~jkakar/commandant/trunk

# Commandant is a framework for building command-oriented tools.

# Copyright (C) 2009-2010 Jamshed Kakar.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License along

# with this program; if not, write to the Free Software Foundation, Inc.,

# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

"""Infrastructure for pretty-printing formatted output."""

def print_columns(outf, rows, shrink_index=None, max_width=78, padding=2):

    """Calculate optimal column widths and print C{rows} to C{outf}.

    @param outf: The stream to write to.

    @param rows: A list of rows to print.  Each row is a tuple of columns.

        All rows must contain the same number of columns.

    @param shrink_index: The index of the column to shrink, if the columns

        provided exceed C{max_width}.  Shrinking is disabled by default.

    @param max_width: The maximum number of characters per line.  Defaults to

        78, though it isn't enforced unless C{shrink_index} is specified.

    @param padding: The number of blank characters to output between columns.

        Defaults to 2.

    """

    if not rows:

        return

    widths = []

    for row in rows:

        if not widths:

            widths = [len(column) for i, column in enumerate(row)]

        else:

            widths = [

                max(widths[i], len(column)) for i, column in enumerate(row)]

    if shrink_index is not None:

        fixed_width = sum(width + padding for i, width in enumerate(widths)

                          if i != shrink_index)

        if fixed_width + widths[shrink_index] > max_width:

            widths[shrink_index] = max_width - fixed_width

    padding_space = "".ljust(padding)

    for row in rows:

        output = []

        for i, column in enumerate(row):

            text = column[:widths[i]].ljust(widths[i])

            if (i + 1 == len(row)):

                text = text.strip()

            output.append(text)

        print >>outf, padding_space.join(output)