From ab97c7a63a9819fef6e2627f31e189fa7a1a06bd Mon Sep 17 00:00:00 2001
From: Andrey Kurilin <andr.kurilin@gmail.com>
Date: Tue, 14 Jun 2016 17:04:53 +0300
Subject: [PATCH] Sort commands by their names

The slice of commands are sorted now automatically while Commands are called.
To turn off this feature, EnableCommandSorting variable is added.
---
 cobra.go        |  4 ++++
 command.go      | 18 +++++++++++++++++-
 command_test.go | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/cobra.go b/cobra.go
index 0c4e2e5..93a2c0f 100644
--- a/cobra.go
+++ b/cobra.go
@@ -41,6 +41,10 @@ var initializers []func()
 // Set this to true to enable it
 var EnablePrefixMatching = false
 
+//EnableCommandSorting controls sorting of the slice of commands, which is turned on by default.
+//To disable sorting, set it to false.
+var EnableCommandSorting = true
+
 //AddTemplateFunc adds a template function that's available to Usage and Help
 //template generation.
 func AddTemplateFunc(name string, tmplFunc interface{}) {
diff --git a/command.go b/command.go
index dc57d63..a8b0fa5 100644
--- a/command.go
+++ b/command.go
@@ -21,6 +21,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
 
 	flag "github.com/spf13/pflag"
@@ -103,6 +104,8 @@ type Command struct {
 	commandsMaxUseLen         int
 	commandsMaxCommandPathLen int
 	commandsMaxNameLen        int
+	// is commands slice are sorted or not
+	commandsAreSorted bool
 
 	flagErrorBuf *bytes.Buffer
 
@@ -721,8 +724,20 @@ func (c *Command) ResetCommands() {
 	c.helpCommand = nil
 }
 
-//Commands returns a slice of child commands.
+// Sorts commands by their names
+type commandSorterByName []*Command
+
+func (c commandSorterByName) Len() int           { return len(c) }
+func (c commandSorterByName) Swap(i, j int)      { c[i], c[j] = c[j], c[i] }
+func (c commandSorterByName) Less(i, j int) bool { return c[i].Name() < c[j].Name() }
+
+// Commands returns a sorted slice of child commands.
 func (c *Command) Commands() []*Command {
+	// do not sort commands if it already sorted or sorting was disabled
+	if EnableCommandSorting && !c.commandsAreSorted{
+		sort.Sort(commandSorterByName(c.commands))
+		c.commandsAreSorted = true
+	}
 	return c.commands
 }
 
@@ -751,6 +766,7 @@ func (c *Command) AddCommand(cmds ...*Command) {
 			x.SetGlobalNormalizationFunc(c.globNormFunc)
 		}
 		c.commands = append(c.commands, x)
+		c.commandsAreSorted = false
 	}
 }
 
diff --git a/command_test.go b/command_test.go
index 291947f..127ca0e 100644
--- a/command_test.go
+++ b/command_test.go
@@ -133,3 +133,44 @@ func Test_DisableFlagParsing(t *testing.T) {
 		t.Errorf("expected: %v, got: %v", as, targs)
 	}
 }
+
+func TestCommandsAreSorted(t *testing.T) {
+	EnableCommandSorting = true
+
+	originalNames := []string{"middle", "zlast", "afirst"}
+	expectedNames := []string{"afirst", "middle", "zlast"}
+
+	var tmpCommand = &Command{Use: "tmp"}
+
+	for _, name := range(originalNames) {
+		tmpCommand.AddCommand(&Command{Use: name})
+	}
+
+	for i, c := range(tmpCommand.Commands()) {
+		if expectedNames[i] != c.Name() {
+			t.Errorf("expected: %s, got: %s", expectedNames[i], c.Name())
+		}
+	}
+
+	EnableCommandSorting = true
+}
+
+func TestEnableCommandSortingIsDisabled(t *testing.T) {
+	EnableCommandSorting = false
+
+	originalNames := []string{"middle", "zlast", "afirst"}
+
+	var tmpCommand = &Command{Use: "tmp"}
+
+	for _, name := range(originalNames) {
+		tmpCommand.AddCommand(&Command{Use: name})
+	}
+
+	for i, c := range(tmpCommand.Commands()) {
+		if originalNames[i] != c.Name() {
+			t.Errorf("expected: %s, got: %s", originalNames[i], c.Name())
+		}
+	}
+
+	EnableCommandSorting = true
+}