c0fa8764ef
Sadly there's still a lot of open issues, but this tackles some of the more pressing ones. Each commit has its own description along with the issues it closes.
196 lines
6.5 KiB
Rust
196 lines
6.5 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Integer and floating-point number formatting
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// FIXME: #6220 Implement floating point formatting
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#![allow(unsigned_negate)]
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use collections::Collection;
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use fmt;
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use iter::DoubleEndedIterator;
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use num::{Int, cast, zero};
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use slice::{ImmutableVector, MutableVector};
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#[cfg(stage0)]
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use iter::Iterator; // NOTE(stage0): Remove after snapshot.
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#[cfg(stage0)]
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use option::{Some, None}; // NOTE(stage0): Remove after snapshot.
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/// A type that represents a specific radix
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#[doc(hidden)]
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trait GenericRadix {
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/// The number of digits.
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fn base(&self) -> u8;
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/// A radix-specific prefix string.
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fn prefix(&self) -> &'static str { "" }
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/// Converts an integer to corresponding radix digit.
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fn digit(&self, x: u8) -> u8;
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/// Format an integer using the radix using a formatter.
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fn fmt_int<T: Int>(&self, mut x: T, f: &mut fmt::Formatter) -> fmt::Result {
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// The radix can be as low as 2, so we need a buffer of at least 64
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// characters for a base 2 number.
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let mut buf = [0u8, ..64];
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let base = cast(self.base()).unwrap();
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let mut curr = buf.len();
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let is_positive = x >= zero();
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if is_positive {
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// Accumulate each digit of the number from the least significant
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// to the most significant figure.
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for byte in buf.mut_iter().rev() {
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let n = x % base; // Get the current place value.
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x = x / base; // Deaccumulate the number.
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*byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
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curr -= 1;
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if x == zero() { break; } // No more digits left to accumulate.
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}
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} else {
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// Do the same as above, but accounting for two's complement.
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for byte in buf.mut_iter().rev() {
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let n = -(x % base); // Get the current place value.
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x = x / base; // Deaccumulate the number.
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*byte = self.digit(cast(n).unwrap()); // Store the digit in the buffer.
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curr -= 1;
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if x == zero() { break; } // No more digits left to accumulate.
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}
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}
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f.pad_integral(is_positive, self.prefix(), buf.slice_from(curr))
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}
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}
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/// A binary (base 2) radix
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#[deriving(Clone, PartialEq)]
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struct Binary;
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/// An octal (base 8) radix
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#[deriving(Clone, PartialEq)]
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struct Octal;
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/// A decimal (base 10) radix
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#[deriving(Clone, PartialEq)]
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struct Decimal;
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/// A hexadecimal (base 16) radix, formatted with lower-case characters
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#[deriving(Clone, PartialEq)]
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struct LowerHex;
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/// A hexadecimal (base 16) radix, formatted with upper-case characters
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#[deriving(Clone, PartialEq)]
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pub struct UpperHex;
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macro_rules! radix {
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($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
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impl GenericRadix for $T {
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fn base(&self) -> u8 { $base }
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fn prefix(&self) -> &'static str { $prefix }
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fn digit(&self, x: u8) -> u8 {
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match x {
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$($x => $conv,)+
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x => fail!("number not in the range 0..{}: {}", self.base() - 1, x),
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}
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}
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}
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}
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}
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radix!(Binary, 2, "0b", x @ 0 .. 2 => '0' as u8 + x)
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radix!(Octal, 8, "0o", x @ 0 .. 7 => '0' as u8 + x)
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radix!(Decimal, 10, "", x @ 0 .. 9 => '0' as u8 + x)
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radix!(LowerHex, 16, "0x", x @ 0 .. 9 => '0' as u8 + x,
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x @ 10 ..15 => 'a' as u8 + (x - 10))
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radix!(UpperHex, 16, "0x", x @ 0 .. 9 => '0' as u8 + x,
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x @ 10 ..15 => 'A' as u8 + (x - 10))
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/// A radix with in the range of `2..36`.
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#[deriving(Clone, PartialEq)]
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pub struct Radix {
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base: u8,
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}
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impl Radix {
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fn new(base: u8) -> Radix {
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assert!(2 <= base && base <= 36, "the base must be in the range of 2..36: {}", base);
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Radix { base: base }
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}
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}
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impl GenericRadix for Radix {
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fn base(&self) -> u8 { self.base }
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fn digit(&self, x: u8) -> u8 {
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match x {
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x @ 0 ..9 => '0' as u8 + x,
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x if x < self.base() => 'a' as u8 + (x - 10),
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x => fail!("number not in the range 0..{}: {}", self.base() - 1, x),
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}
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}
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}
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/// A helper type for formatting radixes.
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pub struct RadixFmt<T, R>(T, R);
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/// Constructs a radix formatter in the range of `2..36`.
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///
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/// # Example
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///
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/// ~~~
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/// use std::fmt::radix;
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/// assert_eq!(format!("{}", radix(55i, 36)), "1j".to_string());
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/// ~~~
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pub fn radix<T>(x: T, base: u8) -> RadixFmt<T, Radix> {
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RadixFmt(x, Radix::new(base))
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}
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macro_rules! radix_fmt {
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($T:ty as $U:ty, $fmt:ident) => {
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impl fmt::Show for RadixFmt<$T, Radix> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match *self { RadixFmt(ref x, radix) => radix.$fmt(*x as $U, f) }
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}
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}
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}
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}
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macro_rules! int_base {
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($Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
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impl fmt::$Trait for $T {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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$Radix.fmt_int(*self as $U, f)
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}
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}
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}
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}
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macro_rules! integer {
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($Int:ident, $Uint:ident) => {
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int_base!(Show for $Int as $Int -> Decimal)
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int_base!(Signed for $Int as $Int -> Decimal)
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int_base!(Binary for $Int as $Uint -> Binary)
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int_base!(Octal for $Int as $Uint -> Octal)
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int_base!(LowerHex for $Int as $Uint -> LowerHex)
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int_base!(UpperHex for $Int as $Uint -> UpperHex)
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radix_fmt!($Int as $Int, fmt_int)
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int_base!(Show for $Uint as $Uint -> Decimal)
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int_base!(Unsigned for $Uint as $Uint -> Decimal)
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int_base!(Binary for $Uint as $Uint -> Binary)
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int_base!(Octal for $Uint as $Uint -> Octal)
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int_base!(LowerHex for $Uint as $Uint -> LowerHex)
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int_base!(UpperHex for $Uint as $Uint -> UpperHex)
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radix_fmt!($Uint as $Uint, fmt_int)
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}
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}
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integer!(int, uint)
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integer!(i8, u8)
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integer!(i16, u16)
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integer!(i32, u32)
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integer!(i64, u64)
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