latexdiff with counters and \ifnum

[chanGimeno]

% latexdiff --version
This is LATEXDIFF 1.2.0  (Algorithm::Diff 1.15 so, Perl v5.18.2)
  (c) 2004-2016 F J Tilmann

Overview

I am trying to use latexdiff in a tex-project which uses structures of the following type:

\newcounter{IOF}
\setcounter{IOF}{1}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do this}
\stepcounter{IOF}

latexdiff deliveres good results whenever there is a change in the sectioning (see example). But, when a new heading is added, latexdiff add \DIFadd{}'s around the counter (IOF in my case) and the numeric condition \value{IOF}<10:

\subsection{\DIFadd{Function-}\ifnum \value{\DIFadd{IOF}}\DIFadd{<10 0}\fi\DIFadd{\arabic{IOF}: do more things}}

leading to errors when compiling the latexdiff'ed file.

I could go around this issue by using regular expressions,

latexdiff ${oldfile} ${newfile} > $diff_file sed -i -e 's/\\value{\\DIFadd{\(.*\)}}\(.\)/\\value{\1}\2/g' -e 's/\\DIFadd{<10\ 0}/<10\ \\DIFadd{0}/g' $diff_file

Example

Old file ifnum_counter_old.tex

\documentclass{article}
\begin{document}
\tableofcontents
\section{Functions}
\newcounter{IOF}
\setcounter{IOF}{1}
\subsection{Function-\ifnum \value{IOF} <10 0 \fi \arabic{IOF}: do this}
\stepcounter{IOF}
\subsection{Function-\ifnum \value{IOF} <10 0 \fi \arabic{IOF}: do same}
\stepcounter{IOF}
\end{document}

New file ifnum_counter_new.tex

\documentclass{article}
\begin{document}
\tableofcontents
\section{Functions}
\newcounter{IOF}
\setcounter{IOF}{1}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do this}
\stepcounter{IOF}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do something else}
\stepcounter{IOF}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do more things}
\stepcounter{IOF}
This is the value of the counter IOF: \ifnum \value{IOF}<10 0\fi\arabic{IOF}
\end{document}

latexdiff-file ifnum_counter_latexdiff.tex

\documentclass{article}
%DIF LATEXDIFF DIFFERENCE FILE
%DIF DEL ifnum_counter_old.tex   Thu Oct 20 15:09:35 2016
%DIF ADD ifnum_counter_new.tex   Thu Oct 20 16:07:13 2016
%DIF PREAMBLE EXTENSION ADDED BY LATEXDIFF
%DIF UNDERLINE PREAMBLE %DIF PREAMBLE
\RequirePackage[normalem]{ulem} %DIF PREAMBLE
\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1} %DIF PREAMBLE
\providecommand{\DIFadd}[1]{{\protect\color{blue}\uwave{#1}}} %DIF PREAMBLE
\providecommand{\DIFdel}[1]{{\protect\color{red}\sout{#1}}}                      %DIF PREAMBLE
%DIF SAFE PREAMBLE %DIF PREAMBLE
\providecommand{\DIFaddbegin}{} %DIF PREAMBLE
\providecommand{\DIFaddend}{} %DIF PREAMBLE
\providecommand{\DIFdelbegin}{} %DIF PREAMBLE
\providecommand{\DIFdelend}{} %DIF PREAMBLE
%DIF FLOATSAFE PREAMBLE %DIF PREAMBLE
\providecommand{\DIFaddFL}[1]{\DIFadd{#1}} %DIF PREAMBLE
\providecommand{\DIFdelFL}[1]{\DIFdel{#1}} %DIF PREAMBLE
\providecommand{\DIFaddbeginFL}{} %DIF PREAMBLE
\providecommand{\DIFaddendFL}{} %DIF PREAMBLE
\providecommand{\DIFdelbeginFL}{} %DIF PREAMBLE
\providecommand{\DIFdelendFL}{} %DIF PREAMBLE
%DIF END PREAMBLE EXTENSION ADDED BY LATEXDIFF
\begin{document}
\tableofcontents
\section{Functions}
\newcounter{IOF}
\setcounter{IOF}{1}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do this}
\stepcounter{IOF}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do \DIFdelbegin \DIFdel{same}\DIFdelend \DIFaddbegin \DIFadd{something else}\DIFaddend }
\stepcounter{IOF}
\DIFaddbegin 
\subsection{\DIFadd{Function-}\ifnum \value{\DIFadd{IOF}}\DIFadd{<10 0}\fi\DIFadd{\arabic{IOF}: do more things}}
\stepcounter{IOF}
\DIFadd{This is the value of the counter IOF: }\ifnum \value{\DIFadd{IOF}}\DIFadd{<10 0}\fi\DIFadd{\arabic{IOF}
}\DIFaddend 
\end{document}

