Replace Instances of `NSRegularExpression` with static instances (creating an instance of NSRegularExpression requires a lot of resources)

AlphaWallet/Browser/Types/BrowserURLParser.swift

@@ -3,7 +3,7 @@
 import Foundation
 
 final class BrowserURLParser {
-    private let urlRegEx = try! NSRegularExpression(pattern: "^(http(s)?://)?[a-z0-9-_]+(\\.[a-z0-9-_]+)+(/)?", options: .caseInsensitive)
+    private static let urlRegEx = try? NSRegularExpression(pattern: "^(http(s)?://)?[a-z0-9-_]+(\\.[a-z0-9-_]+)+(/)?", options: .caseInsensitive)
     private let validSchemes = ["http", "https"]
     let engine: SearchEngine
 
@@ -15,8 +15,9 @@ final class BrowserURLParser {
 
     /// Determines if a string is an address or a search query and returns the appropriate URL.
     func url(from string: String) -> URL? {
+        guard let regex = BrowserURLParser.urlRegEx else { return nil }
         let range = NSRange(string.startIndex ..< string.endIndex, in: string)
-        if urlRegEx.firstMatch(in: string, options: .anchored, range: range) != nil {
+        if regex.firstMatch(in: string, options: .anchored, range: range) != nil {
             if !validSchemes.contains(where: { string.hasPrefix("\($0)://") }) {
                 return URL(string: "http://" + string)
             } else {

AlphaWallet/TokenScriptClient/Models/GeneralisedTime.swift

@@ -47,11 +47,10 @@ struct GeneralisedTime: Codable {
         self.date = date
         self.timeZone = timeZone
     }
-
+    private static let regex = try? NSRegularExpression(pattern: "([+-])(\\d\\d)(\\d\\d)$", options: [])
     /// Given "20180619210000+0300", extract "+0300" and convert to seconds
     private static func extractTimeZoneSecondsFromGMT(string: String) -> Int? {
-        let pattern = "([+-])(\\d\\d)(\\d\\d)$"
-        guard let regex = try? NSRegularExpression(pattern: pattern, options: []) else { return nil }
+        guard let regex = GeneralisedTime.regex else { return nil }
         let matches = regex.matches(in: string, options: [], range: NSRange(location: 0, length: string.count))
         guard matches.count == 1 else { return nil }
         guard matches[0].numberOfRanges == 4 else { return nil }

AlphaWallet/TokenScriptClient/Models/TokenScriptFilterParser.swift

@@ -452,12 +452,12 @@ struct TokenScriptFilterParser {
             guard let interpolatedValue = interpolate(value: value) else { return nil }
             return op.isTrueFor(attributeValue: attributeValue, value: interpolatedValue)
         }
-
+        private static let regex = try? NSRegularExpression(pattern: "\\$\\{(?<attribute>[a-zA-Z][a-zA-Z0-9]*)\\}", options: [])
         //TODO replace the very dumb regex for now. And also recursively interpolates (not good). Should involve parser
         private func interpolate(value: String) -> String? {
             var value = value
             repeat {
-                guard let regex = try? NSRegularExpression(pattern: "\\$\\{(?<attribute>[a-zA-Z][a-zA-Z0-9]*)\\}", options: []) else { return nil }
+                guard let regex = Parser.regex else { return nil }
                 let range = NSRange(value.startIndex ..< value.endIndex, in: value)
                 let matches = regex.matches(in: value, options: [], range: range)
                 guard matches.count >= 1 else { return value }

AlphaWallet/TokenScriptClient/Models/XMLHandler.swift

@@ -655,11 +655,11 @@ private class PrivateXMLHandler {
         ]
         return .init(namespacePrefix: rootNamespacePrefix, namespaces: namespaces, lang: lang)
     }
-
+    private static let regex = try? NSRegularExpression(pattern: "<\\!ENTITY\\s+(.*)\\s+SYSTEM\\s+\"(.*)\">", options: [])
     fileprivate static func getEntities(inXml xml: String) -> [TokenScriptFileIndices.Entity] {
         var entities = [TokenScriptFileIndices.Entity]()
-        let pattern = "<\\!ENTITY\\s+(.*)\\s+SYSTEM\\s+\"(.*)\">"
-        if let regex = try? NSRegularExpression(pattern: pattern, options: []) {
+
+        if let regex = Self.regex {
             regex.enumerateMatches(in: xml, options: [], range: .init(xml.startIndex..<xml.endIndex, in: xml)) { match, _, _ in
                 guard let match = match else { return }
                 guard match.numberOfRanges == 3 else { return }
@@ -986,4 +986,4 @@ public class XMLHandler {
             return overrides
         }
     }
-}
+}

AlphaWallet/UI/Form/PrivateKeyValidator.swift

@@ -8,6 +8,7 @@ struct ValidationError: Error {
 
 struct PrivateKeyValidator {
     private let validationError: ValidationError
+    private static let regex = try? NSRegularExpression(pattern: "^[0-9a-fA-F]{64}$")
 
     init(msg: String = R.string.localizable.importWalletImportInvalidPrivateKey()) {
         validationError = ValidationError(msg: msg)
@@ -16,7 +17,7 @@ struct PrivateKeyValidator {
     func isValid(value: String) -> ValidationError? {
         //allows for private key import to have 0x or not
         let drop0xKey = value.drop0x
-        let regex = try! NSRegularExpression(pattern: "^[0-9a-fA-F]{64}$")
+        guard let regex = PrivateKeyValidator.regex else { return nil }
         let range = NSRange(location: 0, length: drop0xKey.utf16.count)
         let result = regex.matches(in: drop0xKey, range: range)
         let matched = !result.isEmpty