Force LaTeX to break a nonsensical line with a hyphen

Question

I have a long text containing many sequences of International Phonetic Alphabet (IPA) characters, and obviously they do not make up any meaningful English words.

I would like to insert this long text in my thesis, but because they do not consist meaningful words, the IPA sequences do not linebreak with hyphens.

Minimal code (XeLaTex):

\documentclass{article}
\usepackage{fontspec}
\setmainfont{XITS}

\begin{document}

∅ p b f v m t d s z n c ɟ ʃ ʒ ɲ k ɡ x h l r r̝ j [pbfvmtdszncɟʃʒɲkɡxhlrr̝j][pbtdɡfvszʃʒxjrr̝lmnɲ] [tdkvszxhjrr̝lpbɡfʃʒxmnɲ][pbtdkfvszʃʒxhr̝mnɲ][pbtdcɟkvsʃʒxhmnɲjr̝rl] [thlpbtdfvszʃʒmnɲ][tkszxhr̝dʃʒ][pbtdkvsʃxhmnɲ][vmnɲjr̝rl] [fvsz][tdsz]kvj

\end{document}

Result:

How can I force LaTeX to just break the long string anywhere with a hyphen? I can't break lines manually, because like I said, there are many sequences like this, so I can't go through every one of them manually.

Answer 1

It wasn't clear if you want a hyphen at the break, I show without and with - here, also it wasn't clear if the space between some ] [ was meaningful, I do nothing outside [...] here so ] [ allows a break (and shows a space if no break occurs) and ][ shows no space and does not allow a break.

\documentclass{article}
\usepackage{fontspec}
\setmainfont{XITS}
\def\x#1{#1\linebreak[0]\x}
\def\xstop#1\x{}
\begin{document}

∅ p b f v m t d s z n c ɟ ʃ ʒ ɲ k ɡ x h l r r̝ j [\x pbfvmtdszncɟʃʒɲkɡxhlrr̝j\xstop][\x pbtdɡfvszʃʒxjrr̝lmnɲ\xstop] [\x tdkvszxhjrr̝lpbɡfʃʒxmnɲ\xstop][\x pbtdkfvszʃʒxhr̝mnɲ\xstop][\x pbtdcɟkvsʃʒxhmnɲjr̝rl\xstop] [\x thlpbtdfvszʃʒmnɲ\xstop][\x tkszxhr̝dʃʒ\xstop][\x pbtdkvsʃxhmnɲ\xstop][\x vmnɲjr̝rl\xstop] [\x fvsz\xstop][\x tdsz\xstop]kvj


\def\x#1{#1\-\x}

∅ p b f v m t d s z n c ɟ ʃ ʒ ɲ k ɡ x h l r r̝ j [\x pbfvmtdszncɟʃʒɲkɡxhlrr̝j\xstop][\x pbtdɡfvszʃʒxjrr̝lmnɲ\xstop] [\x tdkvszxhjrr̝lpbɡfʃʒxmnɲ\xstop][\x pbtdkfvszʃʒxhr̝mnɲ\xstop][\x pbtdcɟkvsʃʒxhmnɲjr̝rl\xstop] [\x thlpbtdfvszʃʒmnɲ\xstop][\x tkszxhr̝dʃʒ\xstop][\x pbtdkvsʃxhmnɲ\xstop][\x vmnɲjr̝rl\xstop] [\x fvsz\xstop][\x tdsz\xstop]kvj

\end{document}

Answer 2

This adds \- between all characters, but care is taken not to do it too early (three leading characters and three trailing ones are not considered) and not to tamper with combining characters (from U+0301 up to U+036F).

You probably want a better name than \foo.

