source: python/trunk/Lib/idlelib/MultiCall.py

"""
MultiCall - a class which inherits its methods from a Tkinter widget (Text, for
example), but enables multiple calls of functions per virtual event - all
matching events will be called, not only the most specific one. This is done
by wrapping the event functions - event_add, event_delete and event_info.
MultiCall recognizes only a subset of legal event sequences. Sequences which
are not recognized are treated by the original Tk handling mechanism. A
more-specific event will be called before a less-specific event.

The recognized sequences are complete one-event sequences (no emacs-style
Ctrl-X Ctrl-C, no shortcuts like <3>), for all types of events.
Key/Button Press/Release events can have modifiers.
The recognized modifiers are Shift, Control, Option and Command for Mac, and
Control, Alt, Shift, Meta/M for other platforms.

For all events which were handled by MultiCall, a new member is added to the
event instance passed to the binded functions - mc_type. This is one of the
event type constants defined in this module (such as MC_KEYPRESS).
For Key/Button events (which are handled by MultiCall and may receive
modifiers), another member is added - mc_state. This member gives the state
of the recognized modifiers, as a combination of the modifier constants
also defined in this module (for example, MC_SHIFT).
Using these members is absolutely portable.

The order by which events are called is defined by these rules:
1. A more-specific event will be called before a less-specific event.
2. A recently-binded event will be called before a previously-binded event,
   unless this conflicts with the first rule.
Each function will be called at most once for each event.
"""

import sys
import string
import re
import Tkinter
from idlelib import macosxSupport

# the event type constants, which define the meaning of mc_type
MC_KEYPRESS=0; MC_KEYRELEASE=1; MC_BUTTONPRESS=2; MC_BUTTONRELEASE=3;
MC_ACTIVATE=4; MC_CIRCULATE=5; MC_COLORMAP=6; MC_CONFIGURE=7;
MC_DEACTIVATE=8; MC_DESTROY=9; MC_ENTER=10; MC_EXPOSE=11; MC_FOCUSIN=12;
MC_FOCUSOUT=13; MC_GRAVITY=14; MC_LEAVE=15; MC_MAP=16; MC_MOTION=17;
MC_MOUSEWHEEL=18; MC_PROPERTY=19; MC_REPARENT=20; MC_UNMAP=21; MC_VISIBILITY=22;
# the modifier state constants, which define the meaning of mc_state
MC_SHIFT = 1<<0; MC_CONTROL = 1<<2; MC_ALT = 1<<3; MC_META = 1<<5
MC_OPTION = 1<<6; MC_COMMAND = 1<<7

# define the list of modifiers, to be used in complex event types.
if macosxSupport.runningAsOSXApp():
    _modifiers = (("Shift",), ("Control",), ("Option",), ("Command",))
    _modifier_masks = (MC_SHIFT, MC_CONTROL, MC_OPTION, MC_COMMAND)
else:
    _modifiers = (("Control",), ("Alt",), ("Shift",), ("Meta", "M"))
    _modifier_masks = (MC_CONTROL, MC_ALT, MC_SHIFT, MC_META)

# a dictionary to map a modifier name into its number
_modifier_names = dict([(name, number)
                         for number in range(len(_modifiers))
                         for name in _modifiers[number]])

# A binder is a class which binds functions to one type of event. It has two
# methods: bind and unbind, which get a function and a parsed sequence, as
# returned by _parse_sequence(). There are two types of binders:
# _SimpleBinder handles event types with no modifiers and no detail.
# No Python functions are called when no events are binded.
# _ComplexBinder handles event types with modifiers and a detail.
# A Python function is called each time an event is generated.

