rgoue/game/object.go

package game

// ObjectKind is the category of an item. In C this was the o_type byte,
// which doubled as the character drawn on the map; the port separates the
// category (ObjectKind) from its display character (Glyph).
type ObjectKind int

// Item categories.
const (
	KindNone ObjectKind = iota
	KindPotion
	KindScroll
	KindFood
	KindWeapon
	KindArmor
	KindRing
	KindWand // a "stick": wand or staff
	KindAmulet
	KindGold
)

// Prompt-filter pseudo-kinds for item selection (rogue.h CALLABLE and
// R_OR_S): they never appear on an Object, only as getItem filters.
const (
	KindCallable    ObjectKind = -1
	KindRingOrStick ObjectKind = -2
)

// kindGlyphs maps each kind to the character Rogue draws for it.
var kindGlyphs = [...]byte{
	KindNone:   ' ',
	KindPotion: Potion,
	KindScroll: Scroll,
	KindFood:   Food,
	KindWeapon: Weapon,
	KindArmor:  Armor,
	KindRing:   Ring,
	KindWand:   Stick,
	KindAmulet: Amulet,
	KindGold:   Gold,
}

// Glyph returns the map/display character for this kind of object.
func (k ObjectKind) Glyph() byte {
	if k < 0 || int(k) >= len(kindGlyphs) {
		return ' '
	}

	return kindGlyphs[k]
}

// String names the category the way the C type_name() did.
func (k ObjectKind) String() string {
	switch k {
	case KindPotion:
		return "potion"
	case KindScroll:
		return "scroll"
	case KindFood:
		return "food"
	case KindWeapon:
		return "weapon"
	case KindArmor:
		return "suit of armor"
	case KindRing:
		return "ring"
	case KindWand:
		return "wand or staff"
	case KindAmulet:
		return "amulet"
	case KindGold:
		return "gold"
	case KindRingOrStick:
		return "ring, wand or staff"
	}

	return "bizarre thing"
}

// objectKindForGlyph is the reverse of Glyph: what category of item does a
// map character denote. Returns KindNone for non-item characters.
func objectKindForGlyph(ch byte) ObjectKind {
	for k, g := range kindGlyphs {
		if g == ch && ObjectKind(k) != KindNone {
			return ObjectKind(k)
		}
	}

	return KindNone
}

// MergesInPack reports whether picking up another of this kind merges into
// an existing pack entry's count (rogue.h ISMULT).
func (k ObjectKind) MergesInPack() bool {
	return k == KindPotion || k == KindScroll || k == KindFood
}

// Object is the _o arm of the C THING union: anything that can lie on the
// floor or ride in a pack.
type Object struct {
	Kind       ObjectKind // what kind of object it is (o_type)
	Pos        Coord      // where it lives on the screen
	Text       string     // what it says if you read it
	Launch     WeaponKind // what you need to launch it (noWeapon if none)
	PackCh     byte       // what character it is in the pack
	Damage     DiceSpec   // damage if used like sword
	HurlDmg    DiceSpec   // damage if thrown
	Count      int        // count for plural objects
	Which      int        // which object of a type it is (index for the Kind's table)
	HPlus      int        // plusses to hit
	DPlus      int        // plusses to damage
	ArmorClass int        // armor protection (armor only)
	Charges    int        // charges remaining (wands and staffs only)
	GoldValue  int        // worth (gold piles only)
	Bonus      int        // magic bonus (rings only: protection, add strength, ...)
	Flags      ObjFlags
	Group      int    // group number for this object
	Label      string // label for object
}

// newObject is list.c new_item() for objects: a zeroed Object with the
// same non-zero defaults the C code relies on.
func newObject() *Object {
	return &Object{Launch: noWeapon}
}

// PotionKind returns Which as a potion kind; valid only for KindPotion.
func (o *Object) PotionKind() PotionKind { return PotionKind(o.Which) }

// ScrollKind returns Which as a scroll kind; valid only for KindScroll.
func (o *Object) ScrollKind() ScrollKind { return ScrollKind(o.Which) }

// RingKind returns Which as a ring kind; valid only for KindRing.
func (o *Object) RingKind() RingKind { return RingKind(o.Which) }

// WandKind returns Which as a wand kind; valid only for KindWand.
func (o *Object) WandKind() WandKind { return WandKind(o.Which) }

// WeaponKind returns Which as a weapon kind; valid only for KindWeapon.
func (o *Object) WeaponKind() WeaponKind { return WeaponKind(o.Which) }

// ArmorKind returns Which as an armor kind; valid only for KindArmor.
func (o *Object) ArmorKind() ArmorKind { return ArmorKind(o.Which) }

// attachObj is list.c attach(): push item onto the front of a list.
func attachObj(list *[]*Object, item *Object) {
	*list = append([]*Object{item}, *list...)
}

// detachObj is list.c detach(): remove item (by identity) from a list.
func detachObj(list *[]*Object, item *Object) {
	for i, o := range *list {
		if o == item {
			*list = append((*list)[:i], (*list)[i+1:]...)

			return
		}
	}
}