fix

slots/slots.go

@@ -0,0 +1,41 @@
+// Package slots defines the sixteen code slots each player has. Slots 1-3 hold
+// the built-in example programs and are read-only; slots 4-16 belong to the
+// player, who saves source code in them and picks one when launching a ship.
+package slots
+
+import (
+	"io/fs"
+	"strings"
+
+	"halcyon/examples"
+)
+
+const Count = 16
+
+// builtin lists the example programs, in slot order (slot 1 is the first).
+var builtin = []string{"echo", "telemetry", "pursue"}
+
+// FirstUser is the first slot a player can write to.
+var FirstUser = len(builtin) + 1
+
+type Slot struct {
+	Number  int
+	Name    string
+	Source  string
+	Builtin bool
+}
+
+// Valid reports whether n is one of the sixteen slots.
+func Valid(n int) bool { return n >= 1 && n <= Count }
+
+// Builtin returns the example that occupies slot n, if it is one of the first three.
+func Builtin(n int) (Slot, bool) {
+	if n < 1 || n > len(builtin) {
+		return Slot{}, false
+	}
+	src, err := fs.ReadFile(examples.FS, builtin[n-1]+".s")
+	if err != nil {
+		return Slot{}, false
+	}
+	return Slot{Number: n, Name: strings.ToUpper(builtin[n-1]), Source: string(src), Builtin: true}, true
+}