Extract MessageLine, Player pack ops, and Level list management

Refactor step 6. MessageLine (was MsgLine) owns the msg/addmsg/endmsg
machinery, wired to its screen, pre---More-- redraw, and input via
attach(); RogueGame keeps one-line msg/addmsgf/endmsg shorthands so
the ~400 call sites are unchanged. Player gains nextPackChar and
removeFromPack (the state half of pack.c leave_pack); leavePack keeps
only the LastPick repeat-command tracking. Level gains ObjectAt
(misc.c find_obj) and AddObject/RemoveObject/AddMonster/RemoveMonster,
replacing direct attach/detach calls on the level lists. Inventory and
pickup UI flows stay on RogueGame: display and orchestration, not
state surgery. Behavior and RNG order unchanged; suite green.

game/chase.go

@@ -169,7 +169,7 @@ func (g *RogueGame) chaseStep(th *Monster) (removed bool) {
 		} else if this == *th.Dest {
 			for _, obj := range g.Level.Objects {
 				if th.Dest == &obj.Pos {
-					detachObj(&g.Level.Objects, obj)
+					g.Level.RemoveObject(obj)
 					attachObj(&th.Pack, obj)
 
 					if th.Room.Flags.Has(Gone) {

game/creature.go

@@ -50,6 +50,47 @@ func (p *Player) IsWearing(ring RingKind) bool {
 	return p.IsRing(Left, ring) || p.IsRing(Right, ring)
 }
 
+// nextPackChar claims and returns the next unused pack character (pack.c
+// pack_char).
+func (p *Player) nextPackChar() byte {
+	for i := range p.PackUsed {
+		if !p.PackUsed[i] {
+			p.PackUsed[i] = true
+
+			return byte(i) + 'a'
+		}
+	}
+
+	return byte(len(p.PackUsed)) + 'a' // C would walk off the array here
+}
+
+// removeFromPack takes an item out of the pack: the whole entry, or one
+// of a stack when all is false (the bookkeeping half of pack.c
+// leave_pack). It returns the object that left the pack — a copy when
+// newobj asks for a split.
+func (p *Player) removeFromPack(obj *Object, newobj, all bool) *Object {
+	p.Inpack--
+
+	nobj := obj
+	if obj.Count > 1 && !all {
+		obj.Count--
+		if obj.Group != 0 {
+			p.Inpack++
+		}
+
+		if newobj {
+			copied := *obj
+			nobj = &copied
+			nobj.Count = 1
+		}
+	} else {
+		p.PackUsed[obj.PackCh-'a'] = false
+		detachObj(&p.Pack, obj)
+	}
+
+	return nobj
+}
+
 // attachMon pushes a monster onto the front of a list (list.c attach).
 func attachMon(list *[]*Monster, item *Monster) {
 	*list = append([]*Monster{item}, *list...)

game/fight.go

@@ -549,7 +549,7 @@ func (g *RogueGame) removeMon(mp Coord, tp *Monster, waskill bool) {
 
 	g.Level.SetMonsterAt(mp.Y, mp.X, nil)
 	g.mvaddch(mp.Y, mp.X, tp.OldCh)
-	detachMon(&g.Level.Monsters, tp)
+	g.Level.RemoveMonster(tp)
 
 	if tp.On(Targeted) {
 		g.Kamikaze = false

game/game.go

@@ -110,7 +110,7 @@ type RogueGame struct {
 
 	// screen / messages
 	scr         *Screen
-	Msgs        MsgLine
+	Msgs        MessageLine
 	statusCache statusCache
 	invPage     invPage // things.c discovery-list pagination statics
 
@@ -169,6 +169,7 @@ func NewGame(cfg Config) *RogueGame {
 	g.InvDescribe = true
 	g.Msgs.SaveMsg = true
 	g.scr = NewScreen(cfg.Term)
+	g.Msgs.attach(g.scr, g.look, g.readchar)
 	g.FileName = cfg.Home + "/rogue.save"
 
 	g.rogueOpts = cfg.RogueOpts

game/io.go

@@ -10,9 +10,11 @@ import (
 // maxMsg is io.c MAXMSG: how much message fits before --More--.
 const maxMsg = NumCols - len("--More--") - 1
 