class _SimpleBinder:
    def __init__(self, type, widget, widgetinst):
        self.type = type
        self.sequence = '<'+_types[type][0]+'>'
        self.widget = widget
        self.widgetinst = widgetinst
        self.bindedfuncs = []
        self.handlerid = None

    def bind(self, triplet, func):
        if not self.handlerid:
            def handler(event, l = self.bindedfuncs, mc_type = self.type):
                event.mc_type = mc_type
                wascalled = {}
                for i in range(len(l)-1, -1, -1):
                    func = l[i]
                    if func not in wascalled:
                        wascalled[func] = True
                        r = func(event)
                        if r:
                            return r
            self.handlerid = self.widget.bind(self.widgetinst,
                                              self.sequence, handler)
        self.bindedfuncs.append(func)

    def unbind(self, triplet, func):
        self.bindedfuncs.remove(func)
        if not self.bindedfuncs:
            self.widget.unbind(self.widgetinst, self.sequence, self.handlerid)
            self.handlerid = None

    def __del__(self):
        if self.handlerid:
            self.widget.unbind(self.widgetinst, self.sequence, self.handlerid)

# An int in range(1 << len(_modifiers)) represents a combination of modifiers
# (if the least significent bit is on, _modifiers[0] is on, and so on).
# _state_subsets gives for each combination of modifiers, or *state*,
# a list of the states which are a subset of it. This list is ordered by the
# number of modifiers is the state - the most specific state comes first.
_states = range(1 << len(_modifiers))
_state_names = [''.join(m[0]+'-'
                        for i, m in enumerate(_modifiers)
                        if (1 << i) & s)
                for s in _states]

def expand_substates(states):
    '''For each item of states return a list containing all combinations of
    that item with individual bits reset, sorted by the number of set bits.
    '''
    def nbits(n):
        "number of bits set in n base 2"
        nb = 0
        while n:
            n, rem = divmod(n, 2)
            nb += rem
        return nb
    statelist = []
    for state in states:
        substates = list(set(state & x for x in states))
        substates.sort(key=nbits, reverse=True)
        statelist.append(substates)
    return statelist

_state_subsets = expand_substates(_states)

# _state_codes gives for each state, the portable code to be passed as mc_state
_state_codes = []
for s in _states:
    r = 0
    for i in range(len(_modifiers)):
        if (1 << i) & s:
            r |= _modifier_masks[i]
    _state_codes.append(r)

class _ComplexBinder:
    # This class binds many functions, and only unbinds them when it is deleted.
    # self.handlerids is the list of seqs and ids of binded handler functions.
    # The binded functions sit in a dictionary of lists of lists, which maps
    # a detail (or None) and a state into a list of functions.
    # When a new detail is discovered, handlers for all the possible states
    # are binded.

    def __create_handler(self, lists, mc_type, mc_state):
        def handler(event, lists = lists,
                    mc_type = mc_type, mc_state = mc_state,
                    ishandlerrunning = self.ishandlerrunning,
                    doafterhandler = self.doafterhandler):
            ishandlerrunning[:] = [True]
            event.mc_type = mc_type
            event.mc_state = mc_state
            wascalled = {}
            r = None
            for l in lists:
                for i in range(len(l)-1, -1, -1):
                    func = l[i]
                    if func not in wascalled:
                        wascalled[func] = True
                        r = l[i](event)
                        if r:
                            break
                if r:
                    break
            ishandlerrunning[:] = []
            # Call all functions in doafterhandler and remove them from list
            for f in doafterhandler:
                f()
            doafterhandler[:] = []
            if r:
                return r
        return handler

    def __init__(self, type, widget, widgetinst):
        self.type = type
        self.typename = _types[type][0]
        self.widget = widget
        self.widgetinst = widgetinst
        self.bindedfuncs = {None: [[] for s in _states]}
        self.handlerids = []
        # we don't want to change the lists of functions while a handler is
        # running - it will mess up the loop and anyway, we usually want the
        # change to happen from the next event. So we have a list of functions
        # for the handler to run after it finishes calling the binded functions.
        # It calls them only once.
        # ishandlerrunning is a list. An empty one means no, otherwise - yes.
        # this is done so that it would be mutable.
        self.ishandlerrunning = []
        self.doafterhandler = []
        for s in _states:
            lists = [self.bindedfuncs[None][i] for i in _state_subsets[s]]
            handler = self.__create_handler(lists, type, _state_codes[s])
            seq = '<'+_state_names[s]+self.typename+'>'
            self.handlerids.append((seq, self.widget.bind(self.widgetinst,
                                                          seq, handler)))