\documentclass[twocolumn]{article}
\usepackage{fontspec}
\setmainfont{XITS}

\ExplSyntaxOn
\NewDocumentCommand{\foo}{m}
 {
  [
  % split the input at its items (characters)
  \seq_set_split:Nnn \l_tmpa_seq { } { #1 }
  % map the input, considering also the index of each item
  % ##1 is the index, ##2 is the item
  \seq_map_indexed_inline:Nn \l_tmpa_seq
   {
    % check that the character is not a combining one
    % and that we're have at least three characters
    % before and after
    \bool_lazy_and:nnT
     {
      ! \int_compare_p:n { "0301 <= `##2 <= "036F } % not a combining
     }
     {
      \int_compare_p:n { 3 < ##1 < \seq_count:N \l_tmpa_seq - 1 } % we're in the middle
     }
     { \- } % add a discretionary
    % print the character
    ##2
   }
  ]
 }
\ExplSyntaxOff

\begin{document}

∅ p b f v m t d s z n c ɟ ʃ ʒ ɲ k ɡ x h l r r̝ j 
\foo{pbfvmtdszncɟʃʒɲkɡxhlrr̝j}\foo{pbtdɡfvszʃʒxjrr̝lmnɲ} 
\foo{tdkvszxhjrr̝lpbɡfʃʒxmnɲ}\foo{pbtdkfvszʃʒxhr̝mnɲ}\foo{pbtdcɟkvsʃʒxhmnɲjr̝rl} 
\foo{thlpbtdfvszʃʒmnɲ}\foo{tkszxhr̝dʃʒ}\foo{pbtdkvsʃxhmnɲ}\foo{vmnɲjr̝rl} 
\foo{fvsz}\foo{tdsz}kvj

%\parbox{0pt}{\hspace{0pt}\foo{pbfvmtdszncɟʃʒɲkɡxhlrr̝j} \foo{pbtdkvsʃxhmnɲ}}

\end{document}

Uncomment the \parbox line to see all the points where \- is added.

Answer 3

If you're free to use LuaLaTeX, it's straightforward to set up a Lua function that modifies the string so that line breaks are possibly everywhere. The code can handle pretty much all utf8-encoded characters -- they need not be ascii-encoded.

Please note that this approach does not generate hyphenation characters at line ends. In my view, the absence of hyphenation characters may actually be an advantage, since there's now no ambiguity as to whether a - character that happens to occur at the very end of a line is a hyphenation character inserted by LaTeX or is already present in the long string. If you do require a line to end with a hyphenation character, just change '%1\\hspace{0pt}' to '%1\\-' in the code below.

\documentclass{article}
\usepackage{fontspec}
\setmainfont{XITS}
\usepackage{luacode} % for 'luacode' env. and '\luastringN' macro
\begin{luacode}

function gentle_split ( s )
   s = unicode.utf8.gsub ( s , '(.)' , '%1\\hspace{0pt}' )
   tex.sprint ( s )
end

\end{luacode}
\newcommand{\GentleSplit}[1]{\directlua{gentle_split(\luastringN{#1})}}

\begin{document}

\noindent
\GentleSplit{∅ p b f v m t d s z n c ɟ ʃ ʒ ɲ k ɡ x h l r r̝ j [pbfvmtdszncɟʃʒɲkɡxhlrr̝j][pbtdɡfvszʃʒxjrr̝lmnɲ] [tdkvszxhjrr̝lpbɡfʃʒxmnɲ][pbtdkfvszʃʒxhr̝mnɲ][pbtdcɟkvsʃʒxhmnɲjr̝rl] [thlpbtdfvszʃʒmnɲ][tkszxhr̝dʃʒ][pbtdkvsʃxhmnɲ][vmnɲjr̝rl] [fvsz][tdsz]kvj}

\medskip
\noindent
\GentleSplit{[ɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒɟʃʒ]}
\end{document}

Answer 4

Still another approach based on luatex, which allows \patterns in the document. A new language is declared and a set of hyphenation patterns are then assigned to it.

\documentclass{article}

\newlanguage\ipalang
\begingroup
  \language\ipalang
  \patterns{1∅ 1p 1b 1f 1v 1m 1t 1d 1s 1z 1n 1c 1ɟ 1ʃ 1ʒ 1ɲ 1k 1ɡ 1x 1h
  1l 1r 1r̝ 1j}
  % \prehyphenchar=-1 % If you don’t want hyphens
\endgroup

\usepackage{fontspec}
\setmainfont{XITS}

\newcommand\ipatext[1]{{%
  \language\ipalang
  \lefthyphenmin=1
  \righthyphenmin=1
  #1}}

\begin{document}

\hsize1pt

Start paragraph
\ipatext{[vmtdszncɟʃʒɲkɡxhlrr̝j][dɡfvszʃʒxjrr̝lmnɲ]}
End paragraph.

\end{document}