-// MsgLine is the io.c message machinery: the static msgbuf/newpos pair plus
-// the related globals (mpos, huh, and the message-behavior flags).
-type MsgLine struct {
+// MessageLine is the io.c message machinery: the static msgbuf/newpos
+// pair plus the related globals (mpos, huh, and the message-behavior
+// flags). It owns the top line of the screen; attach wires in the
+// display and input it needs.
+type MessageLine struct {
 	buf      strings.Builder // msgbuf
 	newpos   int
 	Mpos     int    // where cursor is on top line
@@ -20,49 +22,52 @@ type MsgLine struct {
 	SaveMsg  bool   // remember last msg
 	LowerMsg bool   // messages should start w/lower case
 	MsgEsc   bool   // check for ESC from msg's --More--
+
+	scr      *Screen           // the top line lives on scr.Std
+	look     func(wakeup bool) // redraw before a --More-- (misc.c look)
+	readChar func() byte       // input for --More-- prompts
 }
 
 // Msg displays a message at the top of the screen (io.c msg). It returns
-// Escape if the player escaped out of a --More--, ^Escape otherwise (the C
-// convention: callers compare against ESCAPE).
-func (g *RogueGame) msg(format string, a ...any) int {
+// Escape if the player escaped out of a --More--, ^Escape otherwise (the
+// C convention: callers compare against ESCAPE).
+func (m *MessageLine) Msg(format string, a ...any) int {
 	// if the string is "", just clear the line
 	if format == "" {
-		g.move(0, 0)
-		g.clrtoeol()
-		g.Msgs.Mpos = 0
+		m.scr.Std.Move(0, 0)
+		m.scr.Std.Clrtoeol()
+		m.Mpos = 0
 
 		return ^Escape
 	}
 	// otherwise add to the message and flush it out
-	g.doaddf(format, a...)
+	m.doaddf(format, a...)
 
-	return g.endmsg()
+	return m.End()
 }
 
-// addmsgf adds things to the current message (io.c addmsg).
-func (g *RogueGame) addmsgf(format string, a ...any) {
-	g.doaddf(format, a...)
+// Addf adds things to the current message (io.c addmsg).
+func (m *MessageLine) Addf(format string, a ...any) {
+	m.doaddf(format, a...)
 }
 
-// endmsg displays a new msg, giving the player a chance to see the previous
+// End displays a new msg, giving the player a chance to see the previous
 // one if it is up there with the --More-- (io.c endmsg).
-func (g *RogueGame) endmsg() int {
-	m := &g.Msgs
+func (m *MessageLine) End() int {
 	if m.SaveMsg {
 		m.Huh = m.buf.String()
 	}
 
 	if m.Mpos != 0 {
-		g.look(false)
-		g.mvaddstr(0, m.Mpos, "--More--")
-		g.refresh()
+		m.look(false)
+		m.scr.Std.MvAddStr(0, m.Mpos, "--More--")
+		m.scr.Refresh()
 
 		if !m.MsgEsc {
-			g.waitFor(' ')
+			m.waitForSpace()
 		} else {
 			for {
-				ch := g.readchar()
+				ch := m.readChar()
 				if ch == ' ' {
 					break
 				}
@@ -85,30 +90,60 @@ func (g *RogueGame) endmsg() int {
 		out = string(toUpper(out[0])) + out[1:]
 	}
 
-	g.mvaddstr(0, 0, out)
-	g.clrtoeol()
+	m.scr.Std.MvAddStr(0, 0, out)
+	m.scr.Std.Clrtoeol()
 
 	m.Mpos = m.newpos
 	m.newpos = 0
 	m.buf.Reset()
-	g.refresh()
+	m.scr.Refresh()
 
 	return ^Escape
 }
 
-// doaddf performs an add onto the message buffer (io.c doadd).
-func (g *RogueGame) doaddf(format string, a ...any) {
-	m := &g.Msgs
+// attach wires the message line to its display and input; NewGame and
+// Restore call it once the screen and game exist.
+func (m *MessageLine) attach(scr *Screen, look func(bool), readChar func() byte) {
+	m.scr = scr
+	m.look = look
+	m.readChar = readChar
+}
 
