| // pest. The Elegant Parser |
| // Copyright (c) 2018 DragoČ™ 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 std::collections::HashMap; |
| |
| use crate::ast::*; |
| |
| pub fn skip(rule: Rule, map: &HashMap<String, Expr>) -> Rule { |
| fn populate_choices( |
| expr: Expr, |
| map: &HashMap<String, Expr>, |
| mut choices: Vec<String>, |
| ) -> Option<Expr> { |
| match expr { |
| Expr::Choice(lhs, rhs) => { |
| if let Expr::Str(string) = *lhs { |
| choices.push(string); |
| populate_choices(*rhs, map, choices) |
| } else if let Expr::Ident(name) = *lhs { |
| // Try inlining rule in choices |
| if let Some(Expr::Skip(mut inlined_choices)) = map |
| .get(&name) |
| .and_then(|expr| populate_choices(expr.clone(), map, vec![])) |
| { |
| choices.append(&mut inlined_choices); |
| populate_choices(*rhs, map, choices) |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| } |
| Expr::Str(string) => { |
| choices.push(string); |
| Some(Expr::Skip(choices)) |
| } |
| // Try inlining single rule |
| Expr::Ident(name) => map |
| .get(&name) |
| .and_then(|expr| populate_choices(expr.clone(), map, choices)), |
| _ => None, |
| } |
| } |
| |
| let Rule { name, ty, expr } = rule; |
| Rule { |
| name, |
| ty, |
| expr: if ty == RuleType::Atomic { |
| expr.map_top_down(|expr| { |
| if let Expr::Rep(expr) = expr.clone() { |
| if let Expr::Seq(lhs, rhs) = *expr { |
| if let (Expr::NegPred(expr), Expr::Ident(ident)) = (*lhs, *rhs) { |
| if ident == "ANY" { |
| if let Some(expr) = populate_choices(*expr, map, vec![]) { |
| return expr; |
| } |
| } |
| } |
| } |
| }; |
| |
| expr |
| }) |
| } else { |
| expr |
| }, |
| } |
| } |