formatter.py

"""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.
"""

importsys
importwarnings
warnings.warn('the formatter module is deprecated', DeprecationWarning,
stacklevel=2)


AS_IS=None


classNullFormatter:
"""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.

 """

def__init__(self, writer=None):
ifwriterisNone:
writer=NullWriter()
self.writer=writer
defend_paragraph(self, blankline): pass
defadd_line_break(self): pass
defadd_hor_rule(self, *args, **kw): pass
defadd_label_data(self, format, counter, blankline=None): pass
defadd_flowing_data(self, data): pass
defadd_literal_data(self, data): pass
defflush_softspace(self): pass
defpush_alignment(self, align): pass
defpop_alignment(self): pass
defpush_font(self, x): pass
defpop_font(self): pass
defpush_margin(self, margin): pass
defpop_margin(self): pass
defset_spacing(self, spacing): pass
defpush_style(self, *styles): pass
defpop_style(self, n=1): pass
defassert_line_data(self, flag=1): pass


classAbstractFormatter:
"""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.

 """

# 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.

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

defend_paragraph(self, blankline):
ifnotself.hard_break:
self.writer.send_line_break()
self.have_label=0
ifself.parskip<blanklineandnotself.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

defadd_line_break(self):
ifnot (self.hard_breakorself.para_end):
self.writer.send_line_break()
self.have_label=self.parskip=0
self.hard_break=self.nospace=1
self.softspace=0

defadd_hor_rule(self, *args, **kw):
ifnotself.hard_break:
self.writer.send_line_break()
self.writer.send_hor_rule(*args, **kw)
self.hard_break=self.nospace=1
self.have_label=self.para_end=self.softspace=self.parskip=0

defadd_label_data(self, format, counter, blankline=None):
ifself.have_labelornotself.hard_break:
self.writer.send_line_break()
ifnotself.para_end:
self.writer.send_paragraph((blanklineand1) or0)
ifisinstance(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

defformat_counter(self, format, counter):
label=''
forcinformat:
ifc=='1':
label=label+ ('%d'%counter)
elifcin'aA':
ifcounter>0:
label=label+self.format_letter(c, counter)
elifcin'iI':
ifcounter>0:
label=label+self.format_roman(c, counter)
else:
label=label+c
returnlabel

defformat_letter(self, case, counter):
label=''
whilecounter>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
returnlabel

defformat_roman(self, case, counter):
ones= ['i', 'x', 'c', 'm']
fives= ['v', 'l', 'd']
label, index='', 0
# This will die of IndexError when counter is too big
whilecounter>0:
counter, x=divmod(counter, 10)
ifx==9:
label=ones[index] +ones[index+1] +label
elifx==4:
label=ones[index] +fives[index] +label
else:
ifx>=5:
s=fives[index]
x=x-5
else:
s=''
s=s+ones[index]*x
label=s+label
index=index+1
ifcase=='I':
returnlabel.upper()
returnlabel

defadd_flowing_data(self, data):
ifnotdata: return
prespace=data[:1].isspace()
postspace=data[-1:].isspace()
data=" ".join(data.split())
ifself.nospaceandnotdata:
return
elifprespaceorself.softspace:
ifnotdata:
ifnotself.nospace:
self.softspace=1
self.parskip=0
return
ifnotself.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)

defadd_literal_data(self, data):
ifnotdata: return
ifself.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)

defflush_softspace(self):
ifself.softspace:
self.hard_break=self.para_end=self.parskip= \
self.have_label=self.softspace=0
self.nospace=1
self.writer.send_flowing_data(' ')

defpush_alignment(self, align):
ifalignandalign!=self.align:
self.writer.new_alignment(align)
self.align=align
self.align_stack.append(align)
else:
self.align_stack.append(self.align)

defpop_alignment(self):
ifself.align_stack:
delself.align_stack[-1]
ifself.align_stack:
self.align=align=self.align_stack[-1]
self.writer.new_alignment(align)
else:
self.align=None
self.writer.new_alignment(None)

defpush_font(self, font):
size, i, b, tt=font
ifself.softspace:
self.hard_break=self.para_end=self.softspace=0
self.nospace=1
self.writer.send_flowing_data(' ')
ifself.font_stack:
csize, ci, cb, ctt=self.font_stack[-1]
ifsizeisAS_IS: size=csize
ifiisAS_IS: i=ci
ifbisAS_IS: b=cb
ifttisAS_IS: tt=ctt
font= (size, i, b, tt)
self.font_stack.append(font)
self.writer.new_font(font)

