Starting WHERE clause parsing in the Linq overhaul

src/LinqTests/playing.cs

@@ -58,7 +58,7 @@ public async Task try_linq()
 
         var targets = await theSession.Query<Target>()
             .OrderBy(x => x.Double)
-            //.Where(x => x.Number == 5)
+            .Where(x => x.Number == 5)
             .Take(5)
             .ToListAsync();
 

src/Marten/Linq/New/CollectionUsage.cs

@@ -39,13 +39,22 @@ public NewStatement BuildStatement(DocumentCollection collection)
             Offset = _offset
         };
 
-        // TODO - Skip, Ordering, Where
+        // TODO - Where
 
         foreach (var ordering in Ordering)
         {
             statement.Ordering.Expressions.Add(ordering.BuildExpression(collection));
         }
 
+        // TODO -- watch for "ANDS"
+        var parser = new WhereClauseParser(collection, statement);
+        foreach (var expression in Wheres)
+        {
+            parser.Visit(expression);
+        }
+
+        // TODO -- have the document storage wrap or using default where fragments
+
 
         return statement;
     }

src/Marten/Linq/New/Fragments/EqualsFragment.cs

@@ -0,0 +1,19 @@
+using Weasel.Postgresql;
+using Weasel.Postgresql.SqlGeneration;
+
+namespace Marten.Linq.New.Fragments;
+
+public record EqualsFragment(string Locator, object Value) : ISqlFragment
+{
+    public void Apply(CommandBuilder builder)
+    {
+        builder.Append(Locator);
+        builder.Append(" = ");
+        builder.AppendParameter(Value);
+    }
+
+    public bool Contains(string sqlText)
+    {
+        return false;
+    }
+}

src/Marten/Linq/New/NewStatement.cs

@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using System.Linq;
-using System.Runtime.Intrinsics.X86;
 using Marten.Linq.SqlGeneration;
 using Weasel.Postgresql;
 using Weasel.Postgresql.SqlGeneration;
@@ -46,9 +45,10 @@ bool ISqlFragment.Contains(string sqlText)
         // TODO -- revisit this later for multi-tenancy searching
         return false;
     }
+
 }
 
-public class NewSelectorStatement : NewStatement
+public class NewSelectorStatement : NewStatement, IWhereFragmentHolder
 {
     //public ISqlFragment FromClause { get; set; }
 
@@ -85,6 +85,13 @@ protected override void apply(CommandBuilder builder)
 
 
     public List<ISqlFragment> Wheres { get; } = new();
+
+    public void Register(ISqlFragment fragment)
+    {
+        Wheres.Add(fragment);
+    }
+
+
     public OrderByFragment Ordering { get; } = new();
 
     // TODO -- this would conceivably overwritten depending on usage of

src/Marten/Linq/New/WhereClauseParser.cs

@@ -0,0 +1,45 @@
+using System.Linq.Expressions;
+using Remotion.Linq.Clauses.Expressions;
+using Remotion.Linq.Parsing;
+using Weasel.Postgresql.SqlGeneration;
+
+namespace Marten.Linq.New;
+
+public class WhereClauseParser : RelinqExpressionVisitor
+{
+    private readonly IQueryableCollection _collection;
+    private readonly IWhereFragmentHolder _holder;
+
+    public WhereClauseParser(IQueryableCollection collection, IWhereFragmentHolder holder)
+    {
+        _collection = collection;
+        _holder = holder;
+    }
+
+    protected override Expression VisitNew(NewExpression expression)
+    {
+        return base.VisitNew(expression);
+    }
+
+    protected override Expression VisitSubQuery(SubQueryExpression expression)
+    {
+        return base.VisitSubQuery(expression);
+    }
+
+    protected override Expression VisitQuerySourceReference(QuerySourceReferenceExpression expression)
+    {
+        return base.VisitQuerySourceReference(expression);
+    }
+
+    protected override Expression VisitBinary(BinaryExpression node)
+    {
+        return base.VisitBinary(node);
+    }
+
+    protected override Expression VisitUnary(UnaryExpression node)
+    {
+        return base.VisitUnary(node);
+    }
+
+
+}

src/Marten/Linq/Parsing/WhereClauseParser.BinarySide.cs

@@ -19,7 +19,7 @@ public BinarySide(Expression memberExpression)
         public IField Field { get; set; }
         public IComparableFragment Comparable { get; set; }
 
-        public Expression MemberExpression { get; }
+        public Expression MemberExpression { get; }s
 
         public ISqlFragment CompareTo(BinarySide right, string op)
         {