cfg 0.10.1

Library for manipulating context-free grammars.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147

#![cfg(feature = "cfg-classify")]

mod support;

use cfg::Cfg;
use cfg::classify::CfgClassifyExt;
use cfg_symbol_bit_matrix::CfgRemapSymbolsExt;

#[test]
fn test_remap_unused_symbols() {
    let mut cfg: Cfg = Cfg::new();
    let [start, a, x, b, c, _gg, y] = cfg.sym();

    cfg.rule(start)
        .rhs([a, x, b])
        .rhs([c])
        .rule(b)
        .rhs([a, a])
        .rhs([a, c])
        .rule(c)
        .rhs([x])
        .rhs([y])
        .rule(a)
        .rhs([]);

    cfg.set_roots([start]);

    cfg.remap().remove_unused_symbols();

    {
        let mut equivalent: Cfg = Cfg::new();
        let [start, a, x, b, c, y] = equivalent.sym();
        equivalent
            .rule(start)
            .rhs([a, x, b])
            .rhs([c])
            .rule(b)
            .rhs([a, a])
            .rhs([a, c])
            .rule(c)
            .rhs([x])
            .rule(a)
            .rhs([])
            .rule(c)
            .rhs([y]);
        support::assert_eq_rules(equivalent.rules(), cfg.rules());
    };

    assert!(cfg.usefulness().all_useful());
}

#[test]
fn test_reorder_symbols() {
    let mut cfg: Cfg = Cfg::new();
    //  (0      1  2  3  4  5)
    let [start, a, x, b, c, y] = cfg.sym();

    cfg.rule(start)
        .rhs([a, x, b, c, y])
        .rhs([c])
        .rule(b)
        .rhs([a, a])
        .rhs([a, c])
        .rule(c)
        .rhs([x])
        .rhs([y])
        .rule(a)
        .rhs([]);

    cfg.set_roots([start]);

    let ordering = &[
        /* start => */ 1, /* a => */ 2, /* x => */ 5, /* b => */ 3,
        /* c => */ 4, /* y => */ 6,
    ];
    cfg.remap()
        .reorder_symbols(|left, right| ordering[left.usize()].cmp(&ordering[right.usize()]));

    {
        let mut equivalent: Cfg = Cfg::new();
        //  (0      1  2  3  4  5)
        let [start, a, b, c, x, y] = equivalent.sym();
        equivalent
            .rule(a)
            .rhs([])
            .rule(start)
            .rhs([a, x, b, c, y])
            .rhs([c])
            .rule(b)
            .rhs([a, a])
            .rhs([a, c])
            .rule(c)
            .rhs([x])
            .rhs([y]);
        support::assert_eq_rules(equivalent.rules(), cfg.rules());
    };
    assert!(cfg.usefulness().all_useful());
}

#[test]
fn test_maps() {
    let mut cfg: Cfg = Cfg::new();
    //  (0      1  2  3  4  5)
    let [start, a, x, b, c, y] = cfg.sym();

    cfg.rule(start)
        .rhs([a, x, b, c, y])
        .rhs([c])
        .rule(b)
        .rhs([a, a])
        .rhs([a, c])
        .rule(c)
        .rhs([x])
        .rhs([y])
        .rule(a)
        .rhs([]);

    cfg.set_roots([start]);

    assert!(cfg.usefulness().all_useful());

    let ordering = &[
        /* start => */ 1, /* a => */ 2, /* x => */ 5, /* b => */ 3,
        /* c => */ 4, /* y => */ 6,
    ];

    let mut remap = cfg.remap();
    remap.reorder_symbols(|left, right| ordering[left.usize()].cmp(&ordering[right.usize()]));
    let maps = remap.get_mapping();

    let mut equivalent: Cfg = Cfg::new();
    //  (0      1  2  3  4  5)
    let [start2, a2, b2, c2, x2, y2] = equivalent.sym();

    assert_eq!(maps.to_external, &[start, a, b, c, x, y]);
    assert_eq!(
        maps.to_internal,
        &[
            Some(start2),
            Some(a2),
            Some(x2),
            Some(b2),
            Some(c2),
            Some(y2)
        ]
    );
}