Automatically insert "in the next [chapter/section/subsection]" if reference is sequential

Question

I'm aware of the cleveref package \cref which adds the correct reference name (see: Automatically inserting "Section", "Subsection", etc). I have a few references which refer to the very next section and some find it odd to give the number in this case rather than just say "in the next section". Sometimes I've moved sections around and these references suddenly become quite broken. To have the best of both worlds, is there a way to automate this change?

E.g.: replace "this is discussed further in section 1.4" with "this is discussed further in the next section"

Answer 1

Here is a solution based on cleveref package. If the hyperref package is loaded, the word "section" (or chapter/subsection/...) is a clickable hyperlink.

\documentclass{article}

%\usepackage{hyperref}
\usepackage{cleveref}
\crefname{subsection}{subsection}{subsections}

\providecommand\hyperref[2][]{#2}

\makeatletter
\newcommand{\mt@ref}[1]{%
\cref@gettype{#1}{\@temptype}%
\cref@getcounter{#1}{\@tempctr}%
\def\mtt{\the\csname c@\@temptype\endcsname}%
\ifnum\mtt=\numexpr\@tempctr-1\relax \mtcase the next \hyperref[#1]{\@temptype}\else%
\ifnum\mtt=\numexpr\@tempctr+1\relax \mtcase the previous \hyperref[#1]{\@temptype}\else%
\cref{#1}\fi\fi}

\newcommand{\mtref}{\let\mtcase\relax\mt@ref}
\newcommand{\Mtref}{\let\mtcase\MakeUppercase\mt@ref}
\makeatother


\begin{document}
\section{Foo}\label{sec:foo}
this is \Mtref{sec:bar} and this is \mtref{sec:baz}
\subsection{Sub foo}\label{ss:sfoo}
this is \mtref{sec:baz} and this is \mtref{sec:bar}
and \mtref{ss:sfbla} and \mtref{ss:sfbaz}
\subsection{Bla foo}\label{ss:sfbla}
bla bla bla
\subsection{Bar foo}\label{ss:sfbar}
bla bla bla
\subsection{Baz foo}\label{ss:sfbaz}
bla bla bla
\section{Bar}\label{sec:bar}
bla bla bla
\section{Baz}\label{sec:baz}
bla bla bla

\end{document}

The result looks approximately like this (compiled with a previous version of the code):

Answer 2

Revised Attempt

In addition to \Unitref{<label>} which provides the unit name along with the ref, as in "section 2" or "subsection 1.1", etc. (see original attempt), I now also introduce \Ref{<unit>}{<label>}, where <unit> is what is to be compared, "section", "subsection", or "subsubsection". If \ref{<label>} is, in fact, the next increment of the unit, it will output "the next ". If \ref{<label>} is not the next increment of the unit, it will output " \ref{<label>}".

\documentclass{article}
\usepackage{ifthen}
\let\svsection\section
\let\svsubsection\subsection
\let\svsubsubsection\subsubsection

\def\section{\xdef\Unit{section}\svsection}
\def\subsection{\xdef\Unit{subsection}\svsubsection}
\def\subsubsection{\xdef\Unit{subsubsection}\svsubsubsection}

\let\svlabel\label
\def\label#1{\expandafter\xdef\csname Unit-#1\endcsname{\Unit}\svlabel{#1}}

\def\Unitref#1{\csname Unit-#1\endcsname~\ref{#1}}

\def\thenextsection{\the\numexpr\thesection+1\relax}
\def\thenextsubsection{\thesection.\the\numexpr\arabic{subsection}+1\relax}
\def\thenextsubsubsection{\thesection.\arabic{subsection}%
  .\the\numexpr\arabic{subsubsection}+1\relax}

\def\Ref#1#2{%
  \ifthenelse{\equal{\ref{#2}}{\csname thenext#1\endcsname}}%
  {the next #1}{#1~\ref{#2}}
}
\begin{document}

\section{The First Section\label{s:first}}

``The First Subsection'' is \Ref{subsection}{ss:first},
whereas ``The Second Subsection'' is \Ref{subsection}{ss:second}.

