"""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.

"""

import sys

AS_IS = None

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.

    """

    def __init__(self, writer=None):

        if writer is None:

            writer = NullWriter()

        self.writer = writer

    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

    def add_flowing_data(self, data): pass

    def add_literal_data(self, data): pass

    def flush_softspace(self): pass

    def push_alignment(self, align): pass

    def pop_alignment(self): pass

    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

    def push_style(self, *styles): pass

    def pop_style(self, n=1): pass

    def assert_line_data(self, flag=1): pass

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.

    """

    #  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

    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

    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

    def add_hor_rule(self, *args, **kw):

        if not self.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

    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

    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:

                label = label + c

        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

    def format_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

        while counter > 0:

            counter, x = divmod(counter, 10)

            if x == 9:

                label = ones[index] + ones[index+1] + label

            elif x == 4:

                label = ones[index] + fives[index] + label

            else:

                if x >= 5:

                    s = fives[index]

                    x = x-5

                else:

                    s = ''

                s = s + ones[index]*x

                label = s + label

            index = index + 1

        if case == 'I':

            return label.upper()

        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)

    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)

    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(' ')

    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)

    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)

    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)

    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)

    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))

    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))

    def set_spacing(self, spacing):

        self.spacing = spacing

        self.writer.new_spacing(spacing)

    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))

    def pop_style(self, n=1):

        del self.style_stack[-n:]

        self.writer.new_styles(tuple(self.style_stack))

    def assert_line_data(self, flag=1):

        self.nospace = self.hard_break = not flag

        self.para_end = self.parskip = self.have_label = 0

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

    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

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.

    """

    def new_alignment(self, align):

        print "new_alignment(%r)" % (align,)

    def new_font(self, font):

        print "new_font(%r)" % (font,)

    def new_margin(self, margin, level):

        print "new_margin(%r, %d)" % (margin, level)

    def new_spacing(self, spacing):

        print "new_spacing(%r)" % (spacing,)

    def new_styles(self, styles):

        print "new_styles(%r)" % (styles,)

    def send_paragraph(self, blankline):

        print "send_paragraph(%r)" % (blankline,)

    def send_line_break(self):

        print "send_line_break()"

    def send_hor_rule(self, *args, **kw):

        print "send_hor_rule()"

    def send_label_data(self, data):

        print "send_label_data(%r)" % (data,)

    def send_flowing_data(self, data):

        print "send_flowing_data(%r)" % (data,)

    def send_literal_data(self, data):

        print "send_literal_data(%r)" % (data,)

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.

    """

    def __init__(self, file=None, maxcol=72):

        self.file = file or sys.stdout

        self.maxcol = maxcol

        NullWriter.__init__(self)

        self.reset()

    def reset(self):

        self.col = 0

        self.atbreak = 0

    def send_paragraph(self, blankline):

        self.file.write('\n'*blankline)

        self.col = 0

        self.atbreak = 0

    def send_line_break(self):

        self.file.write('\n')

        self.col = 0

        self.atbreak = 0

    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

    def send_literal_data(self, data):

        self.file.write(data)

        i = data.rfind('\n')

        if i >= 0:

            self.col = 0

            data = data[i+1:]

        data = data.expandtabs()

        self.col = self.col + len(data)

        self.atbreak = 0

    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

        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()

def test(file = None):

    w = DumbWriter()

    f = AbstractFormatter(w)

    if file is not None:

        fp = open(file)

    elif sys.argv[1:]:

        fp = open(sys.argv[1])

    else:

        fp = sys.stdin

    for line in fp:

        if line == '\n':

            f.end_paragraph(1)

        else:

            f.add_flowing_data(line)

    f.end_paragraph(0)

if __name__ == '__main__':

    test()