cpython/Lib/formatter.py

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"""Generic output formatting.
Formatter objects transform an abstract flow of formatting events into
specific output events on writer objects. Formatters manage several stack
structures to allow various properties of a writer object to be changed and
restored; writers need not be able to handle relative changes nor any sort
of ``change back'' operation. Specific writer properties which may be
controlled via formatter objects are horizontal alignment, font, and left
margin indentations. A mechanism is provided which supports providing
arbitrary, non-exclusive style settings to a writer as well. Additional
interfaces facilitate formatting events which are not reversible, such as
paragraph separation.
Writer objects encapsulate device interfaces. Abstract devices, such as
file formats, are supported as well as physical devices. The provided
implementations all work with abstract devices. The interface makes
available mechanisms for setting the properties which formatter objects
manage and inserting data into the output.
"""
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import string
import sys
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from types import StringType
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AS_IS = None
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class NullFormatter:
def __init__(self, writer=None):
if not writer:
writer = NullWriter()
self.writer = writer
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def end_paragraph(self, blankline): pass
def add_line_break(self): pass
def add_hor_rule(self, *args, **kw): pass
def add_label_data(self, format, counter, blankline=None): pass
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def add_flowing_data(self, data): pass
def add_literal_data(self, data): pass
def flush_softspace(self): pass
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def push_alignment(self, align): pass
def pop_alignment(self): pass
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def push_font(self, x): pass
def pop_font(self): pass
def push_margin(self, margin): pass
def pop_margin(self): pass
def set_spacing(self, spacing): pass
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def push_style(self, *styles): pass
def pop_style(self, n=1): pass
def assert_line_data(self, flag=1): pass
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class AbstractFormatter:
# Space handling policy: blank spaces at the boundary between elements
# are handled by the outermost context. "Literal" data is not checked
# to determine context, so spaces in literal data are handled directly
# in all circumstances.
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def __init__(self, writer):
self.writer = writer # Output device
self.align = None # Current alignment
self.align_stack = [] # Alignment stack
self.font_stack = [] # Font state
self.margin_stack = [] # Margin state
self.spacing = None # Vertical spacing state
self.style_stack = [] # Other state, e.g. color
self.nospace = 1 # Should leading space be suppressed
self.softspace = 0 # Should a space be inserted
self.para_end = 1 # Just ended a paragraph
self.parskip = 0 # Skipped space between paragraphs?
self.hard_break = 1 # Have a hard break
self.have_label = 0
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def end_paragraph(self, blankline):
if not self.hard_break:
self.writer.send_line_break()
self.have_label = 0
if self.parskip < blankline and not self.have_label:
self.writer.send_paragraph(blankline - self.parskip)
self.parskip = blankline
self.have_label = 0
self.hard_break = self.nospace = self.para_end = 1
self.softspace = 0
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def add_line_break(self):
if not (self.hard_break or self.para_end):
self.writer.send_line_break()
self.have_label = self.parskip = 0
self.hard_break = self.nospace = 1
self.softspace = 0
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def add_hor_rule(self, *args, **kw):
if not self.hard_break:
self.writer.send_line_break()
apply(self.writer.send_hor_rule, args, kw)
self.hard_break = self.nospace = 1
self.have_label = self.para_end = self.softspace = self.parskip = 0
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def add_label_data(self, format, counter, blankline = None):
if self.have_label or not self.hard_break:
self.writer.send_line_break()
if not self.para_end:
self.writer.send_paragraph((blankline and 1) or 0)
if type(format) is StringType:
self.writer.send_label_data(self.format_counter(format, counter))
else:
self.writer.send_label_data(format)
self.nospace = self.have_label = self.hard_break = self.para_end = 1
self.softspace = self.parskip = 0
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def format_counter(self, format, counter):
label = ''
for c in format:
try:
if c == '1':
label = label + ('%d' % counter)
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elif c in 'aA':
if counter > 0:
label = label + self.format_letter(c, counter)
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elif c in 'iI':
if counter > 0:
label = label + self.format_roman(c, counter)
else:
label = label + c
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except:
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label = label + c
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return label
def format_letter(self, case, counter):
label = ''
while counter > 0:
counter, x = divmod(counter-1, 26)
s = chr(ord(case) + x)
label = s + label
return label
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def format_roman(self, case, counter):
ones = ['i', 'x', 'c', 'm']
fives = ['v', 'l', 'd']
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label, index = '', 0
# This will die of IndexError when counter is too big
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while counter > 0:
counter, x = divmod(counter, 10)
if x == 9:
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label = ones[index] + ones[index+1] + label
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elif x == 4:
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label = ones[index] + fives[index] + label
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else:
if x >= 5:
s = fives[index]
x = x-5
else:
s = ''
s = s + ones[index]*x
label = s + label
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index = index + 1
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if case == 'I':
return string.upper(label)
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return label
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def add_flowing_data(self, data,
# These are only here to load them into locals:
whitespace = string.whitespace,
join = string.join, split = string.split):
if not data: return
# The following looks a bit convoluted but is a great improvement over
# data = regsub.gsub('[' + string.whitespace + ']+', ' ', data)
prespace = data[:1] in whitespace
postspace = data[-1:] in whitespace
data = join(split(data))
if self.nospace and not data:
return
elif prespace or self.softspace:
if not data:
if not self.nospace:
self.softspace = 1
self.parskip = 0
return
if not self.nospace:
data = ' ' + data
self.hard_break = self.nospace = self.para_end = \
self.parskip = self.have_label = 0
self.softspace = postspace
