1 | """RFC 3676 format=flowed text processing. |
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2 | |
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3 | This module provides an API to create and display text/plain; format=flowed |
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4 | mimetype text. |
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5 | |
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6 | """ |
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7 | |
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8 | # Copyright (C) 2005 Martijn Pieters |
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9 | # Written by Martijn Pieters <mj@zopatista.com> |
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10 | # Development was sponsored by Logicalware (http://www.logicalware.org/) |
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11 | # Licensed as Open Source under the same terms as the Python 2.4.1 license, |
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12 | # as available at http://www.python.org/2.4.1/license.html |
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13 | |
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14 | __revision_id__ = '$Id: formatflowed.py 27 2005-09-17 19:13:48Z mj $' |
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15 | |
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16 | import re |
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17 | import textwrap |
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18 | |
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19 | __all__ = [ |
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20 | 'PARAGRAPH', |
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21 | 'FIXED', |
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22 | 'SIGNATURE_SEPARATOR', |
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23 | 'FormatFlowedDecoder', |
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24 | 'FormatFlowedEncoder', |
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25 | 'decode', |
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26 | 'encode', |
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27 | 'convertToWrapped', |
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28 | 'convertToFlowed' |
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29 | ] |
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30 | |
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31 | # Constants denoting the various text chunk types recognized by format=flowed |
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32 | PARAGRAPH, FIXED, SIGNATURE_SEPARATOR = range(3) |
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33 | |
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34 | |
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35 | # -- Public classes ---------------------------------------------------- |
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36 | |
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37 | |
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38 | class FormatFlowedDecoder: |
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39 | """Object for converting format=flowed text to other formats |
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40 | |
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41 | The following instance attributes influence the interpretation of |
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42 | format=flowed text: |
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43 | delete_space (default: False) |
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44 | Delete the trailing space before the CRLF on flowed lines before |
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45 | interpreting the line on flowed input, corresponds to the DelSp mime |
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46 | parameter |
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47 | character_set (default: us-ascii) |
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48 | The encoding of text passed in. Text is decoded to unicode using this |
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49 | encoding, using the default error handing scheme. |
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50 | |
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51 | """ |
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52 | def __init__(self, delete_space=False, character_set='us-ascii'): |
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53 | self.delete_space = delete_space |
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54 | self.character_set = character_set |
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55 | |
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56 | # -- Private methods ----------------------------------------------- |
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57 | |
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58 | def _stripquotes(self, line): |
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59 | """Remove quotemarks from the start of the line |
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60 | |
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61 | Returns the number of quotemarks stripped and the stripped line: |
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62 | |
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63 | >>> decoder = FormatFlowedDecoder() |
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64 | >>> decoder._stripquotes(u'>>> quoted line') |
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65 | (3, u' quoted line') |
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66 | |
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67 | Non-quoted lines are returned unchanged: |
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68 | |
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69 | >>> decoder._stripquotes(u'non-quoted line') |
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70 | (0, u'non-quoted line') |
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71 | |
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72 | """ |
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73 | stripped = line.lstrip('>') |
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74 | return len(line) - len(stripped), stripped |
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75 | |
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76 | def _stripstuffing(self, line): |
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77 | """Remove the optional leading space |
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78 | |
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79 | Returns the stripped line: |
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80 | |
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81 | >>> decoder = FormatFlowedDecoder() |
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82 | >>> decoder._stripstuffing(u' stuffed line') |
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83 | u'stuffed line' |
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84 | |
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85 | Non-stuffed lines are returned unchanged: |
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86 | |
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87 | >>> decoder._stripstuffing(u'non-stuffed line') |
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88 | u'non-stuffed line' |
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89 | |
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90 | Additional spacing is preserved: |
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91 | |
