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1 | """Latex filters. |
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1 | """Latex filters. | |
2 |
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2 | |||
3 | Module of useful filters for processing Latex within Jinja latex templates. |
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3 | Module of useful filters for processing Latex within Jinja latex templates. | |
4 | """ |
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4 | """ | |
5 | #----------------------------------------------------------------------------- |
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5 | #----------------------------------------------------------------------------- | |
6 | # Copyright (c) 2013, the IPython Development Team. |
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6 | # Copyright (c) 2013, the IPython Development Team. | |
7 | # |
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7 | # | |
8 | # Distributed under the terms of the Modified BSD License. |
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8 | # Distributed under the terms of the Modified BSD License. | |
9 | # |
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9 | # | |
10 | # The full license is in the file COPYING.txt, distributed with this software. |
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10 | # The full license is in the file COPYING.txt, distributed with this software. | |
11 | #----------------------------------------------------------------------------- |
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11 | #----------------------------------------------------------------------------- | |
12 |
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12 | |||
13 | #----------------------------------------------------------------------------- |
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13 | #----------------------------------------------------------------------------- | |
14 | # Imports |
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14 | # Imports | |
15 | #----------------------------------------------------------------------------- |
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15 | #----------------------------------------------------------------------------- | |
16 | import re |
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16 | import re | |
17 |
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17 | |||
18 | #----------------------------------------------------------------------------- |
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18 | #----------------------------------------------------------------------------- | |
19 | # Globals and constants |
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19 | # Globals and constants | |
20 | #----------------------------------------------------------------------------- |
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20 | #----------------------------------------------------------------------------- | |
21 |
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21 | |||
22 | LATEX_RE_SUBS = ( |
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22 | LATEX_RE_SUBS = ( | |
23 | (re.compile(r'\.\.\.+'), r'\\ldots'), |
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23 | (re.compile(r'\.\.\.+'), r'\\ldots'), | |
24 | ) |
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24 | ) | |
25 |
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25 | |||
26 | # Latex substitutions for escaping latex. |
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26 | # Latex substitutions for escaping latex. | |
27 | # see: http://stackoverflow.com/questions/16259923/how-can-i-escape-latex-special-characters-inside-django-templates |
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27 | # see: http://stackoverflow.com/questions/16259923/how-can-i-escape-latex-special-characters-inside-django-templates | |
28 |
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28 | |||
29 | LATEX_SUBS = { |
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29 | LATEX_SUBS = { | |
30 | '&': r'\&', |
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30 | '&': r'\&', | |
31 | '%': r'\%', |
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31 | '%': r'\%', | |
32 | '$': r'\$', |
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32 | '$': r'\$', | |
33 | '#': r'\#', |
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33 | '#': r'\#', | |
34 | '_': r'\_', |
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34 | '_': r'\_', | |
35 | '{': r'\{', |
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35 | '{': r'\{', | |
36 | '}': r'\}', |
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36 | '}': r'\}', | |
37 | '~': r'\textasciitilde{}', |
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37 | '~': r'\textasciitilde{}', | |
38 | '^': r'\^{}', |
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38 | '^': r'\^{}', | |
39 | '\\': r'\textbackslash{}', |
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39 | '\\': r'\textbackslash{}', | |
40 | } |
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40 | } | |
41 |
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41 | |||
42 |
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42 | |||
43 | #----------------------------------------------------------------------------- |
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43 | #----------------------------------------------------------------------------- | |
44 | # Functions |
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44 | # Functions | |
45 | #----------------------------------------------------------------------------- |
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45 | #----------------------------------------------------------------------------- | |
46 |
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46 | |||
47 | __all__ = ['escape_latex', |
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47 | __all__ = ['escape_latex', | |
48 | 'strip_math_space'] |
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48 | 'strip_math_space'] | |
49 |
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49 | |||
50 | def escape_latex(text): |
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50 | def escape_latex(text): | |
51 | """ |
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51 | """ | |
52 |
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52 | Escape characters that may conflict with latex. | |
53 |
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53 | |||
54 | Parameters |
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54 | Parameters | |
55 | ---------- |
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55 | ---------- | |
56 | text : str |
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56 | text : str | |
57 | Text containing characters that may conflict with Latex |
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57 | Text containing characters that may conflict with Latex | |
58 | """ |
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58 | """ | |
59 | text = ''.join(LATEX_SUBS.get(c, c) for c in text) |
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59 | text = ''.join(LATEX_SUBS.get(c, c) for c in text) | |
60 | for pattern, replacement in LATEX_RE_SUBS: |
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60 | for pattern, replacement in LATEX_RE_SUBS: | |
