CardSimEngine/cardsim/messages.go

package cardsim

import "fmt"

// Message is an opaque interface representing a displayable message.
// Using an interface here allows for implementation of new message display
// and formatting features without rewriting all existing callers.
type Message interface {
	fmt.Stringer
}

type stringMessage string

func (s stringMessage) String() string {
	return string(s)
}

// MsgStr returns a Message representing a fixed string.
func MsgStr(s string) Message {
	return stringMessage(s)
}

// Msgf is a Sprintf-like function that produces a Message equivalent to the
// one created by MsgStr.
func Msgf(f string, args ...any) Message {
	return stringMessage(fmt.Sprintf(f, args...))
}

// A SpecialMessage is a specific, uniquely identifiable message.
type SpecialMessage struct {
	msg Message
}

// String implements Message.
func (s *SpecialMessage) String() string {
	if s == nil {
		return ""
	}
	return s.msg.String()
}

// Messages that various display surfaces or other components may have a special interpretation of
// and identify specifically. These are largely sentinel values. Nil is a paragraph break.
var (
	SectionBreak = &SpecialMessage{MsgStr("      --------------------------------------------------------------------      ")}
	ChapterBreak = &SpecialMessage{MsgStr("      ====================================================================      ")}
)

// IsSpecialMessage returns whether a provided Message is a specific SpecialMessage.
func IsSpecialMessage(m Message, s *SpecialMessage) bool {
	if m == nil {
		return s == nil
	}
	if s2, ok := m.(*SpecialMessage); ok {
		return s == s2
	}
	return false
}