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92 | >>> decoder._stripstuffing(u' extra leading space') |
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93 | u' extra leading space' |
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94 | |
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95 | """ |
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96 | if line.startswith(u' '): |
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97 | return line[1:] |
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98 | return line |
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99 | |
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100 | def _stripflow(self, line): |
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101 | """Remove the trailing flow space is delete_space is set |
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102 | |
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103 | The instance attribute delete_space is False by default thus this |
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104 | method returns the line unchanged: |
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105 | |
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106 | >>> decoder = FormatFlowedDecoder() |
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107 | >>> decoder._stripflow(u'flowed line ') |
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108 | u'flowed line ' |
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109 | |
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110 | But if the delete_space attribute has been set to True the flow space |
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111 | is removed: |
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112 | |
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113 | >>> decoder = FormatFlowedDecoder(delete_space=True) |
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114 | >>> decoder._stripflow(u'flowed line ') |
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115 | u'flowed line' |
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116 | |
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117 | Only one flow space is removed: |
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118 | >>> decoder._stripflow(u'extra whitespace ') |
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119 | u'extra whitespace ' |
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120 | |
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121 | """ |
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122 | if self.delete_space and line.endswith(u' '): |
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123 | return line[:-1] |
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124 | return line |
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125 | |
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126 | # -- Public API ---------------------------------------------------- |
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127 | |
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128 | def decode(self, flowed): |
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129 | """Decode flowed text |
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130 | |
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131 | Returns an iterable serving a sequence of (information, chunk) |
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132 | tuples. information is a dictionary with the following fields: |
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133 | type |
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134 | One of PARAGRAPH, FIXED, SIGNATURE_SEPARATOR |
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135 | quotedepth |
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136 | Number of quotemarks found on the text chunk |
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137 | |
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138 | chunk is a unicode string. All text is unwrapped and without any |
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139 | quotemarks; when displaying these chunks, the appropriate quotemarks |
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140 | should be added again, and chunks of type PARAGRAPH should be |
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141 | displayed wrapped. Chunks of type FIXED should be displayed |
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142 | unwrapped. |
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143 | |
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144 | |
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145 | Examples |
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146 | -------- |
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147 | |
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148 | Here is a simple example: |
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149 | |
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150 | >>> CRLF = '\\r\\n' |
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151 | >>> decoder = FormatFlowedDecoder() |
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152 | >>> result = decoder.decode(CRLF.join(( |
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153 | ... ">> `Take some more tea,' the March Hare said to Alice, very ", |
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154 | ... ">> earnestly.", |
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155 | ... ">", |
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156 | ... "> `I've had nothing yet,' Alice replied in an offended ", |
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157 | ... "> tone, `so I can't take more.'", |
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158 | ... "", |
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159 | ... "`You mean you can't take less,' said the Hatter: `it's very ", |
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160 | ... "easy to take more than nothing.'", |
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161 | ... "", |
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162 | ... "-- ", |
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163 | ... "Lewis Carroll"))) |
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164 | >>> list(result) == [ |
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165 | ... ({'quotedepth': 2, 'type': PARAGRAPH}, |
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166 | ... u"`Take some more tea,' the March Hare said to Alice, " |
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167 | ... u"very earnestly."), |
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168 | ... ({'quotedepth': 1, 'type': FIXED}, u""), |
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169 | ... ({'quotedepth': 1, 'type': PARAGRAPH}, |
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170 | ... u"`I've had nothing yet,' Alice replied in an offended " |
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171 | ... u"tone, `so I can't take more.'"), |
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172 | ... ({'quotedepth': 0, 'type': FIXED}, u""), |
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173 | ... ({'quotedepth': 0, 'type': PARAGRAPH}, |
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174 | ... u"`You mean you can't take less,' said the Hatter: `it's " |
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175 | ... u"very easy to take more than nothing.'"), |
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176 | ... ({'quotedepth': 0, 'type': FIXED}, u""), |
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177 | ... ({'quotedepth': 0, 'type': SIGNATURE_SEPARATOR}, u"-- "), |
