scribble/bnf: add `BNF-seq-lines'

original commit: 563909c3285cd30f076b37619b5623c24888f2c0

collects/scribble/bnf.rkt

@@ -1,11 +1,14 @@
-(module bnf mzscheme
+(module bnf racket
   (require "struct.rkt"
            "decode.rkt"
+           (only-in "core.rkt" 
+                    make-style
+                    make-table-columns)
            mzlib/kw)
 
   (provide BNF 
            nonterm
-           BNF-seq
+           BNF-seq BNF-seq-lines
            BNF-alt  BNF-alt/close ; single-line alternatives
            BNF-etc
            BNF-group
@@ -15,11 +18,19 @@
   (define equals (make-element 'tt (list spacer "::=" spacer)))
   (define alt (make-element 'tt (list spacer spacer "|" spacer spacer)))
 
-  (define (as-flow i) (make-flow (list (make-paragraph (list i)))))
+  (define (as-flow i) (make-flow (list (if (block? i)
+                                           i
+                                           (make-paragraph (list i))))))
+
+
+  (define baseline (make-style #f '(baseline)))
 
   (define (BNF . defns)
     (make-table
-     #f
+     (make-style #f
+                 (list
+                  (make-table-columns
+                   (list baseline baseline baseline baseline))))
      (apply
       append
       (map (lambda (defn)
@@ -42,6 +53,10 @@
         ""
         (interleave l spacer)))
 
+  (define (BNF-seq-lines . l)
+    (make-table #f (map (lambda (row) (list (as-flow (apply BNF-seq row))))
+                        l)))
+
   (define (BNF-alt . l)
     (interleave l alt))
 

collects/scribblings/scribble/bnf.scrbl

@@ -43,7 +43,7 @@ produces the output
 
 See also @racket[racketgrammar].
 
-@defproc[(BNF [prod (cons element? (listof element?))] ...) table?]{
+@defproc[(BNF [prod (cons element? (listof (or/c block? element?)))] ...) table?]{
 
 Typesets a grammar table. Each production starts with an element
 (typically constructed with @racket[nonterm]) for the non-terminal
@@ -58,6 +58,11 @@ Typesets a non-terminal: italic in angle brackets.}
 
 Typesets a sequence.}
 
+@defproc[(BNF-seq-lines [elems (listof element?)] ...) block?]{
+
+Typesets a sequence that is broken into multiple lines, where each
+@racket[elems] is one line.}
+
 @defproc[(BNF-group [pre-content any/c] ...) element?]{
 
 Typesets a group surrounded by curly braces (so the entire group can