1"""ParenMatch -- An IDLE extension for parenthesis matching.
2
3When you hit a right paren, the cursor should move briefly to the left
4paren.  Paren here is used generically; the matching applies to
5parentheses, square brackets, and curly braces.
6"""
7from idlelib.hyperparser import HyperParser
8from idlelib.config import idleConf
9
10_openers = {')':'(',']':'[','}':'{'}
11CHECK_DELAY = 100 # milliseconds
12
13class ParenMatch:
14    """Highlight matching parentheses
15
16    There are three supported style of paren matching, based loosely
17    on the Emacs options.  The style is select based on the
18    HILITE_STYLE attribute; it can be changed used the set_style
19    method.
20
21    The supported styles are:
22
23    default -- When a right paren is typed, highlight the matching
24        left paren for 1/2 sec.
25
26    expression -- When a right paren is typed, highlight the entire
27        expression from the left paren to the right paren.
28
29    TODO:
30        - extend IDLE with configuration dialog to change options
31        - implement rest of Emacs highlight styles (see below)
32        - print mismatch warning in IDLE status window
33
34    Note: In Emacs, there are several styles of highlight where the
35    matching paren is highlighted whenever the cursor is immediately
36    to the right of a right paren.  I don't know how to do that in Tk,
37    so I haven't bothered.
38    """
39    menudefs = [
40        ('edit', [
41            ("Show surrounding parens", "<<flash-paren>>"),
42        ])
43    ]
44    STYLE = idleConf.GetOption('extensions','ParenMatch','style',
45            default='expression')
46    FLASH_DELAY = idleConf.GetOption('extensions','ParenMatch','flash-delay',
47            type='int',default=500)
48    HILITE_CONFIG = idleConf.GetHighlight(idleConf.CurrentTheme(),'hilite')
49    BELL = idleConf.GetOption('extensions','ParenMatch','bell',
50            type='bool',default=1)
51
52    RESTORE_VIRTUAL_EVENT_NAME = "<<parenmatch-check-restore>>"
53    # We want the restore event be called before the usual return and
54    # backspace events.
55    RESTORE_SEQUENCES = ("<KeyPress>", "<ButtonPress>",
56                         "<Key-Return>", "<Key-BackSpace>")
57
58    def __init__(self, editwin):
59        self.editwin = editwin
60        self.text = editwin.text
61        # Bind the check-restore event to the function restore_event,
62        # so that we can then use activate_restore (which calls event_add)
63        # and deactivate_restore (which calls event_delete).
64        editwin.text.bind(self.RESTORE_VIRTUAL_EVENT_NAME,
65                          self.restore_event)
66        self.bell = self.text.bell if self.BELL else lambda: None
67        self.counter = 0
68        self.is_restore_active = 0
69        self.set_style(self.STYLE)
70
71    def activate_restore(self):
72        if not self.is_restore_active:
73            for seq in self.RESTORE_SEQUENCES:
74                self.text.event_add(self.RESTORE_VIRTUAL_EVENT_NAME, seq)
75            self.is_restore_active = True
76
77    def deactivate_restore(self):
78        if self.is_restore_active:
79            for seq in self.RESTORE_SEQUENCES:
80                self.text.event_delete(self.RESTORE_VIRTUAL_EVENT_NAME, seq)
81            self.is_restore_active = False
82
83    def set_style(self, style):
84        self.STYLE = style
85        if style == "default":
86            self.create_tag = self.create_tag_default
87            self.set_timeout = self.set_timeout_last
88        elif style == "expression":
89            self.create_tag = self.create_tag_expression
90            self.set_timeout = self.set_timeout_none
91
92    def flash_paren_event(self, event):
93        indices = (HyperParser(self.editwin, "insert")
94                   .get_surrounding_brackets())
95        if indices is None:
96            self.bell()
97            return
98        self.activate_restore()
99        self.create_tag(indices)
100        self.set_timeout_last()
101
102    def paren_closed_event(self, event):
103        # If it was a shortcut and not really a closing paren, quit.
104        closer = self.text.get("insert-1c")
105        if closer not in _openers:
106            return
107        hp = HyperParser(self.editwin, "insert-1c")
108        if not hp.is_in_code():
109            return
110        indices = hp.get_surrounding_brackets(_openers[closer], True)
111        if indices is None:
112            self.bell()
113            return
114        self.activate_restore()
115        self.create_tag(indices)
116        self.set_timeout()
117
118    def restore_event(self, event=None):
119        self.text.tag_delete("paren")
120        self.deactivate_restore()
121        self.counter += 1   # disable the last timer, if there is one.
122
123    def handle_restore_timer(self, timer_count):
124        if timer_count == self.counter:
125            self.restore_event()
126
127    # any one of the create_tag_XXX methods can be used depending on
128    # the style
129
130    def create_tag_default(self, indices):
131        """Highlight the single paren that matches"""
132        self.text.tag_add("paren", indices[0])
133        self.text.tag_config("paren", self.HILITE_CONFIG)
134
135    def create_tag_expression(self, indices):
136        """Highlight the entire expression"""
137        if self.text.get(indices[1]) in (')', ']', '}'):
138            rightindex = indices[1]+"+1c"
139        else:
140            rightindex = indices[1]
141        self.text.tag_add("paren", indices[0], rightindex)
142        self.text.tag_config("paren", self.HILITE_CONFIG)
143
144    # any one of the set_timeout_XXX methods can be used depending on
145    # the style
146
147    def set_timeout_none(self):
148        """Highlight will remain until user input turns it off
149        or the insert has moved"""
150        # After CHECK_DELAY, call a function which disables the "paren" tag
151        # if the event is for the most recent timer and the insert has changed,
152        # or schedules another call for itself.
153        self.counter += 1
154        def callme(callme, self=self, c=self.counter,
155                   index=self.text.index("insert")):
156            if index != self.text.index("insert"):
157                self.handle_restore_timer(c)
158            else:
159                self.editwin.text_frame.after(CHECK_DELAY, callme, callme)
160        self.editwin.text_frame.after(CHECK_DELAY, callme, callme)
161
162    def set_timeout_last(self):
163        """The last highlight created will be removed after .5 sec"""
164        # associate a counter with an event; only disable the "paren"
165        # tag if the event is for the most recent timer.
166        self.counter += 1
167        self.editwin.text_frame.after(
168            self.FLASH_DELAY,
169            lambda self=self, c=self.counter: self.handle_restore_timer(c))
170
171
172if __name__ == '__main__':
173    import unittest
174    unittest.main('idlelib.idle_test.test_parenmatch', verbosity=2)
175