Name

Text::FriBidi

Synopsis

Single line reordering

use Text::FriBidi::Line;
use Test;
plan 1;

enum ( :Shin<ש>, :Resh<ר>, :He<ה> );

my $text = "Sarah ({Shin~Resh~He})";
my Text::FriBidi::Line $line .= new: :$text;
my $visual = $line.Str;
is-deeply $visual, "Sarah ({He~Resh~Shin})";
is $line[7], He;

Multiple lines reordering (experimental)

use Text::FriBidi::Lines;
use Test;
plan 1;

constant $LRO = "\c[LEFT-TO-RIGHT OVERRIDE]";
constant $RLO = "\c[RIGHT-TO-LEFT OVERRIDE]";
constant $PDF = "\c[POP DIRECTIONAL FORMATTING]";

@lines = "Left", "{$RLO}Right{$PDF}", "{$LRO}left{$PDF}";
my Text::FriBidi::Lines $para .= new: :@lines;
is-deeply $para.lines, ('Left', 'thgiR', 'left');

Description

The Unicode standard calls for characters to be ordered 'logically', i.e. in the sequence they are intended to be interpreted, as opposed to 'visually', the sequence they appear.

The Unicode® Bidirectional Algorithm (BiDi Algorithm) is then used to reorder for visual display.

This algorithm primarily based on character detection, but also uses special BiDi control characters available for manual control.

FriBidi is a library that implements the Unicode BiDi algorithm to reorder text for visual display. This module provides Raku bindings to FriBidi.

Text::FriBidi::Line Methods

new()

use Text::FriBidi::Defs :FriBidiType, :FriBidiFlag;
method new(
    Str:D :$text!,      # text, in logical order
    UInt:D :$direction = FRIBIDI_TYPE_LTR, # default direction
    UInt:D :$flags = FRIBIDI_FLAGS_DEFAULT +| FRIBIDI_FLAGS_ARABIC,
)

:$text option

Input text, in logical reading/processing order. Possibly including Unicode BiDi control characters.

Text::FriBidi::Lines Methods

new()

use Text::FriBidi::Defs :FriBidiType, :FriBidiFlag;
method new(
    Str:D :@lines!,      # paragraph lines, in logical order
    UInt:D :$direction = FRIBIDI_TYPE_LTR, # default direction
    UInt:D :$flags = FRIBIDI_FLAGS_DEFAULT +| FRIBIDI_FLAGS_ARABIC,
)

:@lines option

Input text lines, in logical reading/processing order. Possibly including Unicode BiDi control characters.

Common Options

:$flags option

A set of 'ored` flag, including:

• FRIBIDI_FLAG_SHAPE_MIRRORING: Do mirroring.
• FRIBIDI_FLAG_SHAPE_ARAB_PRES: Shape Arabic characters to their presentation form glyphs.
• FRIBIDI_FLAG_SHAPE_ARAB_LIGA: Form mandatory Arabic ligatures.
• FRIBIDI_FLAG_REMOVE_SPECIALS: Remove Bidi marks from output

:$direction option

Base text direction; one of:

• FRIBIDI_TYPE_LTR: Left to right
• FRIBIDI_TYPE_RTL: Right to left
• FRIBIDI_TYPE_WLTR: Weak left to right
• FRIBIDI_TYPE_WRTL: Weak right to left
• FRIBIDI_TYPE_LTR: Left to right
• FRIBIDI_TYPE_RTL: Right to left

Str()

The string, after applying any mirroring, shaping and directional ordering and with BiDi control characters removed (by default).

AT-POS, List, Array

Methods for obtaining individual visual characters.

Note that Raku may perform its own Unicode normalizations on strings. These methods can be used to get corresponding characters and properties.

use Text::FriBidi::Line;
my Text::FriBidi::Line $line .= new(:text("A\r\nB"));
say $line.Str.comb.raku; # "A", "\r\n", "B"
say $line.List.raku; # "A" "\r" "\n" "B"
say $line[3] ~ ' has type ' ~ $line.bidi-types[3];

Installation

Debian/Ubuntu Linux

sudo apt-get install libfribidi-dev

Mac OS X

brew update
brew install fribidi

See Also

• UAX #9: Unicode Bidirectional Algorithm
• fribidi GitHub repository
• Text::Bidi Perl Module