nom_operator/
expr.rs

1// Copyright 2017 The nom-operator project developers
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9//! Expression tree
10
11/// A parsed expression
12#[derive(PartialEq)]
13pub enum Expr<Atom, Operator> {
14    /// An atom is whatever the return type of the atom parser returns
15    Atom(Atom),
16
17    /// UnExpr is a unary expression for example -10
18    UnExpr {
19        /// Item is the sub expression that the operator applies to.
20        /// It is not called lhs because it can be either postfix
21        /// or prefix
22        item: Box<Expr<Atom, Operator>>,
23
24        /// Operator token
25        op: Operator,
26    },
27
28    /// BinExpr is a binary expression for example 10 * 10
29    BinExpr {
30        /// Left hand side sub expression
31        left: Box<Expr<Atom, Operator>>,
32
33        /// Operator token
34        op: Operator,
35
36        /// Right hand side sub expression
37        right: Box<Expr<Atom, Operator>>,
38    },
39
40    /// TreExpr is a trenary expression such as true ? 2 : 3
41    TreExpr {
42        /// Left side sub expression
43        left: Box<Expr<Atom, Operator>>,
44
45        /// First operator token
46        lop: Operator,
47
48        /// Middle sub expression
49        middle: Box<Expr<Atom, Operator>>,
50
51        /// Right operator token
52        rop: Operator,
53
54        /// Right side sub expression
55        right: Box<Expr<Atom, Operator>>,
56    }
57}
58
59use std::fmt;
60impl<Atom, Operator> fmt::Debug for Expr<Atom, Operator>
61    where Atom: fmt::Debug, Operator: fmt::Debug {
62        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
63            use expr::Expr::*;
64            match *self {
65                Atom(ref a) => write!(f, "A({:?})", a),
66                UnExpr {
67                    ref item,
68                    ref op
69                } => write!(f, "U({:?} {:?})", op, item),
70                BinExpr {
71                    ref left,
72                    ref op,
73                    ref right
74                } => write!(f, "B({:?} {:?} {:?})", left, op, right),
75                TreExpr{
76                    ref left,
77                    ref lop,
78                    ref middle,
79                    ref rop,
80                    ref right
81                } => write!(f, "{:?} {:?} {:?} {:?} {:?}",
82                            left, lop, middle, rop, right),
83            }
84        }
85    }
86
nom_operator/expr.rs

nom_operator/
expr.rs
