feat: dynamic

Adds `Func`-able properties to all fields to allow dynamic updates
based on updates in other parts of the group.

Note that bindings must be specified. Bindings allow the Function to
know when it should update as the functoin re-evaluates only when the
value of the binding changes.

.gitignore

@@ -19,3 +19,6 @@
 
 # Go workspace file
 go.work
+
+# Debugging
+debug.log

eval.go

@@ -0,0 +1,79 @@
+package huh
+
+import (
+	"time"
+
+	"github.com/mitchellh/hashstructure/v2"
+)
+
+type Eval[T any] struct {
+	val T
+	fn  func() T
+
+	bindings     any
+	bindingsHash uint64
+	cache        map[uint64]T
+
+	loading      bool
+	loadingStart time.Time
+}
+
+const spinnerShowThreshold = 25 * time.Millisecond
+
+func hash(val any) uint64 {
+	hash, _ := hashstructure.Hash(val, hashstructure.FormatV2, nil)
+	return hash
+}
+
+func (e *Eval[T]) shouldUpdate() (bool, uint64) {
+	if e.fn == nil {
+		return false, 0
+	}
+	newHash := hash(e.bindings)
+	return e.bindingsHash != newHash, newHash
+}
+
+func (e *Eval[T]) loadFromCache() bool {
+	val, ok := e.cache[e.bindingsHash]
+	if ok {
+		e.loading = false
+		e.val = val
+	}
+	return ok
+}
+
+func (e *Eval[T]) update(val T) {
+	e.val = val
+	e.cache[e.bindingsHash] = val
+	e.loading = false
+}
+
+type updateTitleMsg struct {
+	id    int
+	hash  uint64
+	title string
+}
+
+type updateDescriptionMsg struct {
+	id          int
+	hash        uint64
+	description string
+}
+
+type updatePlaceholderMsg struct {
+	id          int
+	hash        uint64
+	placeholder string
+}
+
+type updateSuggestionsMsg struct {
+	id          int
+	hash        uint64
+	suggestions []string
+}
+
+type updateOptionsMsg[T comparable] struct {
+	id      int
+	hash    uint64
+	options []Option[T]
+}

examples/conditional/main.go

@@ -38,44 +38,40 @@ func main() {
 						huh.NewOption("A vegetable", vegetables),
 						huh.NewOption("A drink", drinks),
 					),
-			),
-
-			huh.NewGroup(
-				huh.NewSelect[string]().
-					Title("Okay, what kind of fruit are you in the mood for?").
-					Options(
-						huh.NewOption("Tangerine", "tangerine"),
-						huh.NewOption("Canteloupe", "canteloupe"),
-						huh.NewOption("Pomelo", "pomelo"),
-						huh.NewOption("Grapefruit", "grapefruit"),
-					).
-					Value(&choice),
-			).WithHideFunc(func() bool { return category != fruits }),
-
-			huh.NewGroup(
-				huh.NewSelect[string]().
-					Title("Okay, what kind of vegetable are you in the mood for?").
-					Options(
-						huh.NewOption("Carrot", "carrot"),
-						huh.NewOption("Jicama", "jicama"),
-						huh.NewOption("Kohlrabi", "kohlrabi"),
-						huh.NewOption("Fennel", "fennel"),
-						huh.NewOption("Ginger", "ginger"),
-					).
-					Value(&choice),
-			).WithHideFunc(func() bool { return category != vegetables }),
 
-			huh.NewGroup(
 				huh.NewSelect[string]().
-					Title(fmt.Sprintf("Okay, what kind of %s are you in the mood for?", category)).
-					Options(
-						huh.NewOption("Coffee", "coffee"),
-						huh.NewOption("Tea", "tea"),
-						huh.NewOption("Bubble Tea", "bubble tea"),
-						huh.NewOption("Agua Fresca", "agua-fresca"),
-					).
-					Value(&choice),
-			).WithHideFunc(func() bool { return category != drinks }),
+					Value(&choice).
+					Height(7).
+					TitleFunc(func() string {
+						return fmt.Sprintf("Okay, what kind of %s are you in the mood for?", category)
+					}, &category).
+					OptionsFunc(func() []huh.Option[string] {
+						switch category {
+						case fruits:
+							return []huh.Option[string]{
+								huh.NewOption("Tangerine", "tangerine"),
+								huh.NewOption("Canteloupe", "canteloupe"),
+								huh.NewOption("Pomelo", "pomelo"),
+								huh.NewOption("Grapefruit", "grapefruit"),
+							}
+						case vegetables:
+							return []huh.Option[string]{
+								huh.NewOption("Carrot", "carrot"),
+								huh.NewOption("Jicama", "jicama"),
+								huh.NewOption("Kohlrabi", "kohlrabi"),
+								huh.NewOption("Fennel", "fennel"),
+								huh.NewOption("Ginger", "ginger"),
+							}
+						default:
+							return []huh.Option[string]{
+								huh.NewOption("Coffee", "coffee"),
+								huh.NewOption("Tea", "tea"),
+								huh.NewOption("Bubble Tea", "bubble tea"),
+								huh.NewOption("Agua Fresca", "agua-fresca"),
+							}
+						}
+					}, &category),
+			),
 		).Run()
 
 	if err != nil {

examples/dynamic/dynamic-all/main.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"log"
+	"strconv"
+
+	"github.com/charmbracelet/huh"
+)
+
+func main() {
+	var value string = "Dynamic"
+
+	f := huh.NewForm(
+		huh.NewGroup(
+			huh.NewInput().Value(&value).Title("Dynamic").Description("Dynamic"),
+			huh.NewNote().
+				TitleFunc(func() string { return value }, &value).
+				DescriptionFunc(func() string { return value }, &value),
+			huh.NewSelect[string]().
+				Height(7).
+				TitleFunc(func() string { return value }, &value).
+				DescriptionFunc(func() string { return value }, &value).
+				OptionsFunc(func() []huh.Option[string] {
+					var options []huh.Option[string]
+					for i := 1; i < 6; i++ {
+						options = append(options, huh.NewOption(value+" "+strconv.Itoa(i), value+strconv.Itoa(i)))
+					}
+					return options
+				}, &value),
+			huh.NewMultiSelect[string]().
+				Height(7).
+				TitleFunc(func() string { return value }, &value).
+				DescriptionFunc(func() string { return value }, &value).
+				OptionsFunc(func() []huh.Option[string] {
+					var options []huh.Option[string]
+					for i := 1; i < 6; i++ {
+						options = append(options, huh.NewOption(value+" "+strconv.Itoa(i), value+strconv.Itoa(i)))
+					}
+					return options
+				}, &value),
+			huh.NewConfirm().
+				TitleFunc(func() string { return value }, &value).
+				DescriptionFunc(func() string { return value }, &value),
+			huh.NewText().
+				TitleFunc(func() string { return value }, &value).
+				DescriptionFunc(func() string { return value }, &value).
+				PlaceholderFunc(func() string { return value }, &value),
+		),
+	)
+	err := f.Run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}