When I search my phone contacts for someone named Albéric, Maïté, Eugène, Éric or Søren I want to type "alberic", "maite", "eugene", "eric" or "soren" without thinking about uppercase nor accents that are sometimes difficult or impossible to type. I want a Accent and uppercase insensitive search.

It works very well in most apps such as Google Contacts, but it is actually not trivial at all. Because it did not work in Signal, I investigated how to achieve it using a regex (GLOB) search in SQLite.

Here a a set of regex ranges that cover variantions from latin characters from the unicode blocks :

• Latin-1 Supplement
• Latin Extended-A
• Latin Extended-B
• Latin Extended Additional

a : [À-Åà-åĀ-ąǍǎǞ-ǡǺ-ǻȀ-ȃȦȧȺɐ-ɒḀḁẚẠ-ặ]
b : [ßƀ-ƅɃɓḂ-ḇ]
c : [çÇĆ-čƆ-ƈȻȼɔḈḉ]
d : [ÐðĎ-đƉ-ƍȡɖɗḊ-ḓ]
e : [È-Ëè-ëĒ-ěƎ-ƐǝȄ-ȇȨȩɆɇɘ-ɞḔ-ḝẸ-ệ]
f : [ƑƒḞḟ]
g : [Ĝ-ģƓǤ-ǧǴǵḠḡ]
h : [Ĥ-ħƕǶȞȟḢ-ḫẖ]
i : [Ì-Ïì-ïĨ-ıƖƗǏǐȈ-ȋɨɪḬ-ḯỈ-ị]
j : [ĴĵǰȷɈɉɟ]
k : [Ķ-ĸƘƙǨǩḰ-ḵ]
l : [Ĺ-łƚȴȽɫ-ɭḶ-ḽ]
m : [Ɯɯ-ɱḾ-ṃ]
n : [ÑñŃ-ŋƝƞǸǹȠȵɲ-ɴṄ-ṋ]
o : [Ò-ÖØò-öøŌ-őƟ-ơǑǒǪ-ǭǾǿȌ-ȏȪ-ȱṌ-ṓỌ-ợ]
p : [ƤƥṔ-ṗ]
q : []
r : [Ŕ-řƦȐ-ȓɌɍṘ-ṟ]
s : [Ś-šƧƨȘșȿṠ-ṩ]
t : [Ţ-ŧƫ-ƮȚțȾṪ-ṱẗ]
u : [Ù-Üù-üŨ-ųƯ-ƱǓ-ǜȔ-ȗɄṲ-ṻỤ-ự]
v : [ƲɅṼ-ṿ]
w : [ŴŵẀ-ẉẘ]
x : [Ẋ-ẍ]
y : [ÝýÿŶ-ŸƔƳƴȲȳɎɏẎẏỲ-ỹỾỿẙ]
z : [Ź-žƵƶɀẐ-ẕ]

This was visually verified using https://regex101.com/r/vaN0J8/1. If you spot any error, please let me know on the gist directly.