Add typed command input bindings

command.go

@@ -3,6 +3,7 @@ package commandkit
 import (
 	"fmt"
 	"strings"
+	"unicode"
 )
 
 // Command is an opaque command declaration. Use NewCommand or Group to create
@@ -49,9 +50,12 @@ type Flag[I any] struct {
 }
 
 type flagBinding[I any] struct {
-	meta    FlagMeta
-	prepare func([]string) (func(*I), error)
-	valid   bool
+	meta        FlagMeta
+	defaultText string
+	repeated    bool
+	boolean     bool
+	prepare     func([]string) (func(*I), error)
+	valid       bool
 }
 
 // Argument represents a typed binding for a positional command argument.
@@ -91,7 +95,7 @@ type CommandSpec[I any] struct {
 type commandPayload interface {
 	validate() error
 	hasRun() bool
-	newInput() any
+	prepare([][]string, []string, bool) (func() any, error)
 	run(Invocation, any) Outcome
 }
 
@@ -107,12 +111,15 @@ func (c typedCommand[I]) hasRun() bool {
 	return c.spec.Run != nil
 }
 
-func (c typedCommand[I]) newInput() any {
-	var input I
-	if c.spec.NewInput != nil {
-		input = c.spec.NewInput()
+func (c typedCommand[I]) prepare(flagValues [][]string, operands []string, enforceRequired bool) (func() any, error) {
+	prepared, err := prepareInput(c.spec, flagValues, operands, enforceRequired)
+	if err != nil {
+		return nil, err
 	}
-	return &input
+	return func() any {
+		input := prepared.build()
+		return &input
+	}, nil
 }
 
 func (c typedCommand[I]) run(invocation Invocation, input any) Outcome {
@@ -222,8 +229,8 @@ func validateBindings[I any](flags []Flag[I], arguments []Argument[I]) error {
 	shortNames := make(map[string]struct{}, len(flags))
 	for _, flag := range flags {
 		binding := flag.binding
-		if binding.meta.Name == "" || strings.ContainsAny(binding.meta.Name, " \t\r\n") || strings.HasPrefix(binding.meta.Name, "-") {
-			return fmt.Errorf("flag name %q must be a nonempty token without leading dashes", binding.meta.Name)
+		if !validFlagName(binding.meta.Name) {
+			return fmt.Errorf("flag name %q must use lowercase hyphen-separated words", binding.meta.Name)
 		}
 		if binding.meta.Name == "help" {
 			return fmt.Errorf("flag name %q is reserved for help", binding.meta.Name)
@@ -263,3 +270,24 @@ func validateBindings[I any](flags []Flag[I], arguments []Argument[I]) error {
 	}
 	return nil
 }
+
+func validFlagName(name string) bool {
+	if name == "" || name[0] == '-' || name[len(name)-1] == '-' {
+		return false
+	}
+	segmentHasCharacter := false
+	for _, character := range name {
+		if character == '-' {
+			if !segmentHasCharacter {
+				return false
+			}
+			segmentHasCharacter = false
+			continue
+		}
+		if !unicode.IsLower(character) && !unicode.IsDigit(character) {
+			return false
+		}
+		segmentHasCharacter = true
+	}
+	return segmentHasCharacter
+}