Regular-Expresso Changeset

Changeset - 7e640b0cffa7

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Laman - 10 months ago 2024-06-18 16:21:22

handling unparsable patterns

6 files changed with 112 insertions and 30 deletions:

regexp.py

src/lib.rs

src/main.rs

src/regexp.rs

src/regexp/token.rs

tests/test_regexp.rs

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regexp.py

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 from abc import abstractmethod
 class ParsingError(Exception):
 	pass
 class Token:
 	is_skippable = False
@@ @@ -111,7 +115,7 @@ def find_closing_parenthesis(pattern, k) @@
 		if counter == 0:
 			return k+i
-	return None
+	raise ParsingError(f'A closing parenthesis not found. Pattern: "{pattern}", position: {k}')
 def parse(pattern, offset=0):
@@ @@ -126,13 +130,21 @@ def parse(pattern, offset=0): @@
 			res.append(inner_content)
 			i = j+1
 		elif c == "*":
 			token = res.pop()
 			try:
 				token = res.pop()
 			except IndexError as e:
 				raise ParsingError(f'The asterisk operator is missing an argument. Pattern: "{pattern}", position {i}')
 			res.append(Asterisk(token))
 			i += 1
 		elif c == "+":
 			token = res.pop()
 			try:
 				token = res.pop()
 			except IndexError as e:
 				raise ParsingError(f'The plus operator is missing an argument. Pattern: "{pattern}", position {i}')
 			res.append(Plus(token))
 			i += 1
 		elif c == ")":
 			raise ParsingError(f'An opening parenthesis not found. Pattern: "{pattern}", position: {i}')
 		else:
 			res.append(Symbol(i+offset, c))
 			i += 1
@@ @@ -228,9 +240,14 @@ class RegexpDFA: @@
 if __name__ == "__main__":
 	tests = ["", "a", "ab", "aabb", "abab", "abcd", "abcbcdbcd"]
-	for pattern in ["a*b*", "a+b+", "(ab)*", "(ab)+", "a((bc)*d)*"]:
+	for pattern in ["*", "((a)", "a)"]:
 		print("#", pattern)
 		r = RegexpDFA(pattern)
 		try:
 			r = RegexpDFA(pattern)
 		except ParsingError as e:
 			print("Failed to parse the regexp:")
 			print(e)
 			continue
 		for t in tests:
 			print(t, r.match(t))
 		print()

src/lib.rs

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 mod regexp;
 pub use regexp::Regexp;
+pub use regexp::{Regexp, ParsingError};

src/main.rs

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@@ @@ -2,9 +2,15 @@ use regexp::Regexp; @@
 fn main() {
 	let tests = ["", "a", "ab", "aabb", "abab", "abcd", "abcbcdbcd"];
-	for pattern in ["a*b*", "a+b+", "(ab)*", "(ab)+", "a((bc)*d)*"] {
+	for pattern in ["*", "((a)", "a)", "+a"] {
 		println!("# {pattern}");
 		let r = Regexp::new(&pattern.to_string()).determinize();
 		let r = match Regexp::new(&pattern.to_string()) {
 			Ok(r1) => r1.determinize(),
 			Err(e) => {
 				println!("{e}");
 				continue;
+			}
 		};
 		for &t in tests.iter() {
 			println!("{t} {}", r.eval(t.to_string()));
+		}

src/regexp.rs

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 use std::collections::{HashMap, HashSet};
 mod token;
 pub use token::ParsingError;
 use token::{Token, parse};
 const START: usize = usize::MAX;
@@ @@ -28,14 +29,15 @@ fn decode_set(x: u64) ->HashSet<usize> { @@
 	return res;
+}
 #[derive(Debug)]
 pub struct Regexp {
 	rules: HashMap<(usize, char), HashSet<usize>>,
 	end_states: HashSet<usize>
+}
 impl Regexp {
 	pub fn new(pattern: &String) -> Regexp {
 		let r = parse(pattern, 0);
 	pub fn new(pattern: &String) -> Result<Regexp, ParsingError> {
 		let r = parse(pattern, 0)?;
 		let pattern_chars = Vec::from_iter(pattern.chars());
 		let mut rules: HashMap<(usize, char), HashSet<usize>> = HashMap::new();
@@ @@ -62,7 +64,7 @@ impl Regexp { @@
 			end_states.insert(START);
+		}
 		return Regexp{rules, end_states};
+		return Ok(Regexp{rules, end_states});
+	}
 	pub fn eval(&self, s: String) -> bool {

