370 lines
12 KiB
Rust
370 lines
12 KiB
Rust
// Copyright 2012-2014 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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//! Character manipulation.
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//!
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//! For more details, see ::unicode::char (a.k.a. std::char)
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#![allow(non_snake_case_functions)]
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#![doc(primitive = "char")]
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use mem::transmute;
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use option::{None, Option, Some};
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use iter::range_step;
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// UTF-8 ranges and tags for encoding characters
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static TAG_CONT: u8 = 0b1000_0000u8;
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static TAG_TWO_B: u8 = 0b1100_0000u8;
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static TAG_THREE_B: u8 = 0b1110_0000u8;
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static TAG_FOUR_B: u8 = 0b1111_0000u8;
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static MAX_ONE_B: u32 = 0x80u32;
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static MAX_TWO_B: u32 = 0x800u32;
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static MAX_THREE_B: u32 = 0x10000u32;
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static MAX_FOUR_B: u32 = 0x200000u32;
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/*
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Lu Uppercase_Letter an uppercase letter
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Ll Lowercase_Letter a lowercase letter
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Lt Titlecase_Letter a digraphic character, with first part uppercase
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Lm Modifier_Letter a modifier letter
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Lo Other_Letter other letters, including syllables and ideographs
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Mn Nonspacing_Mark a nonspacing combining mark (zero advance width)
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Mc Spacing_Mark a spacing combining mark (positive advance width)
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Me Enclosing_Mark an enclosing combining mark
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Nd Decimal_Number a decimal digit
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Nl Letter_Number a letterlike numeric character
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No Other_Number a numeric character of other type
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Pc Connector_Punctuation a connecting punctuation mark, like a tie
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Pd Dash_Punctuation a dash or hyphen punctuation mark
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Ps Open_Punctuation an opening punctuation mark (of a pair)
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Pe Close_Punctuation a closing punctuation mark (of a pair)
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Pi Initial_Punctuation an initial quotation mark
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Pf Final_Punctuation a final quotation mark
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Po Other_Punctuation a punctuation mark of other type
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Sm Math_Symbol a symbol of primarily mathematical use
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Sc Currency_Symbol a currency sign
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Sk Modifier_Symbol a non-letterlike modifier symbol
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So Other_Symbol a symbol of other type
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Zs Space_Separator a space character (of various non-zero widths)
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Zl Line_Separator U+2028 LINE SEPARATOR only
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Zp Paragraph_Separator U+2029 PARAGRAPH SEPARATOR only
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Cc Control a C0 or C1 control code
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Cf Format a format control character
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Cs Surrogate a surrogate code point
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Co Private_Use a private-use character
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Cn Unassigned a reserved unassigned code point or a noncharacter
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*/
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/// The highest valid code point
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pub static MAX: char = '\U0010ffff';
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/// Converts from `u32` to a `char`
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#[inline]
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pub fn from_u32(i: u32) -> Option<char> {
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// catch out-of-bounds and surrogates
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if (i > MAX as u32) || (i >= 0xD800 && i <= 0xDFFF) {
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None
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} else {
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Some(unsafe { transmute(i) })
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}
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}
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///
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/// Checks if a `char` parses as a numeric digit in the given radix
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///
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/// Compared to `is_digit()`, this function only recognizes the
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/// characters `0-9`, `a-z` and `A-Z`.
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///
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/// # Return value
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///
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/// Returns `true` if `c` is a valid digit under `radix`, and `false`
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/// otherwise.
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///
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/// # Failure
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///
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/// Fails if given a `radix` > 36.
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///
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/// # Note
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///
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/// This just wraps `to_digit()`.
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///
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#[inline]
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pub fn is_digit_radix(c: char, radix: uint) -> bool {
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match to_digit(c, radix) {
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Some(_) => true,
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None => false,
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}
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}
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///
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/// Converts a `char` to the corresponding digit
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///
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/// # Return value
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///
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/// If `c` is between '0' and '9', the corresponding value
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/// between 0 and 9. If `c` is 'a' or 'A', 10. If `c` is
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/// 'b' or 'B', 11, etc. Returns none if the `char` does not
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/// refer to a digit in the given radix.
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///
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/// # Failure
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///
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/// Fails if given a `radix` outside the range `[0..36]`.
