1 //! Integer and floating-point number formatting
7 use ops::{Div, Rem, Sub};
14 trait Int: PartialEq + PartialOrd + Div<Output=Self> + Rem<Output=Self> +
15 Sub<Output=Self> + Copy {
17 fn from_u8(u: u8) -> Self;
18 fn to_u8(&self) -> u8;
19 fn to_u16(&self) -> u16;
20 fn to_u32(&self) -> u32;
21 fn to_u64(&self) -> u64;
22 fn to_u128(&self) -> u128;
26 ($($t:ident)*) => ($(impl Int for $t {
28 fn from_u8(u: u8) -> $t { u as $t }
29 fn to_u8(&self) -> u8 { *self as u8 }
30 fn to_u16(&self) -> u16 { *self as u16 }
31 fn to_u32(&self) -> u32 { *self as u32 }
32 fn to_u64(&self) -> u64 { *self as u64 }
33 fn to_u128(&self) -> u128 { *self as u128 }
36 doit! { i8 i16 i32 i64 i128 isize u8 u16 u32 u64 u128 usize }
38 /// A type that represents a specific radix
41 /// The number of digits.
44 /// A radix-specific prefix string.
45 const PREFIX: &'static str;
47 /// Converts an integer to corresponding radix digit.
48 fn digit(x: u8) -> u8;
50 /// Format an integer using the radix using a formatter.
51 fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
52 // The radix can be as low as 2, so we need a buffer of at least 128
53 // characters for a base 2 number.
55 let is_nonnegative = x >= zero;
56 let mut buf: [u8; 128] = unsafe { mem::uninitialized() };
57 let mut curr = buf.len();
58 let base = T::from_u8(Self::BASE);
60 // Accumulate each digit of the number from the least significant
61 // to the most significant figure.
62 for byte in buf.iter_mut().rev() {
63 let n = x % base; // Get the current place value.
64 x = x / base; // Deaccumulate the number.
65 *byte = Self::digit(n.to_u8()); // Store the digit in the buffer.
68 // No more digits left to accumulate.
73 // Do the same as above, but accounting for two's complement.
74 for byte in buf.iter_mut().rev() {
75 let n = zero - (x % base); // Get the current place value.
76 x = x / base; // Deaccumulate the number.
77 *byte = Self::digit(n.to_u8()); // Store the digit in the buffer.
80 // No more digits left to accumulate.
85 let buf = unsafe { str::from_utf8_unchecked(&buf[curr..]) };
86 f.pad_integral(is_nonnegative, 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 hexadecimal (base 16) radix, formatted with lower-case characters
99 #[derive(Clone, PartialEq)]
102 /// A hexadecimal (base 16) radix, formatted with upper-case characters
103 #[derive(Clone, PartialEq)]
107 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
108 impl GenericRadix for $T {
109 const BASE: u8 = $base;
110 const PREFIX: &'static str = $prefix;
111 fn digit(x: u8) -> u8 {
114 x => panic!("number not in the range 0..={}: {}", Self::BASE - 1, x),
121 radix! { Binary, 2, "0b", x @ 0 ..= 1 => b'0' + x }
122 radix! { Octal, 8, "0o", x @ 0 ..= 7 => b'0' + x }
123 radix! { LowerHex, 16, "0x", x @ 0 ..= 9 => b'0' + x,
124 x @ 10 ..= 15 => b'a' + (x - 10) }
125 radix! { UpperHex, 16, "0x", x @ 0 ..= 9 => b'0' + x,
126 x @ 10 ..= 15 => b'A' + (x - 10) }
128 macro_rules! int_base {
129 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
130 #[stable(feature = "rust1", since = "1.0.0")]
131 impl fmt::$Trait for $T {
132 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
133 $Radix.fmt_int(*self as $U, f)
141 #[stable(feature = "rust1", since = "1.0.0")]
142 impl fmt::Debug for $T {
144 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
145 if f.debug_lower_hex() {
146 fmt::LowerHex::fmt(self, f)
147 } else if f.debug_upper_hex() {
148 fmt::UpperHex::fmt(self, f)
150 fmt::Display::fmt(self, f)
157 macro_rules! integer {
158 ($Int:ident, $Uint:ident) => {
159 int_base! { Binary for $Int as $Uint -> Binary }
160 int_base! { Octal for $Int as $Uint -> Octal }
161 int_base! { LowerHex for $Int as $Uint -> LowerHex }
162 int_base! { UpperHex for $Int as $Uint -> UpperHex }
165 int_base! { Binary for $Uint as $Uint -> Binary }
166 int_base! { Octal for $Uint as $Uint -> Octal }
167 int_base! { LowerHex for $Uint as $Uint -> LowerHex }
168 int_base! { UpperHex for $Uint as $Uint -> UpperHex }
172 integer! { isize, usize }
174 integer! { i16, u16 }
175 integer! { i32, u32 }
176 integer! { i64, u64 }
177 integer! { i128, u128 }
179 const DEC_DIGITS_LUT: &'static[u8] =
180 b"0001020304050607080910111213141516171819\
181 2021222324252627282930313233343536373839\
182 4041424344454647484950515253545556575859\
183 6061626364656667686970717273747576777879\
184 8081828384858687888990919293949596979899";
186 macro_rules! impl_Display {
187 ($($t:ident),*: $conv_fn:ident) => ($(
188 #[stable(feature = "rust1", since = "1.0.0")]
189 impl fmt::Display for $t {
190 #[allow(unused_comparisons)]
191 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
192 let is_nonnegative = *self >= 0;
193 let mut n = if is_nonnegative {
196 // convert the negative num to positive by summing 1 to it's 2 complement
197 (!self.$conv_fn()).wrapping_add(1)
199 let mut buf: [u8; 39] = unsafe { mem::uninitialized() };
200 let mut curr = buf.len() as isize;
201 let buf_ptr = buf.as_mut_ptr();
202 let lut_ptr = DEC_DIGITS_LUT.as_ptr();
205 // need at least 16 bits for the 4-characters-at-a-time to work.
206 if ::mem::size_of::<$t>() >= 2 {
207 // eagerly decode 4 characters at a time
209 let rem = (n % 10000) as isize;
212 let d1 = (rem / 100) << 1;
213 let d2 = (rem % 100) << 1;
215 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
216 ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
220 // if we reach here numbers are <= 9999, so at most 4 chars long
221 let mut n = n as isize; // possibly reduce 64bit math
223 // decode 2 more chars, if > 2 chars
225 let d1 = (n % 100) << 1;
228 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
231 // decode last 1 or 2 chars
234 *buf_ptr.offset(curr) = (n as u8) + b'0';
238 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
242 let buf_slice = unsafe {
243 str::from_utf8_unchecked(
244 slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize))
246 f.pad_integral(is_nonnegative, "", buf_slice)
251 impl_Display!(i8, u8, i16, u16, i32, u32: to_u32);
252 impl_Display!(i64, u64: to_u64);
253 impl_Display!(i128, u128: to_u128);
254 #[cfg(target_pointer_width = "16")]
255 impl_Display!(isize, usize: to_u16);
256 #[cfg(target_pointer_width = "32")]
257 impl_Display!(isize, usize: to_u32);
258 #[cfg(target_pointer_width = "64")]
259 impl_Display!(isize, usize: to_u64);