\subsection{The First Subsection\label{ss:first}}

In the prior unit, \Unitref{s:first}, not to be confused with the 
current unit, \Unitref{ss:first}, we have successfully captured the data

``A Subsubsection'' is \Ref{subsubsection}{sss:first},
whereas ``Second Subsubsection'' is \Ref{subsubsection}{sss:second}.

\subsubsection{A subsubsection\label{sss:first}}

``The First Section'' is \Ref{section}{s:first},
whereas ``The Second Section'' is \Ref{section}{s:second}.

\section{The Second Section\label{s:second}}

\subsection{The Section Subsection\label{ss:second}}

The prior unit, \Unitref{s:second} is not to be confused with the 
way back references to either \Unitref{s:first}, \Unitref{ss:first},
or \Unitref{sss:first}. But the current unit is \Unitref{ss:second}.
We have successfully captured the data.

\subsubsection{Second subsubsection\label{sss:second}}

\end{document}

Areas that need improvement include optional capitalization of the "unit" name, if appearing at the beginning of a sentence, for example. Also, \Ref can only compare "apples and apples". That is, if the label is that of a subsection, \Ref can only be used to see if it is the next subsection, which is why argument #1 of \Ref has to currently be specified explicitly.

Original (misguided) attempt

Here I just played around a little in the preamble and created \Unitref{} to get "section 2" or "subsection 1.1", etc.

What I do is save the name "section", "subsection", etc. in a macro \Unit whenever I enter such a unit. Then, when invoking \label, I use the current value of \Unit as the value of a new macro \csname Unit-<label>\endcsname.

Finally, when invoking \Unitref{<label>}, it calls upon \csname Unit-<label>\endcsname and follows up with a hard space and a call to \ref{<label>}

\documentclass{article}
\let\svsection\section
\let\svsubsection\subsection
\let\svsubsubsection\subsubsection

\def\section{\xdef\Unit{section}\svsection}
\def\subsection{\xdef\Unit{subsection}\svsubsection}
\def\subsubsection{\xdef\Unit{subsubsection}\svsubsubsection}

\let\svlabel\label
\def\label#1{\expandafter\xdef\csname Unit-#1\endcsname{\Unit}\svlabel{#1}}

\def\Unitref#1{\csname Unit-#1\endcsname~\ref{#1}}
\begin{document}

\section{The First Section\label{s:first}}

\subsection{First Subsection\label{ss:first}}

In the prior unit, \Unitref{s:first}, not to be confused with the 
current unit, \Unitref{ss:first}, we have successfully captured the data

\subsubsection{A subsubsection\label{sss:first}}

Blah-Blah

\section{The Next Section\label{s:second}}

\subsection{Next Subsection\label{ss:second}}

The prior unit, \Unitref{s:second} is not to be confused with the 
way back references to either \Unitref{s:first}, \Unitref{ss:first},
or \Unitref{sss:first}. But the current unit is \Unitref{ss:second}.
We have successfully captured the data.

\end{document}

Answer 3

(Too long for a comment, hence posted as an answer.)

The basic LaTeX \label mechanism, which the cleveref package uses to generate its output, stores only two characteristics associated with an "item" (such as a section, equation, theorem, etc): the item's number -- more precisely, the value of whatever counter value was most recently incremented via a \refstepcounter instruction -- and the number of the page on which the item's number is output.

Unfortunately, because \label doesn't capture other item characteristics -- such as the chapter, section, or subsection number -- you can't use \cref to create a call-out of the type "in the next section" (instead of "in section 1.4") if the cross-referencing call-out happens to occur in section 1.3.

You may want to look into the zref package to build an enhanced cross-referencing functionality of the type you describe.