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///
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#[inline]
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pub fn to_digit(c: char, radix: uint) -> Option<uint> {
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if radix > 36 {
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fail!("to_digit: radix is too high (maximum 36)");
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}
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let val = match c {
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'0' .. '9' => c as uint - ('0' as uint),
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'a' .. 'z' => c as uint + 10u - ('a' as uint),
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'A' .. 'Z' => c as uint + 10u - ('A' as uint),
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_ => return None,
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};
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if val < radix { Some(val) }
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else { None }
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}
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///
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/// Converts a number to the character representing it
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///
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/// # Return value
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///
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/// Returns `Some(char)` if `num` represents one digit under `radix`,
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/// using one character of `0-9` or `a-z`, or `None` if it doesn't.
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///
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/// # Failure
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///
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/// Fails if given an `radix` > 36.
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///
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#[inline]
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pub fn from_digit(num: uint, radix: uint) -> Option<char> {
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if radix > 36 {
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fail!("from_digit: radix is to high (maximum 36)");
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}
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if num < radix {
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unsafe {
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if num < 10 {
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Some(transmute(('0' as uint + num) as u32))
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} else {
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Some(transmute(('a' as uint + num - 10u) as u32))
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}
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}
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} else {
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None
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}
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}
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///
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/// Returns the hexadecimal Unicode escape of a `char`
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///
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/// The rules are as follows:
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///
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/// - chars in [0,0xff] get 2-digit escapes: `\\xNN`
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/// - chars in [0x100,0xffff] get 4-digit escapes: `\\uNNNN`
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/// - chars above 0x10000 get 8-digit escapes: `\\UNNNNNNNN`
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///
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pub fn escape_unicode(c: char, f: |char|) {
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// avoid calling str::to_str_radix because we don't really need to allocate
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// here.
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f('\\');
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let pad = match () {
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_ if c <= '\xff' => { f('x'); 2 }
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_ if c <= '\uffff' => { f('u'); 4 }
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_ => { f('U'); 8 }
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};
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for offset in range_step::<i32>(4 * (pad - 1), -1, -4) {
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let offset = offset as uint;
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unsafe {
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match ((c as i32) >> offset) & 0xf {
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i @ 0 .. 9 => { f(transmute('0' as i32 + i)); }
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i => { f(transmute('a' as i32 + (i - 10))); }
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}
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}
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}
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}
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///
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/// Returns a 'default' ASCII and C++11-like literal escape of a `char`
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///
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/// The default is chosen with a bias toward producing literals that are
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/// legal in a variety of languages, including C++11 and similar C-family
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/// languages. The exact rules are:
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///
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/// - Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
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/// - Single-quote, double-quote and backslash chars are backslash-escaped.
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/// - Any other chars in the range [0x20,0x7e] are not escaped.
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/// - Any other chars are given hex unicode escapes; see `escape_unicode`.
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///
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pub fn escape_default(c: char, f: |char|) {
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match c {
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'\t' => { f('\\'); f('t'); }
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'\r' => { f('\\'); f('r'); }
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'\n' => { f('\\'); f('n'); }
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'\\' => { f('\\'); f('\\'); }
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'\'' => { f('\\'); f('\''); }
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'"' => { f('\\'); f('"'); }
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'\x20' .. '\x7e' => { f(c); }
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_ => c.escape_unicode(f),
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}
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}
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/// Returns the amount of bytes this `char` would need if encoded in UTF-8
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pub fn len_utf8_bytes(c: char) -> uint {
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let code = c as u32;
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match () {
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_ if code < MAX_ONE_B => 1u,
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_ if code < MAX_TWO_B => 2u,
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_ if code < MAX_THREE_B => 3u,
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_ if code < MAX_FOUR_B => 4u,
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_ => fail!("invalid character!"),
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}
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}
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/// Basic `char` manipulations.
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pub trait Char {
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/// Checks if a `char` parses as a numeric digit in the given radix.
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///
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/// Compared to `is_digit()`, this function only recognizes the characters
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/// `0-9`, `a-z` and `A-Z`.
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///
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/// # Return value
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///
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/// Returns `true` if `c` is a valid digit under `radix`, and `false`
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/// otherwise.
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///
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/// # Failure
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///
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/// Fails if given a radix > 36.
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fn is_digit_radix(&self, radix: uint) -> bool;
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/// Converts a character to the corresponding digit.
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///
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/// # Return value
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///
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/// If `c` is between '0' and '9', the corresponding value between 0 and
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/// 9. If `c` is 'a' or 'A', 10. If `c` is 'b' or 'B', 11, etc. Returns
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/// none if the character does not refer to a digit in the given radix.
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///
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/// # Failure
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///
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/// Fails if given a radix outside the range [0..36].
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fn to_digit(&self, radix: uint) -> Option<uint>;
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/// Converts a number to the character representing it.