    def bind(self, triplet, func):
        if triplet[2] not in self.bindedfuncs:
            self.bindedfuncs[triplet[2]] = [[] for s in _states]
            for s in _states:
                lists = [ self.bindedfuncs[detail][i]
                          for detail in (triplet[2], None)
                          for i in _state_subsets[s]       ]
                handler = self.__create_handler(lists, self.type,
                                                _state_codes[s])
                seq = "<%s%s-%s>"% (_state_names[s], self.typename, triplet[2])
                self.handlerids.append((seq, self.widget.bind(self.widgetinst,
                                                              seq, handler)))
        doit = lambda: self.bindedfuncs[triplet[2]][triplet[0]].append(func)
        if not self.ishandlerrunning:
            doit()
        else:
            self.doafterhandler.append(doit)

    def unbind(self, triplet, func):
        doit = lambda: self.bindedfuncs[triplet[2]][triplet[0]].remove(func)
        if not self.ishandlerrunning:
            doit()
        else:
            self.doafterhandler.append(doit)

    def __del__(self):
        for seq, id in self.handlerids:
            self.widget.unbind(self.widgetinst, seq, id)

# define the list of event types to be handled by MultiEvent. the order is
# compatible with the definition of event type constants.
_types = (
    ("KeyPress", "Key"), ("KeyRelease",), ("ButtonPress", "Button"),
    ("ButtonRelease",), ("Activate",), ("Circulate",), ("Colormap",),
    ("Configure",), ("Deactivate",), ("Destroy",), ("Enter",), ("Expose",),
    ("FocusIn",), ("FocusOut",), ("Gravity",), ("Leave",), ("Map",),
    ("Motion",), ("MouseWheel",), ("Property",), ("Reparent",), ("Unmap",),
    ("Visibility",),
)

# which binder should be used for every event type?
_binder_classes = (_ComplexBinder,) * 4 + (_SimpleBinder,) * (len(_types)-4)

# A dictionary to map a type name into its number
_type_names = dict([(name, number)
                     for number in range(len(_types))
                     for name in _types[number]])

_keysym_re = re.compile(r"^\w+$")
_button_re = re.compile(r"^[1-5]$")
def _parse_sequence(sequence):
    """Get a string which should describe an event sequence. If it is
    successfully parsed as one, return a tuple containing the state (as an int),
    the event type (as an index of _types), and the detail - None if none, or a
    string if there is one. If the parsing is unsuccessful, return None.
    """
    if not sequence or sequence[0] != '<' or sequence[-1] != '>':
        return None
    words = string.split(sequence[1:-1], '-')

    modifiers = 0
    while words and words[0] in _modifier_names:
        modifiers |= 1 << _modifier_names[words[0]]
        del words[0]

    if words and words[0] in _type_names:
        type = _type_names[words[0]]
        del words[0]
    else:
        return None

    if _binder_classes[type] is _SimpleBinder:
        if modifiers or words:
            return None
        else:
            detail = None
    else:
        # _ComplexBinder
        if type in [_type_names[s] for s in ("KeyPress", "KeyRelease")]:
            type_re = _keysym_re
        else:
            type_re = _button_re

        if not words:
            detail = None
        elif len(words) == 1 and type_re.match(words[0]):
            detail = words[0]
        else:
            return None

    return modifiers, type, detail

def _triplet_to_sequence(triplet):
    if triplet[2]:
        return '<'+_state_names[triplet[0]]+_types[triplet[1]][0]+'-'+ \
               triplet[2]+'>'
    else:
        return '<'+_state_names[triplet[0]]+_types[triplet[1]][0]+'>'

