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input_history.py

# coding: UTF-8
"""
Copyright (c) 2009 Marian Tietz
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
"""

"""
- no entries, no scrolling
- typed but not confirmed stuff is the latest item
- confirmed stuff is pushed into a stack

- button up: no entries: abort
- button up: an entry: set position to entry, return entry
- button up: on top: abort

- button down: check for typed OR no entries: abort
- button down: an entry: set position to entry, return entry
- button down: on bottom: check for typed OR abort
"""

from ..typecheck import types

00045 class InputHistory (object):

      _history = []
      _size = 20
      _position = None
      _get_text_callback = lambda: ""
      _origin_text = ""

      @types (size=int)
      def __init__ (self, size=20, text_callback=lambda: ""):
            self._size = size
            self._history = []
            self._position = None
            self._origin_text = ""
            self._get_text_callback = text_callback

      def reset(self):
            self._position = None

      @types (fun=type(lambda:""))
      def set_text_callback(self, fun):
            self._get_text_callback = fun

      @types (entry=basestring)
00069       def add_entry (self, entry):
            """ add a string to the history """
            self._history.append (entry)

            if len(self._history) == self._size:
                  del self._history[0]

00076       def get_previous(self):
            """ walk the stack down to zero, button up """
            if self._position == None:
                  # first call, return the latest item
                  if not self._history:
                        return None
                  # get the original text
                  self._origin_text = self._get_text_callback()
                  self._position = len(self._history)-1
                  return self._history[-1]

            if self._position == 0:
                  # abort
                  return None

            self._position -= 1
            return self._history[self._position]

00094       def get_next(self):
            """ walk the stack up to self._size, button down """
            if self._position == None:
                  # first call, get the origin text and return None
                  self._origin_text = self._get_text_callback()
                  return None

            if self._position == len(self._history)-1:
                  # the old input should be restored by
                  # the calling method
                  self._position = None
                  return self._origin_text

            self._position += 1
            return self._history[self._position]

      @types (index=int)
      def get_value(self, index):
            try:
                  return self._history[index]
            except IndexError:
                  return None
            return None

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