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178 | ... ({'quotedepth': 0, 'type': FIXED}, u"Lewis Carroll") |
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179 | ... ] |
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180 | True |
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181 | |
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182 | |
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183 | Improperly closed paragraphs |
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184 | ---------------------------- |
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185 | |
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186 | The decoder can deal with various cases of improperly format=flowed |
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187 | messages. Paragraphs normally end with a fixed line, but the following |
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188 | cases are also considered paragraph-closing cases: |
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189 | |
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190 | - A change in quotedepth: |
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191 | |
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192 | >>> result = decoder.decode(CRLF.join(( |
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193 | ... "> Depth one paragraph with flow space. ", |
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194 | ... ">> Depth two paragraph with flow space. ", |
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195 | ... "Depth zero paragraph with fixed line."))) |
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196 | >>> list(result) == [ |
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197 | ... ({'quotedepth': 1, 'type': PARAGRAPH}, |
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198 | ... u"Depth one paragraph with flow space. "), |
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199 | ... ({'quotedepth': 2, 'type': PARAGRAPH}, |
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200 | ... u"Depth two paragraph with flow space. "), |
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201 | ... ({'quotedepth': 0, 'type': FIXED}, |
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202 | ... u"Depth zero paragraph with fixed line.")] |
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203 | True |
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204 | |
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205 | - A signature separator: |
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206 | |
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207 | >>> result = decoder.decode(CRLF.join(( |
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208 | ... "A paragraph with flow space. ", |
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209 | ... "-- "))) |
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210 | >>> list(result) == [ |
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211 | ... ({'quotedepth': 0, 'type': PARAGRAPH}, |
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212 | ... u"A paragraph with flow space. "), |
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213 | ... ({'quotedepth': 0, 'type': SIGNATURE_SEPARATOR}, u"-- ")] |
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214 | True |
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215 | |
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216 | - The end of the message: |
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217 | |
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218 | >>> result = decoder.decode(CRLF.join(( |
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219 | ... "A paragraph with flow space. ",))) |
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220 | >>> list(result) == [ |
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221 | ... ({'quotedepth': 0, 'type': PARAGRAPH}, |
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222 | ... u"A paragraph with flow space. ")] |
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223 | True |
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224 | |
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225 | |
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226 | Decoder options |
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227 | --------------- |
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228 | |
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229 | The delete_space attribute of the FormatFlowedDecoder class can be used |
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230 | to control wether or not the trailing space on flowed lines should be |
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231 | retained; this is used to encode flowed text where spaces are rare: |
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232 | |
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233 | >>> decoder = FormatFlowedDecoder(delete_space=True) |
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234 | >>> result = decoder.decode(CRLF.join(( |
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235 | ... "Contrived example with a word- ", |
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236 | ... "break across the paragraph."))) |
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237 | >>> list(result) == [ |
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238 | ... ({'quotedepth': 0, 'type': PARAGRAPH}, |
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239 | ... u'Contrived example with a word-break across the ' |
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240 | ... u'paragraph.')] |
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241 | True |
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242 | |
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243 | Note that the characterset determines what how to interpret a space |
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244 | and a quote marker. The cp037 characterset does not encode these |
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245 | characters the same way, for example: |
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246 | |
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247 | >>> decoder = FormatFlowedDecoder(character_set='cp037') |
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248 | >>> result = decoder.decode(CRLF.join(( |
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249 | ... "n@\\xe3\\x88\\x89\\xa2@\\x89\\xa2@\\x81@\\x98\\xa4\\x96\\xa3" |
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250 | ... "\\x85\\x84@\\x97\\x81\\x99\\x81\\x87\\x99\\x81\\x97\\x88@", |
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251 | ... "n@\\x85\\x95\\x83\\x96\\x84\\x85\\x84@\\x89\\x95@\\x83\\x97" |
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252 | ... "\\xf0\\xf3\\xf7K"))) |
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253 | >>> list(result) == [ |
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254 | ... ({'quotedepth': 1, 'type': PARAGRAPH}, |
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255 | ... u'This is a quoted paragraph encoded in cp037.')] |
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256 | True |
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257 | |
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258 | """ |
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259 | para = u'' |
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260 | pinfo = {'type': PARAGRAPH} |
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261 | for line in flowed.split('\r\n'): |
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262 | line = line.decode(self.character_set) |
