"""optik.help
Provides HelpFormatter and subclasses -- used by OptionParser
to generate formatted help text.
"""
# Copyright (c) 2001-2004 Gregory P. Ward. All rights reserved.
# See the README.txt distributed with Optik for licensing terms.
import os
import string
import textwrap
from pyi_optik.option import NO_DEFAULT
from pyi_optik.errors import gettext
_ = gettext
__revision__ = "$Id: help.py 470 2004-12-07 01:39:56Z gward $"
__all__ = ['HelpFormatter', 'IndentedHelpFormatter', 'TitledHelpFormatter']
class HelpFormatter:
"""
Abstract base class for formatting option help. OptionParser
instances should use one of the HelpFormatter subclasses for
formatting help; by default IndentedHelpFormatter is used.
Instance attributes:
parser : OptionParser
the controlling OptionParser instance
indent_increment : int
the number of columns to indent per nesting level
max_help_position : int
the maximum starting column for option help text
help_position : int
the calculated starting column for option help text;
initially the same as the maximum
width : int
total number of columns for output (pass None to constructor for
this value to be taken from the $COLUMNS environment variable)
level : int
current indentation level
current_indent : int
current indentation level (in columns)
help_width : int
number of columns available for option help text (calculated)
default_tag : str
text to replace with each option's default value, "%default"
by default. Set to false value to disable default value expansion.
option_strings : { Option : str }
maps Option instances to the snippet of help text explaining
the syntax of that option, e.g. "-h, --help" or
"-fFILE, --file=FILE"
_short_opt_fmt : str
format string controlling how short options with values are
printed in help text. Must be either "%s%s" ("-fFILE") or
"%s %s" ("-f FILE"), because those are the two syntaxes that
Optik supports.
_long_opt_fmt : str
similar but for long options; must be either "%s %s" ("--file FILE")
or "%s=%s" ("--file=FILE").
"""
NO_DEFAULT_VALUE = "none"
def __init__(self,
indent_increment,
max_help_position,
width,
short_first):
self.parser = None
self.indent_increment = indent_increment
self.help_position = self.max_help_position = max_help_position
if width is None:
try:
width = int(os.environ['COLUMNS'])
except (KeyError, ValueError):
width = 80
width = width - 2
self.width = width
self.current_indent = 0
self.level = 0
self.help_width = None # computed later
self.short_first = short_first
self.default_tag = "%default"
self.option_strings = {}
self._short_opt_fmt = "%s %s"
self._long_opt_fmt = "%s=%s"
def set_parser(self, parser):
self.parser = parser
def set_short_opt_delimiter(self, delim):
if delim not in ("", " "):
raise ValueError(
"invalid metavar delimiter for short options: %r" % delim)
self._short_opt_fmt = "%s" + delim + "%s"
def set_long_opt_delimiter(self, delim):
if delim not in ("=", " "):
raise ValueError(
"invalid metavar delimiter for long options: %r" % delim)
self._long_opt_fmt = "%s" + delim + "%s"
def indent(self):
self.current_indent = self.current_indent + self.indent_increment
self.level = self.level + 1
def dedent(self):
self.current_indent = self.current_indent - self.indent_increment
assert self.current_indent >= 0, "Indent decreased below 0."
self.level = self.level - 1
def format_usage(self, usage):
raise NotImplementedError, "subclasses must implement"
def format_heading(self, heading):
raise NotImplementedError, "subclasses must implement"
def format_description(self, description):
if not description:
return ""
desc_width = self.width - self.current_indent
indent = " "*self.current_indent
return textwrap.fill(description,
desc_width,
initial_indent=indent,
subsequent_indent=indent) + "\n"
def expand_default(self, option):
if self.parser is None or not self.default_tag:
return option.help
default_value = self.parser.defaults.get(option.dest)
if default_value is NO_DEFAULT or default_value is None:
default_value = self.NO_DEFAULT_VALUE
return string.replace(option.help, self.default_tag, str(default_value))
def format_option(self, option):
# The help for each option consists of two parts:
# * the opt strings and metavars
# eg. ("-x", or "-fFILENAME, --file=FILENAME")
# * the user-supplied help string
# eg. ("turn on expert mode", "read data from FILENAME")
#
# If possible, we write both of these on the same line:
# -x turn on expert mode
#
# But if the opt string list is too long, we put the help
# string on a second line, indented to the same column it would
# start in if it fit on the first line.
# -fFILENAME, --file=FILENAME
# read data from FILENAME
result = []
opts = self.option_strings[option]
opt_width = self.help_position - self.current_indent - 2
if len(opts) > opt_width:
opts = "%*s%s\n" % (self.current_indent, "", opts)
indent_first = self.help_position
else: # start help on same line as opts
opts = "%*s%-*s " % (self.current_indent, "", opt_width, opts)
indent_first = 0
result.append(opts)
if option.help:
help_text = self.expand_default(option)
help_lines = textwrap.wrap(help_text, self.help_width)
result.append("%*s%s\n" % (indent_first, "", help_lines[0]))
for line in help_lines[1:]:
result.append("%*s%s\n" % (self.help_position, "", line))
elif opts[-1] != "\n":
result.append("\n")
return string.join(result, "")
def store_option_strings(self, parser):
self.indent()
max_len = 0
for opt in parser.option_list:
strings = self.format_option_strings(opt)
self.option_strings[opt] = strings
max_len = max(max_len, len(strings) + self.current_indent)
self.indent()
for group in parser.option_groups:
for opt in group.option_list:
strings = self.format_option_strings(opt)
self.option_strings[opt] = strings
max_len = max(max_len, len(strings) + self.current_indent)
self.dedent()
self.dedent()
self.help_position = min(max_len + 2, self.max_help_position)
self.help_width = self.width - self.help_position
def format_option_strings(self, option):
"""Return a comma-separated list of option strings & metavariables."""
if option.takes_value():
metavar = option.metavar or string.upper(option.dest)
short_opts = []
for sopt in option._short_opts:
short_opts.append(self._short_opt_fmt % (sopt, metavar))
long_opts = []
for lopt in option._long_opts:
long_opts.append(self._long_opt_fmt % (lopt, metavar))
else:
short_opts = option._short_opts
long_opts = option._long_opts
if self.short_first:
opts = short_opts + long_opts
else:
opts = long_opts + short_opts
return string.join(opts, ", ")
class IndentedHelpFormatter (HelpFormatter):
"""Format help with indented section bodies.
"""
def __init__(self,
indent_increment=2,
max_help_position=24,
width=None,
short_first=1):
HelpFormatter.__init__(
self, indent_increment, max_help_position, width, short_first)
def format_usage(self, usage):
return _("usage: %s\n") % usage
def format_heading(self, heading):
return "%*s%s:\n" % (self.current_indent, "", heading)
class TitledHelpFormatter (HelpFormatter):
"""Format help with underlined section headers.
"""
def __init__(self,
indent_increment=0,
max_help_position=24,
width=None,
short_first=0):
HelpFormatter.__init__ (
self, indent_increment, max_help_position, width, short_first)
def format_usage(self, usage):
return "%s %s\n" % (self.format_heading(_("Usage")), usage)
def format_heading(self, heading):
return "%s\n%s\n" % (heading, "=-"[self.level] * len(heading))
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