More robust interface to Pygments (#230)

pollen/private/external/pipe.py

@@ -1,8 +1,22 @@
 # This allows us to launch Python and pygments once, and pipe to it
-# continuously. Input format is:
+# continuously.
 #
-#     <lexer-name>
-#     <list-of-highlighted-lines>
+# There are four options:
+#   1. Language (used to determine the lexer)
+#   2. Line numbers to highlight
+#   3. Encoding to use for the output
+#   4. HTML Class to use for the output
+#
+# These can be specified as arguments when this script is first invoked, or on a
+# per invocation.
+#
+# To set the options for each invocation, the format is:
+#
+#     __LANG__ <lexer-name>
+#     __LINENOS__ <true|false>
+#     __LINES__ <list-of-highlighted-lines>
+#     __CSS__ <CSS-class>
+#     __ENC__ <encoding>
 #     <code>
 #     ...
 #     __END__
@@ -17,57 +31,120 @@
 #     ...
 #     __END__
 
+from __future__ import print_function
 import sys
 import optparse
+
 from pygments import highlight
 from pygments.lexers import get_lexer_by_name
 from pygments.util import ClassNotFound
 from pygments.formatters import HtmlFormatter
 
+def get_lexer(lang):
+    if not lang:
+        get_lexer_by_name("text", encoding="guess")
+
+    try:
+        return get_lexer_by_name(lang, encoding="guess")
+    except ClassNotFound:
+        print("No lexer was found for the given language. Using plain text instead.", file=sys.stderr)
+        return  get_lexer_by_name("text", encoding="guess")
+
 parser = optparse.OptionParser()
 parser.add_option('--linenos', action="store_true", dest="linenos")
 parser.add_option('--cssclass', default="source", dest="cssclass")
+parser.add_option('--encoding', default="utf-8", dest="encoding")
+parser.add_option('--language', dest="language")
 (options, _) = parser.parse_args()
 
-lexer = ""
+# Set initial options
+config = {
+    'linenos': options.linenos,
+    'cssclass': options.cssclass,
+    'encoding': options.encoding,
+    'hl_lines': []
+}
+lexer = get_lexer(options.language)
 code = ""
-lines_to_highlight = ""
+
 py_version = sys.version_info.major
 sys.stdout.write("ready\n")
 sys.stdout.flush()
+
 while 1:
     line_raw = sys.stdin.readline()
     if not line_raw:
         break
     # Without trailing space, \n, or \n
     line = line_raw.rstrip()
+
     if line == '__EXIT__':
         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)
+        formatter = HtmlFormatter(linenos=config['linenos'],
+                                  cssclass=config['cssclass'],
+                                  encoding=config['encoding'],
+                                  hl_lines=config['hl_lines'])
         if py_version >= 3:
           sys.stdout.write(highlight(code, lexer, formatter).decode("utf-8"))
         else:
           sys.stdout.write(highlight(code, lexer, formatter))
         sys.stdout.write('\n__END__\n')
         sys.stdout.flush()
-        lexer = ""
+
+        # Reset the configuration for the next invocation. Most options are
+        # actually persisted between runs, except for the code itself and the
+        # lines to be highlighted.
         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()]
+        config['hl_lines'] = []
+
+    elif code == "":
+        # Only check for new options at the beginning of a a fresh invocation
+        if line.startswith("__LANG__"):
+        # Use the provided language to find the appropriate lexer.
+            try:
+                lang = line.split()[1]
+                lexer = get_lexer(lang)
+            except IndexError:
+                print("No lexer was found for the given language. Using plain text instead.", file=sys.stderr)
+                lexer = get_lexer_by_name("text", encoding="guess")
+
+        elif line.startswith("__LINENOS__"):
+            try:
+                option = line.split()[1]
+                if option.lower() == "true":
+                    config['linenos'] = True
+                elif option.lower() == "false":
+                    config['linenos'] = False
+                else:
+                    pass
+            except IndexError:
+                print("__LINENOS__ option must be given a `true` or `false` value",
+                      file=sys.stderr)
+
+        elif line.startswith("__LINES__"):
+            # The list of lines to highlight is formatted as string of
+            # whitespace-separated integers
+            lines = line.split()[1:]
+            config['hl_lines'] = [int(str) for str in lines]
+
+        elif line.startswith("__CSS__"):
+            try:
+                config['cssclass'] = line.split[1]
+            except IndexError:
+                print("Could not parse CSS class line.", file=sys.stderr)
+
+        elif line.startswith("__ENC__"):
+            try:
+                config['encoding'] = line.split[1]
+            except IndexError:
+                print("Could not parse encoding line.", file=sys.stderr)
+        else:
+            # Done with configuration for this invocation, start accumulating
+            # code. Use `line_raw` because we want trailing space, \n, \r
+            code += line_raw
+
     else:
         # Accumulate more code
         # Use `line_raw`: Do want trailing space, \n, \r

pollen/unstable/pygments.rkt

@@ -130,11 +130,18 @@ if zero is False:
   (unless (running?)
     (start python-executable line-numbers? css-class))
   (cond [(running?)
-         ;; order of writing arguments is significant: cooperates with pipe.py
-         (displayln lang pyg-out)
-         (displayln (string-join (map number->string hl-lines) " ") pyg-out)
+         ;; This works with a simple wrapper around Pygments defined in pipe.py.
+         ;; First send over the configuration options, then code to highlight.
+         ;; pipe.py also supports an encoding option, but seems unnecessary to
+         ;; use at this point.
+         (fprintf pyg-out "__LANG__ ~a~n" lang)
+         (fprintf pyg-out "__LINES__ ~a~n" (string-join (map number->string hl-lines) " "))
+         (fprintf pyg-out "__LINENOS__ ~a~n"
+                  (if line-numbers? "true" "false"))
          (displayln code pyg-out)
          (displayln "__END__" pyg-out)
+
+         ;; Read back the highlighted code
          (let loop ([s ""])
            (match (read-line pyg-in 'any)
              ["__END__" (with-input-from-string s read-html-as-xexprs)]