1 #!/usr/bin/python2.5

     2 #

     3 # Copyright 2009 the Melange authors.

     4 #

     5 # Licensed under the Apache License, Version 2.0 (the "License");

     6 # you may not use this file except in compliance with the License.

     7 # You may obtain a copy of the License at

     8 #

     9 #   http://www.apache.org/licenses/LICENSE-2.0

    10 #

    11 # Unless required by applicable law or agreed to in writing, software

    12 # distributed under the License is distributed on an "AS IS" BASIS,

    13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    14 # See the License for the specific language governing permissions and

    15 # limitations under the License.

    16 

    17 from __future__ import with_statement

    18 

    19 """User prompting and file access utilities."""

    20 

    21 __authors__ = [

    22     # alphabetical order by last name, please

    23     '"David Anderson" <dave@natulte.net>',

    24     ]

    25 

    26 import error

    27 import log

    28 

    29 

    30 class Error(error.Error):

    31   pass

    32 

    33 

    34 class FileAccessError(Error):

    35   """An error occured while accessing a file."""

    36   pass

    37 

    38 

    39 def getString(prompt):

    40   """Prompt for and return a string."""

    41   prompt += ' '

    42   log.stdout.write(prompt)

    43   log.stdout.flush()

    44 

    45   response = sys.stdin.readline()

    46   log.terminal_echo(prompt + response.strip())

    47   if not response:

    48     raise error.AbortedByUser('Aborted by ctrl+D')

    49 

    50   return response.strip()

    51 

    52 

    53 def confirm(prompt, default=False):

    54   """Ask a yes/no question and return the answer.

    55 

    56   Will reprompt the user until one of "yes", "no", "y" or "n" is

    57   entered. The input is case insensitive.

    58 

    59   Args:

    60     prompt: The question to ask the user.

    61     default: The answer to return if the user just hits enter.

    62 

    63   Returns:

    64     True if the user answered affirmatively, False otherwise.

    65   """

    66   if default:

    67     question = prompt + ' [Yn]'

    68   else:

    69     question = prompt + ' [yN]'

    70   while True:

    71     answer = getString(question)

    72     if not answer:

    73       return default

    74     elif answer in ('y', 'yes'):

    75       return True

    76     elif answer in ('n', 'no'):

    77       return False

    78     else:

    79       log.error('Please answer yes or no.')

    80 

    81 

    82 def getNumber(prompt):

    83   """Prompt for and return a number.

    84 

    85   Will reprompt the user until a number is entered.

    86   """

    87   while True:

    88     value_str = getString(prompt)

    89     try:

    90       return int(value_str)

    91     except ValueError:

    92       log.error('Please enter a number. You entered "%s".' % value_str)

    93 

    94 

    95 def getChoice(intro, prompt, choices, done=None, suggest=None):

    96   """Prompt for and return a choice from a menu.

    97 

    98   Will reprompt the user until a valid menu entry is chosen.

    99 

   100   Args:

   101     intro: Text to print verbatim before the choice menu.

   102     prompt: The prompt to print right before accepting input.

   103     choices: The list of string choices to display.

   104     done: If not None, the list of indices of previously

   105       selected/completed choices.

   106     suggest: If not None, the index of the choice to highlight as

   107       the suggested choice.

   108 

   109   Returns:

   110     The index in the choices list of the selection the user made.

   111   """

   112   done = set(done or [])

   113   while True:

   114     print intro

   115     print

   116     for i, entry in enumerate(choices):

   117       done_text = ' (done)' if i in done else ''

   118       indent = '--> ' if i == suggest else '    '

   119       print '%s%2d. %s%s' % (indent, i+1, entry, done_text)

   120     print

   121     choice = getNumber(prompt)

   122     if 0 < choice <= len(choices):

   123       return choice-1

   124     log.error('%d is not a valid choice between %d and %d' %

   125               (choice, 1, len(choices)))

   126     print

   127 

   128 

   129 def fileToLines(path):

   130   """Read a file and return it as a list of lines."""

   131   try:

   132     with file(path) as f:

   133       return f.read().split('\n')

   134   except (IOError, OSError), e:

   135     raise FileAccessError(str(e))

   136 

   137 

   138 def linesToFile(path, lines):

   139   """Write a list of lines to a file."""

   140   try:

   141     with file(path, 'w') as f:

   142       f.write('\n'.join(lines))

   143   except (IOError, OSError), e:

   144     raise FileAccessError(str(e))