src/regexp/token.rs

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 use std::fmt;
 #[derive(Debug, Clone)]
 pub enum ParsingError {
 	Asterisk {s: String, pos: usize},
 	Plus {s: String, pos: usize},
 	OpeningParenthesis {s: String, pos: usize},
 	ClosingParenthesis {s: String, pos: usize}
+}
 impl fmt::Display for ParsingError {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		match self {
 			ParsingError::Asterisk {s, pos} => {
 				write!(f, "The asterisk operator is missing an argument. Pattern \"{s}\", position {pos}")
 			},
 			ParsingError::Plus {s, pos} => {
 				write!(f, "The plus operator is missing an argument. Pattern \"{s}\", position {pos}")
 			},
 			ParsingError::OpeningParenthesis {s, pos} => {
 				write!(f, "An opening parenthesis not found. Pattern \"{s}\", position {pos}")
 			},
 			ParsingError::ClosingParenthesis {s, pos} => {
 				write!(f, "An closing parenthesis not found. Pattern \"{s}\", position {pos}")
+			}
+		}
+	}
+}
 pub trait Token {
 	fn is_skippable(&self) -> bool {false}
 	fn list_first(&self) -> Vec<usize>;
@@ @@ -144,7 +173,7 @@ fn find_closing_parenthesis(s: &String) @@
 	return None;
+}
 pub fn parse(pattern: &String, offset: usize) -> Chain {
+pub fn parse(pattern: &String, offset: usize) -> Result<Chain, ParsingError> {
 	let chars: Vec<char> = pattern.chars().collect();
 	let mut res: Vec<Box<dyn Token>> = Vec::new();
 	let mut i = 0;
@@ @@ -152,21 +181,24 @@ pub fn parse(pattern: &String, offset: u @@
 		let c = chars[i];
 		match c {
 			'(' => {
 				let j = find_closing_parenthesis(&pattern[i..].to_string()).unwrap() + i;
 				let inner_content = parse(&pattern[i+1..j].to_string(), offset+i+1);
 				let j = find_closing_parenthesis(&pattern[i..].to_string()).ok_or(ParsingError::ClosingParenthesis {s: pattern.clone(), pos: i})? + i;
 				let inner_content = parse(&pattern[i+1..j].to_string(), offset+i+1)?;
 				res.push(Box::new(inner_content));
 				i = j+1;
+			}
 			'*' => {
-				let token = res.pop().unwrap();
+				let token = res.pop().ok_or(ParsingError::Asterisk{s: pattern.clone(), pos: i})?;
 				res.push(Box::new(Asterisk{content: token}));
 				i += 1;
+			}
 			'+' => {
-				let token = res.pop().unwrap();
+				let token = res.pop().ok_or(ParsingError::Plus{s: pattern.clone(), pos: i})?;
 				res.push(Box::new(Plus{content: token}));
 				i += 1;
+			}
 			')' => {
 				return Err(ParsingError::OpeningParenthesis {s: pattern.clone(), pos: i});
+			}
 			c => {
 				res.push(Box::new(Symbol{position: i+offset, value: c}));
 				i += 1;
@@ @@ -174,7 +206,7 @@ pub fn parse(pattern: &String, offset: u @@
+		}
+	}
 	return Chain{content: res};
+	return Ok(Chain{content: res});
+}
 mod test {

tests/test_regexp.rs

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 use regexp::Regexp;
 use regexp::ParsingError;
 #[test]
 fn test_eval_basic_nfa() {
 	let r = Regexp::new(&String::from("abc"));
+	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")));
@@ @@ -10,7 +11,7 @@ fn test_eval_basic_nfa() { @@
 #[test]
 fn test_eval_basic_dfa() {
 	let r = Regexp::new(&String::from("abc")).determinize();
+	let r = Regexp::new(&String::from("abc")).unwrap().determinize();
 	assert!(r.eval(String::from("abc")));
 	assert!(!r.eval(String::from("ab")));
 	assert!(!r.eval(String::from("abcd")));
@@ @@ -18,22 +19,22 @@ fn test_eval_basic_dfa() { @@
 #[test]
 fn test_eval_empty_nfa() {
 	assert!(Regexp::new(&String::from("a*")).eval(String::from("")));
 	assert!(Regexp::new(&String::from("")).eval(String::from("")));
 	assert!(!Regexp::new(&String::from("")).eval(String::from("a")));
 	assert!(!Regexp::new(&String::from("a")).eval(String::from("")));
 	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*")).determinize().eval(String::from("")));
 	assert!(Regexp::new(&String::from("")).determinize().eval(String::from("")));
 	assert!(!Regexp::new(&String::from("")).determinize().eval(String::from("a")));
 	assert!(Regexp::new(&String::from("a*")).unwrap().determinize().eval(String::from("")));
 	assert!(Regexp::new(&String::from("")).unwrap().determinize().eval(String::from("")));
 	assert!(!Regexp::new(&String::from("")).unwrap().determinize().eval(String::from("a")));
+}
 #[test]
 fn test_eval_asterisk_nfa() {
 	let r = Regexp::new(&String::from("a*b*"));
+	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")));
@@ @@ -42,7 +43,7 @@ fn test_eval_asterisk_nfa() { @@
 #[test]
 fn test_eval_asterisk_dfa() {
 	let r = Regexp::new(&String::from("a*b*")).determinize();
+	let r = Regexp::new(&String::from("a*b*")).unwrap().determinize();
 	assert!(r.eval(String::from("a")));
 	assert!(r.eval(String::from("ab")));
 	assert!(r.eval(String::from("aabb")));
@@ @@ -51,7 +52,7 @@ fn test_eval_asterisk_dfa() { @@
 #[test]
 fn test_eval_plus_nfa() {
 	let r = Regexp::new(&String::from("(ab)+"));
+	let r = Regexp::new(&String::from("(ab)+")).unwrap();
 	assert!(!r.eval(String::from("a")));
 	assert!(r.eval(String::from("ab")));
 	assert!(r.eval(String::from("abab")));
@@ @@ -60,9 +61,33 @@ fn test_eval_plus_nfa() { @@
 #[test]
 fn test_eval_plus_dfa() {
 	let r = Regexp::new(&String::from("(ab)+")).determinize();
+	let r = Regexp::new(&String::from("(ab)+")).unwrap().determinize();
 	assert!(!r.eval(String::from("a")));
 	assert!(r.eval(String::from("ab")));
 	assert!(r.eval(String::from("abab")));
 	assert!(!r.eval(String::from("aabb")));
+}
 #[test]
 fn test_invalid_asterisk() {
 	let x = Regexp::new(&String::from("*"));
 	assert!(matches!(x, Err(ParsingError::Asterisk{s: _, pos: 0})));
+}
 #[test]
 fn test_invalid_plus() {
 	let x = Regexp::new(&String::from("+"));
 	assert!(matches!(x, Err(ParsingError::Plus{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})));
+}

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