嵌套列表上有垂直线的列表环境

Question

我想要一个列表环境，它沿着每个嵌套列表显示一条垂直线，但不显示最外层的垂直线，如下例所示：

如何在 LaTeX 中实现这一点？

编辑：这是我迄今为止尝试过的：

    \documentclass[english]{article}
    \usepackage{lmodern}
    \usepackage[T1]{fontenc}
    \usepackage[latin9]{inputenc}
    \usepackage[a4paper]{geometry}
    \geometry{verbose,tmargin=2cm,bmargin=2cm,lmargin=3cm,rmargin=2cm}
    \setlength{\parskip}{\medskipamount}
    \setlength{\parindent}{0pt}

    \makeatletter
    \usepackage{tcolorbox}
    \tcbuselibrary{breakable,skins}
    \newenvironment{mylist}
    {
        \vspace{5pt}
        \begin{tcolorbox}[blanker,left=3mm,right=3mm,top=2mm,bottom=2mm,borderline west={1pt}{2pt}{gray!25!white}]
    }
    {
        \end{tcolorbox}
    }

    \usepackage{babel}
    \begin{document}
    This is normal text. This is normal text. This is normal text.

    This is normal text. This is normal text. This is normal text.
    \begin{mylist}
        First element of the outermost list
        \begin{mylist}
            First element of a nested list\\
            Second element of a nested list
            \begin{mylist}
                First element of a nested list\\
                Second element of a nested list
            \end{mylist}
        \end{mylist}
        Second element of the outermost list
        \begin{mylist}
            First element of a nested list\\
            Second element of a nested list
        \end{mylist}
    \end{mylist}

    \end{document}

Answer 1

这是一个解决方案tikzmark：

\documentclass{article}
\usepackage{enumitem,tikz}
\usetikzlibrary{tikzmark,calc}
\begin{document}

\begin{itemize}[label={}]
    \item First element of the outermost list
    \begin{itemize}[label={}]
        \item \tikzmark{s1}First element of a nested list
        \item Second element of a nested list
        \begin{itemize}[label={}]
            \item \tikzmark{s2}First element of a nested list
            \item \tikzmark{e1}Second element of a nested list
         \end{itemize} 
     \end{itemize} 
    \item Second element of the outermost list
    \begin{itemize}[label={}]
        \item \tikzmark{s3}First element of a nested list
        \item \tikzmark{e2}Second element of a nested list
    \end{itemize}
\end{itemize}

\begin{tikzpicture}[overlay,remember picture,xshift=-1.6em,line width=.7pt,draw=gray!50]
\path (pic cs:s1)|-coordinate(E)(pic cs:e1);
\draw ($(pic cs:s1)+(0,\ht\strutbox)$)--(E) 
($(pic cs:s2)+(0,\ht\strutbox)$)--(pic cs:e1) 
($(pic cs:s3)+(0,\ht\strutbox)$)--(pic cs:e2);
\end{tikzpicture}

\end{document}

这可以自动化，但我现在没有太多时间。

Answer 2

如果的选项列表mylist包含every box/.style定义，则此设置对每个嵌入的都有效，但对最外层的无效（在那里，使用tcolorbox全局和空的）。every box

因此，设置

every box/.style={borderline west={1pt}{2pt}{gray!25!white}},

只对嵌入的框/列表有效。

我还添加了一个breakable选项，假设您需要这个。可破坏性仅适用于最外层列表（内部列表不可破坏）。

完整代码如下：

\documentclass[english]{article}
\usepackage{lmodern}
\usepackage[T1]{fontenc}
\usepackage[latin9]{inputenc}
\usepackage[a4paper]{geometry}
\geometry{verbose,tmargin=2cm,bmargin=2cm,lmargin=3cm,rmargin=2cm}
\setlength{\parskip}{\medskipamount}
\setlength{\parindent}{0pt}
\usepackage{babel}

\usepackage{tcolorbox}
\tcbuselibrary{breakable,skins}

\newtcolorbox{mylist}{blanker,
  breakable,
  left=3mm,right=3mm,top=2mm,bottom=2mm,
  before skip=5pt,after skip=5pt,
  every box/.style={borderline west={1pt}{2pt}{gray!25!white}},
}

\begin{document}
This is normal text. This is normal text. This is normal text.

This is normal text. This is normal text. This is normal text.
\begin{mylist}
    First element of the outermost list
    \begin{mylist}
        First element of a nested list\\
        Second element of a nested list
        \begin{mylist}
            First element of a nested list\\
            Second element of a nested list
        \end{mylist}
    \end{mylist}
    Second element of the outermost list
    \begin{mylist}
        First element of a nested list\\
        Second element of a nested list
    \end{mylist}
\end{mylist}

\end{document}