Add tree display option.

Resolves #18

format/tree.go

@@ -0,0 +1,20 @@
+package format
+
+import (
+  "fmt"
+  "github.com/drn/nerd-ls/node"
+  "github.com/drn/nerd-ls/list"
+)
+
+// Tree - Format listing in tree format.
+func Tree(nodes []node.Node, options map[string]int) {
+  for _, node := range nodes {
+    prefix := ""
+    if options["prefix"] == 1 { prefix = "-" }
+    fmt.Printf("%s%s\n", prefix, nodeColor(node).Sprint(node.Name))
+    if node.IsDir {
+      nodes := list.Fetch(node.Name, options)
+      Tree(nodes, options)
+    }
+  }
+}

options/root.go

@@ -5,6 +5,7 @@ type Options struct {
   All bool `short:"a" long:"all" description:"Include directory entries whose names begin with a dot (.)"`
   Long bool `short:"l" long:"long" description:"List in long format"`
   Icon bool `short:"i" long:"icon" description:"Display nerd-font icons"`
+  Tree bool `short:"T" long:"tree" description:"Recurse into directories as a tree"`
 }
 
 // Parse - Converts flags to string -> int map