diff --git a/swift/swift5/Cpp/SwiftSupport.cpp b/swift/swift5/Cpp/SwiftSupport.cpp
index 56e5ef7535..200e5a1971 100644
--- a/swift/swift5/Cpp/SwiftSupport.cpp
+++ b/swift/swift5/Cpp/SwiftSupport.cpp
@@ -146,8 +146,8 @@ SwiftSupport::OperatorCharacter::OperatorCharacter()
 SwiftSupport::LeftWS::LeftWS() {
     set(Swift5Parser::WS);
     set(Swift5Parser::LPAREN);
-    set(Swift5Parser::Interpolataion_multi_line);
-    set(Swift5Parser::Interpolataion_single_line);
+    set(Swift5Parser::Interpolation_multi_line);
+    set(Swift5Parser::Interpolation_single_line);
     set(Swift5Parser::LBRACK);
     set(Swift5Parser::LCURLY);
     set(Swift5Parser::COMMA);
@@ -248,6 +248,10 @@ bool SwiftSupport::isBinaryOp(antlr4::TokenStream* tokens) {
     bool nextIsWS = isRightOperatorWS(nextToken);
     //String text = tokens.getText(Interval.of(start, stop));
     //System.out.println("isBinaryOp: '"+prevToken+"','"+text+"','"+nextToken+"' is "+result);
+    // accept only '??'' as binary operator
+    if (currentToken->getType() == Swift5Lexer::QUESTION && start == stop) {
+        return false;
+    }
     if (prevIsWS) {
         return nextIsWS;
     } else {
diff --git a/swift/swift5/Java/SwiftSupport.java b/swift/swift5/Java/SwiftSupport.java
index 952516a85c..878c055f0a 100644
--- a/swift/swift5/Java/SwiftSupport.java
+++ b/swift/swift5/Java/SwiftSupport.java
@@ -133,8 +133,8 @@ To use it in the ternary conditional (? :) operator, it must have
 
         leftWS.set(Swift5Parser.WS);
         leftWS.set(Swift5Parser.LPAREN);
-        leftWS.set(Swift5Parser.Interpolataion_multi_line);
-        leftWS.set(Swift5Parser.Interpolataion_single_line);
+        leftWS.set(Swift5Parser.Interpolation_multi_line);
+        leftWS.set(Swift5Parser.Interpolation_single_line);
         leftWS.set(Swift5Parser.LBRACK);
         leftWS.set(Swift5Parser.LCURLY);
         leftWS.set(Swift5Parser.COMMA);
@@ -252,6 +252,10 @@ public static boolean isBinaryOp(TokenStream tokens) {
         boolean nextIsWS = isRightOperatorWS(nextToken);
         //String text = tokens.getText(Interval.of(start, stop));
         //System.out.println("isBinaryOp: '"+prevToken+"','"+text+"','"+nextToken+"' is "+result);
+        // accept only '??'' as binary operator
+        if (currentToken.getType() == Swift5Lexer.QUESTION && start == stop) {
+            return false;
+        }
         if (prevIsWS) {
             return nextIsWS;
         } else {
diff --git a/swift/swift5/Swift5Lexer.g4 b/swift/swift5/Swift5Lexer.g4
index a4622936ec..ba66caf004 100644
--- a/swift/swift5/Swift5Lexer.g4
+++ b/swift/swift5/Swift5Lexer.g4
@@ -151,6 +151,8 @@ HASH_IMAGE_LITERAL : '#imageLiteral';
 GETTER             : 'getter';
 SETTER             : 'setter';
 
+UNDERSCORE : '_';
+
 Identifier:
     Identifier_head Identifier_characters?
     | Implicit_parameter_name
@@ -249,7 +251,6 @@ COLON      : ':';
 SEMI       : ';';
 LT         : '<';
 GT         : '>';
-UNDERSCORE : '_';
 BANG       : '!';
 QUESTION   : '?';
 AT         : '@';
@@ -346,7 +347,7 @@ Single_line_string_open: '"' -> pushMode(SingleLine);
 
 mode SingleLine;
 
