I really have to apologise for the long delay on this answer. As you discovered this was an unintentional change made while a lot of the package was being re-implemented.
I've spent some time today looking into how this could be resolved; I'm not really sure what the best option is, so I've reverted the package to the old behaviour (not the old code, though note). I express doubts on this in that I'm not sure it's wise to select faces within a family that use different renderers, but it probably can't hurt in this case.
This will be fixed in v2.3 of fontspec.
I got it working with a lua script. Your minimal example becomes:
\documentclass{minimal}
\usepackage{unicode-math}
\setmathfont{XITS Math}
\AtBeginDocument{\directlua{require("combining_preprocessor.lua")}}
\newcommand{\⃗}[1]{\ensuremath{\vec{#1}}}
\begin{document}
$v⃗$
\end{document}
The idea is that it's difficult to make LaTeX handle a command or macro that comes after its argument, which is how Unicode combining characters work, so we use would like a preprocessor to move the accent so it comes before its argument. That is, map v⃗ to \⃗{v} in a script, and then define whatever action you want \⃗ to have. (That's a backslash followed by a combining arrow, which should be printed above the backslash.)
My lua script does most (all?) of the combining characters, so you just need to define what they should do in the .tex file. Many accents on the same character is possible. Example:
\documentclass{minimal}
\usepackage{unicode-math}
\setmathfont{XITS Math}
\AtBeginDocument{\directlua{require("combining_preprocessor.lua")}}
\newcommand{\̂}[1]{\ensuremath{\hat{#1}}}
\newcommand{\⃑}[1]{\ensuremath{\vec{#1}}}
\newcommand{\̱}[1]{\ensuremath{\underline{#1}}}
\newcommand{\́}[1]{\ensuremath{\acute{#1}}}
\usepackage{stackrel}
\newcommand{\᷽}[1]{\ensuremath{\stackrel[\approx]{}{#1}}}
\begin{document}
Hello
$ℂ̂$ is hat on $ℂ$, more on $ℂ̂⃑$ (stress test)
$ℂ̂ x̂$
Many combining accents on $x᷽̱̂́⃑$ is cool.
\end{document}
(My browser doesn't do the many combining characters justice here, but it looks nice in the PDF file.)
Not sure if this is the ideal way of doing things, but for what it's worth, here is combining_preprocessor.lua:
function minornil(a, b)
if a == nil and b == nil then
return nil
elseif a == nil then
return b
elseif b == nil then
return a
else
return math.min(a, b)
end
end
function findfirstcombining(line, n)
local a = string.find(line, "\204[\128-\191]", n) -- From U0300,
local b = string.find(line, "\205[\128-\175]", n) -- to U036F.
a = minornil(a, b)
b = string.find(line, "\226\131[\144-\176]", n) -- U20D0 to U20F0
a = minornil(a, b)
b = string.find(line, "\225\183[\128-\191]", n) -- U1DC0 to U1DFF
a = minornil(a, b)
return a
end
function is_utf8_continuation(byte)
return byte < 191 and byte > 127
end
function find_next_utf8_char(str, n)
while str:byte(n) ~= nil and is_utf8_continuation(str:byte(n)) do
n = n + 1
end
return n
end
function combining_iter(str)
local n = 0
return function ()
n = (n ~= nil) and findfirstcombining(str, n + 1)
return n
end
end
function dobuffer(line)
local n1 = 0
local t = {}
for n2 in combining_iter(line) do
if n2 > n1 then
local n3 = n2
repeat
n3 = n3 - 1
until not is_utf8_continuation(line:byte(n3))
table.insert(t, string.sub(line, n1, n3 - 1))
n1 = find_next_utf8_char(line, n2 + 1)
local comb = {}
table.insert(comb, "\\" .. string.sub(line, n2, n1 - 1) .. "{")
table.insert(comb, string.sub(line, n3, n2 - 1) .. "}")
n2 = findfirstcombining(line, n1)
while n2 == n1 do
n1 = find_next_utf8_char(line, n2 + 1)
table.insert(comb, 1, "\\" .. line:sub(n2, n1 - 1) .. "{")
table.insert(comb, "}")
n2 = findfirstcombining(line, n1)
end
table.insert(t, table.concat(comb))
end
end
table.insert(t, string.sub(line, n1))
return table.concat(t)
end
luatexbase.add_to_callback("process_input_buffer",
dobuffer, "combining_preprocessor", 1)
Best Answer
You need to actually load a font that includes these characters. By default, lualatex uses the computer modern fonts. You can select a font with the
fontspecpackage. Just loadingfontspecwithout explicitly setting a font, makes lualatex use the latin modern fonts, which include the characters.gives
You can load any OTF or TTF font with the
fontspecpackage. For details see the fontspec manual. I do not know if there is an Unicode aware version of Bitstream Charter, but you can use Charis SIL, which is based on it:Note that you have to include
mathdesignbefore\setmainfontso that it doesn't override the document font.