[std, macros] Use "environ" for grammar extraction.

This replaces the use of the "exract" package with the simpler
"environ" package, where the grammar contents are extracted from the
"collected body" \BODY macro via the TeX `\meaning` command. This does
not preserve whitespace as the "extact" approach did, but if we just
spell out whitespace (instead of relying on \obeyspaces), we get the
same results.

Author: tkoeppe

source/grammar.tex

@@ -58,4 +58,4 @@
 	identifier
 \end{ncbnf}
 
-\FlushAndPrintGrammar
+\input{std-gram.ext}

source/macros.tex

@@ -39,20 +39,18 @@
 \newenvironment{addedblock}{\color{addclr}}{\color{black}}
 \newenvironment{removedblock}{\color{remclr}}{\color{black}}
 
-%%--------------------------------------------------
+%%-------------------------------------------------------------
 %% Grammar extraction.
-%%--------------------------------------------------
-\def\gramSec[#1]#2{}
-
+%% Assumes that the output file \gramout is managed externally.
+%%-------------------------------------------------------------
 \makeatletter
-\newcommand{\FlushAndPrintGrammar}{%
-\immediate\closeout\XTR@out%
-\immediate\openout\XTR@out=std-gram-dummy.tmp%
-\def\gramSec[##1]##2{\rSec1[##1]{##2}}%
-\input{std-gram.ext}%
-}
+\newcommand{\gramWrite}[1]{\protected@write\gramout{}{#1}}
+\newcommand{\meaningbody}[1]{\expandafter\strip@prefix\meaning#1}
 \makeatother
 
+\newcommand{\gramSec}[2][]{\gramWrite{%
+\string\rSec1\string[\string#1\string]\string{\string#2\string}}}
+
 %%--------------------------------------------------
 % Escaping for index entries. Replaces ! with "! throughout its argument.
 %%--------------------------------------------------
@@ -701,7 +699,7 @@
  \nonfrenchspacing
  }
 
-\newenvironment{simplebnf}
+\newenvironment{ncsimplebnf}
 {
  \begin{bnfbase}
  \BnfNontermshape
@@ -712,7 +710,7 @@
  \end{bnfbase}
 }
 
-\newenvironment{bnf}
+\newenvironment{ncbnf}
 {
  \begin{bnfbase}
  \begin{bnflist}
@@ -724,6 +722,19 @@
  \end{bnfbase}
 }
 
+% "nc" are the non-copied versions of bnf environments; the non-"nc"
+% versions are copied to the grammar extraction file.
+\NewEnviron{bnf}{\begin{ncbnf}%
+\BODY%
+\gramWrite{\string\begin{ncbnf}\meaningbody\BODY\string\end{ncbnf}}%
+\end{ncbnf}}{}
+
+\NewEnviron{simplebnf}{\begin{ncsimplebnf}%
+\BODY%
+\gramwrite{\string\begin{ncsimplebnf}\meaningbody\BODY\string\end{ncsimplebnf}}%
+\end{ncsimplebnf}}{}
+
+% The regex grammar is never copied.
 \newenvironment{ncrebnf}
 {
  \begin{bnfbase}
@@ -737,12 +748,6 @@
  \end{bnfbase}
 }
 
-% non-copied versions of bnf environments
-\let\ncsimplebnf\simplebnf
-\let\endncsimplebnf\endsimplebnf
-\let\ncbnf\bnf
-\let\endncbnf\endbnf
-
 %%--------------------------------------------------
 %% Environment for imported graphics
 %%--------------------------------------------------

source/std.tex

@@ -46,7 +46,7 @@
             urlcolor=blue,    % ISO/IEC Directives, Part 2, section 6.5
             plainpages=false}
 \usepackage{memhfixc}     % fix interactions between hyperref and memoir
-\usepackage[active,header=false,handles=false,copydocumentclass=false,generate=std-gram.ext,extract-cmdline={gramSec},extract-env={bnf,simplebnf}]{extract} % Grammar extraction
+\usepackage{environ}
 \usepackage{expl3}
 \usepackage{xparse}
 \usepackage{xstring}
@@ -57,6 +57,10 @@
 
 \renewcommand\RSsmallest{5.5pt}  % smallest font size for relsize
 
+% Begin grammar extraction...
+\newwrite\gramout
+\immediate\openout\gramout=std-gram.ext
+
 \input{layout}
 \input{styles}
 \input{macros}
@@ -154,6 +158,9 @@
 
 \numberwithin{table}{chapter}
 
+% ... end grammar extraction.
+\immediate\closeout\gramout
+
 \include{grammar}
 \include{limits}
 \include{compatibility}