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// pest. The Elegant Parser
// Copyright (c) 2018 Dragoș Tiselice
//
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. All files in the project carrying such notice may not be copied,
// modified, or distributed except according to those terms.
use ast::*;
pub fn concatenate(rule: Rule) -> Rule {
match rule {
Rule { name, ty, expr } => Rule {
name,
ty,
expr: expr.map_bottom_up(|expr| {
if ty == RuleType::Atomic {
// TODO: Use box syntax when it gets stabilized.
match expr {
Expr::Seq(lhs, rhs) => match (*lhs, *rhs) {
(Expr::Str(lhs), Expr::Str(rhs)) => Expr::Str(lhs + &rhs),
(Expr::Insens(lhs), Expr::Insens(rhs)) => Expr::Insens(lhs + &rhs),
(lhs, rhs) => Expr::Seq(Box::new(lhs), Box::new(rhs)),
},
expr => expr,
}
} else {
expr
}
}),
},
}
}
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