Add feature for emphasizing some lines in a code block.

A code blocked headed by “:::python{1,3}” now emphasizes the first and third lines. With fences enabled, ```python{1,3} has the same effect.

1 files changed, 29 insertions, 5 deletions

diff --git a/markdown/extensions/codehilite.py b/markdown/extensions/codehilite.py
index 7a3676b..d05d495 100644
--- a/markdown/extensions/codehilite.py
+++ b/markdown/extensions/codehilite.py
@@ -31,6 +31,22 @@ try:
 except ImportError:
     pygments = False
 
+
+def parse_hl_lines(expr):
+    """Support our syntax for emphasizing certain lines of code.
+
+    expr should be like '{1,2}' to emphasize lines 1 and 2 of a code block.
+    Returns a list of ints, the line numbers to emphasize.
+    """
+    if not expr:
+        return []
+
+    try:
+        return map(int, expr.strip('{}').split(','))
+    except ValueError:
+        return []
+
+
 # ------------------ The Main CodeHilite Class ----------------------
 class CodeHilite(object):
     """
@@ -49,6 +65,8 @@ class CodeHilite(object):
 
     * css_class: Set class name of wrapper div ('codehilite' by default).
 
+    * hl_lines: (List of integers) Lines to emphasize, 1-indexed.
+
     Low Level Usage:
         >>> code = CodeHilite()
         >>> code.src = 'some text' # String or anything with a .readline attr.
@@ -59,7 +77,7 @@ class CodeHilite(object):
 
     def __init__(self, src=None, linenums=None, guess_lang=True,
                 css_class="codehilite", lang=None, style='default',
-                noclasses=False, tab_length=4):
+                noclasses=False, tab_length=4, hl_lines=None):
         self.src = src
         self.lang = lang
         self.linenums = linenums
@@ -68,6 +86,7 @@ class CodeHilite(object):
         self.style = style
         self.noclasses = noclasses
         self.tab_length = tab_length
+        self.hl_lines = hl_lines or []
 
     def hilite(self):
         """
@@ -83,7 +102,7 @@ class CodeHilite(object):
         self.src = self.src.strip('\n')
 
         if self.lang is None:
-            self._getLang()
+            self._parseHeader()
 
         if pygments:
             try:
@@ -99,7 +118,8 @@ class CodeHilite(object):
             formatter = HtmlFormatter(linenos=self.linenums,
                                       cssclass=self.css_class,
                                       style=self.style,
-                                      noclasses=self.noclasses)
+                                      noclasses=self.noclasses,
+                                      hl_lines=self.hl_lines)
             return highlight(self.src, lexer, formatter)
         else:
             # just escape and build markup usable by JS highlighting libs
@@ -118,7 +138,7 @@ class CodeHilite(object):
             return '<pre class="%s"><code%s>%s</code></pre>\n'% \
                         (self.css_class, class_str, txt)
 
-    def _getLang(self):
+    def _parseHeader(self):
         """
         Determines language of a code block from shebang line and whether said
         line should be removed or left in place. If the sheband line contains a
@@ -131,6 +151,7 @@ class CodeHilite(object):
         (e.i.: :::python), line numbering is left in the current state - off
         by default.
 
+        Also parses optional list of highlight lines, like :::python{1,3}
         """
 
         import re
@@ -141,9 +162,10 @@ class CodeHilite(object):
         fl = lines.pop(0)
 
         c = re.compile(r'''
-            (?:(?:^::+)|(?P<shebang>^[#]!))	# Shebang or 2 or more colons.
+            (?:(?:^::+)|(?P<shebang>^[#]!)) # Shebang or 2 or more colons
             (?P<path>(?:/\w+)*[/ ])?        # Zero or 1 path
             (?P<lang>[\w+-]*)               # The language
+            (?P<hl_lines>\{.*?})?           # Maybe hl_lines
             ''',  re.VERBOSE)
         # search first line for shebang
         m = c.search(fl)
@@ -159,6 +181,8 @@ class CodeHilite(object):
             if self.linenums is None and m.group('shebang'):
                 # Overridable and Shebang exists - use line numbers
                 self.linenums = True
+
+            self.hl_lines = parse_hl_lines(m.group('hl_lines'))
         else:
             # No match
             lines.insert(0, fl)