| 1 | """Generic output formatting.
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| 2 |
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| 3 | Formatter objects transform an abstract flow of formatting events into
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| 4 | specific output events on writer objects. Formatters manage several stack
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| 5 | structures to allow various properties of a writer object to be changed and
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| 6 | restored; writers need not be able to handle relative changes nor any sort
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| 7 | of ``change back'' operation. Specific writer properties which may be
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| 8 | controlled via formatter objects are horizontal alignment, font, and left
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| 9 | margin indentations. A mechanism is provided which supports providing
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| 10 | arbitrary, non-exclusive style settings to a writer as well. Additional
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| 11 | interfaces facilitate formatting events which are not reversible, such as
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| 12 | paragraph separation.
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| 13 |
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| 14 | Writer objects encapsulate device interfaces. Abstract devices, such as
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| 15 | file formats, are supported as well as physical devices. The provided
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| 16 | implementations all work with abstract devices. The interface makes
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| 17 | available mechanisms for setting the properties which formatter objects
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| 18 | manage and inserting data into the output.
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| 19 | """
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| 20 |
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| 21 | import sys
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| 22 |
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| 23 |
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| 24 | AS_IS = None
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| 25 |
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| 26 |
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| 27 | class NullFormatter:
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| 28 | """A formatter which does nothing.
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| 29 |
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| 30 | If the writer parameter is omitted, a NullWriter instance is created.
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| 31 | No methods of the writer are called by NullFormatter instances.
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| 32 |
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| 33 | Implementations should inherit from this class if implementing a writer
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| 34 | interface but don't need to inherit any implementation.
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| 35 |
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| 36 | """
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| 37 |
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| 38 | def __init__(self, writer=None):
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| 39 | if writer is None:
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| 40 | writer = NullWriter()
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| 41 | self.writer = writer
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| 42 | def end_paragraph(self, blankline): pass
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| 43 | def add_line_break(self): pass
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| 44 | def add_hor_rule(self, *args, **kw): pass
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| 45 | def add_label_data(self, format, counter, blankline=None): pass
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| 46 | def add_flowing_data(self, data): pass
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| 47 | def add_literal_data(self, data): pass
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| 48 | def flush_softspace(self): pass
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| 49 | def push_alignment(self, align): pass
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| 50 | def pop_alignment(self): pass
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| 51 | def push_font(self, x): pass
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| 52 | def pop_font(self): pass
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| 53 | def push_margin(self, margin): pass
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| 54 | def pop_margin(self): pass
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| 55 | def set_spacing(self, spacing): pass
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| 56 | def push_style(self, *styles): pass
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| 57 | def pop_style(self, n=1): pass
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| 58 | def assert_line_data(self, flag=1): pass
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| 59 |
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| 60 |
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| 61 | class AbstractFormatter:
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| 62 | """The standard formatter.
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| 63 |
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| 64 | This implementation has demonstrated wide applicability to many writers,
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| 65 | and may be used directly in most circumstances. It has been used to
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| 66 | implement a full-featured World Wide Web browser.
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| 67 |
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| 68 | """
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| 69 |
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| 70 | # Space handling policy: blank spaces at the boundary between elements
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| 71 | # are handled by the outermost context. "Literal" data is not checked
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| 72 | # to determine context, so spaces in literal data are handled directly
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| 73 | # in all circumstances.
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| 74 |
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| 75 | def __init__(self, writer):
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| 76 | self.writer = writer # Output device
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| 77 | self.align = None # Current alignment
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| 78 | self.align_stack = [] # Alignment stack
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| 79 | self.font_stack = [] # Font state
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| 80 | self.margin_stack = [] # Margin state
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| 81 | self.spacing = None # Vertical spacing state
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| 82 | self.style_stack = [] # Other state, e.g. color
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| 83 | self.nospace = 1 # Should leading space be suppressed
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| 84 | self.softspace = 0 # Should a space be inserted
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| 85 | self.para_end = 1 # Just ended a paragraph
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| 86 | self.parskip = 0 # Skipped space between paragraphs?
