FIX, don't use regex

IPython/nbconvert/filters/latex.py

@@ -1,115 +1,114
 """Latex filters.
 
 Module of useful filters for processing Latex within Jinja latex 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
 
 #-----------------------------------------------------------------------------
 # Globals and constants
 #-----------------------------------------------------------------------------
 
-#Latex substitutions for escaping latex.
-LATEX_SUBS = (
-    (re.compile('\033\[[0-9;]+m'),''),  # handle console escapes
-    (re.compile(r'\\'), r'{\\textbackslash}'),
-    (re.compile(r'([{}_#%&$])'), r'\\\1'),
-    (re.compile(r'~'), r'\~{}'),
-    (re.compile(r'\^'), r'\^{}'),
-    (re.compile(r'"'), r"''"),
-    (re.compile(r'\.\.\.+'), r'\\ldots'),
-)
+# Latex substitutions for escaping latex.
+# see: http://stackoverflow.com/questions/16259923/how-can-i-escape-latex-special-characters-inside-django-templates
+LATEX_SUBS = {
+    '&':  r'\&',
+    '%':  r'\%', 
+    '$':  r'\$', 
+    '#':  r'\#', 
+    '_':  r'\letterunderscore{}', 
+    '{':  r'\letteropenbrace{}', 
+    '}':  r'\letterclosebrace{}',
+    '~':  r'\lettertilde{}', 
+    '^':  r'\letterhat{}', 
+    '\\': r'\letterbackslash{}'}
+
 
 #-----------------------------------------------------------------------------
 # Functions
 #-----------------------------------------------------------------------------
 
-__all__ = [
-    'escape_latex',
-    'strip_math_space'
-]
-
+__all__ = ['escape_latex',
+           'strip_math_space']
 
 def escape_latex(text):
     """
     Escape characters that may conflict with latex.
-    
+
     Parameters
     ----------
     text : str
         Text containing characters that may conflict with Latex
     """
-    return_text = text
-    for pattern, replacement in LATEX_SUBS:
-        return_text = pattern.sub(replacement, return_text)
-    return return_text
+
+    return ''.join([LATEX_SUBS.get(c, c) for c in text])
     
     
 def strip_math_space(text):
     """
     Remove the space between latex math commands and enclosing $ symbols.
     This filter is important because latex isn't as flexible as the notebook
     front end when it comes to flagging math using ampersand symbols.
     
     Parameters
     ----------
     text : str
         Text to filter.
     """
 
     # First, scan through the markdown looking for $.  If
     # a $ symbol is found, without a preceding \, assume
     # it is the start of a math block.  UNLESS that $ is
     # not followed by another within two math_lines.
     math_regions = []
     math_lines = 0
     within_math = False
     math_start_index = 0
     ptext = ''
     last_character = ""
     skip = False
     for index, char in enumerate(text):
 
         #Make sure the character isn't preceeded by a backslash
         if (char == "$" and last_character != "\\"):
 
             # Close the math region if this is an ending $
             if within_math:
                 within_math = False
                 skip = True
                 ptext = ptext+'$'+text[math_start_index+1:index].strip()+'$'
                 math_regions.append([math_start_index, index+1])
             else:
 
                 # Start a new math region
                 within_math = True
                 math_start_index = index
                 math_lines = 0
 
         # If we are in a math region, count the number of lines parsed.
         # Cancel the math region if we find two line breaks!
         elif char == "\n":
             if within_math:
                 math_lines += 1
                 if math_lines > 1:
                     within_math = False
                     ptext = ptext+text[math_start_index:index]
 
         # Remember the last character so we can easily watch
         # for backslashes
         last_character = char
         if not within_math and not skip:
             ptext = ptext+char
         if skip:
             skip = False
     return ptext

IPython/nbconvert/filters/tests/test_latex.py

@@ -1,65 +1,65
 """
 Module with tests for Latex
 """
 
 #-----------------------------------------------------------------------------
 # 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
 #-----------------------------------------------------------------------------
 
 from ...tests.base import TestsBase
 from ..latex import escape_latex, strip_math_space
 
 
 #-----------------------------------------------------------------------------
 # Class
 #-----------------------------------------------------------------------------
 
 class TestLatex(TestsBase):
 
 
     def test_escape_latex(self):
         """escape_latex test"""
         tests = [
-            (r'How are \you doing today?', r'How are \textbackslashyou doing today?'),
-            (r'\escapechar=`\A\catcode`\|=0 |string|foo', r'\textbackslashescapechar=`\textbackslashA\textbackslashcatcode`\textbackslash|=0 |string|foo'),
-            (r'# $ % & ~ _ ^ \ { }',r'\# \$ \% \& \~{} \_ \^{} \textbackslash \{ \}'),
+            (r'How are \you doing today?', r'How are \letterbackslash{}you doing today?'),
+            (r'\escapechar=`\A\catcode`\|=0 |string|foo', r'\letterbackslash{}escapechar=`\letterbackslash{}A\letterbackslash{}catcode`\letterbackslash{}|=0 |string|foo'),
+            (r'# $ % & ~ _ ^ \ { }', r'\# \$ \% \& \lettertilde{} \letterunderscore{} \letterhat{} \letterbackslash{} \letteropenbrace{} \letterclosebrace{}'),
             ('','')]
 
         for test in tests:
             yield self._try_escape_latex(test[0], test[1])
 
 
     def _try_escape_latex(self, test, result):
         """Try to remove latex from string"""
         self.assertEqual(escape_latex(test), result)
 
 
     def test_strip_math_space(self):
         """strip_math_space test"""
         tests = [
             ('$e$','$e$'),
             ('$ e $','$e$'),
             ('xxx$e^i$yyy','xxx$e^i$yyy'),
             ('xxx$ e^i $yyy','xxx$e^i$yyy'),
             ('xxx$e^i $yyy','xxx$e^i$yyy'),
             ('xxx$ e^i$yyy','xxx$e^i$yyy'),
             ('\$ e $ e $','\$ e $e$'),
             ('','')]
 
         for test in tests:
             yield self._try_strip_math_space(test[0], test[1])
 
 
     def _try_strip_math_space(self, test, result):
         """
         Try to remove spaces between dollar symbols and contents correctly
         """
         self.assertEqual(strip_math_space(test), result)