bidi

Text is stored in memory in the order it was typed, but when right to left and left to right scripts are mixed, the order seen on screen is not that order. Browsers and editors do the rearranging with the Unicode bidirectional algorithm.

If you are drawing text yourself somewhere that does not do this for you, onto an image, in a terminal or on a simple display, the bidi package runs the same algorithm and tells you where every character goes.

Each function takes a paragraph direction: DirAuto infers it from the first strong character in the text, and the other two set it in advance. The "level" of each character is a number: even means left to right and odd means right to left.

Constants and variables

const DirAuto: i32 = 0

import bidi

func main:
    s := "abc سلام"
    println bidi.ParagraphLevel(s, bidi.DirAuto), bidi.ParagraphLevel("سلام abc", bidi.DirAuto)
    println bidi.ParagraphLevel(s, bidi.DirRTL), bidi.ParagraphLevel("سلام", bidi.DirLTR)
    println bidi.Levels(s, bidi.DirLTR)
    println bidi.VisualOrder(s, bidi.DirLTR)
    println bidi.Reorder(s, bidi.DirLTR)
end

const DirLTR: i32 = 1

const DirRTL: i32 = 2

Functions

func ParagraphLevel(s: str, dir: int): int

func Levels(s: str, dir: int): Vector<int>

func VisualOrder(s: str, dir: int): Vector<int>

func Reorder(s: str, dir: int): str