Refactor VerbosePolicy.

This allows it to switch between other complete policies, with fallbacks to a default if parts aren't impelemented. Complementing it is the change to BasicPolicy, which throws ErrUnimplemented if fields are missing, which VerbosePolicy uses as a "go ask the default" sign.
This commit is contained in:
Kistaro Windrider 2023-04-03 19:41:32 -07:00
parent 8ce6539c8a
commit a1f55c865d
Signed by: kistaro
SSH Key Fingerprint: SHA256:TBE2ynfmJqsAf0CP6gsflA0q5X5wD5fVKWPsZ7eVUg8

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@ -9,6 +9,14 @@ import (
var (
ErrOptionNotEnabled = errors.New("option not enabled")
ErrPolicyNotEnacted = errors.New("cannot unenact policy that is not enacted")
// ErrUnimplemented and ErrKeepMessaage are "non-errors". They are used
// as special signals that the result needs to be handled in a special way;
// VerbosePolicy uses these to decide when to use the Default instead.
// If these are returned in a context that does not know how to respond
// to them, then they're just errors.
ErrUnimplemented = errors.New("unimplemented policy element")
ErrKeepMessaage = errors.New("use the default behavior but this message")
)
type Policy interface {
@ -100,6 +108,7 @@ func (s *SwitchingCard) Then(p *Player, o CardOption) error {
// BasicPolicy is a straightfoward implementation of Policy. If the currently
// enacted option is re-enacted, it refunds the player's action point.
type BasicPolicy struct {
Desc cardsim.Message
UnenactedDesc cardsim.Message
EnactedDesc cardsim.Message
NothingChanged cardsim.Message
@ -124,13 +133,22 @@ func (b *BasicPolicy) LastEnacted(_ int, p Policy) {
// OptionText implements CardOption.
func (b *BasicPolicy) OptionText(*Player) (cardsim.Message, error) {
if b.currentlyEnacted {
if b.EnactedDesc == nil {
return nil, ErrUnimplemented
}
return b.EnactedDesc, nil
}
if b.UnenactedDesc == nil {
return nil, ErrUnimplemented
}
return b.UnenactedDesc, nil
}
// Enact implements CardOption.
func (b *BasicPolicy) Enact(p *Player) (cardsim.Message, error) {
if b.Do == nil {
return nil, ErrUnimplemented
}
if b.currentlyEnacted {
p.ActionsRemaining++
if b.NothingChanged == nil {
@ -138,10 +156,10 @@ func (b *BasicPolicy) Enact(p *Player) (cardsim.Message, error) {
}
return b.NothingChanged, nil
}
if b.CanDo != nil && !b.CanDo(p) {
return nil, ErrOptionNotEnabled
if b.Enabled(p) {
return b.Do(p)
}
return b.Do(p)
return nil, ErrOptionNotEnabled
}
// Unenact implements Policy.
@ -149,6 +167,9 @@ func (b *BasicPolicy) Unenact(p *Player) error {
if !b.currentlyEnacted {
return ErrPolicyNotEnacted
}
if b.Undo == nil {
return ErrUnimplemented
}
return b.Undo(p)
}
@ -158,7 +179,7 @@ func (b *BasicPolicy) Enabled(p *Player) bool {
return true
}
if b.CanDo == nil {
b.CanDo = YesWeCan
panic(ErrUnimplemented)
}
return b.CanDo(p)
}
@ -170,50 +191,154 @@ func (b *BasicPolicy) Is(p Policy) bool {
return false
}
// A DescResuilt is descriptive text for an option and the text result of
// enacting that option when it was described this way.
type DescResult struct {
Desc cardsim.Message
Result cardsim.Message
}
// A VerbosePolicy is an extension to a BasicPolicy. It emits the BasicPolicy's
// `UnenactedDesc` and the message returned from Do only when no policy has ever
// been enacted for this card; otherwise, it looks up the description and result
// from a slice using the index of the last policy selected.
// A VerbosePolicy is a group of related policies pretending to all be the same
// policy. Which policy is used is determined by what the previous policy for
// the card was (as reported via a call to LastEnacted):
//
// * If no policy has yet been enacted, use FirstTime.
// * If a policy has been enacted, use the Policy at the slot in Variants
// that corresponds to the slot (on the Card) of the currently-enacted policy.
// * If the policy retrieved in this way returns ErrUnimplemented, throw away
// its response and use Default instead. For Enabled, which does not have
// an error component to its return value, look for ErrUnimplemented as the
// argument to a Panic call, instead.
// * If the policy retrieved in this way returns ErrKeepMessage when Enact
// is called, it calls Default for the side effects but ignores its message,
// retaining the message from the original call. This is to avoid having to
// repeat the same Enact function except with different text each time.
