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如何擴展檔案內容以追加和計算行數？

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如何擴展檔案內容以追加和計算行數？

這裡有兩個關於filecontents環境的問題：

  1. 是否可以將內容新增到預先存在的文件中，或至少保持開啟外部文件以將多個filecontents環境的內容附加到同一個外部文件中？

  2. 是否可以知道環境已將多少行寫入外部文件filecontents？

答案1

計算行數filecontents很容易，因為環境逐行處理其內容，讀取，檢查環境是否結束，然後寫入。您只需要建立一個計數器並在每次寫入一行時添加它。

追加比較棘手。首先，TeX（至少沒有 Lua）無法開啟具有「追加」權限的文件，因此排除了這種情況。讓檔案保持開啟狀態，然後稍後恢復寫入的想法一開始似乎更容易，但是您需要跨環境保存一堆變量，然後您將無法寫入 file a，然後b，然後追加到a。

在下面的程式碼中，\filecontents@preappend巨集（append使用該選項時）會讀取臨時巨集參數中的文件，然後將\filecontents@append讀取的巨集放入輸入流中環境的實際內容之前，因此它的工作方式就像你一口氣輸入了所有內容。該append選項意味著overwrite和noheader選項。

為了緊湊性，我試圖將代碼編寫為補丁，但顯然修補命令會丟失字符^^J，然後標題折疊成一行，所以這是 的完整重新定義\filec@ntents，但更改的行被標記。

\documentclass{article}
\usepackage{expl3}
\ExplSyntaxOn
\cs_new_eq:NN \FileSize \file_size:n
\ExplSyntaxOff
\makeatletter
\begingroup%
\@tempcnta=1
\loop
  \catcode\@tempcnta=12  %
  \advance\@tempcnta\@ne %
\ifnum\@tempcnta<32      %
\repeat                  %
\catcode`\^^M\active
\catcode`\^^L\active\let^^L\relax
\catcode`\^^I\active
\gdef\filec@ntents#1{%
  \set@curr@file{\filec@ntents@checkdir#1}%
  \edef\q@curr@file{\expandafter\quote@name\expandafter{\@curr@file}}%
  \filecontents@preappend% <- ADDED for appending
  \gaborit@reset@counter% <- ADDED for counting lines
  \gaborit@reset@append% <- ADDED for counting lines
  \openin\@inputcheck\q@curr@file \space %
  \ifeof\@inputcheck%
    \@latex@warning@no@line%
        {Writing file `\@currdir\@curr@file'}%
    \chardef\reserved@c15 %
    \ch@ck7\reserved@c\write%
    \immediate\openout\reserved@c\q@curr@file\relax%
  \else%
    \if@filesw%
      \@latex@warning@no@line%
          {File `\@curr@file' already \filec@ntents@where.\MessageBreak%
             Not generating it from this source}%
      \let\gaborit@step@counter\@empty% <- ADDED for counting lines
      \let\gaborit@count@header\@empty% <- ADDED for counting lines
      \let\write\@gobbletwo%
      \let\closeout\@gobble%
    \else%
      \edef\reserved@a{#1}%
      \edef\reserved@a{\detokenize\expandafter{\reserved@a}}%
      \edef\reserved@b{\detokenize\expandafter{\jobname}}%
      \ifx\reserved@a\reserved@b%
        \@fileswtrue%
      \else%
        \edef\reserved@b{\reserved@b\detokenize{.tex}}%
        \ifx\reserved@a\reserved@b
          \@fileswtrue%
        \fi%
      \fi%
      \chardef\reserved@c15 %
      \ch@ck7\reserved@c\write%
      \if@filesw%  % Foul ... trying to overwrite \jobname!
      \@latex@error{Trying to overwrite `\jobname.tex'}{You can't %
        write to the file you a reading from!\MessageBreak%
        Data is written to screen instead.}%
      \else%
        \@latex@warning@no@line%
           {Writing or overwriting file `\@currdir\@curr@file'}%
        \immediate\openout\reserved@c#1\relax%
      \fi%
    \fi%
  \fi%
  \closein\@inputcheck%
  \if@tempswa%
    \gaborit@count@header% <- ADDED for counting lines
    \immediate\write\reserved@c{%
      \@percentchar\@percentchar\space%
          \expandafter\@gobble\string\LaTeX2e file `\@curr@file'^^J%
      \@percentchar\@percentchar\space  generated by the %
        `\@currenvir' \expandafter\@gobblefour\string\newenvironment^^J%
      \@percentchar\@percentchar\space from source `\jobname' on %
         \number\year/\two@digits\month/\two@digits\day.^^J%
      \@percentchar\@percentchar}%
  \fi%
  \let\do\@makeother\dospecials%
  \count@ 128\relax%
  \loop%
    \catcode\count@ 11\relax%
    \advance\count@ \@ne%
    \ifnum\count@<\@cclvi%
  \repeat%
  \edef\E{\@backslashchar end\string{\@currenvir\string}}%
  \edef\reserved@b{%
    \def\noexpand\reserved@b%
         ####1\E####2\E####3\relax}%
  \reserved@b{%
    \ifx\gaborit@reset@append##1\relax% <- ADDED for counting lines
      \gaborit@reset@append% <- ADDED for counting lines
    \else% <- ADDED for counting lines
    \ifx\relax##3\relax%
      \immediate\write\reserved@c{##1}%
      \gaborit@step@counter% <- ADDED for counting lines
    \else%
      \edef^^M{\noexpand\end{\@currenvir}}%
      \ifx\relax##1\relax%
      \else%
          \@latex@warning{Writing text `##1' before %
             \string\end{\@currenvir}\MessageBreak as last line of \@curr@file}%
        \immediate\write\reserved@c{##1}%
        \gaborit@step@counter% <- ADDED for counting lines
      \fi%
      \ifx\relax##2\relax%
      \else%
         \@latex@warning{%
           Ignoring text `##2' after \string\end{\@currenvir}}%
      \fi%
    \fi%
    \fi% <- ADDED for counting lines
    ^^M}%
  \catcode`\^^L\active%
  \let\L\@undefined%
  \def^^L{\expandafter\ifx\csname L\endcsname\relax\fi ^^J^^J}%
  \catcode`\^^I\active%
  \let\I\@undefined%
  \def^^I{\expandafter\ifx\csname I\endcsname\relax\fi\space}%
  \catcode`\^^M\active%
  \edef^^M##1^^M{%
    \noexpand\reserved@b##1\E\E\relax}%
  \filecontents@append}% <- ADDED for appending
%
% Code for append
\gdef\gaborit@pre@append{%
  \begingroup%
    \catcode`\^^L\active%
    \catcode`\^^I\active%
    \catcode`\^^M\active%
    \let\do\@makeother\dospecials%
    \count@ 128\relax%
    \loop%
      \catcode\count@ 11\relax%
      \advance\count@ \@ne%
      \ifnum\count@<\@cclvi%
    \repeat%
    \let^^M\relax%
    \edef\gaborit@tmpa{\FileSize{\q@curr@file}}%
    \ifnum\expandafter\@car\gaborit@tmpa\@nil=0\relax%
      \endgroup \def\gaborit@append{^^M\gaborit@reset@append}%
    \else%
      \everyeof{\noexpand}%
      \edef\gaborit@tmpa{\@@input\q@curr@file \space}%
      \edef\x{\endgroup%
        \edef\noexpand\gaborit@append{%
          \noexpand\gaborit@trim@EOF\gaborit@tmpa\noexpand\gaborit@EOF}}\x%
    \fi%
  \filec@ntents@overwrite%
  \filec@ntents@noheader}%
\gdef\gaborit@trim@EOF#1^^M\gaborit@EOF{^^M#1%
  ^^M\noexpand\gaborit@reset@append}%
\endgroup%
\def\filec@ntents@append{%
  \let\filecontents@preappend\gaborit@pre@append
  \def\filecontents@append{\gaborit@append}}
\let\filecontents@preappend\@empty
\let\filecontents@append\@empty
%
% For counting lines
\newcounter{FC@total@lines}
\newcounter{FC@lines}
\def\gaborit@reset@counter{\setcounter{FC@total@lines}{0}}
\def\gaborit@reset@append{\setcounter{FC@lines}{0}}
\def\gaborit@step@counter{%
  \stepcounter{FC@total@lines}%
  \stepcounter{FC@lines}}
\def\gaborit@count@header{%
  \addtocounter{FC@total@lines}{4}%
  \addtocounter{FC@lines}{4}} % Number of lines in the header
\makeatother

