Format ls output into columns.

Fixes #17. Original code by @grantseltzer

cmd/ls.go

@@ -18,11 +18,13 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sort"
 	"strings"
 	"text/tabwriter"
 
 	"github.com/dropbox/dropbox-sdk-go-unofficial/files"
 	"github.com/dustin/go-humanize"
+	"github.com/grantseltzer/golumns"
 	"github.com/spf13/cobra"
 )
 
@@ -93,24 +95,42 @@ func ls(cmd *cobra.Command, args []string) (err error) {
 		}
 	}
 
-	w := new(tabwriter.Writer)
-	w.Init(os.Stdout, 4, 8, 1, ' ', 0)
 	long, _ := cmd.Flags().GetBool("long")
 	if long {
+		w := new(tabwriter.Writer)
+		w.Init(os.Stdout, 4, 8, 1, ' ', 0)
 		fmt.Fprintf(w, "Revision\tSize\tLast modified\tPath\n")
+		for _, entry := range entries {
+			switch entry.Tag {
+			case "folder":
+				printFolderMetadata(w, entry.Folder, long)
+			case "file":
+				printFileMetadata(w, entry.File, long)
+			}
+		}
+		w.Flush()
+	} else {
+		entryNames := listOfEntryNames(entries)
+		golumns.Display(entryNames)
 	}
 
-	for _, e := range entries {
-		switch e.Tag {
+	return err
+}
+
+func listOfEntryNames(entries []*files.Metadata) []string {
+	listOfEntryNames := []string{}
+
+	for _, entry := range entries {
+		switch entry.Tag {
 		case "folder":
-			printFolderMetadata(w, e.Folder, long)
+			listOfEntryNames = append(listOfEntryNames, entry.Folder.Name)
 		case "file":
-			printFileMetadata(w, e.File, long)
+			listOfEntryNames = append(listOfEntryNames, entry.File.Name)
 		}
 	}
-	w.Flush()
 
-	return err
+	sort.Strings(listOfEntryNames)
+	return listOfEntryNames
 }
 
 // lsCmd represents the ls command