From 4a10d22906eee96753c8bb6f8fee217e63a50a02 Mon Sep 17 00:00:00 2001
From: Naveen Gogineni <dear.chap@gmail.com>
Date: Sun, 2 Oct 2022 16:30:09 -0400
Subject: [PATCH] Add generics

---
 flag_impl.go | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 212 insertions(+)
 create mode 100644 flag_impl.go

diff --git a/flag_impl.go b/flag_impl.go
new file mode 100644
index 0000000000..fd46b9ed14
--- /dev/null
+++ b/flag_impl.go
@@ -0,0 +1,212 @@
+package cli
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+)
+
+type flagValue[T any] struct {
+	t *T
+}
+
+func (v flagValue[T]) String() string {
+	if b, err := json.Marshal(v.t); err != nil {
+		return ""
+	} else {
+		return string(b)
+	}
+}
+
+func (v flagValue[T]) Set(s string) error {
+	return json.Unmarshal([]byte(s), v.t)
+}
+
+func (v flagValue[T]) Get() any {
+	return *v.t
+}
+
+// Float64Flag is a flag with type float64
+type flagImpl[T any] struct {
+	Name string
+
+	Category    string
+	DefaultText string
+	FilePath    string
+	Usage       string
+
+	Required   bool
+	Hidden     bool
+	HasBeenSet bool
+
+	Value       T
+	Destination *T
+
+	Aliases []string
+	EnvVars []string
+
+	TakesFile bool
+
+	value flagValue[T]
+}
+
+// GetValue returns the flags value as string representation and an empty
+// string if the flag takes no value at all.
+func (f *flagImpl[T]) GetValue() string {
+	return fmt.Sprintf("%v", f.Value)
+}
+
+// Apply populates the flag given the flag set and environment
+func (f *flagImpl[T]) Apply(set *flag.FlagSet) error {
+	if val, source, found := flagFromEnvOrFile(f.EnvVars, f.FilePath); found {
+		if val != "" {
+			f.value.t = new(T)
+			if err := f.value.Set(val); err != nil {
+				return fmt.Errorf("could not parse %q as %T value from %s for flag %s: %s", val, f.Value, source, f.Name, err)
+			}
+
+			f.Value = *f.value.t
+			f.HasBeenSet = true
+		}
+	}
+
+	for _, name := range f.Names() {
+		if f.Destination != nil {
+			f.value.t = f.Destination
+			*f.Destination = f.Value
+			set.Var(f.value, name, f.Usage)
+			continue
+		}
+		if f.value.t == nil {
+			f.value.t = new(T)
+			*f.value.t = f.Value
+		}
+		set.Var(f.value, name, f.Usage)
+	}
+
+	return nil
+}
+
+// String returns a readable representation of this value (for usage defaults)
+func (f *flagImpl[T]) String() string {
+	return FlagStringer(f)
+}
+
+// IsSet returns whether or not the flag has been set through env or file
+func (f *flagImpl[T]) IsSet() bool {
+	return f.HasBeenSet
+}
+
+// Names returns the names of the flag
+func (f *flagImpl[T]) Names() []string {
+	return FlagNames(f.Name, f.Aliases)
+}
+
+// IsRequired returns whether or not the flag is required
+func (f *flagImpl[T]) IsRequired() bool {
+	return f.Required
+}
+
+// IsVisible returns true if the flag is not hidden, otherwise false
+func (f *flagImpl[T]) IsVisible() bool {
+	return !f.Hidden
+}
+
+// GetCategory returns the category of the flag
+func (f *flagImpl[T]) GetCategory() string {
+	return f.Category
+}
+
+// GetUsage returns the usage string for the flag
+func (f *flagImpl[T]) GetUsage() string {
+	return f.Usage
+}
+
+// GetEnvVars returns the env vars for this flag
+func (f *flagImpl[T]) GetEnvVars() []string {
+	return f.EnvVars
+}
+
+// TakesValue returns true if the flag takes a value, otherwise false
+func (f *flagImpl[T]) TakesValue() bool {
+	return "Float64Flag" != "BoolFlag"
+}
+
+// GetDefaultText returns the default text for this flag
+func (f *flagImpl[T]) GetDefaultText() string {
+	if f.DefaultText != "" {
+		return f.DefaultText
+	}
+	return f.GetValue()
+}
+
+// Get returns the flag’s value in the given Context.
+func (f *flagImpl[T]) Get(ctx *Context) T {
+	if v, ok := ctx.Value(f.Name).(T); ok {
+		return v
+	}
+	var t T
+	return t
+}
+
+type Float64Flag = flagImpl[float64]
+type IntFlag = flagImpl[int]
+type Int64Flag = flagImpl[int64]
+type UintFlag = flagImpl[uint]
+type Uint64Flag = flagImpl[uint64]
+
+//type StringFlag = flagImpl[string]
+
+// Int looks up the value of a local IntFlag, returns
+// 0 if not found
+func (cCtx *Context) Float64(name string) float64 {
+	if v, ok := cCtx.Value(name).(float64); ok {
+		return v
+	}
+	return 0
+}
+
+// Int looks up the value of a local IntFlag, returns
+// 0 if not found
+func (cCtx *Context) Int(name string) int {
+	if v, ok := cCtx.Value(name).(int); ok {
+		return v
+	}
+	return 0
+}
+
+// Int64 looks up the value of a local Int64Flag, returns
+// 0 if not found
+func (cCtx *Context) Int64(name string) int64 {
+	if v, ok := cCtx.Value(name).(int64); ok {
+		return v
+	}
+	return 0
+}
+
+// Int looks up the value of a local IntFlag, returns
+// 0 if not found
+func (cCtx *Context) Uint(name string) uint {
+	if v, ok := cCtx.Value(name).(uint); ok {
+		return v
+	}
+	return 0
+}
+
+// Int64 looks up the value of a local Int64Flag, returns
+// 0 if not found
+func (cCtx *Context) Uint64(name string) uint64 {
+	if v, ok := cCtx.Value(name).(uint64); ok {
+		return v
+	}
+	return 0
+}
+
+// String looks up the value of a local StringFlag, returns
+// "" if not found
+/*func (cCtx *Context) String(name string) string {
+	if v, ok := cCtx.Value(name).(string); ok {
+		return v
+	}
+	return ""
+}*/