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// Copyright 2017 1aim GmbH
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

use std::ops::{Deref, DerefMut};

use regex::{Regex, Error};
use lru::LruCache;

/// An LRU cache for regular expressions.
pub struct Cache(LruCache<String, Regex>);

impl Cache {
	/// Create a new LRU cache with the given size limit.
	pub fn new(capacity: usize) -> Cache {
		Cache(LruCache::new(capacity))
	}

	/// Check if the same `Regex` is already present in the cache and return it,
	/// otherwise tries to create a new one and inserts it into the cache.
	pub fn compile(&mut self, source: &str) -> Result<&Regex, Error> {
		if !self.0.contains_key(source) {
			self.0.insert(source.into(), Regex::new(source)?);
		}

		Ok(self.0.get_mut(source).unwrap())
	}
}

impl Deref for Cache {
	type Target = LruCache<String, Regex>;

	fn deref(&self) -> &Self::Target {
		&self.0
	}
}

impl DerefMut for Cache {
	fn deref_mut(&mut self) -> &mut Self::Target {
		&mut self.0
	}
}

#[cfg(test)]
mod test {
	use cache::Cache;

	#[test]
	fn compile() {
		let mut cache = Cache::new(100);
		assert!(cache.compile("[01]2").unwrap().is_match("12"));
	}
}