Lazy initialisation of LinkedList in TokenOperations constructor -> 7% performance gain for formatter (#1453)

* Lazy initialisation of LinkedList in TokenOperations constructor -> 7% performance gain
Also remove unused method

* remove another unused function

Co-authored-by: Christoph Bergmeister <christoph.bergmeister@bjss.com>

Author: bergmeister

Engine/TokenOperations.cs

@@ -15,7 +15,7 @@ namespace Microsoft.Windows.PowerShell.ScriptAnalyzer
     public class TokenOperations
     {
         private readonly Token[] tokens;
-        private LinkedList<Token> tokensLL;
+        private readonly Lazy<LinkedList<Token>> tokensLL;
         private readonly Ast ast;
 
         public Ast Ast { get { return ast; } }
@@ -39,7 +39,7 @@ public TokenOperations(Token[] tokens, Ast ast)
 
             this.tokens = tokens;
             this.ast = ast;
-            this.tokensLL = new LinkedList<Token>(this.tokens);
+            this.tokensLL = new Lazy<LinkedList<Token>>(() => new LinkedList<Token>(this.tokens));
         }
 
         /// <summary>
@@ -150,68 +150,6 @@ private IEnumerable<Token> GetBraceInCommandElement(TokenKind tokenKind)
             }
         }
 
-        public IEnumerable<Token> GetCloseBraceInOneLineIfStatement()
-        {
-            return GetBraceInOneLineIfStatment(TokenKind.RCurly);
-        }
-
-        public IEnumerable<Token> GetOpenBraceInOneLineIfStatement()
-        {
-            return GetBraceInOneLineIfStatment(TokenKind.LCurly);
-        }
-
-        // TODO Fix code duplication in the following method and GetBraceInCommandElement
-        private IEnumerable<Token> GetBraceInOneLineIfStatment(TokenKind tokenKind)
-        {
-            var ifStatementAsts = ast.FindAll(ast =>
-            {
-                var ifAst = ast as IfStatementAst;
-                if (ifAst == null)
-                {
-                    return false;
-                }
-
-                return ifAst.Extent.StartLineNumber == ifAst.Extent.EndLineNumber;
-            },
-            true);
-
-            if (ifStatementAsts == null)
-            {
-                yield break;
-            }
-
-            var braceTokens = new List<Token>();
-            foreach (var ast in ifStatementAsts)
-            {
-                var ifStatementAst = ast as IfStatementAst;
-                foreach (var clause in ifStatementAst.Clauses)
-                {
-                    var tokenIf
-                        = tokenKind == TokenKind.LCurly
-                            ? GetTokens(clause.Item2).FirstOrDefault()
-                            : GetTokens(clause.Item2).LastOrDefault();
-                    if (tokenIf != null)
-                    {
-                        yield return tokenIf;
-                    }
-                }
-
-                if (ifStatementAst.ElseClause == null)
-                {
-                    continue;
-                }
-
-                var tokenElse
-                    = tokenKind == TokenKind.LCurly
-                            ? GetTokens(ifStatementAst.ElseClause).FirstOrDefault()
-                            : GetTokens(ifStatementAst.ElseClause).LastOrDefault();
-                if (tokenElse != null)
-                {
-                    yield return tokenElse;
-                }
-            }
-        }
-
         public static IEnumerable<Token> GetTokens(Ast outerAst, Ast innerAst, Token[] outerTokens)
         {
             ThrowIfNull(outerAst, nameof(outerAst));
@@ -262,7 +200,7 @@ public IEnumerable<LinkedListNode<Token>> GetTokenNodes(TokenKind kind)
 
         public IEnumerable<LinkedListNode<Token>> GetTokenNodes(Func<Token, bool> predicate)
         {
-            var token = tokensLL.First;
+            var token = tokensLL.Value.First;
             while (token != null)
             {
                 if (predicate(token.Value))
@@ -290,21 +228,6 @@ private IEnumerable<Tuple<Token, int>> GetTokenAndPrecedingWhitespace(TokenKind
             }
         }
 
-        public IEnumerable<Tuple<Token, int>> GetOpenBracesWithWhiteSpacesBefore()
-        {
-            return GetTokenAndPrecedingWhitespace(TokenKind.LCurly);
-        }
-
-        public IEnumerable<Tuple<Token, int>> GetOpenParensWithWhiteSpacesBefore()
-        {
-            return GetTokenAndPrecedingWhitespace(TokenKind.LParen);
-        }
-
-        public static int GetExtentWidth(IScriptExtent extent)
-        {
-            return extent.EndOffset - extent.StartOffset;
-        }
-
         private bool OnSameLine(Token token1, Token token2)
         {
             return token1.Extent.StartLineNumber == token2.Extent.EndLineNumber;