ftml 1.41.0

/*
 * tree/variables.rs
 *
 * ftml - Library to parse Wikidot text
 * Copyright (C) 2019-2026 Wikijump Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

use super::clone::string_map_to_owned;
use std::borrow::Cow;
use std::collections::HashMap;

pub type VariableMap<'t> = HashMap<Cow<'t, str>, Cow<'t, str>>;

#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct VariableScopes {
    scopes: Vec<VariableMap<'static>>,
}

impl VariableScopes {
    #[inline]
    pub fn new() -> Self {
        VariableScopes::default()
    }

    pub fn get(&self, name: &str) -> Option<&str> {
        for scope in self.scopes.iter().rev() {
            if let Some(value) = scope.get(name) {
                return Some(value);
            }
        }

        None
    }

    pub fn push_scope(&mut self, scope: &VariableMap) {
        // We clone here since managing multiple, scope-dependent
        // lifetimes for each call is impractical, and we can't
        // use Rc or RefCell because it is borrowed from Element.
        self.scopes.push(string_map_to_owned(scope));
    }

    pub fn pop_scope(&mut self) {
        self.scopes.pop().expect("Scope stack was empty");
    }
}