+// waitForSpace absorbs input until the player types a space: the
+// --More-- acknowledgement (io.c wait_for).
+func (m *MessageLine) waitForSpace() {
+	for {
+		if m.readChar() == ' ' {
+			return
+		}
+	}
+}
+
+// doaddf performs an add onto the message buffer (io.c doadd).
+func (m *MessageLine) doaddf(format string, a ...any) {
 	s := fmt.Sprintf(format, a...)
 	if len(s)+m.newpos >= maxMsg {
-		g.endmsg()
+		m.End()
 	}
 
 	m.buf.WriteString(s)
 	m.newpos = m.buf.Len()
 }
 
+// msg, addmsgf, and endmsg are the game-side shorthands for the message
+// line; the machinery lives on MessageLine.
+func (g *RogueGame) msg(format string, a ...any) int {
+	return g.Msgs.Msg(format, a...)
+}
+
+func (g *RogueGame) addmsgf(format string, a ...any) {
+	g.Msgs.Addf(format, a...)
+}
+
+func (g *RogueGame) endmsg() {
+	g.Msgs.End()
+}
+
 // stepOk returns true if it is ok to step on ch (io.c step_ok).
 func stepOk(ch byte) bool {
 	switch ch {

game/level.go

@@ -51,6 +51,29 @@ func (l *Level) VisibleChar(y, x int) byte {
 	return l.Char(y, x)
 }
 
+// ObjectAt finds the unclaimed object at (y, x) (misc.c find_obj).
+func (l *Level) ObjectAt(y, x int) *Object {
+	for _, obj := range l.Objects {
+		if obj.Pos.Y == y && obj.Pos.X == x {
+			return obj
+		}
+	}
+
+	return nil
+}
+
+// AddObject puts an object on the level (list.c attach on lvl_obj).
+func (l *Level) AddObject(obj *Object) { attachObj(&l.Objects, obj) }
+
+// RemoveObject takes an object off the level (list.c detach on lvl_obj).
+func (l *Level) RemoveObject(obj *Object) { detachObj(&l.Objects, obj) }
+
+// AddMonster puts a monster on the level (list.c attach on mlist).
+func (l *Level) AddMonster(m *Monster) { attachMon(&l.Monsters, m) }
+
+// RemoveMonster takes a monster off the level (list.c detach on mlist).
+func (l *Level) RemoveMonster(m *Monster) { detachMon(&l.Monsters, m) }
+
 // goldCalc is the GOLDCALC macro: how much a gold pile is worth at depth.
 func (g *RogueGame) goldCalc() int {
 	return g.rnd(50+10*g.Depth) + 2

game/misc.go

@@ -223,17 +223,6 @@ func (g *RogueGame) showFloor() bool {
 	return true
 }
 
-// findObj finds the unclaimed object at (y, x) (misc.c find_obj).
-func (g *RogueGame) findObj(y, x int) *Object {
-	for _, obj := range g.Level.Objects {
-		if obj.Pos.Y == y && obj.Pos.X == x {
-			return obj
-		}
-	}
-
-	return nil
-}
-
 // eat lets her try to eat something (misc.c eat).
 func (g *RogueGame) eat() {
 	obj, ok := g.promptPackItem("eat", KindFood)

game/monsters.go

@@ -31,7 +31,7 @@ func (g *RogueGame) randMonster(wander bool) byte {
 func (g *RogueGame) newMonster(tp *Monster, typ byte, cp Coord) {
 	levAdd := max(g.Depth-AmuletLevel, 0)
 
