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.

2 files changed, 50 insertions, 11 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)
diff --git a/markdown/extensions/fenced_code.py b/markdown/extensions/fenced_code.py
index c5aaa6a..64ff769 100644
--- a/markdown/extensions/fenced_code.py
+++ b/markdown/extensions/fenced_code.py
@@ -59,6 +59,20 @@ Optionally backticks instead of tildes as per how github's code block markdown i
     ~~~~~ # these tildes will not close the block
     </code></pre>
 
+If the codehighlite extension and Pygments are installed, lines can be highlighted:
+
+    >>> text = '''
+    ... ```{1,3}
+    ... line 1
+    ... line 2
+    ... line 3
+    ... ```'''
+    >>> print markdown.markdown(text, extensions=['codehilite', 'fenced_code'])
+    <pre><code><span class="hilight">line 1</span>
+    line 2
+    <span class="hilight">line 3</span>
+    </code></pre>
+
 Copyright 2007-2008 [Waylan Limberg](http://achinghead.com/).
 
 Project website: <http://packages.python.org/Markdown/extensions/fenced_code_blocks.html>
@@ -77,7 +91,7 @@ from __future__ import absolute_import
 from __future__ import unicode_literals
 from . import Extension
 from ..preprocessors import Preprocessor
-from .codehilite import CodeHilite, CodeHiliteExtension
+from .codehilite import CodeHilite, CodeHiliteExtension, parse_hl_lines
 import re
 
 
@@ -93,10 +107,10 @@ class FencedCodeExtension(Extension):
 
 
 class FencedBlockPreprocessor(Preprocessor):
-    FENCED_BLOCK_RE = re.compile( \
-        r'(?P<fence>^(?:~{3,}|`{3,}))[ ]*(\{?\.?(?P<lang>[a-zA-Z0-9_+-]*)\}?)?[ ]*\n(?P<code>.*?)(?<=\n)(?P=fence)[ ]*$',
-        re.MULTILINE|re.DOTALL
-    )
+    FENCED_BLOCK_RE = re.compile(r'''
+(?P<fence>^(?:~{3,}|`{3,}))[ ]*(\{?\.?(?P<lang>[a-zA-Z0-9_+-]*)\}?)?[ ]*(?P<hl_lines>\{.*?})?[ ]*\n
+(?P<code>.*?)(?<=\n)
+(?P=fence)[ ]*$''', re.MULTILINE | re.DOTALL | re.VERBOSE)
     CODE_WRAP = '<pre><code%s>%s</code></pre>'
     LANG_TAG = ' class="%s"'
 
@@ -135,7 +149,8 @@ class FencedBlockPreprocessor(Preprocessor):
                             css_class=self.codehilite_conf['css_class'][0],
                             style=self.codehilite_conf['pygments_style'][0],
                             lang=(m.group('lang') or None),
-                            noclasses=self.codehilite_conf['noclasses'][0])
+                            noclasses=self.codehilite_conf['noclasses'][0],
+                            hl_lines=parse_hl_lines(m.group('hl_lines')))
 
                     code = highliter.hilite()
                 else: