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1"Implement Idle Shell history mechanism with History class"
2
3from idlelib.configHandler import idleConf
4
5class History:
6    ''' Implement Idle Shell history mechanism.
7
8    store - Store source statement (called from PyShell.resetoutput).
9    fetch - Fetch stored statement matching prefix already entered.
10    history_next - Bound to <<history-next>> event (default Alt-N).
11    history_prev - Bound to <<history-prev>> event (default Alt-P).
12    '''
13    def __init__(self, text):
14        '''Initialize data attributes and bind event methods.
15
16        .text - Idle wrapper of tk Text widget, with .bell().
17        .history - source statements, possibly with multiple lines.
18        .prefix - source already entered at prompt; filters history list.
19        .pointer - index into history.
20        .cyclic - wrap around history list (or not).
21        '''
22        self.text = text
23        self.history = []
24        self.prefix = None
25        self.pointer = None
26        self.cyclic = idleConf.GetOption("main", "History", "cyclic", 1, "bool")
27        text.bind("<<history-previous>>", self.history_prev)
28        text.bind("<<history-next>>", self.history_next)
29
30    def history_next(self, event):
31        "Fetch later statement; start with ealiest if cyclic."
32        self.fetch(reverse=False)
33        return "break"
34
35    def history_prev(self, event):
36        "Fetch earlier statement; start with most recent."
37        self.fetch(reverse=True)
38        return "break"
39
40    def fetch(self, reverse):
41        '''Fetch statememt and replace current line in text widget.
42
43        Set prefix and pointer as needed for successive fetches.
44        Reset them to None, None when returning to the start line.
45        Sound bell when return to start line or cannot leave a line
46        because cyclic is False.
47        '''
48        nhist = len(self.history)
49        pointer = self.pointer
50        prefix = self.prefix
51        if pointer is not None and prefix is not None:
52            if self.text.compare("insert", "!=", "end-1c") or \
53                    self.text.get("iomark", "end-1c") != self.history[pointer]:
54                pointer = prefix = None
55                self.text.mark_set("insert", "end-1c")  # != after cursor move
56        if pointer is None or prefix is None:
57            prefix = self.text.get("iomark", "end-1c")
58            if reverse:
59                pointer = nhist  # will be decremented
60            else:
61                if self.cyclic:
62                    pointer = -1  # will be incremented
63                else:  # abort history_next
64                    self.text.bell()
65                    return
66        nprefix = len(prefix)
67        while 1:
68            pointer += -1 if reverse else 1
69            if pointer < 0 or pointer >= nhist:
70                self.text.bell()
71                if not self.cyclic and pointer < 0:  # abort history_prev
72                    return
73                else:
74                    if self.text.get("iomark", "end-1c") != prefix:
75                        self.text.delete("iomark", "end-1c")
76                        self.text.insert("iomark", prefix)
77                    pointer = prefix = None
78                break
79            item = self.history[pointer]
80            if item[:nprefix] == prefix and len(item) > nprefix:
81                self.text.delete("iomark", "end-1c")
82                self.text.insert("iomark", item)
83                break
84        self.text.see("insert")
85        self.text.tag_remove("sel", "1.0", "end")
86        self.pointer = pointer
87        self.prefix = prefix
88
89    def store(self, source):
90        "Store Shell input statement into history list."
91        source = source.strip()
92        if len(source) > 2:
93            # avoid duplicates
94            try:
95                self.history.remove(source)
96            except ValueError:
97                pass
98            self.history.append(source)
99        self.pointer = None
100        self.prefix = None
101
102if __name__ == "__main__":
103    from unittest import main
104    main('idlelib.idle_test.test_idlehistory', verbosity=2, exit=False)
105