lalrpop 0.23.0

convenient LR(1) parser generator
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

use crate::parser;
use crate::test_util::compare;

use super::expand_macros;

#[test]
fn test_comma() {
    let grammar = parser::parse_grammar(
        r#"
grammar;
    Comma<E>: Vec<E> =
       <v:(<E> ",")*> <e:E?> =>
           v.into_iter().chain(e.into_iter()).collect();

    Ids = Comma<"Id">;
"#,
    )
    .unwrap();

    let actual = expand_macros(grammar, 20).unwrap();

    let expected = parser::parse_grammar(
        r##"
grammar;
    Ids = `Comma<"Id">`;

    `Comma<"Id">`: Vec<#"Id"#> =
        <v:`(<"Id"> ",")*`> <e:`"Id"?`> => v.into_iter().chain(e.into_iter()).collect();

    #[inline]
    `"Id"?`: Option<#"Id"#> = {
        "Id" => Some(<>),
        => None
    };

    #[inline]
    `(<"Id"> ",")*`: alloc::vec::Vec<#`(<"Id"> ",")`#> = {
        => alloc::vec![],
        <v:`(<"Id"> ",")+`> => v,
    };

    #[inline]
    `(<"Id"> ",")`: #"Id"# = {
        <"Id"> "," => <>,
    };

    `(<"Id"> ",")+`: alloc::vec::Vec<#`(<"Id"> ",")`#> = {
        `(<"Id"> ",")` => alloc::vec![<>],
        <v:`(<"Id"> ",")+`> <e:`(<"Id"> ",")`> => { let mut v = v; v.push(e); v },
    };
"##,
    )
    .unwrap();

    compare(actual, expected);
}

#[test]
fn test_if_match() {
    let grammar = parser::parse_grammar(
        r#"
grammar;
    Expr<E> = {
       "A" if E == "A*C",
       "B" if E ~~ "^A*C$",
       "C" if E != "A*C",
       "D" if E !~ "^A*C$"
    };

    Expr1 = Expr<"A*C">;
    Expr2 = Expr<"AAC">;
    Expr3 = Expr<"ABC">;
"#,
    )
    .unwrap();

    let actual = expand_macros(grammar, 20).unwrap();

    let expected = parser::parse_grammar(
        r#"
grammar;
    Expr1 = `Expr<"A*C">`;
    Expr2 = `Expr<"AAC">`;
    Expr3 = `Expr<"ABC">`;

    `Expr<"ABC">` = { "C", "D" };
    `Expr<"AAC">` = { "B", "C" };
    `Expr<"A*C">` = { "A", "D" };
"#,
    )
    .unwrap();

    compare(actual, expected);
}

#[test]
fn test_lookahead() {
    let grammar = parser::parse_grammar(
        r#"
        grammar;
        Expr = @L;
"#,
    )
    .unwrap();

    let actual = expand_macros(grammar, 20).unwrap();

    let expected = parser::parse_grammar(
        r#"
        grammar;
        Expr = `@L`;
        #[inline] `@L` = =>@L;
"#,
    )
    .unwrap();

    compare(actual, expected);
}

#[test]
fn test_excessive_recursion() {
    let grammar = parser::parse_grammar(
        r#"
        grammar;
        A<I> = { "x" I "y" I "z", A<("." I)> }
        pub P = A<()>;
        "#,
    )
    .unwrap();

    assert!(expand_macros(grammar, 20).is_err());

    let grammar2 = parser::parse_grammar(
        r#"
         grammar;
         A<I> = { "a" B<("." I)> };
         B<I> = { "b" C<("," I)> };
         C<I> = { "c" I };
         pub D = A<"d"> B<"d"> C<"d">;
         "#,
    )
    .unwrap();

    assert!(expand_macros(grammar2.clone(), 2).is_err());

    assert!(expand_macros(grammar2, 3).is_ok());
}