How to use a counter to set section or chapter or subsection based on counter value?

Question

Suppose I have my own counter as in

\newcounter{x}
\setcounter{x}{0}

and now I want to start a new "section" based on the value of x. For example, if x==-1 I want \part, and if x==0 then it will be \chapter and if x==1 it will be \section and so on.

I do not want to write each time something like this (do not even know it is valid syntax)

   \ifnum \value{x} \eq  -1
         \part             
   \else
        \ifnum \value{x} \eq 0
           \chapter
        ...
        \fi
  \fi
  ...

I'd like to just write

  \makeSectionTypeBasedOnThisValue{x}{title of the section of chapter is here}

and this command will map to the correct command based on the value of x. I will make sure x is always between -1 and 5 since these are the valid values. I am using book style.

I have a reason to want to do it this way. (briefly, I am building my large tree of latex documents, combining them to one document, and I want to be able to build it starting from any level going down. Hence depending on where in the tree I start the build, section numbering will be different. One time the same level can be a \section while some other time that level can become a \subsection. So I do not want to hardcode the \section or \chapter commands in Latex files, but I want these to depend on the level the file is in the tree. The counter will represent the level in the tree I am starting the build from)

Is there is an easy way to do this? I am a newbie in Latex.

Answer 1

Using \ifcase, you can selectively step through possible numeric values:

\documentclass{report}
\newcounter{myseccntr}
\newcommand{\makeSectionTypeBasedOnThisValue}[1]{%
  \setcounter{myseccntr}{\numexpr#1+1}%
  \ifcase\value{myseccntr}% -1
    \expandafter\part
  \or % 0
    \expandafter\chapter
  \or % 1
    \expandafter\section
  \or % 2
    \expandafter\subsection
  \or % 3
    \expandafter\subsubsection
  \or % 4
    \expandafter\paragraph
  \or % 5
    \expandafter\subparagraph
  \fi%
}
\begin{document}
\tableofcontents
\makeSectionTypeBasedOnThisValue{-1}{Part}
\makeSectionTypeBasedOnThisValue{0}{Chapter}
\makeSectionTypeBasedOnThisValue{1}{Section}
\makeSectionTypeBasedOnThisValue{2}{Subsection}
\makeSectionTypeBasedOnThisValue{1}{Section}
\makeSectionTypeBasedOnThisValue{-1}{Part}
\makeSectionTypeBasedOnThisValue{0}{Chapter}
\makeSectionTypeBasedOnThisValue{1}{Section}
\end{document}