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263 | quotedepth, line = self._stripquotes(line) |
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264 | line = self._stripstuffing(line) |
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265 | if line == '-- ': |
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266 | # signature separator |
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267 | if para: |
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268 | # exception case: flowed line followed by sig-sep |
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269 | yield (pinfo, para) |
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270 | pinfo = {'type': PARAGRAPH} |
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271 | para = u'' |
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272 | yield ({'type': SIGNATURE_SEPARATOR, |
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273 | 'quotedepth': quotedepth}, line) |
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274 | continue |
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275 | if line.endswith(u' '): |
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276 | # flowed line; collect into a paragraph |
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277 | if quotedepth != pinfo.get('quotedepth', quotedepth): |
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278 | # exception case: flowed line followed by quotedepth change |
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279 | yield (pinfo, para) |
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280 | pinfo = {'type': PARAGRAPH} |
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281 | para = u'' |
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282 | para += self._stripflow(line) |
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283 | pinfo['quotedepth'] = quotedepth |
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284 | continue |
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285 | # fixed line |
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286 | if para: |
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287 | # completed paragraph |
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288 | if quotedepth != pinfo.get('quotedepth', quotedepth): |
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289 | # exception case: flowed line followed by quotedepth change |
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290 | yield (pinfo, para) |
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291 | pinfo = {'type': PARAGRAPH} |
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292 | para = u'' |
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293 | else: |
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294 | yield (pinfo, para + line) |
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295 | pinfo = {'type': PARAGRAPH} |
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296 | para = u'' |
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297 | continue |
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298 | yield ({'type': FIXED, 'quotedepth': quotedepth}, line) |
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299 | |
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300 | if para: |
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301 | # exception case: last line was a flowed line |
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302 | yield (pinfo, para) |
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303 | |
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304 | |
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305 | class FormatFlowedEncoder: |
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306 | """Object to generate format=flowed text |
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307 | |
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308 | The following attributes influence the flowed formatting of text: |
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309 | extra_space (default: False) |
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310 | Use an extra space to create flowed lines; this requires that the |
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311 | DelSpace flag will be set true on the Content-Type mime header. Use |
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312 | this flag on texts that have little or no spaces to break on. |
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313 | character_set (default: us-ascii) |
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314 | Encode the output to this character set. |
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315 | spacestuff_quoted (default: True) |
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316 | Always spacestuff quoted chunks, i.e. place a space between the quote |
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317 | markers and the text. |
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318 | width (default: 78) |
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319 | The maximum line width generated for flowed paragraphs; fixed lines |
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320 | can still exceed this width. This value does not include the CRLF |
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321 | line endings. |
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322 | |
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323 | """ |
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324 | def __init__(self, extra_space=False, character_set='us-ascii', |
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325 | spacestuff_quoted=True, width=78): |
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326 | self.extra_space = extra_space |
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327 | self.character_set = character_set |
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328 | self.spacestuff_quoted = spacestuff_quoted |
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329 | self.width = width |
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330 | |
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331 | def _spacestuff(self, line, force=False): |
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332 | """Prepend a space to lines starting with ' ', '>' or 'From' |
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333 | |
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334 | Returns the altered line. Set 'force' to True to skip the tests and |
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335 | always prepend the space regardless: |
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336 | |
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337 | >>> encoder = FormatFlowedEncoder() |
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338 | >>> encoder._spacestuff(u' leading space needs to be preserved') |
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339 | u' leading space needs to be preserved' |
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340 | >>> encoder._spacestuff(u'> can be confused for a quotemark') |
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341 | u' > can be confused for a quotemark' |
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342 | >>> encoder._spacestuff(u'From is often escaped by MTAs') |
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343 | u' From is often escaped by MTAs' |
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344 | >>> encoder._spacestuff(u'Padding is considered harmless') |
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345 | u'Padding is considered harmless' |