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| 87 | self.hard_break = 1 # Have a hard break
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| 88 | self.have_label = 0
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| 89 |
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| 90 | def end_paragraph(self, blankline):
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| 91 | if not self.hard_break:
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| 92 | self.writer.send_line_break()
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| 93 | self.have_label = 0
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| 94 | if self.parskip < blankline and not self.have_label:
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| 95 | self.writer.send_paragraph(blankline - self.parskip)
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| 96 | self.parskip = blankline
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| 97 | self.have_label = 0
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| 98 | self.hard_break = self.nospace = self.para_end = 1
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| 99 | self.softspace = 0
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| 100 |
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| 101 | def add_line_break(self):
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| 102 | if not (self.hard_break or self.para_end):
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| 103 | self.writer.send_line_break()
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| 104 | self.have_label = self.parskip = 0
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| 105 | self.hard_break = self.nospace = 1
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| 106 | self.softspace = 0
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| 107 |
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| 108 | def add_hor_rule(self, *args, **kw):
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| 109 | if not self.hard_break:
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| 110 | self.writer.send_line_break()
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| 111 | self.writer.send_hor_rule(*args, **kw)
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| 112 | self.hard_break = self.nospace = 1
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| 113 | self.have_label = self.para_end = self.softspace = self.parskip = 0
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| 114 |
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| 115 | def add_label_data(self, format, counter, blankline = None):
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| 116 | if self.have_label or not self.hard_break:
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| 117 | self.writer.send_line_break()
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| 118 | if not self.para_end:
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| 119 | self.writer.send_paragraph((blankline and 1) or 0)
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| 120 | if isinstance(format, str):
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| 121 | self.writer.send_label_data(self.format_counter(format, counter))
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| 122 | else:
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| 123 | self.writer.send_label_data(format)
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| 124 | self.nospace = self.have_label = self.hard_break = self.para_end = 1
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| 125 | self.softspace = self.parskip = 0
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| 126 |
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| 127 | def format_counter(self, format, counter):
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| 128 | label = ''
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| 129 | for c in format:
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| 130 | if c == '1':
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| 131 | label = label + ('%d' % counter)
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| 132 | elif c in 'aA':
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| 133 | if counter > 0:
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| 134 | label = label + self.format_letter(c, counter)
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| 135 | elif c in 'iI':
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| 136 | if counter > 0:
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| 137 | label = label + self.format_roman(c, counter)
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| 138 | else:
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| 139 | label = label + c
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| 140 | return label
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| 141 |
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| 142 | def format_letter(self, case, counter):
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| 143 | label = ''
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| 144 | while counter > 0:
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| 145 | counter, x = divmod(counter-1, 26)
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| 146 | # This makes a strong assumption that lowercase letters
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| 147 | # and uppercase letters form two contiguous blocks, with
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| 148 | # letters in order!
