如何在段落内添加水平空间以将该行的剩余部分移动到某个边距？

Question 1

看起来您想要一个占用最小空间的段落标题。

您需要获取段落标题的文本，将其与所需长度进行比较，如果标题较短，则跳过剩余空间。因此您需要一个条件。使用“etoolbox”，类似以下内容可能会满足您的要求：

\documentclass[]{article}
\usepackage{etoolbox}
\usepackage{lipsum}

\newlength{\myheadlength}
\newlength{\requestedheadspace}
\newlength{\addedheadspace}
\setlength{\requestedheadspace}{.4\textwidth}% <--adjust to taste

\newcommand{\parstart}[1]{%
    \settowidth{\myheadlength}{#1}%
    \setlength{\addedheadspace}{\requestedheadspace}
%    %compare to required width
    \ifdimless{\myheadlength}{\requestedheadspace}{% then
        \addtolength{\addedheadspace}{-\myheadlength}%
        #1\hspace{\addedheadspace}%
    }%
    {%else just print the header
    #1%
    }%
}

\setlength{\parskip}{\baselineskip}
\setlength{\parindent}{0pt}
\raggedright
\begin{document}

\parstart{Dummy}\lipsum[1]

\parstart{Less short dummy}\lipsum[1]

\parstart{And a very very long dummy to go beyond the requested space} Some text \lipsum[1]

\end{document}

（使用 PdfLatex 和 LuaLatex 测试）

Answer

看起来您想要一个占用最小空间的段落标题。

您需要获取段落标题的文本，将其与所需长度进行比较，如果标题较短，则跳过剩余空间。因此您需要一个条件。使用“etoolbox”，类似以下内容可能会满足您的要求：

\documentclass[]{article}
\usepackage{etoolbox}
\usepackage{lipsum}

\newlength{\myheadlength}
\newlength{\requestedheadspace}
\newlength{\addedheadspace}
\setlength{\requestedheadspace}{.4\textwidth}% <--adjust to taste

\newcommand{\parstart}[1]{%
    \settowidth{\myheadlength}{#1}%
    \setlength{\addedheadspace}{\requestedheadspace}
%    %compare to required width
    \ifdimless{\myheadlength}{\requestedheadspace}{% then
        \addtolength{\addedheadspace}{-\myheadlength}%
        #1\hspace{\addedheadspace}%
    }%
    {%else just print the header
    #1%
    }%
}

\setlength{\parskip}{\baselineskip}
\setlength{\parindent}{0pt}
\raggedright
\begin{document}

\parstart{Dummy}\lipsum[1]

\parstart{Less short dummy}\lipsum[1]

\parstart{And a very very long dummy to go beyond the requested space} Some text \lipsum[1]

\end{document}

（使用 PdfLatex 和 LuaLatex 测试）

Question 2

您也可以使用 itemize 样式环境来实现这一点。我不知道在您的情形下使用环境是否可取，但可能值得考虑。

下面我使用enumitem包来创建parswithheads环境（将被替换为更鼓舞人心的名称）并调整其缩进（参见文档了解更多信息）。

\documentclass{article}

%% To match your desired output:
%% (sets parindent to 0pt and parskip to .5\baselineskip plus 2pt)
\usepackage{parskip}

\usepackage{enumitem}
\newlist{parswithheads}{itemize}{1}
\setlist[parswithheads]{
  align=left, %% alignment of labels
  listparindent=\parindent, %% same indentation as in normal text
  parsep=\parskip, %% same parskip as in normal text
  topsep=0pt, %% vertical space above and below list
  partopsep=0pt, %% extra vertical space above and below if separate paragraph
  itemsep=0pt, %% no extra space between items
  font=\normalfont\bfseries, %% font used for labels, you may want to remove \bfseries
  leftmargin=0pt, %% don't indent the entire paragraph
  itemindent=4cm, %% how much to indent the first line by (at least)
  labelsep=.5em, %% space between label and text
  labelindent=0pt, %% label starts at the left margin
  labelwidth=! %% calculated from other values
}
\begin{document}

\framebox[4cm]{$\longleftarrow$\hfill 4cm\hfill$\longrightarrow$}

\begin{parswithheads}
\item[A first part]
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots
\item[A longer first part]
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots
\item[A much much much much much longer first part]
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots
\item[Part]
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots
\end{parswithheads}

\end{document}

以下是所涉及长度的概述。我将leftmargin和设置labelindent为0pt，设置itemindent为4cm和labelsep设置为.5em（默认情况下正常空间可以拉伸到的最大量）。我添加了labelwidth=!，以便从其他长度计算出为标签保留的空间量（因此4cm-.5em在本例中也是如此）。如果实际标签比此长度宽，则会导致项目进一步缩进（如所需）。

无论如何，结果如下：

编辑：如果您认为enumitem仅为此加载有点过度（我可以想象），那么下面的方法也应该有效。结果（据我所知）难以区分。

\documentclass{article}

%% To match your desired output:
%% (sets parindent to 0pt and parskip to .5\baselineskip plus 2pt)
\usepackage{parskip}

\newlength{\partitlewidth}
\setlength{\partitlewidth}{4cm}
\newcommand*\partitle[1]{%
  \begingroup %% To limit the scope of box 0
    \savebox0{\textbf{#1}\hspace{.5em}}% %% Save the title in a box, with some added space
    \ifdim\wd0<\partitlewidth\wd0=\partitlewidth\fi %% Set width of box 0 to \partitlewidth if it is shorter
    \usebox0% %% Print the box
  \endgroup
  \ignorespaces %% Ignore any ensuing following spaces
}

\begin{document}

\framebox[4cm]{$\longleftarrow$\hfill 4cm\hfill$\longrightarrow$}

\partitle{A first part}
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots

\partitle{A longer first part}
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots

\partitle{A much much much much much longer first part}
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots

\partitle{Part}
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris\ldots

\end{document}

宏\partitle将其参数放在一个“框”（连同空格）中，并\partitlewidth在打印框之前将此框的宽度设置为（如果宽度较短）。宏后面的任何空格都将被忽略。（这是必要的，因为空格可以拉伸/收缩，否则会改变缩进。）

Answer