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346 | >>> encoder._spacestuff(u'So forcing it is fine', True) |
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347 | u' So forcing it is fine' |
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348 | |
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349 | Note that empty lines can never be spacestuffed: |
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350 | |
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351 | >>> encoder._spacestuff(u'') |
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352 | u'' |
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353 | |
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354 | """ |
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355 | if not line: |
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356 | return line |
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357 | # Although the RFC doesn't say so explicitly, in practice 'From' only |
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358 | # needs escaping when (1) not quoted and (2) actually encoded as |
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359 | # 'From' (so independent of the unicode sequence u'From'). |
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360 | # For simplicity's sake, we spacestuff it any time a line starts with |
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361 | # it before adding quotemarks and encoding the line. |
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362 | if force or line[0] in (' ', '>') or line.startswith('From'): |
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363 | return u' ' + line |
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364 | return line |
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365 | |
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366 | # -- Public API ---------------------------------------------------- |
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367 | |
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368 | def encode(self, chunks): |
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369 | """Encode chunks of text to format=flowed |
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370 | |
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371 | chunks |
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372 | An iterable sequence of (information, text) tuples, where information |
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373 | is a dictionary with 'type' and 'quotedepth' keys. The 'type' value |
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374 | is one of PARAGRAPH, FIXED or SIGNATURE-SEPARATOR, and the |
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375 | 'quotedepth' value a positive integer indicating the quoting depth. |
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376 | text should be the unicode text to be encoded. |
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377 | |
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378 | Example |
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379 | ------- |
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380 | |
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381 | To illustrate, an example: |
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382 | |
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383 | >>> chunks = ( |
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384 | ... ({'quotedepth': 2, 'type': PARAGRAPH}, |
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385 | ... u"`Take some more tea,' the March Hare said to Alice, " |
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386 | ... u"very earnestly."), |
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387 | ... ({'quotedepth': 1, 'type': FIXED}, u""), |
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388 | ... ({'quotedepth': 1, 'type': PARAGRAPH}, |
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389 | ... u"`I've had nothing yet,' Alice replied in an offended " |
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390 | ... u"tone, `so I can't take more.'"), |
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391 | ... ({'quotedepth': 0, 'type': FIXED}, u""), |
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392 | ... ({'quotedepth': 0, 'type': PARAGRAPH}, |
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393 | ... u"`You mean you can't take less,' said the Hatter: `it's " |
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394 | ... u"very easy to take more than nothing.'"), |
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395 | ... ({'quotedepth': 0, 'type': FIXED}, u""), |
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396 | ... ({'quotedepth': 0, 'type': SIGNATURE_SEPARATOR}, u"-- "), |
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397 | ... ({'quotedepth': 0, 'type': PARAGRAPH}, u"Carol Lewis"), |
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398 | ... ) |
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399 | >>> result = FormatFlowedEncoder(width=45).encode(chunks) |
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400 | >>> result.split('\\r\\n') == [ |
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401 | ... ">> `Take some more tea,' the March Hare said ", |
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402 | ... ">> to Alice, very earnestly.", |
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403 | ... ">", |
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404 | ... "> `I've had nothing yet,' Alice replied in ", |
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405 | ... "> an offended tone, `so I can't take more.'", |
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406 | ... "", |
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407 | ... "`You mean you can't take less,' said the ", |
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408 | ... "Hatter: `it's very easy to take more than ", |
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409 | ... "nothing.'", |
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410 | ... "", |
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411 | ... "-- ", |
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412 | ... "Carol Lewis", |
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413 | ... ""] |
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414 | True |
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415 | |
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416 | """ |
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417 | encoded = [] |
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418 | for info, text in chunks: |
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419 | encoded.append(self.encodeChunk(text, **info)) |
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420 | return ''.join(encoded) |
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421 | |
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422 | def encodeChunk(self, chunk, type=PARAGRAPH, quotedepth=0): |
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423 | """Encode a chunk of text to format=flowed |
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424 | |
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425 | The chunk is encoded to format=flowed text, controlled by the |
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426 | following arguments. |
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427 | chunk |
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428 | The unicode text to be encoded. Newlines are considered to be |
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429 | whitespace and will be converted to spaces. |
