Fixes #464 - Incorrect regex usage on extended grapheme clusters

ElementX/Sources/Other/Extensions/NSRegularExpresion.swift

@@ -0,0 +1,40 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+/// NSRegularExpressions work internally on NSStrings, we need to be careful how we build the ranges for extended grapheme clusters https://stackoverflow.com/a/27880748/730924
+extension NSRegularExpression {
+    func enumerateMatches(in string: String, options: NSRegularExpression.MatchingOptions = [], using block: (NSTextCheckingResult?, NSRegularExpression.MatchingFlags, UnsafeMutablePointer<ObjCBool>) -> Void) {
+        enumerateMatches(in: string, options: options, range: .init(location: 0, length: (string as NSString).length), using: block)
+    }
+    
+    func matches(in string: String, options: NSRegularExpression.MatchingOptions = []) -> [NSTextCheckingResult] {
+        matches(in: string, options: options, range: .init(location: 0, length: (string as NSString).length))
+    }
+    
+    func numberOfMatches(in string: String, options: NSRegularExpression.MatchingOptions = []) -> Int {
+        numberOfMatches(in: string, options: options, range: .init(location: 0, length: (string as NSString).length))
+    }
+    
+    func firstMatch(in string: String, options: NSRegularExpression.MatchingOptions = []) -> NSTextCheckingResult? {
+        firstMatch(in: string, options: options, range: .init(location: 0, length: (string as NSString).length))
+    }
+    
+    func rangeOfFirstMatch(in string: String, options: NSRegularExpression.MatchingOptions = []) -> NSRange {
+        rangeOfFirstMatch(in: string, options: options, range: .init(location: 0, length: (string as NSString).length))
+    }
+}

ElementX/Sources/Other/HTMLParsing/AttributedStringBuilder.swift

@@ -132,14 +132,13 @@ struct AttributedStringBuilder: AttributedStringBuilderProtocol {
     
     private func addLinks(_ attributedString: NSMutableAttributedString) {
         let string = attributedString.string
-        let range = NSRange(location: 0, length: attributedString.string.count)
         
-        var matches = MatrixEntityRegex.userIdentifierRegex.matches(in: string, options: [], range: range)
-        matches.append(contentsOf: MatrixEntityRegex.roomIdentifierRegex.matches(in: string, options: [], range: range))
+        var matches = MatrixEntityRegex.userIdentifierRegex.matches(in: string, options: [])
+        matches.append(contentsOf: MatrixEntityRegex.roomIdentifierRegex.matches(in: string, options: []))
         // As of right now we do not handle event id links in any way so there is no need to add them as links
-//        matches.append(contentsOf: MatrixEntityRegex.eventIdentifierRegex.matches(in: string, options: [], range: range))
-        matches.append(contentsOf: MatrixEntityRegex.roomAliasRegex.matches(in: string, options: [], range: range))
-        matches.append(contentsOf: MatrixEntityRegex.linkRegex.matches(in: string, options: [], range: range))
+//        matches.append(contentsOf: MatrixEntityRegex.eventIdentifierRegex.matches(in: string, options: []))
+        matches.append(contentsOf: MatrixEntityRegex.roomAliasRegex.matches(in: string, options: []))
+        matches.append(contentsOf: MatrixEntityRegex.linkRegex.matches(in: string, options: []))
         
         guard matches.count > 0 else {
             return

ElementX/Sources/Other/MatrixEntityRegex.swift

@@ -49,7 +49,7 @@ enum MatrixEntityRegex: String {
     // swiftlint:enable force_try
     
     static func isMatrixHomeserver(_ homeserver: String) -> Bool {
-        guard let match = homeserverRegex.firstMatch(in: homeserver, range: .init(location: 0, length: homeserver.count)) else {
+        guard let match = homeserverRegex.firstMatch(in: homeserver) else {
             return false
         }
         
@@ -57,7 +57,7 @@ enum MatrixEntityRegex: String {
     }
     
     static func isMatrixUserIdentifier(_ identifier: String) -> Bool {
-        guard let match = userIdentifierRegex.firstMatch(in: identifier, range: .init(location: 0, length: identifier.count)) else {
+        guard let match = userIdentifierRegex.firstMatch(in: identifier) else {
             return false
         }
         
@@ -65,7 +65,7 @@ enum MatrixEntityRegex: String {
     }
     
     static func isMatrixRoomAlias(_ alias: String) -> Bool {
-        guard let match = roomAliasRegex.firstMatch(in: alias, range: .init(location: 0, length: alias.count)) else {
+        guard let match = roomAliasRegex.firstMatch(in: alias) else {
             return false
         }
         
@@ -73,7 +73,7 @@ enum MatrixEntityRegex: String {
     }
     
     static func isMatrixRoomIdentifier(_ identifier: String) -> Bool {
-        guard let match = roomIdentifierRegex.firstMatch(in: identifier, range: .init(location: 0, length: identifier.count)) else {
+        guard let match = roomIdentifierRegex.firstMatch(in: identifier) else {
             return false
         }
         
@@ -81,7 +81,7 @@ enum MatrixEntityRegex: String {
     }
         
     static func isMatrixEventIdentifier(_ identifier: String) -> Bool {
-        guard let match = eventIdentifierRegex.firstMatch(in: identifier, range: .init(location: 0, length: identifier.count)) else {
+        guard let match = eventIdentifierRegex.firstMatch(in: identifier) else {
             return false
         }
         

ElementX/Sources/Other/PermalinkBuilder.swift

@@ -56,18 +56,18 @@ enum PermalinkBuilder {
             fragment = String(fragment.dropFirst(1))
         }
         
-        if let userIdentifierRange = MatrixEntityRegex.userIdentifierRegex.firstMatch(in: fragment, range: .init(location: 0, length: fragment.count))?.range {
+        if let userIdentifierRange = MatrixEntityRegex.userIdentifierRegex.firstMatch(in: fragment)?.range {
             return .userIdentifier((fragment as NSString).substring(with: userIdentifierRange))
         }
         
-        if let roomAliasRange = MatrixEntityRegex.roomAliasRegex.firstMatch(in: fragment, range: .init(location: 0, length: fragment.count))?.range {
+        if let roomAliasRange = MatrixEntityRegex.roomAliasRegex.firstMatch(in: fragment)?.range {
             return .roomAlias((fragment as NSString).substring(with: roomAliasRange))
         }
         
-        if let roomIdentifierRange = MatrixEntityRegex.roomIdentifierRegex.firstMatch(in: fragment, range: .init(location: 0, length: fragment.count))?.range {
+        if let roomIdentifierRange = MatrixEntityRegex.roomIdentifierRegex.firstMatch(in: fragment)?.range {
             let roomIdentifier = (fragment as NSString).substring(with: roomIdentifierRange)
             
-            if let eventIdentifierRange = MatrixEntityRegex.eventIdentifierRegex.firstMatch(in: fragment, range: .init(location: 0, length: fragment.count))?.range {
+            if let eventIdentifierRange = MatrixEntityRegex.eventIdentifierRegex.firstMatch(in: fragment)?.range {
                 let eventIdentifier = (fragment as NSString).substring(with: eventIdentifierRange)
                 return .event(roomIdentifier: roomIdentifier, eventIdentifier: eventIdentifier)
             }