tiny refactor to nbconvert ansi filter

was looking at this code for another project, and was irked by what I
saw here, so just cleaned it up.

IPython/nbconvert/filters/ansi.py

@@ -1,177 +1,178
 """Filters for processing ANSI colors within Jinja templates.
 """
 #-----------------------------------------------------------------------------
 # Copyright (c) 2013, the IPython Development Team.
 #
 # Distributed under the terms of the Modified BSD License.
 #
 # The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import re
 from IPython.utils import coloransi
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 __all__ = [
     'strip_ansi',
     'ansi2html',
     'single_ansi2latex',
     'ansi2latex'
 ]
 
 def strip_ansi(source):
     """
     Remove ansi from text
     
     Parameters
     ----------
     source : str
         Source to remove the ansi from
     """
     
     return re.sub(r'\033\[(\d|;)+?m', '', source)
 
 
-def ansi2html(text):
-    """
-    Conver ansi colors to html colors.
-    
-    Parameters
-    ----------
-    text : str
-        Text containing ansi colors to convert to html
-    """
-    
     ansi_colormap = {
         '30': 'ansiblack',
         '31': 'ansired',
         '32': 'ansigreen',
         '33': 'ansiyellow',
         '34': 'ansiblue',
         '35': 'ansipurple',
         '36': 'ansicyan',
         '37': 'ansigrey',
         '01': 'ansibold',
     }
 
-    # do ampersand first
-    text = text.replace('&', '&')
     html_escapes = {
         '<': '&lt;',
         '>': '&gt;',
         "'": '&apos;',
         '"': '&quot;',
         '`': '&#96;',
     }
+ansi_re = re.compile('\x1b' + r'\[([\dA-Fa-f;]*?)m')
+
+def ansi2html(text):
+    """
+    Convert ansi colors to html colors.
+    
+    Parameters
+    ----------
+    text : str
+        Text containing ansi colors to convert to html
+    """
+
+    # do ampersand first
+    text = text.replace('&', '&amp;')
     
     for c, escape in html_escapes.items():
         text = text.replace(c, escape)
 
-    ansi_re = re.compile('\x1b' + r'\[([\dA-Fa-f;]*?)m')
     m = ansi_re.search(text)
     opened = False
     cmds = []
     opener = ''
     closer = ''
     while m:
         cmds = m.groups()[0].split(';')
         closer = '</span>' if opened else ''
         
         # True if there is there more than one element in cmds, *or*
         # if there is only one but it is not equal to a string of zeroes.
         opened = len(cmds) > 1 or cmds[0] != '0' * len(cmds[0])
         classes = []
         for cmd in cmds:
             if cmd in ansi_colormap:
-                classes.append(ansi_colormap.get(cmd))
+                classes.append(ansi_colormap[cmd])
 
         if classes:
             opener = '<span class="%s">' % (' '.join(classes))
         else:
             opener = ''
         text = re.sub(ansi_re, closer + opener, text, 1)
 
         m = ansi_re.search(text)
 
     if opened:
         text += '</span>'
     return text
 
 
 def single_ansi2latex(code):
     """Converts single ansi markup to latex format.
 
     Return latex code and number of open brackets.
 
     Accepts codes like '\x1b[1;32m' (bold, red) and the short form '\x1b[32m' (red)
 
     Colors are matched to those defined in coloransi, which defines colors
     using the 0, 1 (bold) and 5 (blinking) styles. Styles 1 and 5 are
     interpreted as bold. All other styles are mapped to 0. Note that in
     coloransi, a style of 1 does not just mean bold; for example, Brown is
     "0;33", but Yellow is "1;33". An empty string is returned for unrecognised
     codes and the "reset" code '\x1b[m'.
     """
     components = code.split(';')
     if len(components) > 1:
         # Style is digits after '['
         style = int(components[0].split('[')[-1])
         color = components[1][:-1]
     else:
         style = 0
         color = components[0][-3:-1]
         
     # If the style is not normal (0), bold (1) or blinking (5) then treat it as normal
     if style not in [0, 1, 5]:
         style = 0
 
     for name, tcode in coloransi.color_templates:
         tstyle, tcolor = tcode.split(';')
         tstyle = int(tstyle)
         if tstyle == style and tcolor == color:
             break
     else:
         return '', 0
 
     if style == 5:
         name = name[5:]                             # BlinkRed -> Red, etc
     name = name.lower()
 
     if style in [1, 5]:
         return r'\textbf{\color{'+name+'}', 1
     else:
         return r'{\color{'+name+'}', 1
 
 def ansi2latex(text):
     """Converts ansi formated text to latex version
 
     based on https://bitbucket.org/birkenfeld/sphinx-contrib/ansi.py
     """
     color_pattern = re.compile('\x1b\\[([^m]*)m')
     last_end = 0
     openbrack = 0
     outstring = ''
     for match in color_pattern.finditer(text):
         head = text[last_end:match.start()]
         outstring += head
         if openbrack:
             outstring += '}'*openbrack
             openbrack = 0
         code = match.group()
         if not (code == coloransi.TermColors.Normal or openbrack):
             texform, openbrack = single_ansi2latex(code)
             outstring += texform
         last_end = match.end()
     
     # Add the remainer of the string and THEN close any remaining color brackets.
     outstring += text[last_end:]
     if openbrack: 
         outstring += '}'*openbrack
     return outstring.strip()