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430 | type (default: PARAGRAPH) |
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431 | Chunk type; one of PARAGRAPH, FIXED or SIGNATURE_SEPARATOR. When |
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432 | called with type SIGNATURE_SEPARATOR the chunk is ignored and '-- ' |
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433 | is written out. |
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434 | quotedepth (default: 0) |
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435 | The quote depth of the chunk. |
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436 | |
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437 | |
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438 | Examples |
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439 | -------- |
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440 | |
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441 | The encoder has to deal with three types of text chunks. To illustrate, |
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442 | we create a encoder instance geared: |
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443 | |
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444 | >>> encoder = FormatFlowedEncoder(width=45) |
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445 | |
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446 | We can then use this encoder to encode some examples of these different |
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447 | types: |
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448 | |
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449 | - fixed lines: |
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450 | |
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451 | >>> encoder.encodeChunk(u'A fixed line remains unaltered', FIXED) |
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452 | 'A fixed line remains unaltered\\r\\n' |
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453 | >>> encoder.encodeChunk(u'Although quoting is prepended', FIXED, 2) |
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454 | '>> Although quoting is prepended\\r\\n' |
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455 | >>> encoder.encodeChunk(u'Trailing spaces are removed ', FIXED) |
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456 | 'Trailing spaces are removed\\r\\n' |
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457 | >>> encoder.encodeChunk(u'> and special first chars are fluffed', |
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458 | ... FIXED) |
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459 | ' > and special first chars are fluffed\\r\\n' |
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460 | |
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461 | - a paragraph (the default type): |
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462 | |
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463 | >>> result = encoder.encodeChunk( |
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464 | ... u"`Take some more tea,' the March Hare said to Alice, " |
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465 | ... u"very earnestly.") |
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466 | >>> result == ("`Take some more tea,' the March Hare said \\r\\n" |
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467 | ... "to Alice, very earnestly.\\r\\n") |
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468 | True |
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469 | >>> result = encoder.encodeChunk( |
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470 | ... u"`I've had nothing yet,' Alice replied in an offended " |
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471 | ... u"tone, `so I can't take more.'", PARAGRAPH, 1) |
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472 | >>> result == ("> `I've had nothing yet,' Alice replied in \\r\\n" |
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473 | ... "> an offended tone, `so I can't take more.'\\r\\n") |
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474 | True |
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475 | >>> result = encoder.encodeChunk( |
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476 | ... u'The wrapping deals quite well with > eratic ' |
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477 | ... u'spacing and space fluffs characters where needed.') |
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478 | >>> result == ("The wrapping deals quite well with \\r\\n" |
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479 | ... " > eratic spacing and space fluffs \\r\\n" |
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480 | ... "characters where needed.\\r\\n") |
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481 | True |
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482 | |
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483 | - signature separators: |
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484 | |
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485 | >>> encoder.encodeChunk(u'-- ', SIGNATURE_SEPARATOR) |
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486 | '-- \\r\\n' |
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487 | >>> encoder.encodeChunk(u'-- ', SIGNATURE_SEPARATOR, 3) |
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488 | '>>> -- \\r\\n' |
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489 | |
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490 | Note that the actual chunk value is ignored for this type: |
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491 | |
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492 | >>> encoder.encodeChunk(u'foobar', SIGNATURE_SEPARATOR) |
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493 | '-- \\r\\n' |
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494 | |
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495 | |
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496 | Encoder options |
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497 | --------------- |
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498 | |
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499 | The encoding can be influenced by several instance attributes; the |
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500 | width attribute was used for the paragraph demonstrations. Others |
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501 | include 'extra_space', 'character_set' and 'spacestuff_quoted': |
---|
502 | |
---|
503 | - extra_space generates extra spaces on flowed lines so flowed lines |
---|
504 | can be broken on something other than whitespace: |
---|
505 | |
---|
506 | >>> encoder = FormatFlowedEncoder(extra_space=True, width=45) |
---|
507 | >>> result = encoder.encodeChunk( |
---|
508 | ... u'This is useful for texts with many word-breaks or few ' |
---|
509 | ... u'spaces') |
---|
510 | >>> result == ("This is useful for texts with many word- \\r\\n" |
---|
511 | ... "breaks or few spaces\\r\\n") |
---|
512 | True |
---|
513 | |
---|
514 | - character_set controls the output encoding: |
---|
515 | |
---|
516 | >>> encoder = FormatFlowedEncoder(character_set='cp037') |
---|
517 | >>> result = encoder.encodeChunk(u'Can you read me now?', |
---|
518 | ... quotedepth=1) |
---|
519 | >>> result == ('n@\\xc3\\x81\\x95@\\xa8\\x96\\xa4@\\x99\\x85\\x81' |
---|
520 | ... '\\x84@\\x94\\x85@\\x95\x96\\xa6o\\r\\n') |
---|
521 | True |
---|
522 | |
---|
523 | - spacestuff_quoted causes quoted lines to be spacestuffed by default; |
---|
524 | this makes for slightly more readable quoted text output. It is on |
