Regular-Expresso Changeset

Changeset - 4f7b6352013d

Parent rev.

Child rev.

[Not reviewed]

default

0 4 0

Laman - 10 months ago 2024-06-23 22:48:03

added the automaton normalization

4 files changed with 55 insertions and 14 deletions:

regexp.py

src/main.rs

src/regexp.rs

tests/test_regexp.rs

0 comments (0 inline, 0 general)

regexp.py

➞

Show inline comments

 from abc import abstractmethod
 from collections import deque
 class ParsingError(Exception):
 	pass
 class Token:
 	is_skippable = False
 	@abstractmethod
 	def list_first(self):
 		pass
 	@abstractmethod
 	def list_last(self):
 		pass
 	@abstractmethod
 	def list_neighbours(self):
 		pass
 class Lambda(Token):
 	is_skippable = True
@@ @@ -262,92 +263,110 @@ class Regexp: @@
 				new_target = tuple(sorted(target_set))
 				rules[(multistate, c)] = new_target
 				if any(st in self.end_states for st in new_target):
 					end_states.add(new_target)
 				if new_target not in processed_states:
 					stack.append(new_target)
 					processed_states.add(new_target)
 		return (rules, end_states)
 class RegexpDFA:
 	def __init__(self, rules, end_states):
 		self.rules = rules
 		self.end_states = end_states
 	@classmethod
 	def create(cls, pattern):
 		r = Regexp(pattern)
 		(rules, end_states) = r.determinize()
 		return cls(rules, end_states)
 	def match(self, s):
-		st = (-1,)
+		st = 0
 		for c in s:
 			key = (st, c)
 			if key in self.rules:
 				st = self.rules[key]
 			else:
 				return False
 		return st in self.end_states
 	def reduce(self):
 		equivalents = self._find_equivalent_states()
 		(rules, end_states) = self._collapse_states(equivalents)
 		return RegexpDFA(rules, end_states)
 	def normalize(self):
 		index = {(-1,): 0}
 		queue = deque([(-1,)])
 		while queue:
 			state = queue.popleft()
 			edges = [((st, c), t) for ((st, c), t) in self.rules.items() if st == state]
 			edges.sort()
 			for ((st, c), t) in edges:
 				if t not in index:
 					index[t] = len(index)
 					queue.append(t)
 		rules = dict(((index[st], c), index[t]) for ((st, c), t) in self.rules.items())
 		end_states = {index[st] for st in self.end_states}
 		return RegexpDFA(rules, end_states)
 	def _find_equivalent_states(self):
 		state_set = [(-2,), (-1,)] + sorted(set(self.rules.values()))
 		alphabet = {c for (st, c) in self.rules.keys()}
 		equivalents = {(s1, s2) for (i, s1) in enumerate(state_set) for s2 in state_set[i+1:]}
 		for (s1, s2) in equivalents.copy():
 			if (s1 in self.end_states and s2 not in self.end_states) or (s1 not in self.end_states and s2 in self.end_states):
 				equivalents.remove((s1, s2))
 		ctrl = True
 		while ctrl:
 			ctrl = False
 			for (s1, s2) in equivalents.copy():
 				for c in alphabet:
 					t1 = self.rules.get((s1, c), (-2,))
 					t2 = self.rules.get((s2, c), (-2,))
 					key = (min(t1, t2), max(t1, t2))
 					if t1 != t2 and key not in equivalents:
 						equivalents.remove((s1, s2))
 						ctrl = True
 						break
 		return equivalents
 	def _collapse_states(self, equivalents):
 		rules = self.rules.items()
 		end_states = self.end_states.copy()
 		for (s1, s2) in sorted(equivalents):
 			rules = map(
 				lambda item: (item[0], s1 if item[1] == s2 else item[1]),
 				filter(lambda item: item[0][0] != s2, rules)
+			)
 			end_states.discard(s2)
 		return (dict(rules), end_states)
 if __name__ == "__main__":
 	tests = ["", "a", "ab", "aabb", "abab", "abcd", "abcbcdbcd"]
 	for pattern in ["a(b|c)", "a*b*", "(ab)*", "a((bc)*d)*"]:
+	for pattern in ["a(b|c)", "a*b*", "(ab)*", "a((bc)*d)*", "(a|b)*a(a|b)(a|b)(a|b)"]:
 		print("#", pattern)
 		try:
 			r = RegexpDFA.create(pattern).reduce()
+			r = RegexpDFA.create(pattern).reduce().normalize()
 		except ParsingError as e:
 			print("Failed to parse the regexp:")
 			print(e)
 			continue
 		for t in tests:
 			print(t, r.match(t))
 		print()

