liblouis-jsonify-tables

A small app serving to map LibLouis tables to JSON suitable for processing in GUI apps.

Usage

lljt <tables folder> <output JSON file name>

The tables folder is a LibLouis tables/ directory. Sub-tables meant to be pulled in with include rather than selected on their own (.dis, .cti, .uti) are skipped, and a table is written out only if it has both a display name and at least one language — the minimum needed to offer it in a picker. Output is ordered by file name so a regenerated file diffs cleanly against the previous one.

What it reads

LibLouis tables declare metadata in the table header — the run of comment and empty lines before the first translation rule — as #+key: value (queryable) and #-key: value (informative) lines. Two rules from the LibLouis manual govern how they are read:

• metadata after the table header is not metadata, so parsing stops at the first translation rule;
• the same key may appear multiple times in a table, which is why Languages and TableTypes are arrays. he-IL.utb (Israeli braille) declares Hebrew, Arabic and English; ancient-languages-us.utb declares thirty-six languages; the Swedish and Elfdalian 8-dot tables declare both a computer and a literary type.

Keys are matched exactly rather than by substring — the display names of ancient-languages-us.utb and ancient-languages-borger.utb contain the word "language", which a substring match mistakes for the language field.

Output

{
  "FileName": "he-IL.utb",
  "DisplayName": "Israeli braille",
  "IndexName": "Hebrew, modern",
  "Languages": [ "he", "ar", "en" ],
  "Region": "*-IL",
  "TableTypes": [ "literary" ],
  "ContractionType": "no",
  "Grade": "1",
  "DotsMode": 6,
  "Direction": "forward",
  "System": null,
  "Variant": null,
  "Version": null,
  "Locale": null,
  "UnicodeRange": null
}

Every field but FileName is optional in a table header, so most come out null (or an empty array) for most tables.

• FileName — the table file name, from the file itself.
• DisplayName — from #-display-name. Required for a table to be written out at all.
• IndexName — from #-index-name. The sort-friendly "Language, qualifiers" form, e.g. English, U.S., computer, 8-dot.
• Languages — an array, from every #+language. These are RFC 4647 extended language ranges, so entries such as akk-Latn and *-fonipa occur; match them, don't compare them as strings.
• Region — from #+region. Also an extended language range, e.g. en-US or *-IL.
• TableTypes — an array, from every #+type: literary, computer, math.
• ContractionType — from #+contraction: no, partial or full.
• Grade — from #+grade. A string, not a number: alongside 0, 1, 2 and 3, LibLouis ships tables graded 1.2, 1.3, 1.4 and 1.5.
• DotsMode — from #+dots: 6 or 8, or 0 when the table declares none.
• Direction — from #+direction: forward, backward or both.
• System — from #+system. The Braille code the table implements, e.g. ueb, ebae, ddp.
• Variant — from #+variant. Distinguishes otherwise-alike tables, e.g. detailed, compact.
• Version — from #+version. The edition of the Braille standard, usually a year.
• Locale — from #+locale. The conventions assumed, where these differ from the language.
• UnicodeRange — from #+unicode-range: ucs2 or ucs4.

Consumers

The JSON is consumed by SharpLouis, whose TableCollection and TranslationTable types mirror this schema.

License

Copyright © 2024–2026 André Polykanine, AccessMind LLC., and contributors. Licensed under the Apache License, Version 2.0. See LICENSE.md.