-	attachMon(&g.Level.Monsters, tp)
+	g.Level.AddMonster(tp)
 	tp.Type = typ
 	tp.Disguise = typ
 	tp.Pos = cp

game/newlevel.go

@@ -105,7 +105,7 @@ func (g *RogueGame) putThings() {
 		if g.rnd(100) < 36 {
 			// Pick a new object and link it in the list
 			obj := g.newThing()
-			attachObj(&g.Level.Objects, obj)
+			g.Level.AddObject(obj)
 			// Put it somewhere
 			obj.Pos, _ = g.findFloor(false)
 			g.Level.SetChar(obj.Pos.Y, obj.Pos.X, obj.Kind.Glyph())
@@ -115,7 +115,7 @@ func (g *RogueGame) putThings() {
 	// yet, put it somewhere on the ground
 	if g.Depth >= AmuletLevel && !g.HasAmulet {
 		obj := newObject()
-		attachObj(&g.Level.Objects, obj)
+		g.Level.AddObject(obj)
 		obj.Damage = dice("0x0")
 		obj.HurlDmg = dice("0x0")
 		obj.ArmorClass = 11
@@ -137,7 +137,7 @@ func (g *RogueGame) treasureRoom() {
 		mp, _ := g.findFloorIn(rp, 2*maxTries, false)
 		tp := g.newThing()
 		tp.Pos = mp
-		attachObj(&g.Level.Objects, tp)
+		g.Level.AddObject(tp)
 		g.Level.SetChar(mp.Y, mp.X, tp.Kind.Glyph())
 	}
 

game/pack.go

@@ -9,7 +9,7 @@ func (g *RogueGame) addPack(obj *Object, silent bool) {
 	fromFloor := false
 
 	if obj == nil {
-		if obj = g.findObj(p.Pos.Y, p.Pos.X); obj == nil {
+		if obj = g.Level.ObjectAt(p.Pos.Y, p.Pos.X); obj == nil {
 			return
 		}
 
@@ -18,7 +18,7 @@ func (g *RogueGame) addPack(obj *Object, silent bool) {
 
 	// Check for and deal with scare monster scrolls
 	if obj.Kind == KindScroll && obj.ScrollKind() == ScrollScareMonster && obj.Flags.Has(WasFound) {
-		detachObj(&g.Level.Objects, obj)
+		g.Level.RemoveObject(obj)
 		g.mvaddch(p.Pos.Y, p.Pos.X, g.floorCh())
 
 		if p.Room.Flags.Has(Gone) {
@@ -34,7 +34,7 @@ func (g *RogueGame) addPack(obj *Object, silent bool) {
 
 	if len(p.Pack) == 0 {
 		p.Pack = append(p.Pack, obj)
-		obj.PackCh = g.packChar()
+		obj.PackCh = p.nextPackChar()
 		p.Inpack++
 	} else {
 		// Walk the pack looking for the insertion point, keeping items of
@@ -112,7 +112,7 @@ func (g *RogueGame) addPack(obj *Object, silent bool) {
 				return
 			}
 
-			obj.PackCh = g.packChar()
+			obj.PackCh = p.nextPackChar()
 			p.Pack = append(p.Pack[:lp+1],
 				append([]*Object{obj}, p.Pack[lp+1:]...)...)
 		}
@@ -168,7 +168,7 @@ func (g *RogueGame) packRoom(fromFloor bool, obj *Object) bool {
 	}
 
 	if fromFloor {
-		detachObj(&g.Level.Objects, obj)
+		g.Level.RemoveObject(obj)
 		g.mvaddch(p.Pos.Y, p.Pos.X, g.floorCh())
 
 		if p.Room.Flags.Has(Gone) {
@@ -181,46 +181,17 @@ func (g *RogueGame) packRoom(fromFloor bool, obj *Object) bool {
 	return true
 }
 
-// leavePack takes an item out of the pack (pack.c leave_pack).
+// leavePack takes an item out of the pack (pack.c leave_pack), keeping
+// the repeat-command bookkeeping; the pack surgery is
+// Player.removeFromPack.
 func (g *RogueGame) leavePack(obj *Object, newobj, all bool) *Object {
-	p := &g.Player
-	p.Inpack--
-
-	nobj := obj
 	if obj.Count > 1 && !all {
 		g.LastPick = obj
-
-		obj.Count--
-		if obj.Group != 0 {
-			p.Inpack++
-		}
-
-		if newobj {
-			copied := *obj
-			nobj = &copied
-			nobj.Count = 1
-		}
 	} else {
 		g.LastPick = nil
-		p.PackUsed[obj.PackCh-'a'] = false
-		detachObj(&p.Pack, obj)
 	}
 
