Extract all emphasized words from latex document

Question

I need to produce a list of all words that are emphasised in my LaTeX document (=which are enclosed by \emph{...}).

How can I use awk to process the .tex file and extract all patterns starting with \emph{ and ending with a } and which do not contain a closing curly bracket within (otherwise almost the whole document would be matching the pattern). Finally, the result of the search should be a list like this:

1. FirstEmphasizedWord
2. AnotherEmphasizedWord
3. TheLastEmphasizedWord

(It would be nice if the list was already formatted as a numbered LaTeX list) What is the correct input for regular expression matching when I want to use awk for this job?

Answer 1

If you are not stuck on using an external script to do this, you can just do it LaTeX by redefining the \emph{} macro:

Notes:

• Note how nested usage of \emph{} is treated (items 4 and 5 in the list). This may or may not be the desired behavior, but this should be fairly easy to change depending on the desired outcome.

References:

• How keep a running list of strings and then process them one at a time
• As egreg pointed out, it is better to use \LetLtxMacro from the letltxmacro package instead of the usual \let because \emph is basically defined with \DeclareRobustCommand. A detailed description of \LetLtxMacro can be found at this question at closed square root symbol.

Code:

\documentclass{article}
\usepackage{letltxmacro}

% https://tex.stackexchange.com/questions/14393/how-keep-a-running-list-of-strings-and-then-process-them-one-at-a-time
\def\ListOfEmphText{}
\makeatletter
\newcommand{\AddToListOfEmphText}[1]{%
    \g@addto@macro\ListOfEmphText{\item {#1}}%
}
\makeatother

\LetLtxMacro\OldEmph\emph
\DeclareRobustCommand{\emph}[1]{\AddToListOfEmphText{#1}\OldEmph{#1}}

\begin{document}
\emph{First emphasized Text,  with a comma} followed by
some normal text.
\emph{Second emphasized Text} followed by
some more normal text.

Some normal text before
\emph{Third emphasized Text} also followed by
some normal text

Here is some nested usage: \emph{abc \emph{def} ghi}, just to test that it works.

\bigskip\noindent
The macro \verb|\emph{}| was used on:
\begin{enumerate}
    \ListOfEmphText
\end{enumerate}

\end{document}

Answer 2

Doing this with awk will be tricky as (AFAIK) it struggles with non-greedy regular expressions. Note that we'll need them to be non-greedy because of lines such as

\emph{multiple}  occurrences on the \emph{same line}

Perl can handle this pretty easily; you run the following script as

perl emphasize.pl myfile.tex

which will output to the terminal. Of course, you can output it into another file, such as

perl emphasize.pl myfile.tex> emphasizedtext.tex

Here's a test case:

myfile.tex

\documentclass{article}
\begin{document}

\emph{first} word is \emph{emphasized} and here's another \emph{one}.

here's another \emph{word} that is \emph{also} emphacized
\begin{enumerate}
  \item \emph{should} also work
  \item anywhere \emph{else too with multiple words}
\end{enumerate}
will struggle with nested: \emph{here is a \emph{nest}}
\end{document}

emhpasize.pl

#!/usr/bin/perl

use strict;
use warnings;

# for emphasized content
my @emphcontent=();
my $emphphrase='';
my $counter=0;

# loop through the lines in the INPUT file
while(<>)
{
    # check for 
    #   \emph{}...
    # and make sure not to match
    #   %\emph{}...
    # which is commented
    if($_ =~ m/\\emph{(.*?)}/ and $_ !~ m/^%/)
    {
      # store the emphasized content
      while($_ =~ m/\\emph{(.*?)}/g){
        push(@emphcontent,$1);
      }
    }
}

# output the emphasized content
foreach $emphphrase (@emphcontent)
{
    $counter++;
    print $counter,". ",$emphphrase,"\n";
}

exit

output

1. first
2. emphasized
3. one
4. word
5. also
6. should
7. else too with multiple words
8. here is a \emph{nest

Or else you might prefer

# start the enumerate environment
print "\\begin{enumerate}\n";

# output the emphasized content
foreach $emphphrase (@emphcontent)
{
    print "\\item ",$emphphrase,"\n";
}
# end the enumerate environment
print "\\end{enumerate}\n";

which gives

\begin{enumerate}
\item first
\item emphasized
\item one
\item word
\item also
\item should
\item else too with multiple words
\item here is a \emph{nest
\end{enumerate}

Limitations

As you'll see, this script fails with nested {} and I have no idea how to fix it without some very convoluted code.

Answer 3

Here's a LuaLaTeX solution using pattern matching. It can handle nesting easily (and by deleting a line can ignore nesting if desired). In addition, it can be turned on and off as desired. On the downside, since it uses the process_input_buffer callback, commented \emph's are included as well. I'm not sure how much of an issue this would be for you.

• \startgetemph turns on emph collection.
• \stopgetemph turns off emph collection.
• \printemphs returns a numbered list of emphs.

Output

---

---

\documentclass{article}
\usepackage{luacode,luatexbase}
\begin{luacode*}

emphs = {}
getemph = function(head)
    for hit in string.gmatch(head,"\emph(%b{})") do
        emphs[#emphs + 1] = hit
        -- if you don't want nesting, then delete the following line
        getemph(hit)
    end
    return true
end

printemphs = function()
    tex.print("\\begin{enumerate}")
    for i = 1, #emphs do
        tex.print("\\item "..emphs[i])
    end
    tex.print("\\end{enumerate}")
end

\end{luacode*}

\def\startgetemph{\directlua{luatexbase.add_to_callback("process_input_buffer", getemph, "getemph")}}
\def\stopgetemph{\directlua{luatexbase.remove_from_callback("process_input_buffer","getemph")}}
\def\printemphs{\directlua{printemphs()}}

\begin{document}

\startgetemph

\noindent
Here is some text where some of it is \emph{emphasized}.  Other parts will be \emph{emphasized \emph{twice}}.
%\emph{Oops, this is commented emphasized text!}
\stopgetemph
After using \verb=\stopgetemph=, \emph{this final emphasized text} will not be grabbed.

\printemphs
\end{document}

Answer 4

In Textwrangler (mac), do a search/replace for \\emph\{[a-z ]+\} Click "find all", you can then copy/paste the results into a new file. Do a new search/replace for all the newlines, inserting \\item. Very low-end.