How to use mmap in XeLaTeX?

Question

I want to map math characters in my PDF output to Unicode characters. XeLaTeX already does this somewhat, but with very unsatisfactory results.

Just for comparison, consider the very simple example $\mathbb E[X] = \sum_x x p(x)$.

1. As baseline, Plain PDFLaTeX gives:

E[X] =
P
x xp(x)

2. PDFLaTeX + \usepackage[noTeX]{mmap} gives:

[] =
Σ︀
 ()

3. Plain XeLaTeX gives:

E[X] =
Σ
x xp(x)

4 Finally, XeLaTeX + \usepackage{unicode-math} gives:

[] = Σ ()

However, I want to avoid unicode-math due to its font management issues (see here and its related questions). Is there any way I can get behavior in 2 and 4 in XeLaTeX without changing math fonts?

Answer 1

mmap uses \pdfglyphtounicode to map the glyphs. xetex to my knowledge doesn't support it, but with lualatex you can use it. As mmap doesn't support lualatex by default you have to map a number of command names to the names of luatex with the luatex845 package:

\documentclass{book}
\usepackage{amssymb}
\usepackage{luatex85}
\usepackage[noTeX]{mmap}
\begin{document}
$\mathbb E[X] = \sum_x x p(x)$
\end{document}