_multicall_dict = {}
def MultiCallCreator(widget):
    """Return a MultiCall class which inherits its methods from the
    given widget class (for example, Tkinter.Text). This is used
    instead of a templating mechanism.
    """
    if widget in _multicall_dict:
        return _multicall_dict[widget]

    class MultiCall (widget):
        assert issubclass(widget, Tkinter.Misc)

        def __init__(self, *args, **kwargs):
            widget.__init__(self, *args, **kwargs)
            # a dictionary which maps a virtual event to a tuple with:
            #  0. the function binded
            #  1. a list of triplets - the sequences it is binded to
            self.__eventinfo = {}
            self.__binders = [_binder_classes[i](i, widget, self)
                              for i in range(len(_types))]

        def bind(self, sequence=None, func=None, add=None):
            #print "bind(%s, %s, %s) called." % (sequence, func, add)
            if type(sequence) is str and len(sequence) > 2 and \
               sequence[:2] == "<<" and sequence[-2:] == ">>":
                if sequence in self.__eventinfo:
                    ei = self.__eventinfo[sequence]
                    if ei[0] is not None:
                        for triplet in ei[1]:
                            self.__binders[triplet[1]].unbind(triplet, ei[0])
                    ei[0] = func
                    if ei[0] is not None:
                        for triplet in ei[1]:
                            self.__binders[triplet[1]].bind(triplet, func)
                else:
                    self.__eventinfo[sequence] = [func, []]
            return widget.bind(self, sequence, func, add)

        def unbind(self, sequence, funcid=None):
            if type(sequence) is str and len(sequence) > 2 and \
               sequence[:2] == "<<" and sequence[-2:] == ">>" and \
               sequence in self.__eventinfo:
                func, triplets = self.__eventinfo[sequence]
                if func is not None:
                    for triplet in triplets:
                        self.__binders[triplet[1]].unbind(triplet, func)
                    self.__eventinfo[sequence][0] = None
            return widget.unbind(self, sequence, funcid)

        def event_add(self, virtual, *sequences):
            #print "event_add(%s,%s) was called"%(repr(virtual),repr(sequences))
            if virtual not in self.__eventinfo:
                self.__eventinfo[virtual] = [None, []]

            func, triplets = self.__eventinfo[virtual]
            for seq in sequences:
                triplet = _parse_sequence(seq)
                if triplet is None:
                    #print >> sys.stderr, "Seq. %s was added by Tkinter."%seq
                    widget.event_add(self, virtual, seq)
                else:
                    if func is not None:
                        self.__binders[triplet[1]].bind(triplet, func)
                    triplets.append(triplet)

        def event_delete(self, virtual, *sequences):
            if virtual not in self.__eventinfo:
                return
            func, triplets = self.__eventinfo[virtual]
            for seq in sequences:
                triplet = _parse_sequence(seq)
                if triplet is None:
                    #print >> sys.stderr, "Seq. %s was deleted by Tkinter."%seq
                    widget.event_delete(self, virtual, seq)
                else:
                    if func is not None:
                        self.__binders[triplet[1]].unbind(triplet, func)
                    triplets.remove(triplet)

        def event_info(self, virtual=None):
            if virtual is None or virtual not in self.__eventinfo:
                return widget.event_info(self, virtual)
            else:
                return tuple(map(_triplet_to_sequence,
                                 self.__eventinfo[virtual][1])) + \
                       widget.event_info(self, virtual)

        def __del__(self):
            for virtual in self.__eventinfo:
                func, triplets = self.__eventinfo[virtual]
                if func:
                    for triplet in triplets:
                        self.__binders[triplet[1]].unbind(triplet, func)


    _multicall_dict[widget] = MultiCall
    return MultiCall

if __name__ == "__main__":
    # Test
    root = Tkinter.Tk()
    text = MultiCallCreator(Tkinter.Text)(root)
    text.pack()
    def bindseq(seq, n=[0]):
        def handler(event):
            print seq
        text.bind("<<handler%d>>"%n[0], handler)
        text.event_add("<<handler%d>>"%n[0], seq)
        n[0] += 1
    bindseq("<Key>")
    bindseq("<Control-Key>")
    bindseq("<Alt-Key-a>")
    bindseq("<Control-Key-a>")
    bindseq("<Alt-Control-Key-a>")
    bindseq("<Key-b>")
    bindseq("<Control-Button-1>")
    bindseq("<Alt-Button-1>")
    bindseq("<FocusOut>")
    bindseq("<Enter>")
    bindseq("<Leave>")
    root.mainloop()