-Interpolataion_single_line: '\\(' { parenthesis.push(1);} -> pushMode(DEFAULT_MODE);
+Interpolation_single_line: '\\(' { parenthesis.push(1);} -> pushMode(DEFAULT_MODE);
 
 Single_line_string_close: '"' -> popMode;
 
@@ -354,7 +355,7 @@ Quoted_single_line_text: Quoted_text;
 
 mode MultiLine;
 
-Interpolataion_multi_line: '\\(' {parenthesis.push(1); } -> pushMode(DEFAULT_MODE);
+Interpolation_multi_line: '\\(' {parenthesis.push(1); } -> pushMode(DEFAULT_MODE);
 
 Multi_line_string_close: '"""' -> popMode;
 
diff --git a/swift/swift5/Swift5Parser.g4 b/swift/swift5/Swift5Parser.g4
index 9f6f930fdb..e43b7cd375 100644
--- a/swift/swift5/Swift5Parser.g4
+++ b/swift/swift5/Swift5Parser.g4
@@ -1186,7 +1186,7 @@ closure_parameter_list
     ;
 
 closure_parameter
-    : closure_parameter_name = identifier (type_annotation range_operator?)?
+    : UNDERSCORE? closure_parameter_name = identifier (type_annotation range_operator?)?
     ;
 
 capture_list
@@ -1326,7 +1326,7 @@ forced_value_suffix
     ;
 
 optional_chaining_suffix
-    : {!this.isBinaryOp(_input)}? QUESTION
+    : {!this.isBinaryOp(_input) && _input.get(_input.index()-1).getType()!=WS}? QUESTION
     ;
 
 // Function Call Expression
@@ -1565,6 +1565,7 @@ identifier
         | SELF_BIG
         | SET
         | CLASS
+        | STRUCT
         | GETTER
         | SETTER
         | OPERATOR
@@ -1573,6 +1574,7 @@ identifier
     )
     | Identifier
     | BACKTICK (keyword | Identifier | DOLLAR) BACKTICK
+    | UNDERSCORE
     ;
 
 identifier_list
@@ -1810,10 +1812,10 @@ static_string_literal
 interpolated_string_literal
     : Single_line_string_open (
         Quoted_single_line_text
-        | Interpolataion_single_line (expression | tuple_element COMMA tuple_element_list) RPAREN
+        | Interpolation_single_line (expression | tuple_element COMMA tuple_element_list) RPAREN
     )* Single_line_string_close
     | Multi_line_string_open (
         Quoted_multi_line_text
-        | Interpolataion_multi_line (expression | tuple_element COMMA tuple_element_list) RPAREN
+        | Interpolation_multi_line (expression | tuple_element COMMA tuple_element_list) RPAREN
     )* Multi_line_string_close
     ;
\ No newline at end of file
diff --git a/swift/swift5/examples/Functions and Closures/Contents.swift b/swift/swift5/examples/Functions and Closures/Contents.swift
index 413e350839..4a659ea9fc 100644
--- a/swift/swift5/examples/Functions and Closures/Contents.swift	
+++ b/swift/swift5/examples/Functions and Closures/Contents.swift	
@@ -98,6 +98,27 @@ print(mappedNumbers)
 let sortedNumbers = numbers.sorted { $0 > $1 }
 print(sortedNumbers)
 
+// : Accepts trailing closure with 2 string parameters and call it
+func printTwoStrings(_ closure: (String, String) -> Void) {
+    closure("Hello", "World")
+}
+
+//: Closure parameter name with an underscore before (closures don't have external parameter names, but underscore is allowed) 
+printTwoStrings { (_ x: String, _ y: String) in
+    print(x, y)
+}
+
+// : Accepts 'struct' as external parameter name
+public func create<T>(struct s: T) {
+    print(s)
+}
+
+create(struct: 1)
+
+// : Return expression with two QUESTION tokens
+public func GetString<T>(_ s: T, _ val: Int) -> String? {
+    return val == 0 ? s as? String : nil
+}
 
 
 //: [Previous](@previous) | [Next](@next)
\ No newline at end of file