// EvalUnary evaluates a unary operator.
func (c *Context) EvalUnary(op string, right value.Value) value.Value {
right = right.Eval(c)
fn := c.UnaryFn[op]
if fn == nil {
return value.Unary(c, op, right)
}
if fn.Body == nil {
value.Errorf("unary %q undefined", op)
}
c.push()
defer c.pop()
c.assignLocal(fn.Right, right)
var v value.Value
for _, e := range fn.Body {
v = e.Eval(c)
}
if v == nil {
value.Errorf("no value returned by %q", op)
}
return v
}
func (u *unary) Eval(context value.Context) value.Value {
return value.Unary(u.op, u.right.Eval(context))
}