Is possible to find all "paired" characters programmatically?
E.g. when i got for example the < character how to find the correspondent "pair" > to it?
The following piece of code prints each "mirrored" ascii characters.
use 5.018;
use warnings;
use charnames qw(:full);
for my $n (0..127) {
my $c = chr $n;
printf "%02x: [%s] - %s\n", $n, $c, charnames::viacode($n) if $c =~ /\p{Bidi_Mirrored=Y}/;
}
prints:
28: [(] - LEFT PARENTHESIS
29: [)] - RIGHT PARENTHESIS
3c: [<] - LESS-THAN SIGN
3e: [>] - GREATER-THAN SIGN
5b: [[] - LEFT SQUARE BRACKET
5d: []] - RIGHT SQUARE BRACKET
7b: [{] - LEFT CURLY BRACKET
7d: [}] - RIGHT CURLY BRACKET
But AFAIK the Bidi_Mirrored property isn't the same as "paired" e.g. left-right pairs, because for example the following char has the Bidi_Mirrored property but probably it has not any "pair".
∰ U+02230 VOLUME INTEGRAL
And if it the Bidi_Mirrored property correct for the "paired" characters, the question is still the same: How to find the "pair's" codepoint? (or name)?
In short: want print all unicode "paired" characters, e.g. pairs like:
« U+000AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
» U+000BB RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
or
≤ U+02264 LESS-THAN OR EQUAL TO
≥ U+02265 GREATER-THAN OR EQUAL TO
etc...
EDIT
Meantime the question got closed, so write my findings here:
I found here the following:
# Bidi_Paired_Bracket is a normative property of type Miscellaneous,
# which establishes a mapping between characters that are treated as
# bracket pairs by the Unicode Bidirectional Algorithm.
#
# Bidi_Paired_Bracket_Type is a normative property of type Enumeration,
# which classifies characters into opening and closing paired brackets
# for the purposes of the Unicode Bidirectional Algorithm.
#
# This file lists the set of code points with Bidi_Paired_Bracket_Type
# property values Open and Close. The set is derived from the character
# properties General_Category (gc), Bidi_Class (bc), Bidi_Mirrored (Bidi_M),
# and Bidi_Mirroring_Glyph (bmg), as follows: two characters, A and B,
# form a bracket pair if A has gc=Ps and B has gc=Pe, both have bc=ON and
# Bidi_M=Y, and bmg of A is B. Bidi_Paired_Bracket (bpb) maps A to B and
# vice versa, and their Bidi_Paired_Bracket_Type (bpt) property values are
# Open (o) and Close (c), respectively.
#
# For legacy reasons, the characters U+FD3E ORNATE LEFT PARENTHESIS and
# U+FD3F ORNATE RIGHT PARENTHESIS do not mirror in bidirectional display
# and therefore do not form a bracket pair.
#
# The Unicode property value stability policy guarantees that characters
# which have bpt=o or bpt=c also have bc=ON and Bidi_M=Y. As a result, an
# implementation can optimize the lookup of the Bidi_Paired_Bracket_Type
# property values Open and Close by restricting the processing to characters
# with bc=ON
Looks, here exists the exact algorithm, but i don't know how to get the Bidi_Mirroring_Glyph aka (bmg) and the Bidi_Paired_Bracket aka (bpb) values in perl. AFAIK the Unicode::UCD doesn't contains these values - or at least i don't know how to get them.
Maybe in the 5.024 and with Unicode 8.0? :) :)
