Tools/idle/UndoDelegator.py

import sys
import string
from Tkinter import *
from Delegator import Delegator


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.set_saved(1)

    def set_saved(self, flag):
        if flag:
            self.saved = self.pointer
        else:
            self.saved = -1
        self.can_merge = 0
        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))

    def addcmd(self, cmd):
        cmd.do(self.delegate)
        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"
            del self.undolist[0]
            self.pointer = self.pointer - 1
            if self.saved >= 0:
                self.saved = self.saved - 1
        self.can_merge = 1
        self.check_saved()

    def undo_event(self, event):
        if self.pointer == 0:
            self.bell()
            return "break"
        cmd = self.undolist[self.pointer - 1]
        cmd.undo(self.delegate)
        self.pointer = self.pointer - 1
        self.can_merge = 0
        self.check_saved()
        return "break"

    def redo_event(self, event):
        if self.pointer >= len(self.undolist):
            self.bell()
            return "break"
        cmd = self.undolist[self.pointer]
        cmd.redo(self.delegate)
        self.pointer = self.pointer + 1
        self.can_merge = 0
        self.check_saved()
        return "break"


class Command:

    # Base class for Undoable commands

    tags = None

    def __init__(self, index1, index2, chars, tags=None):
        self.marks_before = {}
        self.marks_after = {}
        self.index1 = index1
        self.index2 = index2
        self.chars = chars
        if tags:
            self.tags = tags

    def __repr__(self):
        s = self.__class__.__name__
        t = (self.index1, self.index2, self.chars, self.tags)
        if self.tags is None:
            t = t[:-1]
        return s + `t`

    def do(self, text):
        pass

    def redo(self, text):
        pass

    def undo(self, text):
        pass

    def merge(self, cmd):
        return 0

    def save_marks(self, text):
        marks = {}
        for name in text.mark_names():
            if name != "insert" and name != "current":
                marks[name] = text.index(name)
        return marks

    def set_marks(self, text, marks):
        for name, index in marks.items():
            text.mark_set(name, index)


class InsertCommand(Command):

    # Undoable insert command

    def __init__(self, index1, chars, tags=None):
        Command.__init__(self, index1, None, chars, tags)

    def do(self, text):
        self.marks_before = self.save_marks(text)
        self.index1 = text.index(self.index1)
        if text.compare(self.index1, ">", "end-1c"):
            # Insert before the final newline
            self.index1 = text.index("end-1c")
        text.insert(self.index1, self.chars, self.tags)
        self.index2 = text.index("%s+%dc" % (self.index1, len(self.chars)))
        self.marks_after = self.save_marks(text)
        ##sys.__stderr__.write("do: %s\n" % self)

    def redo(self, text):
        text.mark_set('insert', self.index1)
        text.insert(self.index1, self.chars, self.tags)
        self.set_marks(text, self.marks_after)
        text.see('insert')
        ##sys.__stderr__.write("redo: %s\n" % self)

    def undo(self, text):
        text.mark_set('insert', self.index1)
        text.delete(self.index1, self.index2)
        self.set_marks(text, self.marks_before)
        text.see('insert')
        ##sys.__stderr__.write("undo: %s\n" % self)

    def merge(self, cmd):
        if self.__class__ is not cmd.__class__:
            return 0
        if self.index2 != cmd.index1:
            return 0
        if self.tags != cmd.tags:
            return 0
        if len(cmd.chars) != 1:
            return 0
        if self.chars and \
           self.classify(self.chars[-1]) != self.classify(cmd.chars):
            return 0
        self.index2 = cmd.index2
        self.chars = self.chars + cmd.chars
        return 1

    alphanumeric = string.letters + string.digits + "_"

    def classify(self, c):
        if c in self.alphanumeric:
            return "alphanumeric"
        if c == "\n":
            return "newline"
        return "punctuation"


class DeleteCommand(Command):

    # Undoable delete command

    def __init__(self, index1, index2=None):
        Command.__init__(self, index1, index2, None, None)

    def do(self, text):
        self.marks_before = self.save_marks(text)
        self.index1 = text.index(self.index1)
        if self.index2:
            self.index2 = text.index(self.index2)
        else:
            self.index2 = text.index(self.index1 + " +1c")
        if text.compare(self.index2, ">", "end-1c"):
            # Don't delete the final newline
            self.index2 = text.index("end-1c")
        self.chars = text.get(self.index1, self.index2)
        text.delete(self.index1, self.index2)
        self.marks_after = self.save_marks(text)
        ##sys.__stderr__.write("do: %s\n" % self)

    def redo(self, text):
        text.mark_set('insert', self.index1)
        text.delete(self.index1, self.index2)
        self.set_marks(text, self.marks_after)
        text.see('insert')
        ##sys.__stderr__.write("redo: %s\n" % self)

    def undo(self, text):
        text.mark_set('insert', self.index1)
        text.insert(self.index1, self.chars)
        self.set_marks(text, self.marks_before)
        text.see('insert')
        ##sys.__stderr__.write("undo: %s\n" % self)


def main():
    from Percolator import Percolator
    root = Tk()
    root.wm_protocol("WM_DELETE_WINDOW", root.quit)
    text = Text()
    text.pack()
    text.focus_set()
    p = Percolator(text)
    d = UndoDelegator()
    p.insertfilter(d)
    root.mainloop()

if __name__ == "__main__":
    main()