1 files changed, 22 insertions, 2 deletions
diff --git a/source/slang/lexer.h b/source/slang/lexer.h
index 593e07c22..8587cc904 100644
--- a/source/slang/lexer.h
+++ b/source/slang/lexer.h
@@ -38,18 +38,37 @@ namespace Slang
 
     struct TokenReader
     {
+        Token nextToken;
         TokenReader();
         explicit TokenReader(TokenSpan const& tokens)
             : mCursor(tokens.begin())
             , mEnd   (tokens.end  ())
+            , nextToken(tokens.begin() ? *tokens.begin() : GetEndOfFileToken())
         {}
         explicit TokenReader(TokenList const& tokens)
             : mCursor(tokens.begin())
             , mEnd   (tokens.end  ())
+            , nextToken(tokens.begin() ? *tokens.begin() : GetEndOfFileToken())
         {}
-
+        struct ParsingCursor
+        {
+            Token nextToken;
+            Token* tokenReaderCursor = nullptr;
+        };
+        ParsingCursor getCursor()
+        {
+            ParsingCursor rs;
+            rs.nextToken = nextToken;
+            rs.tokenReaderCursor = mCursor;
+            return rs;
+        }
+        void setCursor(ParsingCursor cursor)
+        {
+            mCursor = cursor.tokenReaderCursor;
+            nextToken = cursor.nextToken;
+        }
         bool IsAtEnd() const { return mCursor == mEnd; }
-        Token PeekToken() const;
+        Token& PeekToken();
         TokenType PeekTokenType() const;
         SourceLoc PeekLoc() const;
 
@@ -59,6 +78,7 @@ namespace Slang
 
         Token* mCursor;
         Token* mEnd;
+        static Token GetEndOfFileToken();
     };
 
     typedef unsigned int LexerFlags;