Tool for ordering features.fea ligatures by longest first?

Scripting
10

A lookup can only contain substitutions of one kind, so I guess that

sub a     by X;
sub a b   by Y;
sub a b c by Z;

is internally split into 2 lookups, one with a single substitution type:

sub a     by X;

and one with a ligature substitution type:

sub a b   by Y;
sub a b c by Z;

The rule in the first lookup is evaluated before the second lookup is being processed, so the a never appears in the input glyph sequence for the second lookup.

This may give the impression that the rules are not reordered when in fact they are, per lookup.

2 Likes