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from Tkinter import *

from idlelib.Delegator import Delegator

#$ event <<redo>>
#$ win <Control-y>
#$ unix <Alt-z>

#$ event <<undo>>
#$ win <Control-z>
#$ unix <Control-z>

#$ event <<dump-undo-state>>
#$ win <Control-backslash>
#$ unix <Control-backslash>


class UndoDelegator(Delegator):

    max_undo = 1000

    def __init__(self):
        Delegator.__init__(self)
        self.reset_undo()

    def setdelegate(self, delegate):
        if self.delegate is not None:
            self.unbind("<<undo>>")
            self.unbind("<<redo>>")
            self.unbind("<<dump-undo-state>>")
        Delegator.setdelegate(self, delegate)
        if delegate is not None:
            self.bind("<<undo>>", self.undo_event)
            self.bind("<<redo>>", self.redo_event)
            self.bind("<<dump-undo-state>>", self.dump_event)

    def dump_event(self, event):
        from pprint import pprint
        pprint(self.undolist[:self.pointer])
        print "pointer:", self.pointer,
        print "saved:", self.saved,
        print "can_merge:", self.can_merge,
        print "get_saved():", self.get_saved()
        pprint(self.undolist[self.pointer:])
        return "break"

    def reset_undo(self):
        self.was_saved = -1
        self.pointer = 0
        self.undolist = []
        self.undoblock = 0  # or a CommandSequence instance
        self.set_saved(1)

    def set_saved(self, flag):
        if flag:
            self.saved = self.pointer
        else:
            self.saved = -1
        self.can_merge = False
        self.check_saved()

    def get_saved(self):
        return self.saved == self.pointer

    saved_change_hook = None

    def set_saved_change_hook(self, hook):
        self.saved_change_hook = hook

    was_saved = -1

    def check_saved(self):
        is_saved = self.get_saved()
        if is_saved != self.was_saved:
            self.was_saved = is_saved
            if self.saved_change_hook:
                self.saved_change_hook()

    def insert(self, index, chars, tags=None):
        self.addcmd(InsertCommand(index, chars, tags))

    def delete(self, index1, index2=None):
        self.addcmd(DeleteCommand(index1, index2))

    # Clients should call undo_block_start() and undo_block_stop()
    # around a sequence of editing cmds to be treated as a unit by
    # undo & redo.  Nested matching calls are OK, and the inner calls
    # then act like nops.  OK too if no editing cmds, or only one
    # editing cmd, is issued in between:  if no cmds, the whole
    # sequence has no effect; and if only one cmd, that cmd is entered
    # directly into the undo list, as if undo_block_xxx hadn't been
    # called.  The intent of all that is to make this scheme easy
    # to use:  all the client has to worry about is making sure each
    # _start() call is matched by a _stop() call.

    def undo_block_start(self):
        if self.undoblock == 0:
            self.undoblock = CommandSequence()
        self.undoblock.bump_depth()

    def undo_block_stop(self):
        if self.undoblock.bump_depth(-1) == 0:
            cmd = self.undoblock
            self.undoblock = 0
            if len(cmd) > 0:
                if len(cmd) == 1:
                    # no need to wrap a single cmd
                    cmd = cmd.getcmd(0)
                # this blk of cmds, or single cmd, has already
                # been done, so don't execute it again
                self.addcmd(cmd, 0)

    def addcmd(self, cmd, execute=True):
        if execute:
            cmd.do(self.delegate)
        if self.undoblock != 0:
            self.undoblock.append(cmd)
            return
        if self.can_merge and self.pointer > 0:
            lastcmd = self.undolist[self.pointer-1]
            if lastcmd.merge(cmd):
                return
        self.undolist[self.pointer:] = [cmd]
        if self.saved > self.pointer:
            self.saved = -1
        self.pointer = self.pointer + 1
        if len(self.undolist) > self.max_undo:
            ##print "truncating undo list"