Added support for multiplication, division, block comments.

Author: RyanLamansky

SqlServerSimulator.Tests/SelectTests.cs

@@ -55,6 +55,9 @@ public void SelectParameterValue(string commandText, string name, object value)
     [DataRow("- 1", -1)]
     [DataRow("+1", 1)]
     [DataRow("+ 1", 1)]
+    [DataRow("2 * 2", 4)]
+    [DataRow("2 / 2", 1)]
+    [DataRow("2 / 1", 2)]
     public void Expression(string commandText, object value)
     {
         using var reader = new Simulation().ExecuteReader($"select {commandText}");

SqlServerSimulator.Tests/SimpleCommandTests.cs

@@ -105,4 +105,10 @@ public void SingleLineCommentWithCarriageReturnCommand()
 
         IsFalse(reader.Read());
     }
+
+    [TestMethod]
+    public void BlockComment()
+    {
+        AreEqual(-1, new Simulation().ExecuteNonQuery("/* */"));
+    }
 }

SqlServerSimulator/Parser/Expression.cs

@@ -74,6 +74,14 @@ public static Expression Parse(ParserContext context)
                     context.MoveNextRequired();
                     expression = new Subtract(expression, Parse(context));
                     break;
+                case Operator { Character: '*' }:
+                    context.MoveNextRequired();
+                    expression = new Multiply(expression, Parse(context));
+                    break;
+                case Operator { Character: '/' }:
+                    context.MoveNextRequired();
+                    expression = new Divide(expression, Parse(context));
+                    break;
 
                 case Operator { Character: '.' }:
                     {
@@ -246,6 +254,40 @@ public sealed class Subtract(Expression left, Expression right) : Expression
             return (int)leftValue! - (int)rightValue!; // TODO: Handle varied input types here.
         }
 
+#if DEBUG
+        public override string ToString() => $"{left} + {right}";
+#endif
+    }
+
+    public sealed class Multiply(Expression left, Expression right) : Expression
+    {
+        private readonly Expression left = left, right = right;
+
+        public override object? Run(Func<List<string>, object?> getColumnValue)
+        {
+            var leftValue = left.Run(getColumnValue);
+            var rightValue = right.Run(getColumnValue);
+
+            return (int)leftValue! * (int)rightValue!; // TODO: Handle varied input types here.
+        }
+
+#if DEBUG
+        public override string ToString() => $"{left} + {right}";
+#endif
+    }
+
+    public sealed class Divide(Expression left, Expression right) : Expression
+    {
+        private readonly Expression left = left, right = right;
+
+        public override object? Run(Func<List<string>, object?> getColumnValue)
+        {
+            var leftValue = left.Run(getColumnValue);
+            var rightValue = right.Run(getColumnValue);
+
+            return (int)leftValue! / (int)rightValue!; // TODO: Handle varied input types here.
+        }
+
 #if DEBUG
         public override string ToString() => $"{left} + {right}";
 #endif

SqlServerSimulator/Parser/Tokenizer.cs

@@ -23,6 +23,7 @@ static class Tokenizer
             >= '0' and <= '9' => ParseNumeric(command, ref index),
             '@' => ParseAtOrDoubleAtPrefixedString(command, ref index),
             '-' => ParseMinusOrComment(command, ref index),
+            '/' => ParseForwardSlashOrComment(command, ref index),
             '[' => ParseBracketDelimitedString(command, ref index),
             '+' or '*' or '(' or ')' or ',' or '.' or ';' or '=' => new Operator(command, index),
             var c => throw SimulatedSqlException.SyntaxErrorNear(c) // Might throw on valid-but-unsupported syntax.
@@ -134,6 +135,26 @@ private static Token ParseMinusOrComment(string command, ref int index)
         return new Comment(command, start, --index);
     }
 
+    private static Token ParseForwardSlashOrComment(string command, ref int index)
+    {
+        var start = index;
+        if (++index == command.Length)
+            return new Operator(command, --index);
+        if (command[index] != '*')
+        {
+            index--;
+            return new Operator(command, index);
+        }
+
+        while (++index < command.Length)
+        {
+            if (command[index] == '*' && command.Length >= index + 2 && command[index + 1] == '/')
+                return new Comment(command, start, index += 2);
+        }
+
+        throw SimulatedSqlException.MissingEndCommentMark();
+    }
+
     private static BracketDelimitedString ParseBracketDelimitedString(string command, ref int index)
     {
         var start = index;

SqlServerSimulator/SimulatedSqlException.cs

@@ -104,6 +104,8 @@ internal static SimulatedSqlException IdentifierTooLong(ReadOnlySpan<char> first
 
     internal static SimulatedSqlException InvalidObjectName(StringToken name) => new($"Invalid object name {name}.", 208, 16, 1);
 
+    internal static SimulatedSqlException MissingEndCommentMark() => new("Missing end comment mark '*/'.", 113, 15, 1);
+
     internal static SimulatedSqlException MustDeclareScalarVariable(string name) => new($"Must declare the scalar variable \"@{name}\".", 137, 15, 2);
 
     internal static SimulatedSqlException SyntaxErrorNearKeyword(ReservedKeyword token) => new($"Incorrect syntax near the keyword '{token}'.", 156, 15, 1);