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///
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/// # Return value
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///
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/// Returns `Some(char)` if `num` represents one digit under `radix`,
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/// using one character of `0-9` or `a-z`, or `None` if it doesn't.
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///
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/// # Failure
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///
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/// Fails if given a radix > 36.
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fn from_digit(num: uint, radix: uint) -> Option<Self>;
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/// Returns the hexadecimal Unicode escape of a character.
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///
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/// The rules are as follows:
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///
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/// * Characters in [0,0xff] get 2-digit escapes: `\\xNN`
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/// * Characters in [0x100,0xffff] get 4-digit escapes: `\\uNNNN`.
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/// * Characters above 0x10000 get 8-digit escapes: `\\UNNNNNNNN`.
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fn escape_unicode(&self, f: |char|);
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/// Returns a 'default' ASCII and C++11-like literal escape of a
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/// character.
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///
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/// The default is chosen with a bias toward producing literals that are
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/// legal in a variety of languages, including C++11 and similar C-family
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/// languages. The exact rules are:
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///
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/// * Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
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/// * Single-quote, double-quote and backslash chars are backslash-
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/// escaped.
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/// * Any other chars in the range [0x20,0x7e] are not escaped.
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/// * Any other chars are given hex unicode escapes; see `escape_unicode`.
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fn escape_default(&self, f: |char|);
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/// Returns the amount of bytes this character would need if encoded in
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/// UTF-8.
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fn len_utf8_bytes(&self) -> uint;
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/// Encodes this character as UTF-8 into the provided byte buffer.
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///
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/// The buffer must be at least 4 bytes long or a runtime failure may
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/// occur.
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///
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/// This will then return the number of bytes written to the slice.
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fn encode_utf8(&self, dst: &mut [u8]) -> uint;
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/// Encodes this character as UTF-16 into the provided `u16` buffer.
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///
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/// The buffer must be at least 2 elements long or a runtime failure may
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/// occur.
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///
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/// This will then return the number of `u16`s written to the slice.
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fn encode_utf16(&self, dst: &mut [u16]) -> uint;
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}
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impl Char for char {
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fn is_digit_radix(&self, radix: uint) -> bool { is_digit_radix(*self, radix) }
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fn to_digit(&self, radix: uint) -> Option<uint> { to_digit(*self, radix) }
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fn from_digit(num: uint, radix: uint) -> Option<char> { from_digit(num, radix) }
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fn escape_unicode(&self, f: |char|) { escape_unicode(*self, f) }
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fn escape_default(&self, f: |char|) { escape_default(*self, f) }
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fn len_utf8_bytes(&self) -> uint { len_utf8_bytes(*self) }
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fn encode_utf8<'a>(&self, dst: &'a mut [u8]) -> uint {
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let code = *self as u32;
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if code < MAX_ONE_B {
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dst[0] = code as u8;
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1
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} else if code < MAX_TWO_B {
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dst[0] = (code >> 6u & 0x1F_u32) as u8 | TAG_TWO_B;
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dst[1] = (code & 0x3F_u32) as u8 | TAG_CONT;
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2
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} else if code < MAX_THREE_B {
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dst[0] = (code >> 12u & 0x0F_u32) as u8 | TAG_THREE_B;
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dst[1] = (code >> 6u & 0x3F_u32) as u8 | TAG_CONT;
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dst[2] = (code & 0x3F_u32) as u8 | TAG_CONT;
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3
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} else {
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dst[0] = (code >> 18u & 0x07_u32) as u8 | TAG_FOUR_B;
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dst[1] = (code >> 12u & 0x3F_u32) as u8 | TAG_CONT;
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dst[2] = (code >> 6u & 0x3F_u32) as u8 | TAG_CONT;
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dst[3] = (code & 0x3F_u32) as u8 | TAG_CONT;
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4
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}
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}
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fn encode_utf16(&self, dst: &mut [u16]) -> uint {
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let mut ch = *self as u32;
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if (ch & 0xFFFF_u32) == ch {
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// The BMP falls through (assuming non-surrogate, as it should)
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assert!(ch <= 0xD7FF_u32 || ch >= 0xE000_u32);
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dst[0] = ch as u16;
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1
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} else {
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// Supplementary planes break into surrogates.
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assert!(ch >= 0x1_0000_u32 && ch <= 0x10_FFFF_u32);
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ch -= 0x1_0000_u32;
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dst[0] = 0xD800_u16 | ((ch >> 10) as u16);
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dst[1] = 0xDC00_u16 | ((ch as u16) & 0x3FF_u16);
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2
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}
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}
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}
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