self.writer.send_flowing_data(data)
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def add_literal_data(self, data):
if not data: return
if self.softspace:
self.writer.send_flowing_data(" ")
self.hard_break = data[-1:] == '\n'
self.nospace = self.para_end = self.softspace = \
self.parskip = self.have_label = 0
self.writer.send_literal_data(data)
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def flush_softspace(self):
if self.softspace:
self.hard_break = self.para_end = self.parskip = \
self.have_label = self.softspace = 0
self.nospace = 1
self.writer.send_flowing_data(' ')
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def push_alignment(self, align):
if align and align != self.align:
self.writer.new_alignment(align)
self.align = align
self.align_stack.append(align)
else:
self.align_stack.append(self.align)
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def pop_alignment(self):
if self.align_stack:
del self.align_stack[-1]
if self.align_stack:
self.align = align = self.align_stack[-1]
self.writer.new_alignment(align)
else:
self.align = None
self.writer.new_alignment(None)
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def push_font(self, (size, i, b, tt)):
if self.softspace:
self.hard_break = self.para_end = self.softspace = 0
self.nospace = 1
self.writer.send_flowing_data(' ')
if self.font_stack:
csize, ci, cb, ctt = self.font_stack[-1]
if size is AS_IS: size = csize
if i is AS_IS: i = ci
if b is AS_IS: b = cb
if tt is AS_IS: tt = ctt
font = (size, i, b, tt)
self.font_stack.append(font)
self.writer.new_font(font)
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def pop_font(self):
if self.font_stack:
del self.font_stack[-1]
if self.font_stack:
font = self.font_stack[-1]
else:
font = None
self.writer.new_font(font)
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def push_margin(self, margin):
self.margin_stack.append(margin)
fstack = filter(None, self.margin_stack)
if not margin and fstack:
margin = fstack[-1]
self.writer.new_margin(margin, len(fstack))
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def pop_margin(self):
if self.margin_stack:
del self.margin_stack[-1]
fstack = filter(None, self.margin_stack)
if fstack:
margin = fstack[-1]
else:
margin = None
self.writer.new_margin(margin, len(fstack))
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def set_spacing(self, spacing):
self.spacing = spacing
self.writer.new_spacing(spacing)
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def push_style(self, *styles):
if self.softspace:
self.hard_break = self.para_end = self.softspace = 0
self.nospace = 1
self.writer.send_flowing_data(' ')
for style in styles:
self.style_stack.append(style)
self.writer.new_styles(tuple(self.style_stack))
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def pop_style(self, n=1):
del self.style_stack[-n:]
self.writer.new_styles(tuple(self.style_stack))
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def assert_line_data(self, flag=1):
self.nospace = self.hard_break = not flag
self.para_end = self.parskip = self.have_label = 0
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class NullWriter:
"""Minimal writer interface to use in testing & inheritance."""
def __init__(self): pass
def flush(self): pass
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def new_alignment(self, align): pass
def new_font(self, font): pass
def new_margin(self, margin, level): pass
def new_spacing(self, spacing): pass
def new_styles(self, styles): pass
def send_paragraph(self, blankline): pass
def send_line_break(self): pass
def send_hor_rule(self, *args, **kw): pass
def send_label_data(self, data): pass
def send_flowing_data(self, data): pass
def send_literal_data(self, data): pass
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class AbstractWriter(NullWriter):
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def __init__(self):
pass
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def new_alignment(self, align):
print "new_alignment(%s)" % `align`
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def new_font(self, font):
print "new_font(%s)" % `font`
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def new_margin(self, margin, level):
print "new_margin(%s, %d)" % (`margin`, level)
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def new_spacing(self, spacing):
print "new_spacing(%s)" % `spacing`
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def new_styles(self, styles):
print "new_styles(%s)" % `styles`
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def send_paragraph(self, blankline):
print "send_paragraph(%s)" % `blankline`
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def send_line_break(self):
print "send_line_break()"
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def send_hor_rule(self, *args, **kw):
print "send_hor_rule()"
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def send_label_data(self, data):
print "send_label_data(%s)" % `data`
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def send_flowing_data(self, data):
print "send_flowing_data(%s)" % `data`
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def send_literal_data(self, data):
print "send_literal_data(%s)" % `data`
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class DumbWriter(NullWriter):
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def __init__(self, file=None, maxcol=72):
self.file = file or sys.stdout
self.maxcol = maxcol
NullWriter.__init__(self)
self.reset()
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def reset(self):
self.col = 0
self.atbreak = 0
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def send_paragraph(self, blankline):
self.file.write('\n'*blankline)
self.col = 0
self.atbreak = 0
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def send_line_break(self):
self.file.write('\n')
self.col = 0
self.atbreak = 0
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def send_hor_rule(self, *args, **kw):
self.file.write('\n')
self.file.write('-'*self.maxcol)
self.file.write('\n')
self.col = 0
self.atbreak = 0
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def send_literal_data(self, data):
self.file.write(data)
i = string.rfind(data, '\n')
if i >= 0:
self.col = 0
data = data[i+1:]
data = string.expandtabs(data)
self.col = self.col + len(data)
self.atbreak = 0
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def send_flowing_data(self, data):
if not data: return
atbreak = self.atbreak or data[0] in string.whitespace
col = self.col
maxcol = self.maxcol
write = self.file.write
for word in string.split(data):
if atbreak:
if col + len(word) >= maxcol:
write('\n')
col = 0
else:
write(' ')
col = col + 1
write(word)
col = col + len(word)
atbreak = 1
self.col = col
self.atbreak = data[-1] in string.whitespace
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def test(file = None):
w = DumbWriter()
f = AbstractFormatter(w)
if file:
fp = open(file)
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elif sys.argv[1:]:
fp = open(sys.argv[1])
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else:
fp = sys.stdin
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while 1:
line = fp.readline()
if not line:
break
if line == '\n':
f.end_paragraph(1)
else:
f.add_flowing_data(line)
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f.end_paragraph(0)
if __name__ == '__main__':
test()