1 /** @file
2 * Frequently used accumulators for use with libsigc++
3 */
4 /* Authors:
5 * Krzysztof KosiĆski <tweenk.pl@gmail.com>
6 *
7 * Copyright (C) 2009 Authors
8 * Released under GNU GPL, read the file 'COPYING' for more information
9 */
11 #ifndef SEEN_UTIL_ACCUMULATORS_H
12 #define SEEN_UTIL_ACCUMULATORS_H
14 #include <iterator>
16 namespace Inkscape {
17 namespace Util {
19 /**
20 * Accumulator which evaluates slots in reverse connection order.
21 * The slot that was connected last is evaluated first.
22 */
23 struct Reverse {
24 typedef void result_type;
25 template <typename T_iterator>
26 result_type operator()(T_iterator first, T_iterator last) const {
27 while (first != last) *(--last);
28 }
29 };
31 /**
32 * Accumulator type for interruptible signals. Slots return a boolean value; emission
33 * is stopped when true is returned from a slot.
34 */
35 struct Interruptible {
36 typedef bool result_type;
37 template <typename T_iterator>
38 result_type operator()(T_iterator first, T_iterator last) const {
39 for (; first != last; ++first)
40 if (*first) return true;
41 return false;
42 }
43 };
45 /**
46 * Same as Interruptible, but the slots are called in reverse order of connection,
47 * e.g. the slot that was connected last is evaluated first.
48 */
49 struct ReverseInterruptible {
50 typedef bool result_type;
51 template <typename T_iterator>
52 result_type operator()(T_iterator first, T_iterator last) const {
53 while (first != last) {
54 if (*(--last)) return true;
55 }
56 return false;
57 }
58 };
60 /**
61 * The template parameter specifies how many slots from the beginning of the list
62 * should be evaluated after other slots. Useful for signals which invoke other signals
63 * once complete. Undefined results if the signal does not have at least @c num_chained
64 * slots before first emission.
65 *
66 * For example, if template param = 3, the execution order is as follows:
67 * @verbatim
68 8. 1. 2. 3. 4. 5. 6. 7.
69 S1 S2 S3 S4 S5 S6 S7 S8 @endverbatim
70 */
71 template <unsigned num_chained = 1>
72 struct Chained {
73 typedef void result_type;
74 template <typename T_iterator>
75 result_type operator()(T_iterator first, T_iterator last) const {
76 T_iterator save_first = first;
77 // ARGH, iterator_traits is not defined for slot iterators!
78 //std::advance(first, num_chained);
79 for (unsigned i = 0; i < num_chained && first != last; ++i) ++first;
80 for (; first != last; ++first) *first;
81 for (unsigned i = 0; i < num_chained && save_first != last; ++i, ++save_first)
82 *save_first;
83 }
84 };
86 /**
87 * Executes a logical OR on the results from slots.
88 */
89 struct LogicalOr {
90 typedef bool result_type;
91 template <typename T_iterator>
92 result_type operator()(T_iterator first, T_iterator last) const {
93 bool ret = false;
94 for (; first != last; ++first) ret |= *first;
95 return ret;
96 }
97 };
99 } // namespace Util
100 } // namespace Inkscape
102 #endif
104 /*
105 Local Variables:
106 mode:c++
107 c-file-style:"stroustrup"
108 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
109 indent-tabs-mode:nil
110 fill-column:99
111 End:
112 */
113 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :