feat: general improvements and minor bugs

Author: ReneSchwarzer

src/WebExpress.WebIndex/Wql/IWqlParser.cs

@@ -10,6 +10,18 @@ namespace WebExpress.WebIndex.Wql
     public interface IWqlParser<TIndexItem>
         where TIndexItem : IIndexItem
     {
+        /// <summary>
+        /// Performs an incremental lookahead analysis (ILA) over the given
+        /// wql input. The method determines which portion of the input is syntactically 
+        /// valid so far and which tokens would be permissible at the current position.
+        /// </summary>
+        /// <param name="input">The input WQL string.</param>
+        /// <returns>
+        /// An lookahead object that contains the results of the analysis, including 
+        /// valid tokens and expected next tokens.
+        /// </returns>
+        IWqlLookahead Analyze(string input);
+
         /// <summary>
         /// Parses a given wql query.
         /// </summary>

src/WebExpress.WebIndex/Wql/WqlExpressionType.cs

@@ -1,11 +1,35 @@
 namespace WebExpress.WebIndex.Wql
 {
+    /// <summary>
+    /// Specifies the types of expressions that can be used in a WQL 
+    /// (WebExpress Query Language) query.
+    /// </summary>
     public enum WqlExpressionType
     {
+        /// <summary>
+        /// Represents a value that indicates no value or an absence of data.
+        /// </summary>
         None,
+
+        /// <summary>
+        /// Represents an attribute that can be applied to program entities to provide metadata.
+        /// </summary>
         Attribute,
+
+        /// <summary>
+        /// Specifies the logical operators that can be used to combine boolean expressions.
+        /// </summary>
         LogicalOperator,
+
+        /// <summary>
+        /// Defines a custom operator for the type, enabling user-defined behavior for 
+        /// operations such as addition, subtraction, or comparison.
+        /// </summary>
         Operator,
+
+        /// <summary>
+        /// Represents a parameter that can be used in various contexts.
+        /// </summary>
         Parameter
     }
 }

src/WebExpress.WebIndex/Wql/WqlParser.cs

@@ -121,6 +121,10 @@ internal WqlParser(IIndexDocument<TIndexItem> indexFiled)
         /// valid so far and which tokens would be permissible at the current position.
         /// </summary>
         /// <param name="input">The input WQL string.</param>
+        /// <returns>
+        /// An lookahead object that contains the results of the analysis, including 
+        /// valid tokens and expected next tokens.
+        /// </returns>
         public IWqlLookahead Analyze(string input)
         {
             var ilaQueue = new Queue<WqlLookaheadToken>();