Simplify regex

src/manifest/rule.rs

@@ -25,34 +25,26 @@ impl RegexSegment {
 			// Neighboring doublestar is always responsible for slashes
 			(_, Self::Single(x), Some(Self::DoubleStar)) => x.to_owned(),
 
-			// [^/]+ is a "segment" (a block of non-slash chars)
-			// The "base" doublestar pattern is a segment
-			// followed by zero or more segments prefixed by a slash.
-			//
 			// No additional slashes
-			(None, Self::DoubleStar, None) => "((?:[^/]+(?:[/][^/]+)*)?)".into(),
+			(None, Self::DoubleStar, None) => "((?:.*)?)".into(),
+
+			// Leading slash
+			(Some(Self::Single(_)), Self::DoubleStar, None) => "((?:[/].*)?)".into(),
+
+			// Trailing slash
+			(None, Self::DoubleStar, Some(Self::Single(_))) => "((?:.*[/])?)".into(),
+
+			// Leading and trailing slash.
+			// Also, replace self with a [/] when empty.
+			(Some(Self::Single(_)), Self::DoubleStar, Some(Self::Single(_))) => {
+				"((?:[/].*[/])|[/])".into()
+			}
 
 			// Doublestars cannot be neighbors
 			(_, Self::DoubleStar, Some(Self::DoubleStar))
 			| (Some(Self::DoubleStar), Self::DoubleStar, _) => {
 				unreachable!("consecutive doublestars must be reduced")
 			}
-
-			// Leading slash
-			(Some(Self::Single(_)), Self::DoubleStar, None) => {
-				"((?:[/][^/]+(?:[/][^/]+)*)?)".into()
-			}
-
-			// Trailing slash
-			(None, Self::DoubleStar, Some(Self::Single(_))) => {
-				"((?:[^/]+(?:[/][^/]+)*[/])?)".into()
-			}
-
-			// Leading and trailing slash.
-			// Also, replace self with a [/] when empty.
-			(Some(Self::Single(_)), Self::DoubleStar, Some(Self::Single(_))) => {
-				"((?:[/][^/]+(?:[/][^/]+)*[/])|[/])".into()
-			}
 		}
 	}
 }
@@ -301,6 +293,34 @@ mod tests {
 		assert!(!regex.is_match("root/testfile"));
 		assert!(!regex.is_match("root/testxxfile"));
 	}
+
+	#[test]
+	fn doublestar_nullable() {
+		let regex = rule_regex(&["root/**/file"]);
+
+		assert!(regex.is_match("root/test/file"));
+		assert!(regex.is_match("root/file"));
+		assert!(!regex.is_match("rootfile"));
+	}
+
+	#[test]
+	fn doublestar_nullable_post() {
+		let regex = rule_regex(&["root/**"]);
+
+		assert!(regex.is_match("root"));
+		assert!(regex.is_match("root/file"));
+		assert!(!regex.is_match("rootfile"));
+	}
+
+	#[test]
+	fn doublestar_nullable_pre() {
+		let regex = rule_regex(&["**/file"]);
+
+		assert!(regex.is_match("file"));
+		assert!(regex.is_match("root/file"));
+		assert!(!regex.is_match("rootfile"));
+	}
+
 	#[test]
 	fn doublestar_bad_extension() {
 		let regex = rule_regex(&["**.flac"]);