src/main.rs

➞

Show inline comments

 use regexp::Regexp;
 fn main() {
 	let tests = ["", "a", "ab", "aabb", "abab", "abcd", "abcbcdbcd"];
 	for pattern in ["a(b|c)", "a*b*", "(ab)*", "a((bc)*d)*"] {
+	for pattern in ["a(b|c)", "a*b*", "(ab)*", "a((bc)*d)*", "(a|b)*a(a|b)(a|b)(a|b)"] {
 		println!("# {pattern}");
 		let r = match Regexp::new(&pattern.to_string()) {
 			Ok(r1) => r1.determinize().reduce(),
+			Ok(r1) => r1.determinize().reduce().normalize(),
 			Err(e) => {
 				println!("{e}");
 				continue;
+			}
 		};
 		for &t in tests.iter() {
 			println!("{t} {}", r.eval(t.to_string()));
+		}
 		println!();
+	}
+}

src/regexp.rs

➞

Show inline comments

 use std::collections::{HashMap, HashSet};
+use std::collections::{HashMap, HashSet, VecDeque};
 mod token;
 pub use token::ParsingError;
 use token::parse;
 const START: usize = usize::MAX;
 const FAIL: usize = START-1;
 fn encode_set(set: &HashSet<usize>) -> u64 {
 	let mut res = 0;
 	for x in set.iter() {
 		res ^= 1<<x;
+	}
 	return res;
+}
 fn decode_set(x: u64) ->HashSet<usize> {
 	if x == START as u64 {return HashSet::from([START]);}
 	let mut x = x;
 	let mut res: HashSet<usize> = HashSet::new();
 	while x > 0 {
 		let y = x.trailing_zeros();
@@ @@ -130,48 +130,70 @@ pub struct RegexpDFA { @@
 	rules: HashMap<(u64, char), u64>,
 	end_states: HashSet<u64>
+}
 impl RegexpDFA {
 	pub fn eval(&self, s: String) -> bool {
 		let mut state = START as u64;
 		for c in s.chars() {
 			if let Some(x) = self.rules.get(&(state, c)) {
 				state = *x;
 			} else {
 				return false;
+			}
+		}
 		return self.end_states.contains(&state);
+	}
 	pub fn reduce(&self) -> RegexpDFA {
 		let equivalents = self.find_equivalent_states();
 		return self.collapse_states(equivalents);
+	}
 	pub fn normalize(&self) -> RegexpDFA {
 		let mut index = HashMap::from([(START as u64, START as u64)]);
 		let mut queue = VecDeque::from([START as u64]);
 		while !queue.is_empty() {
 			let state = queue.pop_front().unwrap();
 			let mut edges: Vec<((u64, char), u64)> = self.rules.iter().filter(|((st, c), t)| *st == state).map(|((st, c), t)| ((*st, *c), *t)).collect();
 			edges.sort();
 			for ((_st, _c), t) in edges {
 				if !index.contains_key(&t) {
 					index.insert(t, index.len() as u64);
 					queue.push_back(t);
+				}
+			}
+		}
 		let rules = self.rules.iter().map(|((st, c), t)| ((index[st as &u64], *c), index[t as &u64])).collect();
 		let end_states = self.end_states.iter().map(|st| index[st]).collect();
 		return RegexpDFA{rules, end_states};
+	}
 	fn find_equivalent_states(&self) -> Vec<(u64, u64)> {
 		let state_set: HashSet<u64> = HashSet::from_iter(self.rules.values().copied());
 		let mut state_vec: Vec<u64> = Vec::from_iter(state_set.into_iter());
 		state_vec.push(START as u64);
 		state_vec.push(FAIL as u64);
 		state_vec.sort();
 		state_vec.reverse();
 		let alphabet: HashSet<char> = self.rules.keys().map(|(_st, c)| c).copied().collect();
 		let mut equivalents = HashSet::new();
 		state_vec.iter().enumerate().for_each(|(i, s1)| {
 			equivalents.extend(
 				state_vec[i+1..].iter()
 				.filter(|s2| !(self.end_states.contains(s1)^self.end_states.contains(s2)))
 				.map(|s2| (*s1, *s2))
 			);
 		});
 		let mut n = usize::MAX;
 		while equivalents.len() < n {
 			n = equivalents.len();
 			equivalents = equivalents.iter().filter(|(s1, s2)| {
 				!alphabet.iter().any(|c| {
 					let t1 = self.rules.get(&(*s1, *c)).unwrap_or(&(FAIL as u64));

