Calculate font script and language coverage based on ICU exemplar data

cldr-coverage.py

# Copyright 2020 Khaled Hosny
#
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from icu import Locale, LocaleData


def coverage(font, threshold=10):
    cmap = set(chr(c) for c in font.getBestCmap())

    languages = set()
    scripts = set()
    partial = {}

    for locale in Locale.getAvailableLocales():
        data = LocaleData(locale)
        examplar = set("".join(data.getExemplarSet()))
        if not cmap.isdisjoint(examplar):
            locale = Locale(locale)
            locale.addLikelySubtags()
            diff = examplar - cmap
            if not diff:
                scripts.add(locale.getDisplayScript())
                languages.add(locale.getDisplayLanguage())
            elif len(diff) <= threshold:
                partial[locale.getDisplayLanguage()] = diff

    return scripts, languages, partial


def report(scripts, languages, partial):
    text = []
    if scripts or languages:
        text.append("# Full")

    if scripts:
        scripts = ", ".join(sorted(scripts))
        text.append(f"* Scripts: {scripts}")

    if languages:
        languages = ", ".join(sorted(languages))
        text.append(f"* Languages: {languages}")

    if partial:
        import unicodedata as ucd
        text.append("# Partial")
        for language, missing in partial.items():
            missing = ", ".join((ucd.combining(c) and f"\u25CC{c}" or c) for c in sorted(missing))
            text.append(f"* {language}: {missing}")

    return "\n".join(text)


if __name__ == "__main__":
    import sys
    from fontTools.ttLib import TTFont
    font = TTFont(sys.argv[1])
    print(report(*coverage(font)))