latexdiff pdf:

latexdiff pdf (after the sed fix):

sed -i -e 's/\\value{\\DIFadd{\(.*\)}}\(.\)/\\value{\1}\2/g' -e 's/\\DIFadd{<10\ 0}/<10\ \\DIFadd{0}/g' ifnum_counter_latexdiff.tex

as wanted.

[ftilmann]

\ifnum is TeX rather than LaTeX syntax, and this is something that latexdiff explicitly cannot deal with (it is stated in the manual). The reason is that in order to process all TeX constructs it would essentially be necessary to recode the parsing done in TeX, which I can suggest to use the ifthen package which implements conditionals with latex style commands. Alternatively embed the usage of ifnum in a DIFnomarkup environment (which you previously need to define to do absolutely nothing) (see page 3 of the latexdiff pdf manual)

[chanGimeno]

Thanks for the explanation and for the maintenance of this great tool!

Probably I am missing something, but I tried out both of your suggestions without success. I tried the ifthen and etoolbox packages for conditional implementations, but they produce processing errors when using them in the headings (i.e. \subsection), due to some "paragraphing" in the table of contents

ERROR: Paragraph ended before @dottedtocline was complete.

Same is true using the \begin{DIFnomarkup} and \end{DIFnomarkup} alternative.

It seems that I cannot avoid the sed workaround for this specific case.

[ftilmann]

I don't really know the ifthen package so I guess this simply might not work in a movable argument. However, I just tried the DIFnomarkup solution and it works for me. I edit the new file:

\newenvironment{DIFnomarkup}{}{}
\begin{document}
\tableofcontents
\section{Functions}
\newcounter{IOF}
\setcounter{IOF}{1}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do this}

\stepcounter{IOF}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do something else}
\stepcounter{IOF}
\begin{DIFnomarkup}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do more things}
\stepcounter{IOF}
This is the value of the counter IOF: \ifnum \value{IOF}<10 0\fi\arabic{IOF}
\end{DIFnomarkup}
\end{document}

Of course, the markup in this block disappears (hence it is a workaround, not a solution)

[chanGimeno]

Thanks again!

Inserting \DIFnomarkup{} around the \ifnum \value{IOF}<10 0\fistatement approaches the wanted effect (only the "zero" inside the \ifnum remains black, the rest of the added text becomes blue):

\documentclass{article}
\newenvironment{DIFnomarkup}{}{}
\begin{document}
\tableofcontents
\section{Functions}
\newcounter{IOF}
\setcounter{IOF}{1}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do this}
\stepcounter{IOF}
\subsection{Function-\ifnum \value{IOF}<10 0\fi\arabic{IOF}: do something else}
\stepcounter{IOF}
\subsection{Function-\DIFnomarkup{\ifnum \value{IOF}<10 0\fi}\arabic{IOF}: do more things}
\stepcounter{IOF}
This is the value of the counter IOF: \DIFnomarkup{\ifnum \value{IOF}<10 0\fi}\arabic{IOF}
\end{document}