% Bengali mathematical digits, without changing authored Western digits.
% Part of latexbangla, LPPL 1.3c or later; copyright 2026 Adib Hasan.

% Text fonts contain Bengali digits even when the chosen mathematics font does
% not. amstext's \text follows display/text/script/scriptscript sizing. Emit the
% digit in text mode, where its math-active definition cannot recurse.
% Expand to a grouped math field, not \mathord: TeX's unbraced script scanner
% accepts the group in x^২ or x_৩, but cannot consume a \mathord command there.
% A grouped field is already an ordinary atom in the surrounding expression.
\cs_new_protected:Npn \__latexbangla_math_digit:n #1
  {
    {
      \text
        {
          % Match ordinary math digits: surrounding \textbf does not make
          % mathematics bold. Only the selected math version controls weight.
          \bengalifont\mdseries\upshape
          \str_if_eq:eeT {\math@version} {bold} {\bfseries}
          \char_generate:nn {#1} {12}
        }
    }
  }

% Change only mathcodes. The source characters retain their normal catcodes in
% prose, auxiliary files and bookmarks. Delay installation until unicode-math
% and other preamble font packages have finished configuring their mathcodes.
\cs_new_protected:Npn \__latexbangla_install_math_digits:
  {
    \int_step_inline:nnn {"09E6} {"09EF}
      {
        \cs_gset_protected:cpn {__latexbangla_math_digit_##1:}
          {\__latexbangla_math_digit:n {##1}}
        \char_gset_active_eq:nc {##1} {__latexbangla_math_digit_##1:}
        \tex_mathcode:D ##1 = "8000\scan_stop:
      }
  }
\cs_generate_variant:Nn \char_gset_active_eq:nN {nc}
\AddToHook{begindocument/end}[latexbangla/math]
  {\__latexbangla_install_math_digits:}
\endinput