 9 => b'0' + x,
134 x @ 10 ..= 15 => b'a' + (x - 10) }
135 radix! { UpperHex, 16, "0x", x @ 0 ..= 9 => b'0' + x,
136 x @ 10 ..= 15 => b'A' + (x - 10) }
138 macro_rules! int_base {
139 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
140 #[stable(feature = "rust1", since = "1.0.0")]
141 impl fmt::$Trait for $T {
142 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
143 $Radix.fmt_int(*self as $U, f)
151 #[stable(feature = "rust1", since = "1.0.0")]
152 impl fmt::Debug for $T {
154 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
155 if f.debug_lower_hex() {
156 fmt::LowerHex::fmt(self, f)
157 } else if f.debug_upper_hex() {
158 fmt::UpperHex::fmt(self, f)
160 fmt::Display::fmt(self, f)
167 macro_rules! integer {
168 ($Int:ident, $Uint:ident) => {
169 int_base! { Binary for $Int as $Uint -> Binary }
170 int_base! { Octal for $Int as $Uint -> Octal }
171 int_base! { LowerHex for $Int as $Uint -> LowerHex }
172 int_base! { UpperHex for $Int as $Uint -> UpperHex }
175 int_base! { Binary for $Uint as $Uint -> Binary }
176 int_base! { Octal for $Uint as $Uint -> Octal }
177 int_base! { LowerHex for $Uint as $Uint -> LowerHex }
178 int_base! { UpperHex for $Uint as $Uint -> UpperHex }
182 integer! { isize, usize }
184 integer! { i16, u16 }
185 integer! { i32, u32 }
186 integer! { i64, u64 }
187 integer! { i128, u128 }
189 const DEC_DIGITS_LUT: &'static[u8] =
190 b"0001020304050607080910111213141516171819\
191 2021222324252627282930313233343536373839\
192 4041424344454647484950515253545556575859\
193 6061626364656667686970717273747576777879\
194 8081828384858687888990919293949596979899";
196 macro_rules! impl_Display {
197 ($($t:ident),*: $conv_fn:ident) => ($(
198 #[stable(feature = "rust1", since = "1.0.0")]
199 impl fmt::Display for $t {
200 #[allow(unused_comparisons)]
201 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
202 let is_nonnegative = *self >= 0;
203 let mut n = if is_nonnegative {
206 // convert the negative num to positive by summing 1 to it's 2 complement
207 (!self.$conv_fn()).wrapping_add(1)
209 let mut buf: [u8; 39] = unsafe { mem::uninitialized() };
210 let mut curr = buf.len() as isize;
211 let buf_ptr = buf.as_mut_ptr();
212 let lut_ptr = DEC_DIGITS_LUT.as_ptr();
215 // need at least 16 bits for the 4-characters-at-a-time to work.
216 if ::mem::size_of::<$t>() >= 2 {
217 // eagerly decode 4 characters at a time
219 let rem = (n % 10000) as isize;
222 let d1 = (rem / 100) << 1;
223 let d2 = (rem % 100) << 1;
225 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
226 ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
230 // if we reach here numbers are <= 9999, so at most 4 chars long
231 let mut n = n as isize; // possibly reduce 64bit math
233 // decode 2 more chars, if > 2 chars
235 let d1 = (n % 100) << 1;
238 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
241 // decode last 1 or 2 chars
244 *buf_ptr.offset(curr) = (n as u8) + b'0';
248 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
252 let buf_slice = unsafe {
253 str::from_utf8_unchecked(
254 slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize))
256 f.pad_integral(is_nonnegative, "", buf_slice)
261 impl_Display!(i8, u8, i16, u16, i32, u32: to_u32);
262 impl_Display!(i64, u64: to_u64);
263 impl_Display!(i128, u128: to_u128);
264 #[cfg(target_pointer_width = "16")]
265 impl_Display!(isize, usize: to_u16);
266 #[cfg(target_pointer_width = "32")]
267 impl_Display!(isize, usize: to_u32);
268 #[cfg(target_pointer_width = "64")]
269 impl_Display!(isize, usize: to_u64);