Added all source files

utils.go

@@ -0,0 +1,51 @@
+// utils.go
+package expr
+
+func isString(v any) (ok bool) {
+	_, ok = v.(string)
+	return ok
+}
+
+func isInteger(v any) (ok bool) {
+	_, ok = v.(int64)
+	return ok
+}
+
+func isFloat(v any) (ok bool) {
+	_, ok = v.(float64)
+	return ok
+}
+
+func isNumber(v any) (ok bool) {
+	return isFloat(v) || isInteger(v)
+}
+
+func isNumberString(v any) (ok bool) {
+	return isString(v) || isNumber(v)
+}
+
+func numAsFloat(v any) (f float64) {
+	var ok bool
+	if f, ok = v.(float64); !ok {
+		i, _ := v.(int64)
+		f = float64(i)
+	}
+	return
+}
+
+func toBool(v any) (b bool, ok bool) {
+	ok = true
+	switch x := v.(type) {
+	case string:
+		b = len(x) > 0
+	case float64:
+		b = x != 0.0
+	case int64:
+		b = x != 0
+	case bool:
+		b = x
+	default:
+		ok = false
+	}
+	return
+}