Implemented the modulus operator.

Author: RyanLamansky

SqlServerSimulator.Tests/SelectTests.cs

@@ -58,6 +58,9 @@ public void SelectParameterValue(string commandText, string name, object value)
     [DataRow("2 * 2", 4)]
     [DataRow("2 / 2", 1)]
     [DataRow("2 / 1", 2)]
+    [DataRow("5 % 2", 1)]
+    [DataRow("5 % 3", 2)]
+    [DataRow("5 % 5", 0)]
     [DataRow("1 & 3", 1)]
     [DataRow("1 | 3", 3)]
     [DataRow("1 ^ 3", 2)]

SqlServerSimulator/DataType.cs

@@ -141,6 +141,10 @@ public abstract class NumericCompatibleDataType : DataType
         public abstract object? Divide(object? a, object? b);
 
         public DataValue Divide(DataValue a, DataValue b) => new(Divide(a.Value, b.Value), this);
+
+        public abstract object? Modulus(object? a, object? b);
+
+        public DataValue Modulus(DataValue a, DataValue b) => new(Modulus(a.Value, b.Value), this);
     }
 
     public abstract class BitwiseCompatibleDataType : NumericCompatibleDataType
@@ -178,6 +182,8 @@ private sealed class DbBoolean : BitwiseCompatibleDataType
 
         public override object? Divide(object? a, object? b) => throw new NotImplementedException();
 
+        public override object? Modulus(object? a, object? b) => throw new NotImplementedException();
+
         public override object? BitwiseAnd(object? a, object? b) => throw new NotImplementedException();
 
         public override object? BitwiseOr(object? a, object? b) => throw new NotImplementedException();
@@ -205,6 +211,8 @@ private sealed class DbByte : BitwiseCompatibleDataType
 
         public override object? Divide(object? a, object? b) => throw new NotImplementedException();
 
+        public override object? Modulus(object? a, object? b) => throw new NotImplementedException();
+
         public override object? BitwiseAnd(object? a, object? b) => throw new NotImplementedException();
 
         public override object? BitwiseOr(object? a, object? b) => throw new NotImplementedException();
@@ -232,6 +240,8 @@ private sealed class DbInt16 : BitwiseCompatibleDataType
 
         public override object? Divide(object? a, object? b) => throw new NotImplementedException();
 
+        public override object? Modulus(object? a, object? b) => throw new NotImplementedException();
+
         public override object? BitwiseAnd(object? a, object? b) => throw new NotImplementedException();
 
         public override object? BitwiseOr(object? a, object? b) => throw new NotImplementedException();
@@ -286,6 +296,8 @@ private static bool TryToNative(object? rawA, object? rawB, out int a, out int b
 
         public override object? Divide(object? a, object? b) => TryToNative(a, b, out var nativeA, out var nativeB) ? nativeA / nativeB : null;
 
+        public override object? Modulus(object? a, object? b) => TryToNative(a, b, out var nativeA, out var nativeB) ? nativeA % nativeB : null;
+
         public override object? BitwiseAnd(object? a, object? b) => TryToNative(a, b, out var nativeA, out var nativeB) ? nativeA & nativeB : null;
 
         public override object? BitwiseOr(object? a, object? b) => TryToNative(a, b, out var nativeA, out var nativeB) ? nativeA | nativeB : null;

SqlServerSimulator/Parser/Expression.cs

@@ -90,6 +90,10 @@ public static Expression Parse(ParserContext context)
                     context.MoveNextRequired();
                     expression = new Divide(expression, Parse(context));
                     break;
+                case Operator { Character: '%' }:
+                    context.MoveNextRequired();
+                    expression = new Modulus(expression, Parse(context));
+                    break;
                 case Operator { Character: '&' }:
                     context.MoveNextRequired();
                     expression = new BitwiseAnd(expression, Parse(context));

SqlServerSimulator/Parser/Expressions/Modulus.cs

@@ -0,0 +1,10 @@
+namespace SqlServerSimulator.Parser.Expressions;
+
+internal sealed class Modulus(Expression left, Expression right) : MathExpression(left, right)
+{
+    public override byte Precedence => 3;
+
+    protected override DataValue Run(DataType.NumericCompatibleDataType common, DataValue left, DataValue right) => common.Modulus(left, right);
+
+    protected override char Operator => '+';
+}

SqlServerSimulator/Parser/Tokenizer.cs

@@ -25,7 +25,7 @@ static class Tokenizer
             '-' => ParseMinusOrComment(command, ref index),
             '/' => ParseForwardSlashOrComment(command, ref index),
             '[' => ParseBracketDelimitedString(command, ref index),
-            '+' or '*' or '(' or ')' or ',' or '.' or ';' or '=' or '&' or '|' or '^' or '>' or '<' or '!' => new Operator(command, index),
+            '+' or '*' or '%' or '(' or ')' or ',' or '.' or ';' or '=' or '&' or '|' or '^' or '>' or '<' or '!' => new Operator(command, index),
             var c => throw SimulatedSqlException.SyntaxErrorNear(c) // Might throw on valid-but-unsupported syntax.
         };