1 //! Integer and floating-point number formatting
5 use ops::{Div, Rem, Sub};
12 trait Int: PartialEq + PartialOrd + Div<Output=Self> + Rem<Output=Self> +
13 Sub<Output=Self> + Copy {
15 fn from_u8(u: u8) -> Self;
16 fn to_u8(&self) -> u8;
17 fn to_u16(&self) -> u16;
18 fn to_u32(&self) -> u32;
19 fn to_u64(&self) -> u64;
20 fn to_u128(&self) -> u128;
24 ($($t:ident)*) => ($(impl Int for $t {
26 fn from_u8(u: u8) -> $t { u as $t }
27 fn to_u8(&self) -> u8 { *self as u8 }
28 fn to_u16(&self) -> u16 { *self as u16 }
29 fn to_u32(&self) -> u32 { *self as u32 }
30 fn to_u64(&self) -> u64 { *self as u64 }
31 fn to_u128(&self) -> u128 { *self as u128 }
34 doit! { i8 i16 i32 i64 i128 isize u8 u16 u32 u64 u128 usize }
36 /// A type that represents a specific radix
39 /// The number of digits.
42 /// A radix-specific prefix string.
43 const PREFIX: &'static str;
45 /// Converts an integer to corresponding radix digit.
46 fn digit(x: u8) -> u8;
48 /// Format an integer using the radix using a formatter.
49 fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
50 // The radix can be as low as 2, so we need a buffer of at least 128
51 // characters for a base 2 number.
53 let is_nonnegative = x >= zero;
54 let mut buf = uninitialized_array![u8; 128];
55 let mut curr = buf.len();
56 let base = T::from_u8(Self::BASE);
58 // Accumulate each digit of the number from the least significant
59 // to the most significant figure.
60 for byte in buf.iter_mut().rev() {
61 let n = x % base; // Get the current place value.
62 x = x / base; // Deaccumulate the number.
63 byte.set(Self::digit(n.to_u8())); // Store the digit in the buffer.
66 // No more digits left to accumulate.
71 // Do the same as above, but accounting for two's complement.
72 for byte in buf.iter_mut().rev() {
73 let n = zero - (x % base); // Get the current place value.
74 x = x / base; // Deaccumulate the number.
75 byte.set(Self::digit(n.to_u8())); // Store the digit in the buffer.
78 // No more digits left to accumulate.
83 let buf = &buf[curr..];
84 let buf = unsafe { str::from_utf8_unchecked(slice::from_raw_parts(
85 MaybeUninit::first_ptr(buf),
88 f.pad_integral(is_nonnegative, Self::PREFIX, buf)
92 /// A binary (base 2) radix
93 #[derive(Clone, PartialEq)]
96 /// An octal (base 8) radix
97 #[derive(Clone, PartialEq)]
100 /// A hexadecimal (base 16) radix, formatted with lower-case characters
101 #[derive(Clone, PartialEq)]
104 /// A hexadecimal (base 16) radix, formatted with upper-case characters
105 #[derive(Clone, PartialEq)]
109 ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
110 impl GenericRadix for $T {
111 const BASE: u8 = $base;
112 const PREFIX: &'static str = $prefix;
113 fn digit(x: u8) -> u8 {
116 x => panic!("number not in the range 0..={}: {}", Self::BASE - 1, x),
123 radix! { Binary, 2, "0b", x @ 0 ..= 1 => b'0' + x }
124 radix! { Octal, 8, "0o", x @ 0 ..= 7 => b'0' + x }
125 radix! { LowerHex, 16, "0x", x @ 0 ..= 9 => b'0' + x,
126 x @ 10 ..= 15 => b'a' + (x - 10) }
127 radix! { UpperHex, 16, "0x", x @ 0 ..= 9 => b'0' + x,
128 x @ 10 ..= 15 => b'A' + (x - 10) }
130 macro_rules! int_base {
131 ($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
132 #[stable(feature = "rust1", since = "1.0.0")]
133 impl fmt::$Trait for $T {
134 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
135 $Radix.fmt_int(*self as $U, f)
143 #[stable(feature = "rust1", since = "1.0.0")]
144 impl fmt::Debug for $T {
146 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
147 if f.debug_lower_hex() {
148 fmt::LowerHex::fmt(self, f)
149 } else if f.debug_upper_hex() {
150 fmt::UpperHex::fmt(self, f)
152 fmt::Display::fmt(self, f)
159 macro_rules! integer {
160 ($Int:ident, $Uint:ident) => {
161 int_base! { Binary for $Int as $Uint -> Binary }
162 int_base! { Octal for $Int as $Uint -> Octal }
163 int_base! { LowerHex for $Int as $Uint -> LowerHex }
164 int_base! { UpperHex for $Int as $Uint -> UpperHex }
167 int_base! { Binary for $Uint as $Uint -> Binary }
168 int_base! { Octal for $Uint as $Uint -> Octal }
169 int_base! { LowerHex for $Uint as $Uint -> LowerHex }
170 int_base! { UpperHex for $Uint as $Uint -> UpperHex }
174 integer! { isize, usize }
176 integer! { i16, u16 }
177 integer! { i32, u32 }
178 integer! { i64, u64 }
179 integer! { i128, u128 }
181 const DEC_DIGITS_LUT: &'static[u8] =
182 b"0001020304050607080910111213141516171819\
183 2021222324252627282930313233343536373839\
184 4041424344454647484950515253545556575859\
185 6061626364656667686970717273747576777879\
186 8081828384858687888990919293949596979899";
188 macro_rules! impl_Display {
189 ($($t:ident),*: $conv_fn:ident) => ($(
190 #[stable(feature = "rust1", since = "1.0.0")]
191 impl fmt::Display for $t {
192 #[allow(unused_comparisons)]
193 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
194 let is_nonnegative = *self >= 0;
195 let mut n = if is_nonnegative {
198 // convert the negative num to positive by summing 1 to it's 2 complement
199 (!self.$conv_fn()).wrapping_add(1)
201 let mut buf = uninitialized_array![u8; 39];
202 let mut curr = buf.len() as isize;
203 let buf_ptr = MaybeUninit::first_ptr_mut(&mut buf);
204 let lut_ptr = DEC_DIGITS_LUT.as_ptr();
207 // need at least 16 bits for the 4-characters-at-a-time to work.
208 if ::mem::size_of::<$t>() >= 2 {
209 // eagerly decode 4 characters at a time
211 let rem = (n % 10000) as isize;
214 let d1 = (rem / 100) << 1;
215 let d2 = (rem % 100) << 1;
217 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
218 ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
222 // if we reach here numbers are <= 9999, so at most 4 chars long
223 let mut n = n as isize; // possibly reduce 64bit math
225 // decode 2 more chars, if > 2 chars
227 let d1 = (n % 100) << 1;
230 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
233 // decode last 1 or 2 chars
236 *buf_ptr.offset(curr) = (n as u8) + b'0';
240 ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
244 let buf_slice = unsafe {
245 str::from_utf8_unchecked(
246 slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize))
248 f.pad_integral(is_nonnegative, "", buf_slice)
253 impl_Display!(i8, u8, i16, u16, i32, u32: to_u32);
254 impl_Display!(i64, u64: to_u64);
255 impl_Display!(i128, u128: to_u128);
256 #[cfg(target_pointer_width = "16")]
257 impl_Display!(isize, usize: to_u16);
258 #[cfg(target_pointer_width = "32")]
259 impl_Display!(isize, usize: to_u32);
260 #[cfg(target_pointer_width = "64")]
261 impl_Display!(isize, usize: to_u64);