From 886edb6f5abe5433eaf04ff8fc540efaffc99fcf Mon Sep 17 00:00:00 2001
From: Gerald Kaszuba <gak@gak0.com>
Date: Wed, 23 May 2018 10:22:57 +1000
Subject: [PATCH] Extend Tag for non-core decoders (Fixes #14)

---
 global_test.go |  4 +--
 kong_test.go   |  8 -----
 tag.go         | 79 +++++++++++++++++++++++++++++++-------------------
 3 files changed, 51 insertions(+), 40 deletions(-)

diff --git a/global_test.go b/global_test.go
index fdc5336..e371c62 100644
--- a/global_test.go
+++ b/global_test.go
@@ -9,7 +9,7 @@ import (
 
 func TestParseHandlingBadBuild(t *testing.T) {
 	var cli struct {
-		Enabled bool `kong:"unknown"`
+		Enabled bool `kong:"fail='"`
 	}
 
 	args := os.Args
@@ -21,7 +21,7 @@ func TestParseHandlingBadBuild(t *testing.T) {
 
 	defer func() {
 		if r := recover(); r != nil {
-			require.Equal(t, Error{msg: "unknown is an unknown kong key"}, r)
+			require.Equal(t, Error{msg: "fail=' is not quoted properly"}, r)
 		}
 	}()
 
diff --git a/kong_test.go b/kong_test.go
index bb9a6e1..77638c3 100644
--- a/kong_test.go
+++ b/kong_test.go
@@ -276,14 +276,6 @@ func TestCommaInQuotes(t *testing.T) {
 	require.Equal(t, "1,2", cli.Numbers)
 }
 
-func TestUnknownKey(t *testing.T) {
-	var cli struct {
-		Numbers string `kong:"gak='hi'"`
-	}
-	_, err := New(&cli)
-	require.Error(t, err)
-}
-
 func TestBadString(t *testing.T) {
 	var cli struct {
 		Numbers string `kong:"default='yay'n"`
diff --git a/tag.go b/tag.go
index ef10f99..46e1667 100644
--- a/tag.go
+++ b/tag.go
@@ -1,7 +1,9 @@
 package kong
 
 import (
+	"fmt"
 	"reflect"
+	"strconv"
 	"strings"
 	"unicode/utf8"
 )
@@ -18,6 +20,9 @@ type Tag struct {
 	Placeholder string
 	Env         string
 	Short       rune
+
+	// Storage for all tag keys for arbitrary lookups.
+	items map[string]string
 }
 
 func parseCSV(s string) map[string]string {
@@ -86,44 +91,58 @@ func parseCSV(s string) map[string]string {
 }
 
 func parseTag(fv reflect.Value, s string) *Tag {
-	t := &Tag{}
+	t := &Tag{
+		items: map[string]string{},
+	}
 	if s == "" {
 		return t
 	}
 
-	for k, v := range parseCSV(s) {
-		switch k {
-		case "cmd":
-			t.Cmd = true
-		case "arg":
-			t.Arg = true
-		case "required":
-			t.Required = true
-		case "optional":
-			t.Optional = true
-		case "default":
-			t.Default = v
-		case "help":
-			t.Help = v
-		case "type":
-			t.Type = v
-		case "placeholder":
-			t.Placeholder = v
-		case "env":
-			t.Env = v
-		case "rune":
-			t.Short, _ = utf8.DecodeRuneInString(v)
-			if t.Short == utf8.RuneError {
-				t.Short = 0
-			}
-		default:
-			fail("%v is an unknown kong key", k)
-		}
-	}
+	t.items = parseCSV(s)
 
+	t.Cmd = t.Has("cmd")
+	t.Arg = t.Has("arg")
+	t.Required = t.Has("required")
+	t.Optional = t.Has("optional")
+	t.Default, _ = t.Get("default")
+	t.Help, _ = t.Get("help")
+	t.Type, _ = t.Get("type")
+	t.Env, _ = t.Get("env")
+	t.Short, _ = t.GetRune("short")
+
+	t.Placeholder, _ = t.Get("placeholder")
 	if t.Placeholder == "" {
 		t.Placeholder = strings.ToUpper(dashedString(fv.Type().Name()))
 	}
 
 	return t
 }
+
+func (t *Tag) Has(k string) bool {
+	_, ok := t.items[k]
+	return ok
+}
+
+func (t *Tag) Get(k string) (string, error) {
+	return t.items[k], nil
+}
+
+func (t *Tag) GetBool(k string) (bool, error) {
+	return strconv.ParseBool(t.items[k])
+}
+
+func (t *Tag) GetFloat(k string) (float64, error) {
+	return strconv.ParseFloat(t.items[k], 64)
+}
+
+func (t *Tag) GetInt(k string) (int64, error) {
+	return strconv.ParseInt(t.items[k], 10, 64)
+}
+
+func (t *Tag) GetRune(k string) (rune, error) {
+	r, _ := utf8.DecodeRuneInString(t.items[k])
+	if r == utf8.RuneError {
+		return 0, fmt.Errorf("%v has a rune error", t.items[k])
+	}
+	return r, nil
+}