\begin{filecontents}[overwrite]{testfile.tex}
a
b
c
\end{filecontents}
\typeout{\arabic{FC@total@lines} lines written; \arabic{FC@lines} appended}

\begin{filecontents}[append]{testfile.tex}
d
e
f
g
\end{filecontents}
\typeout{\arabic{FC@total@lines} lines written; \arabic{FC@lines} appended}

\begin{document}
\end{document}

運行此程式碼，TeX 會列印到終端：

LaTeX Warning: Writing or overwriting file `./testfile.tex'.

7 lines written; 7 appended
(./testfile.tex)

LaTeX Warning: Writing or overwriting file `./testfile.tex'.

11 lines written; 4 appended

（FC@total@lines儲存檔案中的總行數，計數器FC@lines僅保存附加行數）並且檔案testfile.tex包含：

%% LaTeX2e file `testfile.tex'
%% generated by the `filecontents' environment
%% from source `test' on 2019/12/20.
%%
a
b
c
d
e
f
g

正如您所指出的，當您這樣做時：

\begin{filecontents*}{testfile.tex}
\end{filecontents*}
%
\begin{filecontents}[append]{testfile.tex}
a
\end{filecontents}

（也就是說，什麼也不寫，然後附加一行a）您得到的文件是：


a

這是因為當 TeX 讀取一個空白文件時，它會將該文件視為具有單一空行1的文件，因此您無法輕鬆區分這兩種情況，並且必須選擇較小的危害：要么有一個虛假的空白行附加到空白文件時在文件開頭刪除行，或在寫入包含單一空白行的文件時刪除空白行。

然而，透過 pdfTeX 中引入的文件實用程式（現在也可在其他引擎中使用），您可以查詢文件的大小（以位元組為單位），因此您可以對空文件有不同的行為。在程式碼中，我使用expl3's\file_size:n來避免處理不存在的檔案。

1.你可以透過這個測試文件看到這一點：

\catcode`\@=11
\newwrite\test
\def\testit#1{\immediate\openout\test \jobname.testfile\relax #1%
  {\catcode`\^^M=13 \everyeof{\noexpand}%
   \edef\tmpa{\ifdefined\@@input \@@input \else \input \fi \jobname.testfile }\show\tmpa}%
  \immediate\closeout\test}%
\testit{}% empty file
\testit{\immediate\write\test{}}% single empty line
\csname stop\endcsname\bye

我認為這種行為是由於 TeX\endlinechar在每行末尾添加了 。當它讀取空文件時，它仍然會讀取一行（即使是空的），然後插入 ( \endlinechar) ^^M，這使得檔案看起來好像只有一個空白行。

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