Merge pull request #22 from frzi/fix/invalid-regex-patterns

Fix/invalid regex patterns

README.md

@@ -63,7 +63,8 @@ Route(path: "user/:id?") { info in
 A view that will only render its contents if its path matches that of the environment. Use `/*` to also match deeper paths. E.g.: the path `news/*` will match the following environment paths: `/news`, `/news/latest`, `/news/article/1` etc.
 
 #### Parameters
-Paths can contain parameters (aka variables) that can be read individually. A parameter's name is prefixed with a colon (`:`). Additionally, a parameter can be considered optional by suffixing it with a question mark (`?`). The parameters are passed down as a `[String : String]` in an `RouteInformation` object to a `Route`'s contents.
+Paths can contain parameters (aka placeholders) that can be read individually. A parameter's name is prefixed with a colon (`:`). Additionally, a parameter can be considered optional by suffixing it with a question mark (`?`). The parameters are passed down as a `[String : String]` in an `RouteInformation` object to a `Route`'s contents.  
+**Note**: Parameters may only exist of alphanumeric characters (A-Z, a-z and 0-9) and *must* start with a letter.
 
 #### Parameter validation
 ```swift
@@ -141,4 +142,4 @@ This object is passed down by default in a `Route` to its contents. It's also ac
 <br>
 
 ## License 📄
-[MIT License](LICENSE).
+[MIT License](LICENSE).

Sources/Route.swift

@@ -16,6 +16,19 @@ import SwiftUI
 /// }
 /// ```
 ///
+/// ## Path parameters (aka placeholders)
+/// Paths may contain one or several parameters. Parameters are placeholders that will be replaced by the
+/// corresponding component of the matching path. Parameters are prefixed with a colon (:). The values of the
+/// parameters are provided via the `RouteInformation` object passed to the contents of the `Route`.
+/// Parameters can be marked as optional by postfixing them with a question mark (?).
+///
+/// **Note:** Only alphanumeric characters (A-Z, a-z, 0-9) are valid for parameters.
+/// ```swift
+/// Route("/news/:id") { routeInfo in
+/// 	NewsItemView(id: routeInfo.parameters["id"]!)
+/// }
+/// ```
+///
 /// ## Validation and parameter transform
 /// `Route`s are given the opportunity to add an extra layer of validation. Use the `validator` argument to pass
 /// down a validator function. This function is given a `RouteInformation` object, containing the path parameters.
@@ -82,16 +95,21 @@ public struct Route<ValidatedData, Content: View>: View {
 		var routeInformation: RouteInformation?
 
 		if !switchEnvironment.isActive || (switchEnvironment.isActive && !switchEnvironment.isResolved) {
-			if let matchInformation = try? pathMatcher.match(glob: resolvedGlob, with: navigator.path),
-			   let validated = validator(matchInformation)
-			{
-				validatedData = validated
-				routeInformation = matchInformation
-
-				if switchEnvironment.isActive {
-					switchEnvironment.isResolved = true
+			do {
+				if let matchInformation = try pathMatcher.match(glob: resolvedGlob, with: navigator.path),
+				   let validated = validator(matchInformation)
+				{
+					validatedData = validated
+					routeInformation = matchInformation
+
+					if switchEnvironment.isActive {
+						switchEnvironment.isResolved = true
+					}
 				}
 			}
+			catch {
+				fatalError("Unable to compile path glob '\(path)' to Regex. Error: \(error)")
+			}
 		}
 
 		return Group {
@@ -155,6 +173,14 @@ final class PathMatcher: ObservableObject {
 		let matchRegex: NSRegularExpression
 		let parameters: Set<String>
 	}
+
+	private enum CompileError: Error {
+		case badParameter(String, culprit: String)
+	}
+
+	private static let variablesRegex = try! NSRegularExpression(pattern: #":([^\/\?]+)"#, options: [])
+
+	//
 
 	private var cached: CompiledRegex?
 
@@ -169,12 +195,21 @@ final class PathMatcher: ObservableObject {
 		var variables = Set<String>()
 
 		let nsrange = NSRange(glob.startIndex..<glob.endIndex, in: glob)
-		let variablesRegex = try NSRegularExpression(pattern: #":([^\/\?]+)"#, options: [])
-		let variableMatches = variablesRegex.matches(in: glob, options: [], range: nsrange)
+		let variableMatches = Self.variablesRegex.matches(in: glob, options: [], range: nsrange)
 
 		for match in variableMatches where match.numberOfRanges > 1 {
 			if let range = Range(match.range(at: 1), in: glob) {
-				variables.insert(String(glob[range]))
+				let variable = String(glob[range])
+
+				#if DEBUG
+				// In debug mode perform an extra check whether parameters contain invalid characters or
+				// whether the parameters starts with something besides a letter.
+				if let r = variable.range(of: "(^[^a-z]|[^a-z0-9])", options: [.regularExpression, .caseInsensitive]) {
+					throw CompileError.badParameter(variable, culprit: String(variable[r]))
+				}
+				#endif
+
+				variables.insert(variable)
 			}
 		}
 
@@ -201,7 +236,7 @@ final class PathMatcher: ObservableObject {
 
 		return cached!
 	}
-	
+
 	func match(glob: String, with path: String) throws -> RouteInformation? {
 		let compiled = try compileRegex(glob)
 
@@ -236,9 +271,6 @@ final class PathMatcher: ObservableObject {
 
 		let resolvedGlob = String(path[range])
 
-		return RouteInformation(
-			path: resolvedGlob,
-			parameters: parameterValues
-		)
+		return RouteInformation(path: resolvedGlob, parameters: parameterValues)
 	}
 }

Tests/SwiftUIRouterTests/SwiftUIRouterTests.swift

@@ -148,7 +148,8 @@ final class SwiftUIRouterTests: XCTestCase {
 			"/:id?",
 			"/:id1/:id2",
 			"/:id1/:id2?",
-			"/:id/*",
+			"/:Movie/*",
+			"/:i", // Single character.
 		]
 
 		for glob in goodGlobs {
@@ -157,6 +158,21 @@ final class SwiftUIRouterTests: XCTestCase {
 				"Glob \(glob) causes bad Regex." 
 			)
 		}
+
+		// These bad globs should throw at Regex compilation.
+		let badGlobs: [String] = [
+			"/:0abc", // Starting with numerics.
+			"/:user-id", // Illegal characters.
+			"/:foo_bar",
+			"/:😀"
+		]
+
+		for glob in badGlobs {
+			XCTAssertThrowsError(
+				try pathMatcher.match(glob: glob, with: ""),
+				"Glob \(glob) should've thrown an error, but didn't."
+			)
+		}
 	}
 
 	/// Test the `Navigator.navigate()` method.