使用宏创建 TikZ 节点

Question

我正在尝试使用 TikZ 创建链接列表。我目前有这个：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{chains,shapes}

\newcommand{chainlabel}[2]{\path [<-, draw, shorten >=10pt] #1 |- node [at end] {#2} ++(-1,1);}

\begin{document}
\begin{tikzpicture}[every node/.style={rectangle split, rectangle split parts=2, rectangle split horizontal}, node distance=1em, start chain, 
 every join/.style={->, shorten <=-4.5pt}]

 \node[draw, on chain, join] { 1  };
 \node[draw, on chain, join] { 7  };
 \node[draw, on chain, join] { 5  };
 \node[draw, on chain, join] { 2  };
 \node[draw, on chain, join] {};

 \chainlabel{chain-1.one north}{head};
\end{tikzpicture}  


\end{document}

问题出在chainlabel命令上。我收到各种有关缺少控制序列的错误。我读到过需要某种expandafter东西，但我不知道如何使用它。

ps chainlabel 背后的想法是我们可以将一个坐标传递给命令和一个标签，它会用提供的文本标记节点。

Answer 1

您在命令定义中犯了一些错误：您忘记了初始反斜杠（而是\chainlabel）chainlabel，并且由于您使用了\path #1 |- ...第一个参数，因此应该有括号，除非您使用\path (#1) |- ...，就像我在下面的例子中所做的那样：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{chains,shapes}

\newcommand{\chainlabel}[2]{\path [<-, draw, shorten >=10pt] (#1) |- node [at end] {#2} ++(-1,1);}

\begin{document}
\begin{tikzpicture}[every node/.style={rectangle split, rectangle split parts=2, rectangle split horizontal}, node distance=1em, start chain, 
 every join/.style={->, shorten <=-4.5pt}]

 \node[draw, on chain, join] { 1  };
 \node[draw, on chain, join] { 7  };
 \node[draw, on chain, join] { 5  };
 \node[draw, on chain, join] { 2  };
 \node[draw, on chain, join] {};
\chainlabel{chain-1.one north}{head};
\end{tikzpicture}  

\end{document}

也许你可以添加一些minimum height，rectangle split这样即使是空的，它们也会有一个统一的大小：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{chains,shapes}

\newcommand{\chainlabel}[2]{\path [<-, draw, shorten >=10pt] (#1) |- node [at end] {#2} ++(-1,1);}

\begin{document}
\begin{tikzpicture}[every node/.style={rectangle split, rectangle split parts=2, rectangle split horizontal,minimum height=14pt}, node distance=1em, start chain,
 every join/.style={->, shorten <=-4.5pt}]

 \node[draw, on chain, join] { 1  };
 \node[draw, on chain, join] { 7  };
 \node[draw, on chain, join] { 5  };
 \node[draw, on chain, join] { 2  };
 \node[draw, on chain, join] {};
\chainlabel{chain-1.one north}{head};
\end{tikzpicture}  

\end{document}