// OptionText does this too, even though OptionText doesn't have side effects,
// so the same helper function can create a "constant message" callback
// that works the same for both fields so someone implementing a card won't
// accidentally fail to enact their policy's effects by using the wrong one
// in the wrong slot.
type VerbosePolicy struct {
*BasicPolicy
lastIdx int
Content []DescResult
Default Policy
FirstTime Policy
lastIdx int
lastWasMe bool
lastEnacted Policy
Variants []Policy
}
func (v *VerbosePolicy) LastEnacted(i int, p Policy) {
v.lastIdx = i
v.BasicPolicy.currentlyEnacted = v.Is(p)
}
v.lastEnacted = p
v.lastWasMe = v.Is(p)
func (v *VerbosePolicy) OptionText(*Player) (cardsim.Message, error) {
if v.lastIdx < 0 {
return v.BasicPolicy.UnenactedDesc, nil
// make sure we can just assume that there is a policy in this slot,
// inserting the default if there is none.
v.fillDefaults()
// Tell the potential candidate policy about this, too. Two special cases:
// * first time -- use first-time policy
// * lastWasMe -- tell the polcy that the last encated policy was itself,
// since it doesn't know it's wrapped in another policy and would not
// recognize itself as v
if i < 0 {
v.FirstTime.LastEnacted(i, p) // p should be nil here...
} else if v.lastWasMe {
v.Variants[i].LastEnacted(i, v.Variants[i])
} else {
v.Variants[i].LastEnacted(i, p)
}
// In case we need it, also prepare the Default for use.
if v.lastWasMe {
v.Default.LastEnacted(i, v.Default)
} else {
v.Default.LastEnacted(i, p)
}
return v.Content[v.lastIdx].Desc, nil
}
func (v *VerbosePolicy) Enact(p *Player) (cardsim.Message, error) {
msg, err := v.BasicPolicy.Enact(p)
if v.lastIdx >= 0 {
msg = v.Content[v.lastIdx].Result
func (v *VerbosePolicy) fillDefaults() {
if v.FirstTime == nil {
v.FirstTime = v.Default
}
for len(v.Variants) <= v.lastIdx {
v.Variants = append(v.Variants, v.Default)
}
if v.Variants[v.lastIdx] == nil {
v.Variants[v.lastIdx] = v.Default
}
}
func (v *VerbosePolicy) OptionText(p *Player) (cardsim.Message, error) {
var msg cardsim.Message
var err error
if v.lastIdx < 0 {
msg, err = v.FirstTime.OptionText(p)
} else {
msg, err = v.Variants[v.lastIdx].OptionText(p)
}
if errors.Is(err, ErrUnimplemented) {
msg, err = v.Default.OptionText(p)
}
return msg, err
}
func (v *VerbosePolicy) Enact(p *Player) (cardsim.Message, error) {
var msg cardsim.Message
var err error
if v.lastIdx < 0 {
msg, err = v.FirstTime.Enact(p)
} else {
msg, err = v.Variants[v.lastIdx].Enact(p)
}
if errors.Is(err, ErrUnimplemented) {
msg, err = v.Default.Enact()
}
return msg, err
}
func (v *VerbosePolicy) Unenact(p *Player) error {
if !v.lastWasMe {
return ErrPolicyNotEnacted
}
var err error
if v.lastIdx < 0 {
err = v.FirstTime.Unenact(p)
} else {
err = v.Variants[v.lastIdx].Unenact(p)
}
if errors.Is(err, ErrUnimplemented) {
err = v.Default.Unenact(p)
}
return err
}
func (v *VerbosePolicy) Is(p Policy) bool {
if o, ok := p.(*VerbosePolicy); ok {
return o == p
return o == v
}
return false
}
func (v *VerbosePolicy) Enabled(p *Player) (result bool) {
// oops, enablement isn't designed to error out. so we have to use
// panic/recover for this.
defer func() {
if x := recover(); x != nil {
if e, ok := x.(error); ok {
if errors.Is(e, ErrUnimplemented) {
// Recover and use the Default to cover for the missing
// Enabled method.
result = v.Default.Enabled(p)
return
}
}
// Whatever we caught, it's not something we're actually ready to recover from.
panic(x)
}
}()
if v.lastIdx < 0 {
result = v.FirstTime.Enabled(p)
return
}
result = v.Variants[v.lastIdx].Enabled(p)
return
}
// ShuffleIntoBottomHalf is a common "what to do with the card after?" behavior.
func ShuffleIntoBottomHalf(c Card, p *Player, _ CardOption) error {
p.Deck.InsertRandomBottom(0.5, c)