-	return nobj
-}
-
-// packChar returns the next unused pack character (pack.c pack_char).
-func (g *RogueGame) packChar() byte {
-	p := &g.Player
-	for i := range p.PackUsed {
-		if !p.PackUsed[i] {
-			p.PackUsed[i] = true
-
-			return byte(i) + 'a'
-		}
-	}
-
-	return byte(len(p.PackUsed)) + 'a' // C would walk off the array here
+	return g.Player.removeFromPack(obj, newobj, all)
 }
 
 // inventory lists what is in the pack; returns true if there is something
@@ -277,7 +248,7 @@ func (g *RogueGame) pickUp(ch byte) {
 		return
 	}
 
-	obj := g.findObj(p.Pos.Y, p.Pos.X)
+	obj := g.Level.ObjectAt(p.Pos.Y, p.Pos.X)
 	if g.MoveOn {
 		g.moveMsg(obj)
 
@@ -291,7 +262,7 @@ func (g *RogueGame) pickUp(ch byte) {
 		}
 
 		g.money(obj.GoldValue)
-		detachObj(&g.Level.Objects, obj)
+		g.Level.RemoveObject(obj)
 
 		p.Room.GoldVal = 0
 	default:

game/rooms.go

@@ -105,7 +105,7 @@ func (g *RogueGame) digRooms() {
 			gold.Flags = Stackable
 			gold.Group = goldGrp
 			gold.Kind = KindGold
-			attachObj(&g.Level.Objects, gold)
+			g.Level.AddObject(gold)
 		}
 		// Put the monster in
 		prob := 25

game/save.go

@@ -618,6 +618,7 @@ func Restore(path string, cfg Config) (*RogueGame, error) {
 		restored:  true,
 	}
 	g.scr = NewScreen(cfg.Term)
+	g.Msgs.attach(g.scr, g.look, g.readchar)
 	g.applySnapshot(&st)
 
 	// defeat multiple restarting from the same place

game/scrolls.go

@@ -104,7 +104,7 @@ func (g *RogueGame) readScroll() {
 				// Or anything else nasty
 				if ch := g.Level.VisibleChar(y, x); stepOk(ch) {
 					if ch == Scroll {
-						if fo := g.findObj(y, x); fo != nil && fo.ScrollKind() == ScrollScareMonster {
+						if fo := g.Level.ObjectAt(y, x); fo != nil && fo.ScrollKind() == ScrollScareMonster {
 							continue
 						}
 					}

game/sticks.go

@@ -85,7 +85,7 @@ func (g *RogueGame) doZap() {
 				}
 			case WandPolymorph:
 				pp := tp.Pack
-				detachMon(&g.Level.Monsters, tp)
+				g.Level.RemoveMonster(tp)
 
 				if g.seeMonst(tp) {
 					g.mvaddch(y, x, g.Level.Char(y, x))

game/things.go

@@ -153,7 +153,7 @@ func (g *RogueGame) dropIt() {
 
 	obj = g.leavePack(obj, true, !obj.Kind.MergesInPack())
 	// Link it into the level object list
-	attachObj(&g.Level.Objects, obj)
+	g.Level.AddObject(obj)
 	g.Level.SetChar(p.Pos.Y, p.Pos.X, obj.Kind.Glyph())
 	g.Level.FlagsAt(p.Pos.Y, p.Pos.X).Set(FDropped)
 

game/weapons.go

@@ -78,7 +78,7 @@ func (g *RogueGame) fall(obj *Object, pr bool) {
 			}
 		}
 
-		attachObj(&g.Level.Objects, obj)
+		g.Level.AddObject(obj)
 
 		return
 	}