import Pmw
_ORIGINAL = 0
_MODIFIED = 1
_DISPLAY = 2
class HistoryText(Pmw.ScrolledText):
def __init__(self, parent = None, **kw):
# Define the megawidget options.
optiondefs = (
('compressany', 1, None),
('compresstail', 1, None),
('historycommand', None, None),
)
self.defineoptions(kw, optiondefs)
# Initialise the base class (after defining the options).
Pmw.ScrolledText.__init__(self, parent)
# Initialise instance variables.
self._list = []
self._currIndex = 0
self._pastIndex = None
self._lastIndex = 0 # pointer to end of history list
# Check keywords and initialise options.
self.initialiseoptions()
def addhistory(self):
text = self.get()
if text[-1] == '\n':
text = text[:-1]
if len(self._list) == 0:
# This is the first history entry. Add it.
self._list.append([text, text, _MODIFIED])
return
currentEntry = self._list[self._currIndex]
if text == currentEntry[_ORIGINAL]:
# The current history entry has not been modified. Check if
# we need to add it again.
if self['compresstail'] and self._currIndex == self._lastIndex:
return
if self['compressany']:
return
# Undo any changes for the current history entry, since they
# will now be available in the new entry.
currentEntry[_MODIFIED] = currentEntry[_ORIGINAL]
historycommand = self['historycommand']
if self._currIndex == self._lastIndex:
# The last history entry is currently being displayed,
# so disable the special meaning of the 'Next' button.
self._pastIndex = None
nextState = 'disabled'
else:
# A previous history entry is currently being displayed,
# so allow the 'Next' button to go to the entry after this one.
self._pastIndex = self._currIndex
nextState = 'normal'
if callable(historycommand):
historycommand('normal', nextState)
# Create the new history entry.
self._list.append([text, text, _MODIFIED])
# Move the pointer into the history entry list to the end.
self._lastIndex = self._lastIndex + 1
self._currIndex = self._lastIndex
def next(self):
if self._currIndex == self._lastIndex and self._pastIndex is None:
self.bell()
else:
self._modifyDisplay('next')
def prev(self):
self._pastIndex = None
if self._currIndex == 0:
self.bell()
else:
self._modifyDisplay('prev')
def undo(self):
if len(self._list) != 0:
self._modifyDisplay('undo')
def redo(self):
if len(self._list) != 0:
self._modifyDisplay('redo')
def gethistory(self):
return self._list
def _modifyDisplay(self, command):
# Modify the display to show either the next or previous
# history entry (next, prev) or the original or modified
# version of the current history entry (undo, redo).
# Save the currently displayed text.
currentText = self.get()
if currentText[-1] == '\n':
currentText = currentText[:-1]
currentEntry = self._list[self._currIndex]
if currentEntry[_DISPLAY] == _MODIFIED:
currentEntry[_MODIFIED] = currentText
elif currentEntry[_ORIGINAL] != currentText:
currentEntry[_MODIFIED] = currentText
if command in ('next', 'prev'):
currentEntry[_DISPLAY] = _MODIFIED
if command in ('next', 'prev'):
prevstate = 'normal'
nextstate = 'normal'
if command == 'next':
if self._pastIndex is not None:
self._currIndex = self._pastIndex
self._pastIndex = None
self._currIndex = self._currIndex + 1
if self._currIndex == self._lastIndex:
nextstate = 'disabled'
elif command == 'prev':
self._currIndex = self._currIndex - 1
if self._currIndex == 0:
prevstate = 'disabled'
historycommand = self['historycommand']
if callable(historycommand):
historycommand(prevstate, nextstate)
currentEntry = self._list[self._currIndex]
else:
if command == 'undo':
currentEntry[_DISPLAY] = _ORIGINAL
elif command == 'redo':
currentEntry[_DISPLAY] = _MODIFIED
# Display the new text.
self.delete('1.0', 'end')
self.insert('end', currentEntry[currentEntry[_DISPLAY]])
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