1"Implement Idle Shell history mechanism with History class"
2
3from idlelib.config import idleConf
4
5
6class History:
7    ''' Implement Idle Shell history mechanism.
8
9    store - Store source statement (called from pyshell.resetoutput).
10    fetch - Fetch stored statement matching prefix already entered.
11    history_next - Bound to <<history-next>> event (default Alt-N).
12    history_prev - Bound to <<history-prev>> event (default Alt-P).
13    '''
14    def __init__(self, text):
15        '''Initialize data attributes and bind event methods.
16
17        .text - Idle wrapper of tk Text widget, with .bell().
18        .history - source statements, possibly with multiple lines.
19        .prefix - source already entered at prompt; filters history list.
20        .pointer - index into history.
21        .cyclic - wrap around history list (or not).
22        '''
23        self.text = text
24        self.history = []
25        self.prefix = None
26        self.pointer = None
27        self.cyclic = idleConf.GetOption("main", "History", "cyclic", 1, "bool")
28        text.bind("<<history-previous>>", self.history_prev)
29        text.bind("<<history-next>>", self.history_next)
30
31    def history_next(self, event):
32        "Fetch later statement; start with ealiest if cyclic."
33        self.fetch(reverse=False)
34        return "break"
35
36    def history_prev(self, event):
37        "Fetch earlier statement; start with most recent."
38        self.fetch(reverse=True)
39        return "break"
40
41    def fetch(self, reverse):
42        '''Fetch statement and replace current line in text widget.
43
44        Set prefix and pointer as needed for successive fetches.
45        Reset them to None, None when returning to the start line.
46        Sound bell when return to start line or cannot leave a line
47        because cyclic is False.
48        '''
49        nhist = len(self.history)
50        pointer = self.pointer
51        prefix = self.prefix
52        if pointer is not None and prefix is not None:
53            if self.text.compare("insert", "!=", "end-1c") or \
54                    self.text.get("iomark", "end-1c") != self.history[pointer]:
55                pointer = prefix = None
56                self.text.mark_set("insert", "end-1c")  # != after cursor move
57        if pointer is None or prefix is None:
58            prefix = self.text.get("iomark", "end-1c")
59            if reverse:
60                pointer = nhist  # will be decremented
61            else:
62                if self.cyclic:
63                    pointer = -1  # will be incremented
64                else:  # abort history_next
65                    self.text.bell()
66                    return
67        nprefix = len(prefix)
68        while 1:
69            pointer += -1 if reverse else 1
70            if pointer < 0 or pointer >= nhist:
71                self.text.bell()
72                if not self.cyclic and pointer < 0:  # abort history_prev
73                    return
74                else:
75                    if self.text.get("iomark", "end-1c") != prefix:
76                        self.text.delete("iomark", "end-1c")
77                        self.text.insert("iomark", prefix)
78                    pointer = prefix = None
79                break
80            item = self.history[pointer]
81            if item[:nprefix] == prefix and len(item) > nprefix:
82                self.text.delete("iomark", "end-1c")
83                self.text.insert("iomark", item)
84                break
85        self.text.see("insert")
86        self.text.tag_remove("sel", "1.0", "end")
87        self.pointer = pointer
88        self.prefix = prefix
89
90    def store(self, source):
91        "Store Shell input statement into history list."
92        source = source.strip()
93        if len(source) > 2:
94            # avoid duplicates
95            try:
96                self.history.remove(source)
97            except ValueError:
98                pass
99            self.history.append(source)
100        self.pointer = None
101        self.prefix = None
102
103
104if __name__ == "__main__":
105    from unittest import main
106    main('idlelib.idle_test.test_history', verbosity=2, exit=False)
107