---|
525 | by default, but can be switched off: |
---|
526 | |
---|
527 | >>> encoder = FormatFlowedEncoder(spacestuff_quoted=False) |
---|
528 | >>> encoder.encodeChunk(u'Look Ma! No space!', quotedepth=1) |
---|
529 | '>Look Ma! No space!\\r\\n' |
---|
530 | |
---|
531 | |
---|
532 | RFC 2822 compliance |
---|
533 | ------------------- |
---|
534 | |
---|
535 | Note that RFC 2822 requires that generated lines never exceed the |
---|
536 | hard limit of 998 characters without the CRLF at the end. The encoder |
---|
537 | has to enforce this by chopping the lines up into pieces not exceeding |
---|
538 | that length: |
---|
539 | |
---|
540 | >>> encoder = FormatFlowedEncoder() |
---|
541 | >>> result = encoder.encodeChunk(u'-' * 1500, FIXED) |
---|
542 | >>> result = result.split('\\r\\n') |
---|
543 | >>> len(result) |
---|
544 | 3 |
---|
545 | >>> len(result[0]) |
---|
546 | 998 |
---|
547 | >>> result == ['-' * 998, '-' * 502, ''] |
---|
548 | True |
---|
549 | |
---|
550 | """ |
---|
551 | # cleanup: replace newlines with spaces and remove trailing spaces |
---|
552 | chunk = ' '.join(chunk.rstrip().splitlines()) |
---|
553 | |
---|
554 | # Pre-encode quoting |
---|
555 | quotemarker = u'>' * quotedepth |
---|
556 | quotemarker = quotemarker.encode(self.character_set) |
---|
557 | forcestuff = self.spacestuff_quoted and quotedepth > 0 |
---|
558 | |
---|
559 | if type == SIGNATURE_SEPARATOR: |
---|
560 | chunk = u'-- ' |
---|
561 | |
---|
562 | if type == PARAGRAPH: |
---|
563 | # Maximum width is reduced by stuffing and quotemarkers |
---|
564 | width = self.width - len(quotemarker) - 2 |
---|
565 | if width <= 0: |
---|
566 | raise ValueError('Not enough width for both quoting and text') |
---|
567 | wrapper = _FlowedTextWrapper(width, self.extra_space) |
---|
568 | chunk = wrapper.wrap(chunk) |
---|
569 | else: |
---|
570 | chunk = [chunk] |
---|
571 | |
---|
572 | lines = [] |
---|
573 | for line in chunk: |
---|
574 | # add space to flowed lines (all but last); this is an extra space |
---|
575 | # if the wrapping of paragraphs included spaces at the end of the |
---|
576 | # lines. |
---|
577 | if line != chunk[-1]: |
---|
578 | line += ' ' |
---|
579 | line = self._spacestuff(line, forcestuff) |
---|
580 | line = quotemarker + line.encode(self.character_set) |
---|
581 | |
---|
582 | # Enforce a hard limit of 998 characters per line (excluding CRLF) |
---|
583 | # Unfortunately we can only enforce this *after* encoding, |
---|
584 | # otherwise we could flow lines that are too long. |
---|
585 | while len(line) > 998: |
---|
586 | lines.append(line[:998]) |
---|
587 | line = line[998:] |
---|
588 | |
---|
589 | lines.append(line) |
---|
590 | |
---|
591 | lines.append('') # ensure last ending CRLF |
---|
592 | return '\r\n'.join(lines) |
---|
593 | |
---|
594 | |
---|
595 | # -- Convenience functions --------------------------------------------- |
---|
596 | |
---|
597 | |
---|
598 | def decode(flowed, **kwargs): |
---|
599 | """Convert format=flowed text |
---|
600 | |
---|
601 | See the FormatFlowedDecoder.decode docstring for more information. All |
---|
602 | keyword arguments are passed to the FormatFlowedDecoder instance. |
---|
603 | |
---|
604 | """ |
---|
605 | decoder = FormatFlowedDecoder(**kwargs) |
---|
606 | return decoder.decode(flowed) |
---|
607 | |
---|
608 | def encode(chunks, **kwargs): |
---|
609 | """Convert chunks of text to format=flowed |
---|
610 | |
---|
611 | See the FormatFlowedEncoder.encode docstring for more information. All |
---|
612 | keyword arguments are passed to the FormatFlowedEncoder instance. |
---|
613 | |
---|
614 | """ |
---|
615 | encoder = FormatFlowedEncoder(**kwargs) |
---|
616 | return encoder.encode(chunks) |
---|
617 | |
---|
618 | def convertToWrapped(flowed, width=78, quote=u'>', wrap_fixed=True, **kwargs): |
---|
619 | """Covert flowed text to encoded and wrapped text |
---|
620 | |
---|
621 | Create text suitable for a proportional font, fixed with, plain text |
---|
622 | display. The argements are interpreted as follows: |
---|
623 | flowed |
---|
624 | The format=flowed formatted text to convert |
---|
625 | width (default: 78) |
---|
626 | The maximum line length at which to wrap paragraphs. |
---|
627 | quote (default: u'>') |
---|
628 | Character sequence to use to mark quote depths; it is multiplied with |
---|
629 | the quotedepth to quote a line. If this sequence does not end in a |
---|
630 | space a space is added between the quotemars and the line. |
---|
631 | wrap_fixed (default: True) |
---|
632 | If true, fixed text chunks are wrapped to the given width as well, |
---|
633 | including hard word breaks if a word exceeds the line width |
---|
634 | |
---|
635 | The remaining arguments are used as arguments to FormatFlowedDecoder. |
---|
636 | |
---|
637 | Here is a simple example: |
---|
638 | |
---|
639 | >>> CRLF = '\\r\\n' |
---|
640 | >>> result = convertToWrapped(CRLF.join(( |
---|
641 | ... ">> `Take some more tea,' the March Hare said to Alice, very ", |
---|
642 | ... ">> earnestly.", |
---|
643 | ... ">", |
---|
644 | ... "> `I've had nothing yet,' Alice replied in an offended ", |
---|
645 | ... "> tone, `so I can't take more.'", |
---|
646 | ... "", |
---|
647 | ... "`You mean you can't take less,' said the Hatter: `it's very ", |
---|
648 | ... "easy to take more than nothing.'", |
---|
649 | ... "", |
---|
650 | ... "-- ", |
---|
651 | ... "Lewis Caroll")), width=60) |
---|
652 | >>> result.split('\\n') == [ |
---|
653 | ... ">> `Take some more tea,' the March Hare said to Alice, very", |
---|
654 | ... ">> earnestly.", |
---|
655 | ... "> ", |
---|
656 | ... "> `I've had nothing yet,' Alice replied in an offended tone,", |
---|
657 | ... "> `so I can't take more.'", |
---|
658 | ... "", |
---|
659 | ... "`You mean you can't take less,' said the Hatter: `it's very", |
---|
660 | ... "easy to take more than nothing.'", |
---|
661 | ... "", |
---|
662 | ... "-- ", |
---|
663 | ... "Lewis Caroll"] |
---|
664 | True |
---|
665 | |
---|
666 | """ |
---|
667 | result = [] |
---|
668 | for info, chunk in decode(flowed, **kwargs): |
---|
669 | type = info['type'] |
---|
670 | quotedepth = info['quotedepth'] |
---|
671 | quotemarker = quotedepth and quote * quotedepth or u'' |
---|
672 | if quotemarker and quote[-1] != u' ': |
---|
673 | quotemarker += u' ' |
---|
674 | if type == FIXED and not wrap_fixed: |
---|
675 | result.append(quotemarker + chunk) |
---|
676 | elif not chunk or type == SIGNATURE_SEPARATOR: |
---|
677 | result.append(quotemarker + chunk) |
---|
678 | else: |
---|
679 | result.extend(textwrap.wrap(chunk, width, |
---|
680 | replace_whitespace=False, |
---|
681 | initial_indent=quotemarker, |
---|
682 | subsequent_indent=quotemarker)) |
---|
683 | return u'\n'.join(result) |
---|
684 | |
---|
685 | def convertToFlowed(text, quotechars=u'>|%', **kwargs): |
---|
686 | """Convert plain text to format=flowed |
---|
687 | |
---|
688 | Attempt to interpret the plain text as paragraphs and fixed lines, |
---|
689 | creating a format=flowed encoded text. The paragraph detection is fairly |
---|
690 | simple and probably not suitable for real-world email. |
---|
691 | |
---|
692 | text |
---|
693 | Unicode text to be converted. Paragraphs are detected based on |
---|
694 | whitelines between them, making all lines with extra linespace at the |
---|
695 | start fixed to preserve that whitespace. |
---|
696 | quotechars (default: u'>|%') |
---|
697 | A set of characters recognized as quote markers; used to detect quote |
---|
698 | depth. |
---|
699 | |
---|
700 | Additional kwargs are passed on to FormatFlowedEncoder. |
---|
701 | |
---|
702 | """ |
---|
703 | encoder = FormatFlowedEncoder(**kwargs) |
---|
