[parsers] extend definition grammar to allow for subfonts in path lookups

1 files changed, 17 insertions, 16 deletions

diff --git a/src/luaotfload-parsers.lua b/src/luaotfload-parsers.lua
index c2b4f2e..8c297ac 100644
--- a/src/luaotfload-parsers.lua
+++ b/src/luaotfload-parsers.lua
@@ -602,6 +602,22 @@ local combodef1         = Ct(comboidx * combomapsep * comboid) --> no chars
 local combodef          = Ct(comboidx * combomapsep * comboidchars)
 local combolist         = Ct(combodef1 * (comborowsep * combodef)^1)
 
+--- subfonts ----------------------------------------------------------
+--- This rule is present in the original parser. It sets the “sub”
+--- field of the specification which allows addressing a specific
+--- font inside a TTC container. Neither in Luatex-Fonts nor in
+--- Luaotfload is this documented, so we might as well silently drop
+--- it. However, as backward compatibility is one of our prime goals we
+--- just insert it here and leave it undocumented until someone cares
+--- to ask. (Note: afair subfonts are numbered, but this rule matches a
+--- string; I won’t mess with it though until someone reports a
+--- problem.)
+--- local subvalue   = P("(") * (C(P(1-S("()"))^1)/issub) * P(")") -- for Kim
+--- Note to self: subfonts apparently start at index 0. Tested with
+--- Cambria.ttc that includes “Cambria Math” at 0 and “Cambria” at 1.
+--- Other values cause luatex to segfault.
+local subfont           = P"(" * Cg((1 - S"()")^1, "sub") * P")"
+
 --- lookups -----------------------------------------------------------
 local fontname          = C((1-S":(/")^1)  --- like luatex-fonts
 local unsupported       = Cmt((1-S":(")^1, check_garbage)
@@ -619,6 +635,7 @@ local prefixed          = P"name:" * ws * Cg(fontname, "name")
                         + P"my:" * ws * Cg(fontname, "my")
 local unprefixed        = Cg(fontname, "anon")
 local path_lookup       = lbrk * Cg(C((1-rbrk)^1), "path") * rbrk
+                        * subfont^-1
 
 --- features ----------------------------------------------------------
 local field_char        = anum + S"+-.!?" --- sic!
@@ -644,22 +661,6 @@ local feature_list      = Cf(Ct""
                            * (featuresep * option^-1)^0
                            , rawset)
                         * featuresep^-1
-
---- other -------------------------------------------------------------
---- This rule is present in the original parser. It sets the “sub”
---- field of the specification which allows addressing a specific
---- font inside a TTC container. Neither in Luatex-Fonts nor in
---- Luaotfload is this documented, so we might as well silently drop
---- it. However, as backward compatibility is one of our prime goals we
---- just insert it here and leave it undocumented until someone cares
---- to ask. (Note: afair subfonts are numbered, but this rule matches a
---- string; I won’t mess with it though until someone reports a
---- problem.)
---- local subvalue   = P("(") * (C(P(1-S("()"))^1)/issub) * P(")") -- for Kim
---- Note to self: subfonts apparently start at index 0. Tested with
---- Cambria.ttc that includes “Cambria Math” at 0 and “Cambria” at 1.
---- Other values cause luatex to segfault.
-local subfont           = P"(" * Cg((1 - S"()")^1, "sub") * P")"
 --- top-level rules ---------------------------------------------------
 --- \font\foo=<specification>:<features>
 local features          = Cg(feature_list, "features")