61 | text = pattern.sub(replacement, text) |
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61 | text = pattern.sub(replacement, text) | |
62 |
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62 | |||
63 | return text |
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63 | return text | |
64 |
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64 | |||
65 |
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65 | |||
66 | def strip_math_space(text): |
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66 | def strip_math_space(text): | |
67 | """ |
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67 | """ | |
68 | Remove the space between latex math commands and enclosing $ symbols. |
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68 | Remove the space between latex math commands and enclosing $ symbols. | |
69 | This filter is important because latex isn't as flexible as the notebook |
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69 | This filter is important because latex isn't as flexible as the notebook | |
70 | front end when it comes to flagging math using ampersand symbols. |
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70 | front end when it comes to flagging math using ampersand symbols. | |
71 |
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71 | |||
72 | Parameters |
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72 | Parameters | |
73 | ---------- |
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73 | ---------- | |
74 | text : str |
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74 | text : str | |
75 | Text to filter. |
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75 | Text to filter. | |
76 | """ |
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76 | """ | |
77 |
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77 | |||
78 | # First, scan through the markdown looking for $. If |
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78 | # First, scan through the markdown looking for $. If | |
79 | # a $ symbol is found, without a preceding \, assume |
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79 | # a $ symbol is found, without a preceding \, assume | |
80 | # it is the start of a math block. UNLESS that $ is |
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80 | # it is the start of a math block. UNLESS that $ is | |
81 | # not followed by another within two math_lines. |
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81 | # not followed by another within two math_lines. | |
82 | math_regions = [] |
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82 | math_regions = [] | |
83 | math_lines = 0 |
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83 | math_lines = 0 | |
84 | within_math = False |
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84 | within_math = False | |
85 | math_start_index = 0 |
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85 | math_start_index = 0 | |
86 | ptext = '' |
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86 | ptext = '' | |
87 | last_character = "" |
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87 | last_character = "" | |
88 | skip = False |
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88 | skip = False | |
89 | for index, char in enumerate(text): |
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89 | for index, char in enumerate(text): | |
90 |
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90 | |||
91 | #Make sure the character isn't preceeded by a backslash |
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91 | #Make sure the character isn't preceeded by a backslash | |
92 | if (char == "$" and last_character != "\\"): |
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92 | if (char == "$" and last_character != "\\"): | |
93 |
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93 | |||
94 | # Close the math region if this is an ending $ |
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94 | # Close the math region if this is an ending $ | |
95 | if within_math: |
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95 | if within_math: | |
96 | within_math = False |
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96 | within_math = False | |
97 | skip = True |
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97 | skip = True | |
98 | ptext = ptext+'$'+text[math_start_index+1:index].strip()+'$' |
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98 | ptext = ptext+'$'+text[math_start_index+1:index].strip()+'$' | |
99 | math_regions.append([math_start_index, index+1]) |
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99 | math_regions.append([math_start_index, index+1]) | |
100 | else: |
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100 | else: | |
101 |
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101 | |||
102 | # Start a new math region |
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102 | # Start a new math region | |
103 | within_math = True |
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103 | within_math = True | |
104 | math_start_index = index |
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104 | math_start_index = index | |
105 | math_lines = 0 |
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105 | math_lines = 0 | |
106 |
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106 | |||
107 | # If we are in a math region, count the number of lines parsed. |
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107 | # If we are in a math region, count the number of lines parsed. | |
108 | # Cancel the math region if we find two line breaks! |
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108 | # Cancel the math region if we find two line breaks! | |
109 | elif char == "\n": |
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109 | elif char == "\n": | |
110 | if within_math: |
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110 | if within_math: | |
111 | math_lines += 1 |
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111 | math_lines += 1 | |
112 | if math_lines > 1: |
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112 | if math_lines > 1: | |
113 | within_math = False |
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113 | within_math = False | |
114 | ptext = ptext+text[math_start_index:index] |
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114 | ptext = ptext+text[math_start_index:index] | |
115 |
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115 | |||
116 | # Remember the last character so we can easily watch |
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116 | # Remember the last character so we can easily watch | |
117 | # for backslashes |
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117 | # for backslashes | |
118 | last_character = char |
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118 | last_character = char | |
119 | if not within_math and not skip: |
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119 | if not within_math and not skip: | |
120 | ptext = ptext+char |
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120 | ptext = ptext+char | |
121 | if skip: |
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121 | if skip: | |
122 | skip = False |
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122 | skip = False | |
123 | return ptext |
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123 | return ptext |
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