pest_meta/optimizer/
concatenator.rs

1// pest. The Elegant Parser
2// Copyright (c) 2018 Dragoș Tiselice
3//
4// Licensed under the Apache License, Version 2.0
5// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
6// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
7// option. All files in the project carrying such notice may not be copied,
8// modified, or distributed except according to those terms.
9
10use crate::ast::*;
11
12pub fn concatenate(rule: Rule) -> Rule {
13    let Rule { name, ty, expr } = rule;
14    Rule {
15        name,
16        ty,
17        expr: expr.map_bottom_up(|expr| {
18            if ty == RuleType::Atomic {
19                match expr {
20                    Expr::Seq(lhs, rhs) => match (*lhs, *rhs) {
21                        (Expr::Str(lhs), Expr::Str(rhs)) => Expr::Str(lhs + &rhs),
22                        (Expr::Insens(lhs), Expr::Insens(rhs)) => Expr::Insens(lhs + &rhs),
23                        (lhs, rhs) => Expr::Seq(Box::new(lhs), Box::new(rhs)),
24                    },
25                    expr => expr,
26                }
27            } else {
28                expr
29            }
30        }),
31    }
32}