[Swift] Make ATNDeserializationOptions a simple struct.

The previous code was ported from Java, which resulted in 70 lines of code
to hold two bools.  Use a struct instead.

runtime/Swift/Sources/Antlr4/Parser.swift

@@ -12,7 +12,7 @@ import Foundation
 /// This field maps from the serialized ATN string to the deserialized _org.antlr.v4.runtime.atn.ATN_ with
 /// bypass alternatives.
 ///
-/// - SeeAlso: org.antlr.v4.runtime.atn.ATNDeserializationOptions#isGenerateRuleBypassTransitions()
+/// - SeeAlso: `ATNDeserializationOptions.generateRuleBypassTransitions`
 ///
 private var bypassAltsAtnCache = [String: ATN]()
 
@@ -421,9 +421,9 @@ open class Parser: Recognizer<ParserATNSimulator> {
                 return cachedResult
             }
 
-            let deserializationOptions = ATNDeserializationOptions()
-            try! deserializationOptions.setGenerateRuleBypassTransitions(true)
-            let result = try! ATNDeserializer(deserializationOptions).deserialize(Array(serializedAtn))
+            var opts = ATNDeserializationOptions()
+            opts.generateRuleBypassTransitions = true
+            let result = try! ATNDeserializer(opts).deserialize(Array(serializedAtn))
             bypassAltsAtnCache[serializedAtn] = result
             return result
         }

runtime/Swift/Sources/Antlr4/atn/ATN.swift

@@ -40,8 +40,7 @@ public class ATN {
     /// 
     /// For lexer ATNs, this maps the rule index to the resulting token type.
     /// For parser ATNs, this maps the rule index to the generated bypass token
-    /// type if the
-    /// _org.antlr.v4.runtime.atn.ATNDeserializationOptions#isGenerateRuleBypassTransitions_
+    /// type if the `ATNDeserializationOptions.generateRuleBypassTransitions`
     /// deserialization option was specified; otherwise, this is `null`.
     /// 
     public final var ruleToTokenType: [Int]!

runtime/Swift/Sources/Antlr4/atn/ATNDeserializationOptions.swift

@@ -4,73 +4,7 @@
 /// can be found in the LICENSE.txt file in the project root.
 /// 
 
-
-
-/// 
-/// 
-/// -  Sam Harwell
-/// 
-
-public class ATNDeserializationOptions {
-
-    static let defaultOptions: ATNDeserializationOptions = {
-
-        let defaultOptions = ATNDeserializationOptions()
-        defaultOptions.makeReadOnly()
-        return defaultOptions
-
-    }()
-
-
-    private var readOnly: Bool = false
-    private var verifyATN: Bool
-    private var generateRuleBypassTransitions: Bool
-
-    public init() {
-        self.verifyATN = true
-        self.generateRuleBypassTransitions = false
-    }
-
-    public init(_ options: ATNDeserializationOptions) {
-        self.verifyATN = options.verifyATN
-        self.generateRuleBypassTransitions = options.generateRuleBypassTransitions
-    }
-
-
-    public static func getDefaultOptions() -> ATNDeserializationOptions {
-        return defaultOptions
-    }
-
-    public final func isReadOnly() -> Bool {
-        return readOnly
-    }
-
-    public final func makeReadOnly() {
-        readOnly = true
-    }
-
-    public final func isVerifyATN() -> Bool {
-        return verifyATN
-    }
-
-    public final func setVerifyATN(_ verifyATN: Bool) throws {
-        try throwIfReadOnly()
-        self.verifyATN = verifyATN
-    }
-
-    public final func isGenerateRuleBypassTransitions() -> Bool {
-        return generateRuleBypassTransitions
-    }
-
-    public final func setGenerateRuleBypassTransitions(_ generateRuleBypassTransitions: Bool) throws {
-        try throwIfReadOnly()
-        self.generateRuleBypassTransitions = generateRuleBypassTransitions
-    }
-
-    internal func throwIfReadOnly() throws {
-        if isReadOnly() {
-            throw ANTLRError.illegalState(msg: "This object is readonly")
-
-        }
-    }
+public struct ATNDeserializationOptions {
+    public var verifyATN = true
+    public var generateRuleBypassTransitions = false
 }

runtime/Swift/Sources/Antlr4/atn/ATNDeserializer.swift

@@ -60,7 +60,7 @@ public class ATNDeserializer {
     private let deserializationOptions: ATNDeserializationOptions
 
     public init(_ deserializationOptions: ATNDeserializationOptions? = nil) {
-        self.deserializationOptions = deserializationOptions ?? ATNDeserializationOptions.getDefaultOptions()
+        self.deserializationOptions = deserializationOptions ?? ATNDeserializationOptions()
     }
 
     /// 
@@ -667,13 +667,13 @@ public class ATNDeserializer {
 
     private func finalizeATN(_ atn: ATN) throws {
         markPrecedenceDecisions(atn)
-        if deserializationOptions.isVerifyATN() {
+        if deserializationOptions.verifyATN {
             try verifyATN(atn)
         }
-        if deserializationOptions.isGenerateRuleBypassTransitions() && atn.grammarType == ATNType.parser {
+        if deserializationOptions.generateRuleBypassTransitions && atn.grammarType == ATNType.parser {
             try generateRuleBypassTransitions(atn)
 
-            if deserializationOptions.isVerifyATN() {
+            if deserializationOptions.verifyATN {
                 // reverify after modification
                 try verifyATN(atn)
             }