feat: general improvements and minor bugs

Author: ReneSchwarzer

src/WebExpress.WebIndex.Test/WQL/UnitTestWqlWordSearchA.cs

@@ -221,8 +221,9 @@ public void AbstracrSyntaxTree()
         /// Performs the incremental lookahead analysis.
         /// </summary>
         [Theory]
-        [InlineData("", true, 0, WqlExpressionType.None, WqlExpressionType.Attribute, WqlExpressionType.OpenParenthesis)]
+        [InlineData("", true, 1, WqlExpressionType.None, WqlExpressionType.Attribute, WqlExpressionType.OpenParenthesis, WqlExpressionType.Order, WqlExpressionType.PartitioningOperator)]
         [InlineData("(", false, 1, WqlExpressionType.OpenParenthesis, WqlExpressionType.Attribute, WqlExpressionType.OpenParenthesis)]
+        [InlineData("t", false, 1, WqlExpressionType.Attribute, WqlExpressionType.Operator)]
         [InlineData("text", false, 1, WqlExpressionType.Attribute, WqlExpressionType.Operator)]
         [InlineData("text ", false, 1, WqlExpressionType.Attribute, WqlExpressionType.Operator)]
         [InlineData("text #", false, 2, WqlExpressionType.Operator, WqlExpressionType.Operator)]

src/WebExpress.WebIndex/Wql/WqlParser.cs

@@ -191,6 +191,11 @@ private IWqlStatement<TIndexItem> Parse(string input, Queue<WqlToken> tokenQueue
 
             if (string.IsNullOrWhiteSpace(input))
             {
+                ilaQueue.Enqueue(new WqlLookaheadToken(new WqlToken() { Value = "" }, WqlExpressionType.None)
+                {
+                    ExpectedNextTokens = [WqlExpressionType.Attribute, WqlExpressionType.OpenParenthesis, WqlExpressionType.Order, WqlExpressionType.PartitioningOperator]
+                });
+
                 return wql;
             }
 
@@ -494,10 +499,10 @@ private static WqlExpressionLogicalOperator ParseLogicalOperator(Queue<WqlToken>
         /// <returns>The attribute node.</returns>
         private WqlExpressionNodeAttribute<TIndexItem> ParseAttribute(Queue<WqlToken> tokenQueue, Queue<WqlLookaheadToken> ilaQueue)
         {
+            var attributeToken = PeekToken(tokenQueue);
+
             try
             {
-                var attributeToken = PeekToken(tokenQueue);
-
                 if (attributeToken is null)
                 {
                     throw new WqlParseException
@@ -507,11 +512,11 @@ private WqlExpressionNodeAttribute<TIndexItem> ParseAttribute(Queue<WqlToken> to
                     );
                 }
 
+                ReadToken(tokenQueue);
+
                 var path = WqlPropertyPath<TIndexItem>.Parse(attributeToken.Value);
                 var property = path.Resolve(typeof(TIndexItem));
 
-                ReadToken(tokenQueue);
-
                 if (property is not null)
                 {
                     ilaQueue.Enqueue(new WqlLookaheadToken(attributeToken, WqlExpressionType.Attribute)
@@ -537,11 +542,15 @@ private WqlExpressionNodeAttribute<TIndexItem> ParseAttribute(Queue<WqlToken> to
             }
             catch (Exception)
             {
-                throw new WqlParseException
-                (
-                    "webexpress.webindex:wql.attribute_unknown",
-                    []
-                );
+                ilaQueue.Enqueue(new WqlLookaheadToken(attributeToken, WqlExpressionType.Attribute)
+                {
+                    ExpectedNextTokens = [WqlExpressionType.Operator],
+                });
+
+                return new WqlExpressionNodeAttribute<TIndexItem>
+                {
+                    Name = attributeToken.Value
+                };
             }
         }