tests/test_regexp.rs

➞

Show inline comments

 use regexp::Regexp;
 use regexp::ParsingError;
 #[test]
 fn test_eval_basic_nfa() {
 	let r = Regexp::new(&String::from("abc")).unwrap();
 	assert!(r.eval(String::from("abc")));
 	assert!(!r.eval(String::from("ab")));
 	assert!(!r.eval(String::from("abcd")));
+}
 #[test]
 fn test_eval_basic_dfa() {
 	let r = Regexp::new(&String::from("abc")).unwrap().determinize().reduce();
+	let r = Regexp::new(&String::from("abc")).unwrap().determinize().reduce().normalize();
 	assert!(r.eval(String::from("abc")));
 	assert!(!r.eval(String::from("ab")));
 	assert!(!r.eval(String::from("abcd")));
+}
 #[test]
 fn test_eval_empty_nfa() {
 	assert!(Regexp::new(&String::from("a*")).unwrap().eval(String::from("")));
 	assert!(Regexp::new(&String::from("")).unwrap().eval(String::from("")));
 	assert!(!Regexp::new(&String::from("")).unwrap().eval(String::from("a")));
 	assert!(!Regexp::new(&String::from("a")).unwrap().eval(String::from("")));
+}
 #[test]
 fn test_eval_empty_dfa() {
 	assert!(Regexp::new(&String::from("a*")).unwrap().determinize().reduce().eval(String::from("")));
 	assert!(Regexp::new(&String::from("")).unwrap().determinize().reduce().eval(String::from("")));
 	assert!(!Regexp::new(&String::from("")).unwrap().determinize().reduce().eval(String::from("a")));
 	assert!(Regexp::new(&String::from("a*")).unwrap().determinize().reduce().normalize().eval(String::from("")));
 	assert!(Regexp::new(&String::from("")).unwrap().determinize().reduce().normalize().eval(String::from("")));
 	assert!(!Regexp::new(&String::from("")).unwrap().determinize().reduce().normalize().eval(String::from("a")));
+}
 #[test]
 fn test_eval_asterisk_nfa() {
 	let r = Regexp::new(&String::from("a*b*")).unwrap();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("ab")));
 	assert!(r.eval(String::from("aabb")));
 	assert!(!r.eval(String::from("abab")));
+}
 #[test]
 fn test_eval_asterisk_dfa() {
 	let r = Regexp::new(&String::from("a*b*")).unwrap().determinize().reduce();
+	let r = Regexp::new(&String::from("a*b*")).unwrap().determinize().normalize().reduce();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("ab")));
 	assert!(r.eval(String::from("aabb")));
 	assert!(!r.eval(String::from("abab")));
+}
 #[test]
 fn test_eval_alternative_nfa() {
 	let r = Regexp::new(&String::from("a|b|c")).unwrap();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("b")));
 	assert!(r.eval(String::from("c")));
 	assert!(!r.eval(String::from("")));
 	assert!(!r.eval(String::from("ab")));
+}
 #[test]
 fn test_eval_alternative_dfa() {
 	let r = Regexp::new(&String::from("a|b|c")).unwrap().determinize().reduce();
+	let r = Regexp::new(&String::from("a|b|c")).unwrap().determinize().reduce().normalize();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("b")));
 	assert!(r.eval(String::from("c")));
 	assert!(!r.eval(String::from("")));
 	assert!(!r.eval(String::from("ab")));
+}
 #[test]
 fn test_eval_lambda_nfa() {
 	let r = Regexp::new(&String::from("a_")).unwrap();
 	assert!(r.eval(String::from("a")));
 	assert!(!r.eval(String::from("")));
 	assert!(!r.eval(String::from("ab")));
 	let r = Regexp::new(&String::from("a|_")).unwrap();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("")));
 	assert!(!r.eval(String::from("b")));
+}
 #[test]
 fn test_eval_lambda_dfa() {
 	let r = Regexp::new(&String::from("a_")).unwrap().determinize().reduce();
+	let r = Regexp::new(&String::from("a_")).unwrap().determinize().reduce().normalize();
 	assert!(r.eval(String::from("a")));
 	assert!(!r.eval(String::from("")));
 	assert!(!r.eval(String::from("ab")));
 	let r = Regexp::new(&String::from("a|_")).unwrap().determinize().reduce();
+	let r = Regexp::new(&String::from("a|_")).unwrap().determinize().reduce().normalize();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("")));
 	assert!(!r.eval(String::from("b")));
+}
 #[test]
 fn test_invalid_asterisk() {
 	let x = Regexp::new(&String::from("*"));
 	assert!(matches!(x, Err(ParsingError::Asterisk{s: _, pos: 0})));
+}
 #[test]
 fn test_invalid_closing_parenthesis() {
 	let x = Regexp::new(&String::from("(a"));
 	assert!(matches!(x, Err(ParsingError::ClosingParenthesis{s: _, pos: 0})));
+}
 #[test]
 fn test_invalid_opening_parenthesis() {
 	let x = Regexp::new(&String::from("a)"));
 	assert!(matches!(x, Err(ParsingError::OpeningParenthesis{s: _, pos: 1})));
+}
 #[test]

0 comments (0 inline, 0 general)