Add an ability to highlight lines for Scribble's Pygments

frog/enhance-body.rkt

@@ -34,19 +34,28 @@
     @racket[find-executable-path], so the default @racket["python"]
     will work if the version of Python that Pygments wants is on the
     path.}
+  (define (highlight brush texts hl-lines)
+    (match brush
+      [(pregexp "\\s*brush:\\s*(.+?)\\s*$" (list _ lang))
+       `(div ([class ,(str "brush: " lang)])
+         ,@(pygmentize (apply string-append texts) lang
+                       #:python-executable python-executable
+                       #:line-numbers? line-numbers?
+                       #:css-class css-class
+                       #:hl-lines hl-lines))]
+      [_ `(pre ,@texts)]))
+
   (let recur ([xs x-expressions])
     (for/list ([x xs])
       (match x
         [(or `(pre ([class ,brush]) (code () ,(? string? texts) ...))
              `(pre ([class ,brush]) ,(? string? texts) ...))
-         (match brush
-           [(pregexp "\\s*brush:\\s*(.+?)\\s*$" (list _ lang))
-            `(div ([class ,(str "brush: " lang)])
-              ,@(pygmentize (apply string-append texts) lang
-                            #:python-executable python-executable
-                            #:line-numbers? line-numbers?
-                            #:css-class css-class))]
-           [_ `(pre ,@texts)])]
+         (highlight brush texts '())]
+        [(or `(pre ([class ,brush] [data-hl-lines ,hl-lines])
+               (code () ,(? string? texts) ...))
+             `(pre ([class ,brush] [data-hl-lines ,hl-lines])
+               ,(? string? texts) ...))
+         (highlight brush texts (map string->number (string-split hl-lines " ")))]
         ;; Check child elements, too. For example as in issue #217
         ;; could be (ol () (li () (pre () ___))).
         [(list* (? symbol? tag) (? list? attributes) elements)
@@ -126,7 +135,19 @@
                     [(`((pre . ,_)
                         (div . ,_)
                         ,_ ...          ;varies: line numbers?
-                        (div ([class "brush: racket"]) . ,_))
+                        (div ([class "brush: racket"]) . ,_)
+                        ,_ ...)
+                      `(span ([class ,(and c (not "c1") (not "hll"))]) . ,xs))
+                     (if code?
+                         `(span ([class ,c]) ,@(->racket-doc-links xs))
+                         x)]
+                    ;; This is the case where the line is highlighted.
+                    [(`((span ([class "hll"]) . ,_)
+                        (pre . ,_)
+                        (div . ,_)
+                        ,_ ...          ;varies: line numbers?
+                        (div ([class "brush: racket"]) . ,_)
+                        ,_ ...)
                       `(span ([class ,(and c (not "c1"))]) . ,xs))
                      (if code?
                          `(span ([class ,c]) ,@(->racket-doc-links xs))

frog/frog.scrbl

@@ -413,19 +413,24 @@ Scribble non-post page} for more information.
 
 @defmodule[frog/scribble]
 
-@defproc[(pygment-code [#:lang lang string?][str string?] ...) paragraph?]{
+@defproc[(pygment-code [#:lang lang string?][#:hl-lines hl-lines list? '()][str string?] ...) paragraph?]{
 In Scribble source files of course you can use @racket[codeblock],
 @racket[racketblock], and friends to write code blocks for languages
 that have DrRacket style syntax-coloring parsers.
 
 For other languages, you can emit a @tt{<pre>} block with a language
 tag (as happens with @secref["markdown-code-blocks"]) so that it can
-be highlighted by Pygments.
+be highlighted by Pygments. You can also additionally supply lines to be
+highlighted via @racket[#:hl-lines].
 
 Example usage:
 @pre|{
 @(require frog/scribble)
-@pygment-code[#:lang "js"]{function foo() {return 1;}}
+@pygment-code[#:lang "js" #:hl-lines '(1 2)]{
+  function foo() {
+    return 1;
+  }
+}
 }|
 }
 

frog/private/enhance-body/syntax-highlight/pipe.py

@@ -2,6 +2,7 @@
 # continuously. Input format is:
 #
 #     <lexer-name>
+#     <list-of-highlighted-lines>
 #     <code>
 #     ...
 #     __END__
@@ -28,12 +29,9 @@
 parser.add_option('--cssclass', default="source", dest="cssclass")
 (options, _) = parser.parse_args()
 
-formatter = HtmlFormatter(linenos=options.linenos,
-                          cssclass=options.cssclass,
-                          encoding="utf-8")
-
 lexer = ""
 code = ""
+lines_to_highlight = ""
 py_version = sys.version_info.major
 sys.stdout.write("ready\n")
 sys.stdout.flush()
@@ -47,6 +45,10 @@
         break
     elif line == '__END__':
         # Lex input finished. Lex it.
+        formatter = HtmlFormatter(linenos=options.linenos,
+                          cssclass=options.cssclass,
+                          encoding="utf-8",
+                          hl_lines=lines_to_highlight)
         if py_version >= 3:
           sys.stdout.write(highlight(code, lexer, formatter).decode("utf-8"))
         else:
@@ -55,12 +57,17 @@
         sys.stdout.flush()
         lexer = ""
         code = ""
+        lines_to_highlight = ""
     elif lexer == "":
         # Starting another lex. First line is the lexer name.
         try:
             lexer = get_lexer_by_name(line, encoding="guess")
         except ClassNotFound:
             lexer = get_lexer_by_name("text", encoding="guess")
+    elif lines_to_highlight == "":
+        # Starting another lex. Second line is list of lines to highlight,
+        # formatted as string of whitespace-separated integers
+        lines_to_highlight = [int(str) for str in line.split()]
     else:
         # Accumulate more code
         # Use `line_raw`: Do want trailing space, \n, \r

frog/private/enhance-body/syntax-highlight/pygments.rkt

@@ -1,6 +1,7 @@
 #lang racket/base
 
 (require racket/format
+         racket/string
          racket/function
          racket/match
          racket/port
@@ -66,13 +67,15 @@
 (define (pygmentize code lang
                     #:python-executable python-executable
                     #:line-numbers? line-numbers?
-                    #:css-class css-class)
+                    #:css-class css-class
+                    #:hl-lines [hl-lines '()])
   (define (default code)
     `((pre () (code () ,code))))
   (unless (running?)
     (start python-executable line-numbers? css-class))
   (cond [(running?)
          (displayln lang pyg-out)
+         (displayln (string-join (map number->string hl-lines) " ") pyg-out)
          (displayln code pyg-out)
          (displayln "__END__" pyg-out)
          (let loop ([s ""])

frog/scribble.rkt

@@ -1,6 +1,7 @@
 #lang racket/base
 
-(require (only-in scribble/core style)
+(require racket/string
+         (only-in scribble/core style)
          (only-in scribble/manual para)
          (only-in scribble/html-properties attributes alt-tag)
          (only-in scribble/base literal))
@@ -17,8 +18,12 @@
 ;;
 ;; @pygment-code[#:lang "js"]{function foo() {return 1;}}
 ;;
-(define (pygment-code #:lang lang . xs)
-  (para #:style (style "brush:"
-                       (list (attributes `([class . ,lang]))
-                             (alt-tag "pre")))
+(define (pygment-code #:lang lang #:hl-lines [hl-lines '()] . xs)
+  (para #:style
+        (style "brush:"
+               (list (attributes
+                      `([class . ,lang]
+                        [data-hl-lines . ,(string-join (map number->string hl-lines)
+                                                       " ")]))
+                     (alt-tag "pre")))
         (apply literal xs)))