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| 149 | s = chr(ord(case) + x)
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| 150 | label = s + label
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| 151 | return label
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| 152 |
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| 153 | def format_roman(self, case, counter):
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| 154 | ones = ['i', 'x', 'c', 'm']
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| 155 | fives = ['v', 'l', 'd']
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| 156 | label, index = '', 0
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| 157 | # This will die of IndexError when counter is too big
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| 158 | while counter > 0:
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| 159 | counter, x = divmod(counter, 10)
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| 160 | if x == 9:
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| 161 | label = ones[index] + ones[index+1] + label
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| 162 | elif x == 4:
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| 163 | label = ones[index] + fives[index] + label
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| 164 | else:
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| 165 | if x >= 5:
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| 166 | s = fives[index]
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| 167 | x = x-5
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| 168 | else:
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| 169 | s = ''
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| 170 | s = s + ones[index]*x
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| 171 | label = s + label
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| 172 | index = index + 1
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| 173 | if case == 'I':
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| 174 | return label.upper()
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| 175 | return label
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| 176 |
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| 177 | def add_flowing_data(self, data):
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| 178 | if not data: return
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| 179 | prespace = data[:1].isspace()
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| 180 | postspace = data[-1:].isspace()
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| 181 | data = " ".join(data.split())
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| 182 | if self.nospace and not data:
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| 183 | return
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| 184 | elif prespace or self.softspace:
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| 185 | if not data:
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| 186 | if not self.nospace:
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| 187 | self.softspace = 1
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| 188 | self.parskip = 0
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| 189 | return
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| 190 | if not self.nospace:
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| 191 | data = ' ' + data
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| 192 | self.hard_break = self.nospace = self.para_end = \
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| 193 | self.parskip = self.have_label = 0
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| 194 | self.softspace = postspace
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| 195 | self.writer.send_flowing_data(data)
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| 196 |
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| 197 | def add_literal_data(self, data):
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| 198 | if not data: return
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| 199 | if self.softspace:
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| 200 | self.writer.send_flowing_data(" ")
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| 201 | self.hard_break = data[-1:] == '\n'
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| 202 | self.nospace = self.para_end = self.softspace = \
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| 203 | self.parskip = self.have_label = 0
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| 204 | self.writer.send_literal_data(data)
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| 205 |
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| 206 | def flush_softspace(self):
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| 207 | if self.softspace:
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| 208 | self.hard_break = self.para_end = self.parskip = \
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| 209 | self.have_label = self.softspace = 0
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| 210 | self.nospace = 1
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| 211 | self.writer.send_flowing_data(' ')
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| 212 |
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| 213 | def push_alignment(self, align):
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| 214 | if align and align != self.align:
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| 215 | self.writer.new_alignment(align)
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| 216 | self.align = align
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| 217 | self.align_stack.append(align)
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| 218 | else:
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| 219 | self.align_stack.append(self.align)
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| 220 |
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| 221 | def pop_alignment(self):
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| 222 | if self.align_stack:
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| 223 | del self.align_stack[-1]
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| 224 | if self.align_stack:
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| 225 | self.align = align = self.align_stack[-1]
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| 226 | self.writer.new_alignment(align)
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| 227 | else:
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| 228 | self.align = None
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| 229 | self.writer.new_alignment(None)
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| 230 |
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| 231 | def push_font(self, (size, i, b, tt)):
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| 232 | if self.softspace:
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| 233 | self.hard_break = self.para_end = self.softspace = 0
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| 234 | self.nospace = 1
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| 235 | self.writer.send_flowing_data(' ')
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| 236 | if self.font_stack:
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| 237 | csize, ci, cb, ctt = self.font_stack[-1]
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| 238 | if size is AS_IS: size = csize
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| 239 | if i is AS_IS: i = ci
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| 240 | if b is AS_IS: b = cb
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| 241 | if tt is AS_IS: tt = ctt
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| 242 | font = (size, i, b, tt)
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| 243 | self.font_stack.append(font)
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| 244 | self.writer.new_font(font)
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| 245 |
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| 246 | def pop_font(self):
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| 247 | if self.font_stack:
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| 248 | del self.font_stack[-1]
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| 249 | if self.font_stack:
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| 250 | font = self.font_stack[-1]
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| 251 | else:
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| 252 | font = None
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| 253 | self.writer.new_font(font)
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| 254 |
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| 255 | def push_margin(self, margin):
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| 256 | self.margin_stack.append(margin)
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| 257 | fstack = filter(None, self.margin_stack)
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| 258 | if not margin and fstack:
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| 259 | margin = fstack[-1]
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| 260 | self.writer.new_margin(margin, len(fstack))
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| 261 |
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| 262 | def pop_margin(self):
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| 263 | if self.margin_stack:
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| 264 | del self.margin_stack[-1]
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| 265 | fstack = filter(None, self.margin_stack)
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| 266 | if fstack:
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| 267 | margin = fstack[-1]
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| 268 | else:
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| 269 | margin = None
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| 270 | self.writer.new_margin(margin, len(fstack))
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| 271 |
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| 272 | def set_spacing(self, spacing):
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| 273 | self.spacing = spacing
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| 274 | self.writer.new_spacing(spacing)
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| 275 |
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| 276 | def push_style(self, *styles):
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| 277 | if self.softspace:
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| 278 | self.hard_break = self.para_end = self.softspace = 0
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| 279 | self.nospace = 1
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| 280 | self.writer.send_flowing_data(' ')
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| 281 | for style in styles:
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| 282 | self.style_stack.append(style)
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| 283 | self.writer.new_styles(tuple(self.style_stack))
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| 284 |
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| 285 | def pop_style(self, n=1):
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| 286 | del self.style_stack[-n:]
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| 287 | self.writer.new_styles(tuple(self.style_stack))
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| 288 |
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| 289 | def assert_line_data(self, flag=1):
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| 290 | self.nospace = self.hard_break = not flag
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| 291 | self.para_end = self.parskip = self.have_label = 0
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| 292 |
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| 293 |
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| 294 | class NullWriter:
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| 295 | """Minimal writer interface to use in testing & inheritance.
