Add support for variadic functions

salix.go

@@ -475,7 +475,10 @@ func (t *Template) execMethodCall(mc ast.MethodCall, local map[string]any) (any,
 // execFunc executes a function call
 func (t *Template) execFunc(fn reflect.Value, node ast.Node, args []ast.Node, local map[string]any) (any, error) {
 	fnType := fn.Type()
-	if fnType.NumIn() != len(args) {
+	lastIndex := fnType.NumIn() - 1
+	isVariadic := fnType.IsVariadic()
+		
+	if !isVariadic && fnType.NumIn() != len(args) {
 		return nil, ast.PosError(node, "%s: invalid parameter amount: %d (expected %d)", valueToString(node), len(args), fnType.NumIn())
 	}
 
@@ -483,7 +486,7 @@ func (t *Template) execFunc(fn reflect.Value, node ast.Node, args []ast.Node, lo
 		return nil, err
 	}
 
-	params := make([]reflect.Value, fnType.NumIn())
+	params := make([]reflect.Value, 0, fnType.NumIn())
 	for i, arg := range args {
 		if _, ok := arg.(ast.Assignment); ok {
 			return nil, ast.PosError(arg, "%s: an assignment cannot be used as a function argument", valueToString(node))
@@ -492,13 +495,21 @@ func (t *Template) execFunc(fn reflect.Value, node ast.Node, args []ast.Node, lo
 		if err != nil {
 			return nil, err
 		}
-		params[i] = reflect.ValueOf(paramVal)
+		params = append(params, reflect.ValueOf(paramVal))
+		if isVariadic && i >= lastIndex {
+			if params[i].CanConvert(fnType.In(lastIndex).Elem()) {
+				params[i] = params[i].Convert(fnType.In(lastIndex).Elem())
+			} else {
+				return nil, ast.PosError(node, "%s: invalid parameter type: %T (expected %s)", valueToString(node), paramVal, fnType.In(i))
+			}
+		} else {
 			if params[i].CanConvert(fnType.In(i)) {
 				params[i] = params[i].Convert(fnType.In(i))
 			} else {
 				return nil, ast.PosError(node, "%s: invalid parameter type: %T (expected %s)", valueToString(node), paramVal, fnType.In(i))
 			}
 		}
+	}
 
 	ret := fn.Call(params)
 	if len(ret) == 1 {

vars.go

@@ -19,6 +19,7 @@ var globalVars = map[string]any{
 	"count":      strings.Count,
 	"split":      strings.Split,
 	"join":       strings.Join,
+	"sprintf":    fmt.Sprintf,
 }
 
 func tmplLen(v any) (int, error) {