187 lines
5.4 KiB
Rust
187 lines
5.4 KiB
Rust
/*
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* meli - text_processing crate.
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*
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* Copyright 2017-2020 Manos Pitsidianakis
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*
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* This file is part of meli.
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*
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* meli is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* meli is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with meli. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* This is an implementation of wcwidth() and wcswidth() as defined in
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* "The Single UNIX Specification, Version 2, The Open Group, 1997"
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* <http://www.UNIX-systems.org/online.html>
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*
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* Markus Kuhn -- 2001-09-08 -- public domain
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*/
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// Update to Unicode 12
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#[macro_export]
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macro_rules! big_if_true {
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($a:expr) => {
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if $a {
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1
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} else {
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0
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}
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};
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}
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type WChar = u32;
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type Interval = (WChar, WChar);
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pub struct CodePointsIterator<'a> {
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rest: &'a [u8],
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}
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/*
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* UTF-8 uses a system of binary prefixes, in which the high bits of each byte mark whether it’s a single byte, the beginning of a multi-byte sequence, or a continuation byte; the remaining bits, concatenated, give the code point index. This table shows how it works:
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*
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* UTF-8 (binary) Code point (binary) Range
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* 0xxxxxxx xxxxxxx U+0000–U+007F
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* 110xxxxx 10yyyyyy xxxxxyyyyyy U+0080–U+07FF
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* 1110xxxx 10yyyyyy 10zzzzzz xxxxyyyyyyzzzzzz U+0800–U+FFFF
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* 11110xxx 10yyyyyy 10zzzzzz 10wwwwww xxxyyyyyyzzzzzzwwwwww U+10000–U+10FFFF
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*
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*/
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impl<'a> Iterator for CodePointsIterator<'a> {
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type Item = WChar;
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fn next(&mut self) -> Option<WChar> {
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if self.rest.is_empty() {
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return None;
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}
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/* Input is UTF-8 valid strings, guaranteed by Rust's std */
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if self.rest[0] & 0b1000_0000 == 0x0 {
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let ret: WChar = WChar::from(self.rest[0]);
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self.rest = &self.rest[1..];
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return Some(ret);
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}
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if self.rest[0] & 0b1110_0000 == 0b1100_0000 {
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let ret: WChar = (WChar::from(self.rest[0]) & 0b0001_1111).rotate_left(6)
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+ (WChar::from(self.rest[1]) & 0b0111_1111);
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self.rest = &self.rest[2..];
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return Some(ret);
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}
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if self.rest[0] & 0b1111_0000 == 0b1110_0000 {
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let ret: WChar = (WChar::from(self.rest[0]) & 0b0000_0111).rotate_left(12)
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+ (WChar::from(self.rest[1]) & 0b0011_1111).rotate_left(6)
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+ (WChar::from(self.rest[2]) & 0b0011_1111);
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self.rest = &self.rest[3..];
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return Some(ret);
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}
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let ret: WChar = (WChar::from(self.rest[0]) & 0b0000_0111).rotate_left(18)
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+ (WChar::from(self.rest[1]) & 0b0011_1111).rotate_left(12)
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+ (WChar::from(self.rest[2]) & 0b0011_1111).rotate_left(6)
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+ (WChar::from(self.rest[3]) & 0b0011_1111);
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self.rest = &self.rest[4..];
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Some(ret)
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}
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}
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pub trait CodePointsIter {
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fn code_points(&self) -> CodePointsIterator;
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}
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impl CodePointsIter for str {
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fn code_points(&self) -> CodePointsIterator {
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CodePointsIterator {
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rest: self.as_bytes(),
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}
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}
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}
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impl CodePointsIter for &str {
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fn code_points(&self) -> CodePointsIterator {
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CodePointsIterator {
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rest: self.as_bytes(),
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}
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}
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}
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/* auxiliary function for binary search in Interval table */
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fn bisearch(ucs: WChar, table: &'static [Interval]) -> bool {
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let mut min = 0;
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let mut mid;
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let mut max = table.len() - 1;
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if ucs < table[0].0 || ucs > table[max].1 {
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return false;
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}
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while max >= min {
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mid = (min + max) / 2;
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if ucs > table[mid].1 {
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min = mid + 1;
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} else if ucs < table[mid].0 {
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max = mid - 1;
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} else {
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return true;
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}
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}
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false
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}
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pub fn wcwidth(ucs: WChar) -> Option<usize> {
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if bisearch(ucs, super::tables::ASCII) {
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Some(1)
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} else if bisearch(ucs, super::tables::PRIVATE) {
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None
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} else if bisearch(ucs, super::tables::NONPRINT) {
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None
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} else if bisearch(ucs, super::tables::COMBINING) {
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None
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} else if bisearch(ucs, super::tables::DOUBLEWIDE) {
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Some(2)
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} else if bisearch(ucs, super::tables::AMBIGUOUS) {
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Some(1)
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} else if bisearch(ucs, super::tables::UNASSIGNED) {
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Some(2)
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} else if bisearch(ucs, super::tables::WIDENEDIN9) {
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Some(2)
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} else {
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Some(1)
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}
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}
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#[test]
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fn test_wcwidth() {
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use crate::text_processing::grapheme_clusters::TextProcessing;
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assert_eq!("●".grapheme_width(), 1);
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assert_eq!("●📎".grapheme_width(), 3);
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assert_eq!("●\u{FE0E}📎\u{FE0E}".grapheme_width(), 3);
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assert_eq!("🎃".grapheme_width(), 2);
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assert_eq!("👻".grapheme_width(), 2);
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}
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pub fn wcswidth(mut pwcs: WChar, mut n: usize) -> Option<usize> {
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let mut width = 0;
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while pwcs > 0 && n > 0 {
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if let Some(w) = wcwidth(pwcs) {
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width += w;
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} else {
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return None;
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}
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pwcs += 1;
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n -= 1;
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}
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Some(width)
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}
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