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| 296 |
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| 297 | A writer which only provides the interface definition; no actions are
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| 298 | taken on any methods. This should be the base class for all writers
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| 299 | which do not need to inherit any implementation methods.
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| 300 |
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| 301 | """
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| 302 | def __init__(self): pass
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| 303 | def flush(self): pass
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| 304 | def new_alignment(self, align): pass
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| 305 | def new_font(self, font): pass
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| 306 | def new_margin(self, margin, level): pass
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| 307 | def new_spacing(self, spacing): pass
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| 308 | def new_styles(self, styles): pass
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| 309 | def send_paragraph(self, blankline): pass
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| 310 | def send_line_break(self): pass
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| 311 | def send_hor_rule(self, *args, **kw): pass
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| 312 | def send_label_data(self, data): pass
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| 313 | def send_flowing_data(self, data): pass
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| 314 | def send_literal_data(self, data): pass
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| 315 |
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| 316 |
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| 317 | class AbstractWriter(NullWriter):
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| 318 | """A writer which can be used in debugging formatters, but not much else.
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| 319 |
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| 320 | Each method simply announces itself by printing its name and
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| 321 | arguments on standard output.
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| 322 |
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| 323 | """
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| 324 |
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| 325 | def new_alignment(self, align):
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| 326 | print "new_alignment(%r)" % (align,)
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| 327 |
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| 328 | def new_font(self, font):
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| 329 | print "new_font(%r)" % (font,)
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| 330 |
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| 331 | def new_margin(self, margin, level):
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| 332 | print "new_margin(%r, %d)" % (margin, level)
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| 333 |
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| 334 | def new_spacing(self, spacing):
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| 335 | print "new_spacing(%r)" % (spacing,)
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| 336 |
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| 337 | def new_styles(self, styles):
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| 338 | print "new_styles(%r)" % (styles,)
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| 339 |
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| 340 | def send_paragraph(self, blankline):
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| 341 | print "send_paragraph(%r)" % (blankline,)
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| 342 |
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| 343 | def send_line_break(self):
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| 344 | print "send_line_break()"
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| 345 |
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| 346 | def send_hor_rule(self, *args, **kw):
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| 347 | print "send_hor_rule()"
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| 348 |
|
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| 349 | def send_label_data(self, data):
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| 350 | print "send_label_data(%r)" % (data,)
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| 351 |
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| 352 | def send_flowing_data(self, data):
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| 353 | print "send_flowing_data(%r)" % (data,)
|
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| 354 |
|
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| 355 | def send_literal_data(self, data):
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|---|
| 356 | print "send_literal_data(%r)" % (data,)
|
|---|
| 357 |
|
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| 358 |
|
|---|
| 359 | class DumbWriter(NullWriter):
|
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| 360 | """Simple writer class which writes output on the file object passed in
|
|---|
| 361 | as the file parameter or, if file is omitted, on standard output. The
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| 362 | output is simply word-wrapped to the number of columns specified by
|
|---|
| 363 | the maxcol parameter. This class is suitable for reflowing a sequence
|
|---|
| 364 | of paragraphs.
