Leftalign labels with enumitem

Question

I'm using the enumitem package to define a legal list:

\usepackage{enumitem}
\newlist{legal}{enumerate}{10}
\setlist[legal]{label*=\arabic*.}

The output for a list looks like this:

1. foo
  1.1 bar
    1.1.1 bla
  1.2 baz
    1.2.1 blubb
2. fuuu

But that gets somewhat clobbered if you have many items and deep nesting. So I want all the labels to align on the leftmost side but keep the indentation for the items themselves like so:

1. foo
1.1    bar
1.1.1      bla
1.2    baz
1.2.1      blubb
2. fuuu

I guess this would make searching for an entry in that list easier. Any ideas on how to achieve that?

I have already tried the align option of the enumitem package but that didn't work as intended.

Answer 1

Here's a solution without any packages and guaranteeing that indentation of the item text will be preserved for every value of the counters < 100 (the other solution exhibits a bad behaviour if any of the counters surpasses 9).

EDIT: this new version allows nesting up to six levels and corrects a little spacing issue of the first version:

\documentclass{article}
\usepackage{lipsum}

\newlength\labwd
\makeatletter
\newcommand\labelenumv{}
\newcommand\labelenumvi{}
\newcounter{enumv}[enumiv]
\newcounter{enumvi}[enumv]
\newenvironment{myenum}
    {\advance\@enumdepth\@ne
    \ifnum \@enumdepth >6\@toodeep\else
    \edef\@enumctr{enum\romannumeral\the\@enumdepth}
    \renewcommand\labelenumi{\arabic{enumi}.}
    \renewcommand\labelenumii{\labelenumi\arabic{enumii}.}
    \renewcommand\labelenumiii{\labelenumii\arabic{enumiii}.}
    \renewcommand\labelenumiv{\labelenumiii\arabic{enumiv}.}
    \renewcommand\labelenumv{\labelenumiv\arabic{enumv}.}
    \renewcommand\labelenumvi{\labelenumv\arabic{enumvi}.}
    \renewcommand\theenumii{\arabic{enumii}}
    \renewcommand\theenumiii{\arabic{enumiii}}
    \renewcommand\theenumiv{\arabic{enumiv}}
    \renewcommand\p@enumii{\theenumi.}
    \renewcommand\p@enumiii{\theenumi.\theenumii.}
    \renewcommand\p@enumiv{\theenumi.\theenumii.\theenumiii.}
    \renewcommand\p@enumv{\theenumi.\theenumii.\theenumiii.\theenumiv.}
    \renewcommand\p@enumvi{\theenumi.\theenumii.\theenumiii.\theenumiv.\theenumv.}
    \begin{list}{\csname label\@enumctr\endcsname}{%
        \usecounter\@enumctr
        \setlength\labelwidth{0pt}
        \setlength\labelsep{0pt}
        \setlength\leftmargin{15pt}
        \setlength\labwd{\ifcase\@enumdepth\or -15pt\or -30pt\or -45pt\or -60pt\or -75pt\or -90pt\fi}%
        \renewcommand\makelabel[1]{\hspace*{\labwd}##1\hfill}%
    }%
    \fi%
    }
    {\ifnum \@enumdepth >6\else\end{list}\fi}
\makeatother


\begin{document}

\lipsum[2]
\begin{myenum}\ignorespaces
  \item\label{a} First item.
  \begin{myenum}\ignorespaces
    \item\label{b} First subitem.
    \begin{myenum}\ignorespaces
      \item\label{c} First subsubitem.
      \item Second subsubitem.
      \begin{myenum}
        \item\label{d} First subsubsubitem.
        \item Second subsubsubitem.
        \begin{myenum}
          \item\label{e} First subsubsubsubitem.
          \item \lipsum[1]
        \end{myenum}
      \end{myenum}
      \item Third subsubitem.
    \end{myenum}
  \item Second subitem.
  \end{myenum}
  \item Second item.
\end{myenum}

\begin{myenum}
  \setcounter{enumi}{8}
  \item First item.
  \begin{myenum}
    \setcounter{enumii}{8}
    \item First subitem.
    \begin{myenum}
      \setcounter{enumiii}{8}
      \item First subsubitem.
      \item Second subsubitem.
      \begin{myenum}
        \setcounter{enumiv}{8}
        \item First subsubsubitem.
        \item Second subsubsubitem. 
      \end{myenum}
      \item Third subsubitem.
    \end{myenum}
  \item Second subitem.
  \end{myenum}
  \item Second item.
\end{myenum}

