类似记录的数据结构？

Question

我需要这样的东西：

\setfield{record1}{field1}{alpha}
\setfield{record1}{field2}{beta}
\setfield{record2}{field1}{gamma}
\setfield{record2}{field2}{delta}
\assign{record3}{record2}
\getfield{record1}{field1} % should expand to alpha
\getfield{record1}{field2} % should expand to beta
\getfield{record2}{field1} % should expand to gamma
\getfield{record2}{field2} % should expand to delta
\getfield{record3}{field1} % should expand to gamma
\getfield{record3}{field2} % should expand to delta

有这个包吗？没有这个assign命令我也能活下去。

Answer 1

本质上\setfield是使用前两个参数构建控制序列。\def仅设置请求的控制序列（不执行错误检查；...如果记录/字段不存在则c返回） 。sname\getfield\csname\endcsname\relax

\documentclass{article}

\usepackage{etoolbox}

\newcommand{\setfield}[3]{%
  \expandafter\def\csname #1@#2\endcsname{#3}%
  \listcsgadd{#1}{#2}%
}
\newcommand{\getfield}[2]{%
  \ifcsname #1@alias\endcsname
    \expandafter\expandafter\expandafter\csname \csname #1@alias\endcsname @#2\endcsname
  \else
    \csname #1@#2\endcsname
  \fi}
\newcommand{\recordalias}[2]{\expandafter\def\csname #2@alias\endcsname{#1}}
\newcommand{\recordcopy}[2]{%
  \renewcommand*{\do}[1]{%
    \expandafter\edef\csname #2@##1\endcsname{\csname #1@##1\endcsname}}%
  \dolistcsloop{#1}%
}

\begin{document}

\setfield{record1}{field1}{alpha}
\setfield{record1}{field2}{$\beta$}
\setfield{record2}{field1}{gamma}
\setfield{record2}{field2}{$\delta$}

\recordalias{record2}{record3}
\recordcopy{record2}{record4}

\getfield{record1}{field1} % should expand to alpha
\getfield{record1}{field2} % should expand to $\beta$
\getfield{record2}{field1} % should expand to gamma
\getfield{record2}{field2} % should expand to $\delta$
\getfield{record3}{field1} % should expand to gamma
\getfield{record3}{field2} % should expand to $\delta$

\setfield{record2}{field1}{$\gamma$}

\getfield{record2}{field1} % should expand to $\gamma$
\getfield{record3}{field1} % should expand to $\gamma$
\getfield{record4}{field1} % should expand to gamma

\end{document}

添加了两种类型的作业：

• 别名通过\recordalias{<first>}{<second>}——这使得该<second>记录成为的别名<first>；
• 复制via \recordcopy{<first>}{<second>}- 这将按顺序复制所有字段，<first>使用<second>由提供的列表处理etoolbox。

Answer 2

\documentclass[10pt]{article}
\usepackage{readarray}
\begin{document}
\readarraysepchar{ }
\def\mydata{alpha beta gamma delta}
\readarray\mydata\myarray[-,2]% Read \mydata as 2 fields into 2-D \myarray
Cell (2,2) has \myarray[2,2]
whereas cell (1,2) has \myarray[1,2]
\end{document}

如果数据在文件中，也没有问题。请注意\readdef，在读取文件时，设置\ncols为第一行中检测到的字段数，并且可以使用，而不是显式的2。\readarray我还演示了如何使用不同的分隔符（逗号而不是空格），并展示了选项如何*删除\readarray前导和尾随空格。

\documentclass[10pt]{article}
\usepackage{readarray,filecontents}
\begin{filecontents*}{mydatafile}
alpha, beta
gamma, delta force
\end{filecontents*}
\begin{document}
\readarraysepchar{,}
\readdef{mydatafile}{\mydata}
\readarray*\mydata\myarray[-,\ncols]% Read \mydata as 2 fields into 2-D \myarray
Cell (2,2) has \myarray[2,2]
whereas cell (1,2) has \myarray[1,2]
\end{document}

最后，如果需要动态更改单元格数据，我在这里实现宏\setfield\<array name>[<row>,<column>]{<data>}：

\documentclass[10pt]{article}
\usepackage{readarray}
\makeatletter
\gdef\setfield#1[#2,#3]#4{%
  \expandafter\gdef\csname\expandafter\@gobble\string#1[#2,#3]\endcsname{#4}}%
\makeatother
\begin{document}
\readarraysepchar{ }
\def\mydata{alpha beta gamma delta}
\readarray\mydata\myarray[-,2]% Read \mydata as 2 fields into 2-D \myarray
Cell (2,2) has \myarray[2,2]
whereas cell (1,2) has \myarray[1,2]

\setfield\myarray[1,2]{$\beta$}
Cell (1,2) now has \myarray[1,2].
\end{document}