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|---|
| 365 |
|
|---|
| 366 | """
|
|---|
| 367 |
|
|---|
| 368 | def __init__(self, file=None, maxcol=72):
|
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| 369 | self.file = file or sys.stdout
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|---|
| 370 | self.maxcol = maxcol
|
|---|
| 371 | NullWriter.__init__(self)
|
|---|
| 372 | self.reset()
|
|---|
| 373 |
|
|---|
| 374 | def reset(self):
|
|---|
| 375 | self.col = 0
|
|---|
| 376 | self.atbreak = 0
|
|---|
| 377 |
|
|---|
| 378 | def send_paragraph(self, blankline):
|
|---|
| 379 | self.file.write('\n'*blankline)
|
|---|
| 380 | self.col = 0
|
|---|
| 381 | self.atbreak = 0
|
|---|
| 382 |
|
|---|
| 383 | def send_line_break(self):
|
|---|
| 384 | self.file.write('\n')
|
|---|
| 385 | self.col = 0
|
|---|
| 386 | self.atbreak = 0
|
|---|
| 387 |
|
|---|
| 388 | def send_hor_rule(self, *args, **kw):
|
|---|
| 389 | self.file.write('\n')
|
|---|
| 390 | self.file.write('-'*self.maxcol)
|
|---|
| 391 | self.file.write('\n')
|
|---|
| 392 | self.col = 0
|
|---|
| 393 | self.atbreak = 0
|
|---|
| 394 |
|
|---|
| 395 | def send_literal_data(self, data):
|
|---|
| 396 | self.file.write(data)
|
|---|
| 397 | i = data.rfind('\n')
|
|---|
| 398 | if i >= 0:
|
|---|
| 399 | self.col = 0
|
|---|
| 400 | data = data[i+1:]
|
|---|
| 401 | data = data.expandtabs()
|
|---|
| 402 | self.col = self.col + len(data)
|
|---|
| 403 | self.atbreak = 0
|
|---|
| 404 |
|
|---|
| 405 | def send_flowing_data(self, data):
|
|---|
| 406 | if not data: return
|
|---|
| 407 | atbreak = self.atbreak or data[0].isspace()
|
|---|
| 408 | col = self.col
|
|---|
| 409 | maxcol = self.maxcol
|
|---|
| 410 | write = self.file.write
|
|---|
| 411 | for word in data.split():
|
|---|
| 412 | if atbreak:
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| 413 | if col + len(word) >= maxcol:
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| 414 | write('\n')
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| 415 | col = 0
|
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| 416 | else:
|
|---|
| 417 | write(' ')
|
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| 418 | col = col + 1
|
|---|
| 419 | write(word)
|
|---|
| 420 | col = col + len(word)
|
|---|
| 421 | atbreak = 1
|
|---|
| 422 | self.col = col
|
|---|
| 423 | self.atbreak = data[-1].isspace()
|
|---|
| 424 |
|
|---|
| 425 |
|
|---|
| 426 | def test(file = None):
|
|---|
| 427 | w = DumbWriter()
|
|---|
| 428 | f = AbstractFormatter(w)
|
|---|
| 429 | if file is not None:
|
|---|
| 430 | fp = open(file)
|
|---|
| 431 | elif sys.argv[1:]:
|
|---|
| 432 | fp = open(sys.argv[1])
|
|---|
| 433 | else:
|
|---|
| 434 | fp = sys.stdin
|
|---|
| 435 | for line in fp:
|
|---|
| 436 | if line == '\n':
|
|---|
| 437 | f.end_paragraph(1)
|
|---|
| 438 | else:
|
|---|
| 439 | f.add_flowing_data(line)
|
|---|
| 440 | f.end_paragraph(0)
|
|---|
| 441 |
|
|---|
| 442 |
|
|---|
| 443 | if __name__ == '__main__':
|
|---|
| 444 | test()
|
|---|