\end{document}

Answer 2

You could use leftmargin=0pt, labelwidth=! which means enumitem will calculate the with of the label to suit a left margin of 0pt. Combining with align=left gives the desired result.

\setlist[legal]{label*=\arabic*., leftmargin=0pt, labelsep=1.5em, align=left, labelwidth=!}

Setting labelsep is not strictly required but I find that 1.5em is more appropriate than the default value.

Answer 3

Here I tried to modify the code by @GonzaloMedina to allow deeper nesting and resolve a problem with the \@toodeep error handling (not added as comment because it's too long).

\documentclass{article}
\usepackage{lipsum}

\newlength\labwd
\makeatletter
\newcommand\labelenumv{}
\newcommand\labelenumvi{}
\newcounter{enumv}[enumiv]
\newcounter{enumvi}[enumv]
\newenvironment{myenum}
    {\advance\@enumdepth\@ne
    \ifnum \@enumdepth >6\@toodeep\else
    \edef\@enumctr{enum\romannumeral\the\@enumdepth}
    \renewcommand\labelenumi{\arabic{enumi}.}
    \renewcommand\labelenumii{\labelenumi\arabic{enumii}.}
    \renewcommand\labelenumiii{\labelenumii\arabic{enumiii}.}
    \renewcommand\labelenumiv{\labelenumiii\arabic{enumiv}.}
    \renewcommand\labelenumv{\labelenumiv\arabic{enumv}.}
    \renewcommand\labelenumvi{\labelenumv\arabic{enumvi}.}
    \begin{list}{\csname label\@enumctr\endcsname}{%
        \usecounter\@enumctr
        \setlength\labelwidth{5pt}
        \setlength\labelsep{\z@}
        \setlength\leftmargin{15pt}
        \setlength\itemindent{5pt}
        \setlength\labwd{\ifcase \@enumdepth \or -15pt\or -30pt\or -45pt\or -60pt\or -75pt\or -90pt\fi}
        \renewcommand\makelabel[1]{\hspace*{\labwd}##1\hfill}
    }%
    \fi
    }
    {\ifnum \@enumdepth >6\else\end{list}\fi}
\makeatother


\begin{document}

\lipsum[2]
\begin{myenum}
  \item First item.
  \begin{myenum}
    \item First subitem.
    \begin{myenum}
      \item First subsubitem.
      \item Second subsubitem.
      \begin{myenum}
        \item First subsubsubitem.
        \item Second subsubsubitem.
        \begin{myenum}
          \item First subsubsubsubitem.
          \item \lipsum[1]
        \end{myenum}
      \end{myenum}
      \item Third subsubitem.
    \end{myenum}
  \item Second subitem.
  \end{myenum}
  \item Second item.
\end{myenum}

\begin{myenum}
  \setcounter{enumi}{8}
  \item First item.
  \begin{myenum}
    \setcounter{enumii}{8}
    \item First subitem.
    \begin{myenum}
      \setcounter{enumiii}{8}
      \item First subsubitem.
      \item Second subsubitem.
      \begin{myenum}
        \setcounter{enumiv}{8}
        \item First subsubsubitem.
        \item Second subsubsubitem. 
      \end{myenum}
      \item Third subsubitem.
    \end{myenum}
  \item Second subitem.
  \end{myenum}
  \item Second item.
\end{myenum}

\end{document}

One open issue is the handling indents in multiline-items — currently the indent of the first line of such an item is about one character too deep — and probably there is a nicer way to write the hacks around it (I'm a LaTeX programming n00b).

Suggestions are welcome.