From ddd52f169d14da4c8c66d526b07252673bc58a82 Mon Sep 17 00:00:00 2001
From: Alexander Luzgarev <mahalex@gmail.com>
Date: Sun, 1 Apr 2018 16:43:56 +0200
Subject: [PATCH] Parse optional comma(s) after switch expression

---
 Parser/MParser.cs       | 12 +++++++++++-
 Parser/SyntaxFactory.cs |  9 ++++++++-
 Parser/SyntaxNode.cs    |  5 ++++-
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/Parser/MParser.cs b/Parser/MParser.cs
index ea2d15c..6dec931 100644
--- a/Parser/MParser.cs
+++ b/Parser/MParser.cs
@@ -594,6 +594,15 @@ namespace Parser
         {
             var switchKeyword = EatIdentifier("switch");
             var expression = ParseExpression();
+            var commas = new List<TokenNode>();
+            while (CurrentToken.Kind == TokenKind.Comma)
+            {
+                commas.Add(Factory.Token(EatToken()));
+            }
+            if (commas.Count == 0)
+            {
+                commas = null;
+            }
             var casesList = new List<SwitchCaseNode>();
             while (CurrentToken.Kind == TokenKind.Identifier
                    && CurrentToken.PureToken.LiteralText == "case")
@@ -606,7 +615,8 @@ namespace Parser
                 Factory.Token(switchKeyword),
                 expression,
                 casesList,
-                Factory.Token(endKeyword));
+                Factory.Token(endKeyword),
+                commas);
         }
 
         public ExpressionStatementNode ParseExpressionStatement()
diff --git a/Parser/SyntaxFactory.cs b/Parser/SyntaxFactory.cs
index 1d278ca..7c65d14 100644
--- a/Parser/SyntaxFactory.cs
+++ b/Parser/SyntaxFactory.cs
@@ -123,9 +123,15 @@ namespace Parser
             ExpressionNode switchExpression,
             List<SwitchCaseNode> cases,
             TokenNode endKeyword,
+            List<TokenNode> optionalCommasAfterExpression,
             TokenNode semicolonOrComma = null)
         {
             var children = new List<SyntaxNode> { switchKeyword, switchExpression };
+            if (optionalCommasAfterExpression != null)
+            {
+                children.AddRange(optionalCommasAfterExpression);
+            }
+
             children.AddRange(cases);
             children.Add(endKeyword);
             if (semicolonOrComma != null)
@@ -139,7 +145,8 @@ namespace Parser
                 switchExpression,
                 cases,
                 endKeyword,
-                semicolonOrComma);
+                semicolonOrComma,
+                optionalCommasAfterExpression);
             SetParent(result);
             return result;
         }
diff --git a/Parser/SyntaxNode.cs b/Parser/SyntaxNode.cs
index 1c2c69f..57ecadf 100644
--- a/Parser/SyntaxNode.cs
+++ b/Parser/SyntaxNode.cs
@@ -219,6 +219,7 @@ namespace Parser
     {
         public TokenNode SwitchKeyword { get; }
         public ExpressionNode SwitchExpression { get; }
+        public List<TokenNode> OptionalCommasAfterExpression { get; }
         public List<SwitchCaseNode> Cases { get; }
         public TokenNode EndKeyword { get; }
 
@@ -228,11 +229,13 @@ namespace Parser
             ExpressionNode switchExpression,
             List<SwitchCaseNode> cases,
             TokenNode endKeyword,
-            TokenNode semicolonOrComma
+            TokenNode semicolonOrComma,
+            List<TokenNode> optionalCommasAfterExpression = null
             ) : base(children, semicolonOrComma)
         {
             SwitchKeyword = switchKeyword;
             SwitchExpression = switchExpression;
+            OptionalCommasAfterExpression = optionalCommasAfterExpression;
             Cases = cases;
             EndKeyword = endKeyword;
         }