Added all source files

operand-func.go

@@ -0,0 +1,33 @@
+// operand-func.go
+package expr
+
+// -------- function term
+func newFuncTerm(tk *Token, args []*term) *term {
+	return &term{
+		tk:       *tk,
+		class:    classVar,
+		kind:     kindUnknown,
+		parent:   nil,
+		children: args,
+		position: posLeaf,
+		priority: priValue,
+		evalFunc: evalFunc,
+	}
+}
+
+// -------- eval func
+func evalFunc(ctx exprContext, self *term) (v any, err error) {
+	name, _ := self.tk.Value.(string)
+	params := make([]any, len(self.children))
+	for i, tree := range self.children {
+		var param any
+		if param, err = tree.compute(ctx); err != nil {
+			break
+		}
+		params[i] = param
+	}
+	if err == nil {
+		v, err = ctx.Call(name, params)
+	}
+	return
+}