Linebreaks in long character strings

Question

I would like to print a number of 256-bit long hashes in hexadecimal (so 64 characters, I'm skipping the usual "0x" without white spaces or punctuation) in line and using a monospaced font.

So, I first went for \texttt, which does not hyphenate my strings. I saw some questions with interesting answers, such as How to get long \texttt sections to break and Automatic linebreak on specific character but those both define linebreak for a specific character and I would find ugly to use their trick for each of the 16 characters of hexadecimal without some sort of natural loop.

Is there a way to define a command such that the text inside will be typed as texttt but break on any character or, even better, a standard way to typeset long hexadecimal strings that takes this issue into account?

MWE:

\documentclass{article}

\newcommand{\hash}[1]{\texttt{#1}}%In a perfect world, this would be changed to allow linebreaks anywhere in #1

\begin{document}
SHA-256 is a hash function with a 256-bit long output: \hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
\end{document}

Answer 1

There is already a package for this:

\documentclass{article}
\usepackage{seqsplit}
\newcommand{\hash}[1]{{\ttfamily\seqsplit{#1}}}
\begin{document}
SHA-256 is a hash function with a 256-bit long output:
\hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
\end{document}

Without packages:

\documentclass{article}
\ExplSyntaxOn
\NewDocumentCommand{\hash}{O{\ttfamily}m}
 {
  \group_begin:
  #1 % font choice, default \ttfamily
  \tl_map_function:nN { #2 } __anab_hash_char:n
  \group_end:
 }
\cs_new:Nn __anab_hash_char:n { #1 \skip_horizontal:n { 0pt plus 0.2pt } }
\ExplSyntaxOff
\begin{document}
SHA-256 is a hash function with a 256-bit long output:
\hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
\noindent\parbox[t]{0.4\textwidth}{%
  SHA-256 is a hash function with a 256-bit long output:
  \hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
}\quad
\parbox[t]{0.4\textwidth}{%
  SHA-256 is a hash function with a 256-bit long output:
  \hash[\sffamily]{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
}
\end{document}

Answer 2

You can add a penalty after each character

\documentclass{article}

\newcommand{\hash}[1]{\texttt{\zz#1\zz}}%In a perfect world, this would be changed to allow linebreaks anywhere in #1

\def\zz#1{%
 \ifx\zz#1\else
   #1\linebreak[1]\expandafter\zz
 \fi}

\begin{document}
SHA-256 is a hash function with a 256-bit long output: \hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
\end{document}

Answer 3

Solution Making TeX Treat Characters like Words

This works, but has the limitation that denoted characters do not work. e.g. using hexidecimal (\char"02C6) or octal notation.

\documentclass{article}
\def\hash#1{\xscan#1\relax}% calls xscan which looks ahead one token, #1
\def\xscan{\afterassignment\xxscan\let\token= }% assign single token to \token and call \xxscan
\def\xxscan{%
\ttfamily% set font style
\ifx\token\relax\ttfamily\else%test for end-of-line or end of group and switch to ttfamily
  \ifcat\token\space%
    \token% token is catcode 10
    \spaceskip=.5em% remove glue from space for fixed-width space
    \xspaceskip=.5em% remove glue from space for fixed-width space
  \else%
    \token\hskip 0pt plus 1sp minus 1sp % add glue to any non-catcode 10 (space)
   \fi
   \spaceskip=0pt% reset space skip
\expandafter\xscan% feed next token to \xscan, which is effectively a recursive call
\fi}
\begin{document}
SHA-256 is a hash function with a 256-bit long output: \hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
%SHA-256 is a hash function with a 256-bit long output: \hash{d270f\char"02C6\relax747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}% \char" denoted char syntax not supported
\end{document}

Related: How can I make LaTeX to recognize spaces in my macro (catcode 10)?

Solution Using Intercharacter Tokens

\XeTeXinterchartokenstate=1                     % turn them on
\XeTeXinterchartoks 0 0 = {\penalty0\relax}#1}  % use insert token

This is my preferred solution if using TeX Live 2017 and using xelatex. This has the advantage that it supports the original capabilities of \texttt-it should-like denoted characters (see comments under David Carlisle's answer).

\documentclass{article}
\newcommand{\hash}[1]{\texttt{\XeTeXinterchartokenstate=1\XeTeXinterchartoks 0 0 = {\penalty0\relax}#1}}%In a perfect world, this would be changed to allow linebreaks anywhere in #1
\begin{document}
SHA-256 is a hash function with a 256-bit long output: \hash{d270f747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
SHA-256 is a hash function with a 256-bit long output: \hash{d270f\char"02C6\relax747a8743f11aef93c10e9cb6932cc0b862464c1133dc0f8889088740d15}
\end{document}

Answer 4

Configure it as a URL. EDITED to do it inside a group as \hexdump{}, so that \url remains unaffected by the redefinitions.

\documentclass{article}
\usepackage{url,lipsum}
\urlstyle{rm}
\newcommand\hexdump[1]{%
  \begingroup\urlstyle{tt}%
  \def\UrlBreaks{%
    \do\1\do\2\do\3\do\4\do\5\do\6\do\7\do\8\do\9\do\0\do\A\do\B\do\C\do\D\do\E\do\F}%
  \url{#1}\endgroup%
}
\textwidth3.34in
\parskip 1ex
\begin{document}
\noindent\hexdump{5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5%
A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC5A0FF349ABC}

\lipsum[1]

URLs should be unaffected: \url{www.xyz.com}
\end{document}