Regular-Expresso Changeset

Changeset - e9496b21cf64

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Laman - 10 months ago 2024-06-20 12:36:50

added the alternative operator

4 files changed with 172 insertions and 5 deletions:

regexp.py

src/main.rs

src/regexp/token.rs

tests/test_regexp.rs

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regexp.py

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@@ @@ -66,6 +66,44 @@ class Asterisk(Plus): @@
 		return str(self.content) + "*"
 class Alternative(Token):
 	def __init__(self, content: list):
 		self.variants = []
 		subsequence = []
 		for token in content:
 			if isinstance(token, AlternativeSeparator):
 				if not subsequence:
 					raise ParsingError("Found an empty Alternative variant.")
 				self.variants.append(Chain(subsequence))
 				subsequence = []
 			else:
 				subsequence.append(token)
 		if not subsequence:
 				raise ParsingError("Found an empty Alternative variant.")
 		self.variants.append(Chain(subsequence))
 	def list_first(self):
 		for x in self.variants:
 			yield from x.list_first()
 	def list_last(self):
 		for x in self.variants:
 			yield from x.list_last()
 	def list_neighbours(self):
 		for x in self.variants:
 			yield from x.list_neighbours()
 	@property
 	def is_skippable(self):
 		return any(x.is_skippable for x in self.variants)
 class AlternativeSeparator:
 	pass
 class Chain(Token):
 	def __init__(self, content: list):
 		self.content = content
@@ @@ -120,6 +158,7 @@ def find_closing_parenthesis(pattern, k) @@
 def parse(pattern, offset=0):
 	res = []
 	is_alternative = False
 	i = 0
 	while i < len(pattern):
@@ @@ -145,11 +184,18 @@ def parse(pattern, offset=0): @@
 			i += 1
 		elif c == ")":
 			raise ParsingError(f'An opening parenthesis not found. Pattern: "{pattern}", position: {i}')
 		elif c == "|":
 			is_alternative = True
 			res.append(AlternativeSeparator())
 			i += 1
 		else:
 			res.append(Symbol(i+offset, c))
 			i += 1
 	return Chain(res)
 	if is_alternative:
 		return Alternative(res)
 	else:
 		return Chain(res)
 class Regexp:

src/main.rs

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@@ @@ -2,7 +2,7 @@ use regexp::Regexp; @@
 fn main() {
 	let tests = ["", "a", "ab", "aabb", "abab", "abcd", "abcbcdbcd"];
-	for pattern in ["*", "((a)", "a)", "+a"] {
+	for pattern in ["a(b|c)", "a*b*", "a+b+", "(ab)*", "(ab)+", "a((bc)*d)*"] {
 		println!("# {pattern}");
 		let r = match Regexp::new(&pattern.to_string()) {
 			Ok(r1) => r1.determinize(),