704 | return encoder.encode(_parseFlowableChunks(text, quotechars)) |
---|
705 | |
---|
706 | |
---|
707 | # -- Private classes and methods --------------------------------------- |
---|
708 | |
---|
709 | |
---|
710 | class _FlowedTextWrapper(textwrap.TextWrapper): |
---|
711 | """Custom text wrapper for flowed text |
---|
712 | |
---|
713 | When not using extra spaces, only break on spaces; when we are using |
---|
714 | extra spaces, don't swallow whitespace at the start and end of lines, but |
---|
715 | do break long words (as they can be reconstructed with DelSpace on). |
---|
716 | |
---|
717 | """ |
---|
718 | def __init__(self, width=78, extra_space=False): |
---|
719 | textwrap.TextWrapper.__init__(self, width, |
---|
720 | break_long_words=extra_space) |
---|
721 | self.extra_space = extra_space |
---|
722 | if not extra_space: |
---|
723 | self.wordsep_re = re.compile(r'(\s+)') |
---|
724 | |
---|
725 | def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width): |
---|
726 | # _handle_long_word taken from python 2.5 CVS speed optimisation |
---|
727 | # Can be removed if this is used with python 2.5 |
---|
728 | space_left = max(width - cur_len, 1) |
---|
729 | if self.break_long_words: |
---|
730 | cur_line.append(reversed_chunks[-1][:space_left]) |
---|
731 | reversed_chunks[-1] = reversed_chunks[-1][space_left:] |
---|
732 | elif not cur_line: |
---|
733 | cur_line.append(reversed_chunks.pop()) |
---|
734 | |
---|
735 | def _wrap(self, chunks): |
---|
736 | # Simplified and customized version of textwrap.TextWrapper |
---|
737 | # Based on textwrapper rev. 1.37 in python CVS, with speed optimisation |
---|
738 | lines = [] |
---|
739 | chunks.reverse() |
---|
740 | while chunks: |
---|
741 | cur_line = [] |
---|
742 | cur_len = 0 |
---|
743 | width = self.width |
---|
744 | |
---|
745 | # Don't strip space at the start of a line when using extra_space |
---|
746 | # because spaces are significant there. |
---|
747 | if chunks[-1].strip() == '' and lines and not self.extra_space: |
---|
748 | del chunks[-1] |
---|
749 | |
---|
750 | while chunks: |
---|
751 | l = len(chunks[-1]) |
---|
752 | if cur_len + l <= width: |
---|
753 | cur_line.append(chunks.pop()) |
---|
754 | cur_len += l |
---|
755 | else: |
---|
756 | break |
---|
757 | |
---|
758 | if chunks and len(chunks[-1]) > width: |
---|
759 | self._handle_long_word(chunks, cur_line, cur_len, width) |
---|
760 | |
---|
761 | # Don't drop space at end of line if using extra_space for |
---|
762 | # marking flowed lines because otherwise there is no space between |
---|
763 | # this line and the next when decoding the flowed text |
---|
764 | if cur_line and cur_line[-1].strip() == '' and not self.extra_space: |
---|
765 | del cur_line[-1] |
---|
766 | |
---|
767 | if cur_line: |
---|
768 | lines.append(''.join(cur_line)) |
---|
769 | return lines |
---|
770 | |
---|
771 | |
---|
772 | def _parseFlowableChunks(text, quotechars='>%|'): |
---|
773 | """Parse out encodeble chunks, determining chunk type |
---|
774 | |
---|
775 | First step is to remove and count quoting marks, determining the quotedepth |
---|
776 | of the text. Then the type of the lines is detected. |
---|
777 | |
---|
778 | Paragraphs are determined by terminating lines; terminating lines are |
---|
779 | changes in quoting (depth or quoting used, signatures or fixed lines (see |
---|
780 | below) |
---|
781 | |
---|
782 | Fixed lines are used for lines with nothing but whitespace and for lines |
---|
783 | with whitespace prepended (indented lines). |
---|
784 | |
---|
785 | Any line with only two dashes at the start and whitespace is a signature |
---|
786 | seperator. |
---|
787 | |
---|
788 | Example code: |
---|
789 | |
---|
790 | >>> result = _parseFlowableChunks(u'\\n'.join(( |
---|
791 | ... u'Normal text, as long as they are not delimited by empty ', |
---|
792 | ... u'lines will be considered paragraphs and will be parsed as ', |
---|
793 | ... u'such.', |
---|
794 | ... u'', |
---|
795 | ... u'> > Quoting will be detected as well, and as long as it is ', |
---|
796 | ... u'> > consistent text will be collected into one paragraph.', |
---|
797 | ... u'> Changes in depth trigger a new paragraph.', |
---|
798 | ... u'> Leading whitespace makes for fixed lines.', |
---|
799 | ... u'Signature separators are dealt with accordingly:', |
---|
800 | ... u'-- ' |
---|
801 | ... ))) |
---|
802 | >>> result.next() == ({'type': PARAGRAPH, 'quotedepth': 0}, |
---|
803 | ... u'Normal text, as long as they are not delimited by empty ' |
---|
804 | ... u'lines will be considered paragraphs and will be parsed as ' |
---|
805 | ... u'such.') |
---|
806 | True |
---|
807 | >>> result.next() == ({'type': FIXED, 'quotedepth': 0}, u'') |
---|
808 | True |
---|
809 | >>> result.next() == ({'type': PARAGRAPH, 'quotedepth': 2}, |
---|
810 | ... u'Quoting will be detected as well, and as long as it is ' |
---|
811 | ... u'consistent text will be collected into one paragraph.') |
---|
812 | True |
---|
813 | >>> result.next() == ({'type': PARAGRAPH, 'quotedepth': 1}, |
---|
814 | ... u'Changes in depth trigger a new paragraph.') |
---|
815 | True |
---|
816 | >>> result.next() == ({'type': FIXED, 'quotedepth': 1}, |
---|
817 | ... u' Leading whitespace makes for fixed lines.') |
---|
818 | True |
---|
819 | >>> result.next() == ({'type': PARAGRAPH, 'quotedepth': 0}, |
---|
820 | ... u'Signature separators are dealt with accordingly:') |
---|
821 | True |
---|
822 | >>> result.next() == ({'type': SIGNATURE_SEPARATOR, 'quotedepth': 0}, |
---|
823 | ... u'-- ') |
---|
824 | True |
---|
825 | >>> result.next() |
---|
826 | Traceback (most recent call last): |
---|
827 | ... |
---|
828 | StopIteration |
---|
829 | |
---|
830 | """ |
---|
831 | # Match quotemarks with limited whitespace around them |
---|
832 | qm_match = re.compile('(^\s{0,2}([%s]\s?)+)' % quotechars).match |
---|
833 | # Find all quotemarks |
---|
834 | qm_findall = re.compile('[%s]' % quotechars).findall |
---|
835 | |
---|
836 | quotedepth = 0 |
---|
837 | quotemarks = '' |
---|
838 | para = u'' |
---|
839 | |
---|
840 | for line in text.splitlines(): |
---|
841 | has_quotes = qm_match(line) |
---|
842 | same_quotes = quotemarks and line.startswith(quotemarks) |
---|
843 | if (has_quotes and not same_quotes) or (not has_quotes and quotedepth): |
---|
844 | # Change in quoting |
---|
845 | if para: |
---|
846 | yield {'type': PARAGRAPH, 'quotedepth': quotedepth}, para |
---|
847 | para = u'' |
---|
848 | |
---|
849 | quotemarks = has_quotes and has_quotes.group(0) or u'' |
---|
850 | quotedepth = len(qm_findall(quotemarks)) |
---|
851 | |
---|
852 | line = line[len(quotemarks):] |
---|
853 | |
---|
854 | if line.rstrip() == u'--': |
---|
855 | # signature separator |
---|
856 | if para: |
---|
857 | yield {'type': PARAGRAPH, 'quotedepth': quotedepth}, para |
---|
858 | para = u'' |
---|
859 | |
---|
860 | yield {'type': SIGNATURE_SEPARATOR, 'quotedepth': quotedepth}, line |
---|
861 | continue |
---|
862 | |
---|
863 | if line.strip() == u'' or line.lstrip() != line: |
---|
864 | # Fixed line |
---|
865 | if para: |
---|
866 | yield {'type': PARAGRAPH, 'quotedepth': quotedepth}, para |
---|
867 | para = u'' |
---|
868 | |
---|
869 | yield {'type': FIXED, 'quotedepth': quotedepth}, line |
---|
870 | continue |
---|
871 | |
---|
872 | # Paragraph line; store and loop to next line |
---|
873 | para += line |
---|
874 | |
---|
875 | if para: |
---|
876 | yield {'type': PARAGRAPH, 'quotedepth': quotedepth}, para |
---|
877 | |
---|
878 | def _test(verbose=False): |
---|
879 | import doctest |
---|
880 | return doctest.testmod(verbose=verbose) |
---|
881 | |
---|
882 | if __name__ == '__main__': |
---|
883 | import sys |
---|
884 | _test('-v' in sys.argv) |
---|