forked from pest-parser/ast
/
arith.rs
77 lines (61 loc) · 1.38 KB
/
arith.rs
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
use pest_derive;
use pest_derive::Parser;
use from_pest;
use pest_ast;
use pest;
use pest::Parser;
#[derive(Parser)]
#[grammar = "../examples/from-pair.pest"]
pub struct TokenTreeParser;
#[derive(Debug, FromPest)]
struct Program<'i>(Expr<'i>);
#[derive(Debug, FromPest)]
#[pest(expr)]
enum Expr<'i> {
#[pest(primary)]
Primary(Primary<'i>),
#[pest(infix)]
Infix(Box<Expr<'i>>, InfixOp, Box<Expr<'i>>),
#[pest(prefix)]
Prefix(PrefixOp, Box<Expr<'i>>),
#[pest(postfix)]
Postfix(Box<Expr<'i>>, PostfixOp),
}
#[derive(Debug, FromPest)]
enum Primary<'i> {
Term(Term<'i>),
}
#[derive(Debug, FromPest)]
struct Term<'i> {
#[pest(text)]
val: &'i str,
}
#[derive(Debug, FromPest)]
#[pest(infix)]
enum InfixOp {
#[pest(precedence = 1, associativity = "left")]
Add,
#[pest(precedence = 2, associativity = "left")]
Mul,
}
#[derive(Debug, FromPest)]
#[pest(prefix)]
enum PrefixOp {
#[pest(precedence = 3)]
Not,
#[pest(precedence = 3)]
Neg,
}
#[derive(Debug, FromPest)]
#[pest(postfix)]
enum PostfixOp {
#[pest(precedence = 4)]
Try,
}
fn main() {
let source = "!a?+!b?";
let mut token_tree = TokenTreeParser::parse(Rule::Program, source).expect("parse success");
println!("parse tree = {:#?}", token_tree);
let parse_tree = Program::from_pairs(token_tree);
println!("syntax tree = {:#?}", parse_tree);
}