Add: tonumber

src/Lua/Standard/Basic/ToNumberFunction.cs

@@ -0,0 +1,69 @@
+using System.Globalization;
+
+namespace Lua.Standard.Basic;
+
+public sealed class ToNumberFunction : LuaFunction
+{
+    public override string Name => "tonumber";
+    public static readonly ToNumberFunction Instance = new();
+
+    protected override ValueTask<int> InvokeAsyncCore(LuaFunctionExecutionContext context, Memory<LuaValue> buffer, CancellationToken cancellationToken)
+    {
+        var arg0 = context.ReadArgument(0);
+        var arg1 = context.ArgumentCount >= 2
+            ? (int)context.ReadArgument<double>(1)
+            : 10;
+
+        if (arg1 < 2 || arg1 > 36)
+        {
+            throw new LuaRuntimeException(context.State.GetTracebacks(), "bad argument #2 to 'tonumber' (base out of range)");
+        }
+
+        if (arg0.Type is LuaValueType.Number)
+        {
+            buffer.Span[0] = arg0;
+        }
+        else if (arg0.TryRead<string>(out var str))
+        {
+            if ((arg1 == 10 || arg1 == 16) && str.Length >= 3 && str[0] == '0' && str[1] == 'x')
+            {
+                if (int.TryParse(str.AsSpan(2), NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var result))
+                {
+                    buffer.Span[0] = result;
+                }
+                else
+                {
+                    buffer.Span[0] = LuaValue.Nil;
+                }
+            }
+            else if (arg0 == 10)
+            {
+                if (double.TryParse(str, NumberStyles.Float, CultureInfo.InvariantCulture, out double result))
+                {
+                    buffer.Span[0] = result;
+                }
+                else
+                {
+                    buffer.Span[0] = LuaValue.Nil;
+                }
+            }
+            else
+            {
+                try
+                {
+                    buffer.Span[0] = Convert.ToInt64(str, arg1);
+                }
+                catch (FormatException)
+                {
+                    buffer.Span[0] = LuaValue.Nil;
+                }
+            }
+        }
+        else
+        {
+            buffer.Span[0] = LuaValue.Nil;
+        }
+
+        return new(1);
+    }
+}