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
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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
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manage and inserting data into the output.
"""
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import sys
import warnings
warnings.warn('the formatter module is deprecated and will be removed in '
'Python 3.6', DeprecationWarning)
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AS_IS = None
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class NullFormatter:
"""A formatter which does nothing.
If the writer parameter is omitted, a NullWriter instance is created.
No methods of the writer are called by NullFormatter instances.
Implementations should inherit from this class if implementing a writer
interface but don't need to inherit any implementation.
"""
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def __init__(self, writer=None):
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if writer is None:
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:
"""The standard formatter.
This implementation has demonstrated wide applicability to many writers,
and may be used directly in most circumstances. It has been used to
implement a full-featured World Wide Web browser.
"""
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# 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()
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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 isinstance(format, str):
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:
if c == '1':
label = label + ('%d' % counter)
elif c in 'aA':
if counter > 0:
label = label + self.format_letter(c, counter)
elif c in 'iI':
if counter > 0:
label = label + self.format_roman(c, counter)
else:
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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)
# This makes a strong assumption that lowercase letters
# and uppercase letters form two contiguous blocks, with
# letters in order!
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':
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return label.upper()
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return label
def add_flowing_data(self, data):
if not data: return
prespace = data[:1].isspace()
postspace = data[-1:].isspace()
data = " ".join(data.split())
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, font):
size, i, b, tt = font
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 = [m for m in self.margin_stack if m]
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 = [m for m in self.margin_stack if m]
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.
A writer which only provides the interface definition; no actions are
taken on any methods. This should be the base class for all writers
which do not need to inherit any implementation methods.
"""
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):
"""A writer which can be used in debugging formatters, but not much else.
Each method simply announces itself by printing its name and
arguments on standard output.
"""
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def new_alignment(self, align):
print("new_alignment(%r)" % (align,))
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def new_font(self, font):
print("new_font(%r)" % (font,))
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def new_margin(self, margin, level):
print("new_margin(%r, %d)" % (margin, level))
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def new_spacing(self, spacing):
print("new_spacing(%r)" % (spacing,))
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def new_styles(self, styles):
print("new_styles(%r)" % (styles,))
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def send_paragraph(self, blankline):
print("send_paragraph(%r)" % (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(%r)" % (data,))
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def send_flowing_data(self, data):
print("send_flowing_data(%r)" % (data,))
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def send_literal_data(self, data):
print("send_literal_data(%r)" % (data,))
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class DumbWriter(NullWriter):
"""Simple writer class which writes output on the file object passed in
as the file parameter or, if file is omitted, on standard output. The
output is simply word-wrapped to the number of columns specified by
the maxcol parameter. This class is suitable for reflowing a sequence
of paragraphs.
"""
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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)
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i = data.rfind('\n')
if i >= 0:
self.col = 0
data = data[i+1:]
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data = data.expandtabs()
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].isspace()
col = self.col
maxcol = self.maxcol
write = self.file.write
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for word in data.split():
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].isspace()
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def test(file = None):
w = DumbWriter()
f = AbstractFormatter(w)
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if file is not None:
fp = open(file)
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elif sys.argv[1:]:
fp = open(sys.argv[1])
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else:
fp = sys.stdin
Merged revisions 60151-60159,60161-60168,60170,60172-60173,60175 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r60151 | christian.heimes | 2008-01-21 14:11:15 +0100 (Mon, 21 Jan 2008) | 1 line A bunch of header files were not listed as dependencies for object files. Changes to files like Parser/parser.h weren't picked up by make. ........ r60152 | georg.brandl | 2008-01-21 15:16:46 +0100 (Mon, 21 Jan 2008) | 3 lines #1087741: make mmap.mmap the type of mmap objects, not a factory function. Allow it to be subclassed. ........ r60153 | georg.brandl | 2008-01-21 15:18:14 +0100 (Mon, 21 Jan 2008) | 2 lines mmap is an extension module. ........ r60154 | georg.brandl | 2008-01-21 17:28:13 +0100 (Mon, 21 Jan 2008) | 2 lines Fix example. ........ r60155 | georg.brandl | 2008-01-21 17:34:07 +0100 (Mon, 21 Jan 2008) | 2 lines #1555501: document plistlib and move it to the general library. ........ r60156 | georg.brandl | 2008-01-21 17:36:00 +0100 (Mon, 21 Jan 2008) | 2 lines Add a stub for bundlebuilder documentation. ........ r60157 | georg.brandl | 2008-01-21 17:46:58 +0100 (Mon, 21 Jan 2008) | 2 lines Removing bundlebuilder docs again -- it's not to be used anymore (see #779825). ........ r60158 | georg.brandl | 2008-01-21 17:51:51 +0100 (Mon, 21 Jan 2008) | 2 lines #997912: acknowledge nested scopes in tutorial. ........ r60159 | vinay.sajip | 2008-01-21 18:02:26 +0100 (Mon, 21 Jan 2008) | 1 line Fix: #1836: Off-by-one bug in TimedRotatingFileHandler rollover calculation. Patch thanks to Kathryn M. Kowalski. ........ r60161 | georg.brandl | 2008-01-21 18:13:03 +0100 (Mon, 21 Jan 2008) | 2 lines Adapt pydoc to new doc URLs. ........ r60162 | georg.brandl | 2008-01-21 18:17:00 +0100 (Mon, 21 Jan 2008) | 2 lines Fix old link. ........ r60163 | georg.brandl | 2008-01-21 18:22:06 +0100 (Mon, 21 Jan 2008) | 2 lines #1726198: replace while 1: fp.readline() with file iteration. ........ r60164 | georg.brandl | 2008-01-21 18:29:23 +0100 (Mon, 21 Jan 2008) | 2 lines Clarify $ behavior in re docstring. #1631394. ........ r60165 | vinay.sajip | 2008-01-21 18:39:22 +0100 (Mon, 21 Jan 2008) | 1 line Minor documentation change - hyperlink tidied up. ........ r60166 | georg.brandl | 2008-01-21 18:42:40 +0100 (Mon, 21 Jan 2008) | 2 lines #1530959: change distutils build dir for --with-pydebug python builds. ........ r60167 | vinay.sajip | 2008-01-21 19:16:05 +0100 (Mon, 21 Jan 2008) | 1 line Updated to include news on recent logging fixes and documentation changes. ........ r60168 | georg.brandl | 2008-01-21 19:35:49 +0100 (Mon, 21 Jan 2008) | 3 lines Issue #1882: when compiling code from a string, encoding cookies in the second line of code were not always recognized correctly. ........ r60170 | georg.brandl | 2008-01-21 19:36:51 +0100 (Mon, 21 Jan 2008) | 2 lines Add NEWS entry for #1882. ........ r60172 | georg.brandl | 2008-01-21 19:41:24 +0100 (Mon, 21 Jan 2008) | 2 lines Use original location of document, which has translations. ........ r60173 | walter.doerwald | 2008-01-21 21:18:04 +0100 (Mon, 21 Jan 2008) | 2 lines Follow PEP 8 in module docstring. ........ r60175 | georg.brandl | 2008-01-21 21:20:53 +0100 (Mon, 21 Jan 2008) | 2 lines Adapt to latest doctools refactoring. ........
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for line in fp:
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()