Crate unicode_widthCopy item path

Determine displayed width of char and str types according to Unicode Standard Annex #11, other portions of the Unicode standard, and common implementations of POSIX wcwidth(). See the Rules for determining width section for the exact rules.

This crate is #![no_std].

use unicode_width::UnicodeWidthStr;

let teststr = "Ｈｅｌｌｏ, ｗｏｒｌｄ!";
let width = UnicodeWidthStr::width(teststr);
println!("{}", teststr);
println!("The above string is {} columns wide.", width);
let width = teststr.width_cjk();
println!("The above string is {} columns wide (CJK).", width);

§Rules for determining width

This crate currently uses the following rules to determine the width of a character or string, in order of decreasing precedence. These may be tweaked in the future.

1. Emoji presentation sequences have width 2. (The width of a string may therefore differ from the sum of the widths of its characters.)
2. '\u{00AD}' SOFT HYPHEN has width 1.
3. '\u{115F}' HANGUL CHOSEONG FILLER has width 2.
4. The following have width 0:
   • Characters with the Default_Ignorable_Code_Point property.
   • Characters with the Grapheme_Extend property.
   • The following 8 characters, all of which have NFD decompositions consisting of two Grapheme_Extend chracters:
     • '\u{0CC0}' KANNADA VOWEL SIGN II,
     • '\u{0CC7}' KANNADA VOWEL SIGN EE,
     • '\u{0CC8}' KANNADA VOWEL SIGN AI,
     • '\u{0CCA}' KANNADA VOWEL SIGN O,
     • '\u{0CCB}' KANNADA VOWEL SIGN OO,
     • '\u{1B3B}' BALINESE VOWEL SIGN RA REPA TEDUNG,
     • '\u{1B3D}' BALINESE VOWEL SIGN LA LENGA TEDUNG, and
     • '\u{1B43}' BALINESE VOWEL SIGN PEPET TEDUNG.
   • Characters with a Hangul_Syllable_Type of Vowel_Jamo (V) or Trailing_Jamo (T).
   • '\0' NUL.
5. The control characters have no defined width, and are ignored when determining the width of a string.
6. Characters with an East_Asian_Width of Fullwidth (F) or Wide (W) have width 2.
7. Characters with an East_Asian_Width of Ambiguous (A) have width 2 in an East Asian context, and width 1 otherwise.
8. All other characters have width 1.

§Canonical equivalence

The non-CJK width methods guarantee that canonically equivalent strings are assigned the same width. However, this guarantee does not currently hold for the CJK width variants.