luafontid

test.lua

function token.scan_limited_int(max, name)
    local cur_val = token.scan_int()
    if (cur_val < 0) or (cur_val > max) then
        local hlp, msg
        if not name then
            hlp = string.format("Since I expected to read a number between 0 and %d,", max)
            msg = string.format("Bad number (%d)", cur_val)
        else
            hlp = string.format("A %s must be between 0 and %d.", name, max)
            msg = string.format("Bad %s (%d)", name, cur_val)
        end
        tex.error(msg, { hlp, "I changed this one to zero." })
        cur_val = 0
    end
    return cur_val
end

function token.scan_math_family_int()
    return token.scan_limited_int(255, "math family")
end

function token.scan_font_ident()
    local cur_cmd, cur_chr, f
    repeat
        local next = token.scan_token()
        cur_cmd = next.cmdname
        cur_chr = next.mode
    until not (cur_cmd == "spacer")
    if cur_cmd == "def_font" or cur_cmd == "letterspace_font" or cur_cmd == "copy_font" then
        f = font.current()
    elseif cur_cmd == "set_font" then
        f = cur_chr
        -- set_font_touched(f, 1)
    elseif cur_cmd == "def_family" then
        local m = cur_chr
        local cur_val = token.scan_math_family_int()
        f = node.family_font(cur_val, m)
        -- set_font_touched(f, 1)
    else
         tex.error("Missing font identifier", {
             "I was looking for a control sequence whose",
             "current meaning has been defined by \\font."
         })
         f = 0 -- is 0 always nullfont?
    end
    return f
end

test.tex

\directlua{dofile("test.lua")}
\directlua{
local t = lua.get_functions_table()
t[\string#t + 1] = function() tex.sprint(token.scan_font_ident()) end
token.set_lua("luafontid", \string#t)
}

\message{\luafontid\font}
\message{\fontid\font}
\message{\luafontid\nullfont}
\message{\fontid\nullfont}
\message{\luafontid\tenit}
\message{\fontid\tenit}
\message{\luafontid\textfont2}
\message{\fontid\textfont2}

\bye