defpop_font(self):
ifself.font_stack:
delself.font_stack[-1]
ifself.font_stack:
font=self.font_stack[-1]
else:
font=None
self.writer.new_font(font)

defpush_margin(self, margin):
self.margin_stack.append(margin)
fstack= [mforminself.margin_stackifm]
ifnotmarginandfstack:
margin=fstack[-1]
self.writer.new_margin(margin, len(fstack))

defpop_margin(self):
ifself.margin_stack:
delself.margin_stack[-1]
fstack= [mforminself.margin_stackifm]
iffstack:
margin=fstack[-1]
else:
margin=None
self.writer.new_margin(margin, len(fstack))

defset_spacing(self, spacing):
self.spacing=spacing
self.writer.new_spacing(spacing)

defpush_style(self, *styles):
ifself.softspace:
self.hard_break=self.para_end=self.softspace=0
self.nospace=1
self.writer.send_flowing_data(' ')
forstyleinstyles:
self.style_stack.append(style)
self.writer.new_styles(tuple(self.style_stack))

defpop_style(self, n=1):
delself.style_stack[-n:]
self.writer.new_styles(tuple(self.style_stack))

defassert_line_data(self, flag=1):
self.nospace=self.hard_break=notflag
self.para_end=self.parskip=self.have_label=0


classNullWriter:
"""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
defflush(self): pass
defnew_alignment(self, align): pass
defnew_font(self, font): pass
defnew_margin(self, margin, level): pass
defnew_spacing(self, spacing): pass
defnew_styles(self, styles): pass
defsend_paragraph(self, blankline): pass
defsend_line_break(self): pass
defsend_hor_rule(self, *args, **kw): pass
defsend_label_data(self, data): pass
defsend_flowing_data(self, data): pass
defsend_literal_data(self, data): pass


classAbstractWriter(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.

 """

defnew_alignment(self, align):
print("new_alignment(%r)"% (align,))

defnew_font(self, font):
print("new_font(%r)"% (font,))

defnew_margin(self, margin, level):
print("new_margin(%r, %d)"% (margin, level))

defnew_spacing(self, spacing):
print("new_spacing(%r)"% (spacing,))

defnew_styles(self, styles):
print("new_styles(%r)"% (styles,))

defsend_paragraph(self, blankline):
print("send_paragraph(%r)"% (blankline,))

defsend_line_break(self):
print("send_line_break()")

defsend_hor_rule(self, *args, **kw):
print("send_hor_rule()")

defsend_label_data(self, data):
print("send_label_data(%r)"% (data,))

defsend_flowing_data(self, data):
print("send_flowing_data(%r)"% (data,))

defsend_literal_data(self, data):
print("send_literal_data(%r)"% (data,))


classDumbWriter(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.

 """

def__init__(self, file=None, maxcol=72):
self.file=fileorsys.stdout
self.maxcol=maxcol
NullWriter.__init__(self)
self.reset()

defreset(self):
self.col=0
self.atbreak=0

defsend_paragraph(self, blankline):
self.file.write('\n'*blankline)
self.col=0
self.atbreak=0

defsend_line_break(self):
self.file.write('\n')
self.col=0
self.atbreak=0

defsend_hor_rule(self, *args, **kw):
self.file.write('\n')
self.file.write('-'*self.maxcol)
self.file.write('\n')
self.col=0
self.atbreak=0

defsend_literal_data(self, data):
self.file.write(data)
i=data.rfind('\n')
ifi>=0:
self.col=0
data=data[i+1:]
data=data.expandtabs()
self.col=self.col+len(data)
self.atbreak=0

defsend_flowing_data(self, data):
ifnotdata: return
atbreak=self.atbreakordata[0].isspace()
col=self.col
maxcol=self.maxcol
write=self.file.write
forwordindata.split():
ifatbreak:
ifcol+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()


deftest(file=None):
w=DumbWriter()
f=AbstractFormatter(w)
iffileisnotNone:
fp=open(file)
elifsys.argv[1:]:
fp=open(sys.argv[1])
else:
fp=sys.stdin
try:
forlineinfp:
ifline=='\n':
f.end_paragraph(1)
else:
f.add_flowing_data(line)
finally:
iffpisnotsys.stdin:
fp.close()
f.end_paragraph(0)


if__name__=='__main__':
test()