src/regexp/token.rs

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 use std::fmt;
+use std::{borrow::Borrow, 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}
 	ClosingParenthesis {s: String, pos: usize},
 	EmptyAlternativeVariant
+}
 impl fmt::Display for ParsingError {
@@ @@ -22,6 +23,9 @@ impl fmt::Display for ParsingError { @@
 			},
 			ParsingError::ClosingParenthesis {s, pos} => {
 				write!(f, "An closing parenthesis not found. Pattern \"{s}\", position {pos}")
 			},
 			ParsingError::EmptyAlternativeVariant => {
 				write!(f, "Found an empty Alternative variant.")
+			}
+		}
+	}
@@ @@ -39,6 +43,10 @@ pub struct Plus { @@
 	content: Box<Token>
+}
 pub struct Alternative {
 	content: Vec<Box<Token>>
+}
 pub struct Chain {
 	content: Vec<Box<Token>>
+}
@@ @@ -47,6 +55,8 @@ pub enum Token { @@
 	Symbol(Symbol),
 	Asterisk(Asterisk),
 	Plus(Plus),
 	Alternative(Alternative),
 	AlternativeSeparator,
 	Chain(Chain)
+}
@@ @@ -108,6 +118,61 @@ impl Plus { @@
+	}
+}
 impl Alternative {
 	fn new(content: Vec<Box<Token>>) -> Result<Alternative, ParsingError> {
 		let mut variants: Vec<Vec<Box<Token>>> = vec![Vec::new()];
 		content.into_iter().for_each(|x| {
 			if matches!(x.borrow(), Token::AlternativeSeparator) {
 				variants.push(Vec::new());
 			} else {
 				variants.last_mut().unwrap().push(x);
+			}
 		});
 		if variants.iter().any(|x| x.is_empty()) {
 			return Err(ParsingError::EmptyAlternativeVariant);
+		}
 		return Ok(Alternative{
 			content: variants.into_iter().map(
 				|x| Box::new(Token::Chain(Chain{content: x}))
 			).collect()
 		});
+	}
 	fn is_skippable(&self) -> bool {
 			return self.content.iter().any(|x| x.is_skippable());
+	}
 	fn list_first(&self) -> Vec<usize> {
 		let mut res = Vec::new();
 		for token in self.content.iter() {
 			res.append(&mut token.list_first());
+		}
 		return res;
+	}
 	fn list_last(&self) -> Vec<usize> {
 		let mut res = Vec::new();
 		for token in self.content.iter() {
 			res.append(&mut token.list_last());
+		}
 		return res;
+	}
 	fn list_neighbours(&self) -> Vec<(usize, usize)> {
 		let mut res = Vec::new();
 		for token in self.content.iter() {
 			res.append(&mut token.list_neighbours());
+		}
 		return res;
+	}
+}
 impl Chain {
 	fn is_skippable(&self) -> bool {
 		return self.content.iter().all(|x| x.is_skippable());
@@ @@ -163,6 +228,8 @@ impl Token { @@
 			Token::Symbol(_) => false,
 			Token::Asterisk(_) => true,
 			Token::Plus(_) => false,
 			Token::Alternative(t) => t.is_skippable(),
 			Token::AlternativeSeparator => panic!(),
 			Token::Chain(t) => t.is_skippable()
+		}
+	}
@@ @@ -172,6 +239,8 @@ impl Token { @@
 			Token::Symbol(t) => t.list_first(),
 			Token::Asterisk(t) => t.list_first(),
 			Token::Plus(t) => t.list_first(),
 			Token::Alternative(t) => t.list_first(),
 			Token::AlternativeSeparator => panic!(),
 			Token::Chain(t) => t.list_first()
+		}
+	}
@@ @@ -181,6 +250,8 @@ impl Token { @@
 			Token::Symbol(t) => t.list_last(),
 			Token::Asterisk(t) => t.list_last(),
 			Token::Plus(t) => t.list_last(),
 			Token::Alternative(t) => t.list_last(),
 			Token::AlternativeSeparator => panic!(),
 			Token::Chain(t) => t.list_last()
+		}
+	}
@@ @@ -190,6 +261,8 @@ impl Token { @@
 			Token::Symbol(t) => t.list_neighbours(),
 			Token::Asterisk(t) => t.list_neighbours(),
 			Token::Plus(t) => t.list_neighbours(),
 			Token::Alternative(t) => t.list_neighbours(),
 			Token::AlternativeSeparator => panic!(),
 			Token::Chain(t) => t.list_neighbours()
+		}
+	}
@@ @@ -211,6 +284,7 @@ fn find_closing_parenthesis(s: &String) @@
 pub fn parse(pattern: &String, offset: usize) -> Result<Token, ParsingError> {
 	let chars: Vec<char> = pattern.chars().collect();
 	let mut res: Vec<Box<Token>> = Vec::new();
 	let mut is_alternative = false;
 	let mut i = 0;
 	while i < pattern.len() {
 		let c = chars[i];
@@ @@ -234,6 +308,11 @@ pub fn parse(pattern: &String, offset: u @@
 			')' => {
 				return Err(ParsingError::OpeningParenthesis {s: pattern.clone(), pos: i});
+			}
 			'|' => {
 				is_alternative = true;
 				res.push(Box::new(Token::AlternativeSeparator));
 				i += 1;
+			}
 			_c => {
 				res.push(Box::new(Token::Symbol(Symbol{position: i+offset})));
 				i += 1;
@@ @@ -241,7 +320,11 @@ pub fn parse(pattern: &String, offset: u @@
+		}
+	}
 	return Ok(Token::Chain(Chain{content: res}));
 	if is_alternative {
 		return Ok(Token::Alternative(Alternative::new(res)?));
 	} else {
 		return Ok(Token::Chain(Chain{content: res}));
+	}
+}
 mod test {

tests/test_regexp.rs

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@@ @@ -69,6 +69,26 @@ fn test_eval_plus_dfa() { @@
+}
 #[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();
 	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_invalid_asterisk() {
 	let x = Regexp::new(&String::from("*"));
 	assert!(matches!(x, Err(ParsingError::Asterisk{s: _, pos: 0})));
@@ @@ -91,3 +111,21 @@ fn test_invalid_opening_parenthesis() { @@
 	let x = Regexp::new(&String::from("a)"));
 	assert!(matches!(x, Err(ParsingError::OpeningParenthesis{s: _, pos: 1})));
+}
 #[test]
 fn test_invalid_empty_variant_start() {
 	let x = Regexp::new(&String::from("a(|b)"));
 	assert!(matches!(x, Err(ParsingError::EmptyAlternativeVariant)));
+}
 #[test]
 fn test_invalid_empty_variant_end() {
 	let x = Regexp::new(&String::from("a|"));
 	assert!(matches!(x, Err(ParsingError::EmptyAlternativeVariant)));
+}
 #[test]
 fn test_invalid_empty_variant_middle() {
 	let x = Regexp::new(&String::from("a||b"));
 	assert!(matches!(x, Err(ParsingError::EmptyAlternativeVariant)));
+}

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