Hyphenating identifiers printed in typewriter font

Question

I'm typesetting identifier documentation by generating them from a database. These identifiers that are very free-format, i.e. using a mixture of camel-Case and underscores etc. I want to print them in typewriter font, hyphenated.

I have managed the printing of the underscores identifiers with the help of TeX.SX, thanks very much.

However... hyphenation. I want to allow a linebreak between a lowercase character and an uppercase character, and after _ and -, and replace the normal hyphen with another character (\cdot would be nice, but that's not a character in T1) to prevent ambiguity for the latter case.

I think I'd want keep the original hyphenation points (useful for the string "modification" in my example). I guess breaking before or after a number does not need special treatment.

Here is an example of my current \identifier command that does not add extra hyphenation points. I'm not understanding it well enough to mix in the code from e.g. Automatic camel case breaking though - could someone have a go at it for me please?

\documentclass{article}
\usepackage[T1]{fontenc} % better underscore
\usepackage[htt]{hyphenat}
\makeatletter%
\DeclareRobustCommand*{\identifier}[1]{%
  \begingroup\@activeus\scantokens{%
  \ifmmode%
    \expandafter\texttt%
  \else%
    \expandafter\textnhtt%
  \fi{#1}%
    \endinput}\endgroup}%
\begingroup\lccode`\~=`\_\relax
   \lowercase{\endgroup\def\@activeus{\catcode`\_=\active \let~\_}}
\makeatother

\begin{document}
\parbox{0pt}{\hspace{0pt}%
  \identifier{SmartModificationSense}
  \identifier{SmartModification_Sense}
  \identifier{Smart_Modification_Sense2}
  \identifier{smartModification_Sense2}
  \identifier{smartModi-fication_Sense2}
  \identifier{adj_Iref3_5percent}
  \identifier{enable_SPI_1}
}
\end{document}

score 1 · Accepted Answer · answered Aug 15 '16 at 11:21

This adds a centered dot if an identifier is split before an uppercase letter (not preceded by another uppercase letter) or after an underscore and allows normal hyphenation in word fragments.

\documentclass{article}
\usepackage[T1]{fontenc} % better underscore
\usepackage[htt]{hyphenat}
\usepackage{xparse,l3regex}

\ExplSyntaxOn
\NewDocumentCommand{\identifier}{m}
 {
  \cmarqu_identifier:n { #1 }
 }

\tl_new:N \l_cmarqu_identifier_tl

\cs_new:Nn \cmarqu_identifier:n
 {
  \tl_set:Nn \l_cmarqu_identifier_tl { #1 }
  \regex_replace_all:nnN
   { \B([^A-Z])([A-Z]) }
   { \1 \c{cmarqu_period:} \2 }
   \l_cmarqu_identifier_tl
  \regex_replace_all:nnN
   { \cD.}
   { \cO_\c{cmarqu_period:} }
   \l_cmarqu_identifier_tl
  \regex_replace_all:nnN
   { \c{cmarqu_period:}\c{cmarqu_period:} }
   { \c{cmarqu_period:} }
   \l_cmarqu_identifier_tl
  \texttt{\tl_use:N \l_cmarqu_identifier_tl}
 }
\cs_new:Nn \cmarqu_period:
 {
  \nobreak
  \discretionary{\textperiodcentered}{}{}
  \nobreak\hspace{0pt}
 }
\ExplSyntaxOff

\begin{document}
\parbox{0pt}{\hspace{0pt}%
  \identifier{SmartModificationSense}
  \identifier{SmartModification_Sense}
  \identifier{Smart_Modification_Sense2}
  \identifier{smartModification_Sense2}
  \identifier{smartModification_Sense2}
  \identifier{adj_Iref3_5percent}
  \identifier{enable_SPI_1}
}
\end{document}

Thanks very much, after updating my Texlive installation, I had it working like a charm. One thing though - would it also be possible to change all the hyphenation within such an identifier to the centered dot? I fear that the current behaviour is not easily deducible without much context (or explaining it in a "Typography" section). — cmarqu, Aug 15 '16 at 13:33
@cmarqu Unfortunately not; the hyphenation character must belong to the same font. I guess it would be possible with LuaTeX. — egreg, Aug 15 '16 at 16:28

Hyphenating identifiers printed in typewriter font

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