[cpp] Dissolve bnftab, use spaces for alignment.

The result looks neater because the spacing is tighter, it's simpler
to edit, and it lets us get rid of the "tabular bnf" macros.

Author: tkoeppe

source/preprocessor.tex

@@ -47,52 +47,52 @@
     \terminal{\#} conditionally-supported-directive
 \end{bnf}
 
-\begin{bnftab}
+\begin{bnf}\obeyspaces
 \nontermdef{control-line}\br
-\>\terminal{\# include}\>\>pp-tokens new-line\br
-\>\terminal{\# define}\>\>identifier replacement-list new-line\br
-\>\terminal{\# define}\>\>identifier lparen \opt{identifier-list} \terminal{)} replacement-list new-line\br
-\>\terminal{\# define}\>\>identifier lparen \terminal{... )} replacement-list new-line\br
-\>\terminal{\# define}\>\>identifier lparen identifier-list \terminal{, ... )} replacement-list new-line\br
-\>\terminal{\# undef}\>\>identifier new-line\br
-\>\terminal{\# line}\>\>pp-tokens new-line\br
-\>\terminal{\# error}\>\>\opt{pp-tokens} new-line\br
-\>\terminal{\# pragma}\>\>\opt{pp-tokens} new-line\br
-\>\terminal{\# }new-line
-\end{bnftab}
+\terminal{\# include} pp-tokens new-line\br
+\terminal{\# define } identifier replacement-list new-line\br
+\terminal{\# define } identifier lparen \opt{identifier-list} \terminal{)} replacement-list new-line\br
+\terminal{\# define } identifier lparen \terminal{... )} replacement-list new-line\br
+\terminal{\# define } identifier lparen identifier-list \terminal{, ... )} replacement-list new-line\br
+\terminal{\# undef  } identifier new-line\br
+\terminal{\# line   } pp-tokens new-line\br
+\terminal{\# error  } \opt{pp-tokens} new-line\br
+\terminal{\# pragma } \opt{pp-tokens} new-line\br
+\terminal{\# }new-line
+\end{bnf}
 
 \begin{bnf}
 \nontermdef{if-section}\br
     if-group \opt{elif-groups} \opt{else-group} endif-line
 \end{bnf}
 
-\begin{bnftab}
+\begin{bnf}\obeyspaces
 \nontermdef{if-group}\br
-\>\terminal{\# if}\>\>constant-expression new-line \opt{group}\br
-\>\terminal{\# ifdef}\>\>identifier new-line \opt{group}\br
-\>\terminal{\# ifndef}\>\>identifier new-line \opt{group}
-\end{bnftab}
+\terminal{\# if     } constant-expression new-line \opt{group}\br
+\terminal{\# ifdef  } identifier new-line \opt{group}\br
+\terminal{\# ifndef } identifier new-line \opt{group}
+\end{bnf}
 
 \begin{bnf}
 \nontermdef{elif-groups}\br
     elif-group\br
     elif-groups elif-group
 \end{bnf}
 
-\begin{bnftab}
+\begin{bnf}\obeyspaces
 \nontermdef{elif-group}\br
-\>\terminal{\# elif}\>\>constant-expression new-line \opt{group}
-\end{bnftab}
+\terminal{\# elif   } constant-expression new-line \opt{group}
+\end{bnf}
 
-\begin{bnftab}
+\begin{bnf}\obeyspaces
 \nontermdef{else-group}\br
-\>\terminal{\# else}\>\>new-line \opt{group}
-\end{bnftab}
+\terminal{\# else   } new-line \opt{group}
+\end{bnf}
 
-\begin{bnftab}
+\begin{bnf}\obeyspaces
 \nontermdef{endif-line}\br
-\>\terminal{\# endif}\>\>new-line
-\end{bnftab}
+\terminal{\# endif  } new-line
+\end{bnf}
 
 \begin{bnf}
 \nontermdef{text-line}\br
@@ -271,14 +271,12 @@
 
 \pnum
 Preprocessing directives of the forms
-
-\begin{ncbnftab}
+\begin{ncsimplebnf}\obeyspaces
 \indextext{\idxcode{\#if}}%
-\terminal{\# if}\>\>constant-expression new-line \opt{group}\br
+\terminal{\# if     } constant-expression new-line \opt{group}\br
 \indextext{\idxcode{\#elif}}%
-\terminal{\# elif}\>\>constant-expression new-line \opt{group}
-\end{ncbnftab}
-
+\terminal{\# elif   } constant-expression new-line \opt{group}
+\end{ncsimplebnf}
 check whether the controlling constant expression evaluates to nonzero.
 
 \pnum
@@ -367,14 +365,12 @@
 
 \pnum
 Preprocessing directives of the forms
-
-\begin{ncbnftab}
-\terminal{\# ifdef}\>\>identifier new-line \opt{group}\br
+\begin{ncsimplebnf}\obeyspaces
+\terminal{\# ifdef  } identifier new-line \opt{group}\br
 \indextext{\idxcode{\#ifdef}}%
-\terminal{\# ifndef}\>\>identifier new-line \opt{group}
+\terminal{\# ifndef } identifier new-line \opt{group}
 \indextext{\idxcode{\#ifndef}}%
-\end{ncbnftab}
-
+\end{ncsimplebnf}
 check whether the identifier is or is not currently defined as a macro name.
 Their conditions are equivalent to
 \tcode{\#if}