This module provide user-defined Unicode properties that deal with width status of East Asian characters, as specified in http://www.unicode.org/unicode/reports/tr11/.
It exports the following functions to the caller's scope, to be used by Perl's Unicode matching system: 'InEastAsianFullwidth', 'InEastAsianHalfwidth', 'InEastAsianAmbiguous', 'InEastAsianNarrow' 'InEastAsianWide', 'InEastAsianNeutral'.
In accord to TR11 cited above, two additional context-sensitive properties are exported: 'InFullwidth' (union of 'Fullwidth' and 'Wide') and 'InHalfwidth' (union of 'Halfwidth', 'Narrow' and 'Neutral').
Ambiguous characters are treated by default as part of 'InHalfwidth', but you can modify this behaviour by assigning a true value to '$Unicode::EastAsianWidth::EastAsian' at compile time within a 'BEGIN' block before loading this module:
BEGIN { $Unicode::EastAsianWidth::EastAsian = 1; } use Unicode::EastAsianWidth;Setting '$Unicode::EastAsianWidth::EastAsian' at run-time used to work on Perl versions between 5.8 and 5.14 due to an implementation detail, but it will no longer work on Perl 5.16 and later versions, and hence is not recommended.