1 files changed, 366 insertions, 0 deletions
diff --git a/Lib/idlelib/undo.py b/Lib/idlelib/undo.py
new file mode 100644
index 0000000000..4332f10993
--- /dev/null
+++ b/Lib/idlelib/undo.py
@@ -0,0 +1,366 @@
+import string
+
+from idlelib.delegator import Delegator
+
+# tkintter import not needed because module does not create widgets,
+# although many methods operate on text widget arguments.
+
+#$ 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, end=' ')
+        print("saved:", self.saved, end=' ')
+        print("can_merge:", self.can_merge, end=' ')
+        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"
+            del self.undolist[0]
+            self.pointer = self.pointer - 1
+            if self.saved >= 0:
+                self.saved = self.saved - 1
+        self.can_merge = True
+        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 = False
+        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 = False
+        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 + repr(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 False
+        if self.index2 != cmd.index1:
+            return False
+        if self.tags != cmd.tags:
+            return False
+        if len(cmd.chars) != 1:
+            return False
+        if self.chars and \
+           self.classify(self.chars[-1]) != self.classify(cmd.chars):
+            return False
+        self.index2 = cmd.index2
+        self.chars = self.chars + cmd.chars
+        return True
+
+    alphanumeric = string.ascii_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)
+
+
+class CommandSequence(Command):
+    # Wrapper for a sequence of undoable cmds to be undone/redone
+    # as a unit
+
+    def __init__(self):
+        self.cmds = []
+        self.depth = 0
+
+    def __repr__(self):
+        s = self.__class__.__name__
+        strs = []
+        for cmd in self.cmds:
+            strs.append("    %r" % (cmd,))
+        return s + "(\n" + ",\n".join(strs) + "\n)"
+
+    def __len__(self):
+        return len(self.cmds)
+
+    def append(self, cmd):
+        self.cmds.append(cmd)
+
+    def getcmd(self, i):
+        return self.cmds[i]
+
+    def redo(self, text):
+        for cmd in self.cmds:
+            cmd.redo(text)
+
+    def undo(self, text):
+        cmds = self.cmds[:]
+        cmds.reverse()
+        for cmd in cmds:
+            cmd.undo(text)
+
+    def bump_depth(self, incr=1):
+        self.depth = self.depth + incr
+        return self.depth
+
+
+def _undo_delegator(parent):  # htest #
+    from tkinter import Toplevel, Text, Button
+    from idlelib.percolator import Percolator
+    undowin = Toplevel(parent)
+    undowin.title("Test UndoDelegator")
+    x, y = map(int, parent.geometry().split('+')[1:])
+    undowin.geometry("+%d+%d" % (x, y + 175))
+
+    text = Text(undowin, height=10)
+    text.pack()
+    text.focus_set()
+    p = Percolator(text)
+    d = UndoDelegator()
+    p.insertfilter(d)
+
+    undo = Button(undowin, text="Undo", command=lambda:d.undo_event(None))
+    undo.pack(side='left')
+    redo = Button(undowin, text="Redo", command=lambda:d.redo_event(None))
+    redo.pack(side='left')
+    dump = Button(undowin, text="Dump", command=lambda:d.dump_event(None))
+    dump.pack(side='left')
+
+if __name__ == "__main__":
+    import unittest
+    unittest.main('idlelib.idle_test.test_undo', verbosity=2, exit=False)
+
+    from idlelib.idle_test.htest import run
+    run(_undo_delegator)