narutaro · September 6, 2020 02:26 · Sep 6, 2020
diff --git a/tab-completion-with-multi-command.rb b/tab-completion-with-multi-command.rb
@@ -0,0 +1,50 @@
+require "readline"
+require "yaml"
+
+command_tree = {"pet"=>
+  {"buy"=>{"dog"=>nil, "cat"=>nil},
+   "sell"=>{"bird"=>nil, "fox"=>nil},
+   "sellGroup"=>{"pig"=>nil, "kingfisher"=>nil},
+   "list"=>{"all"=>nil, "filter_by"=>nil}},
+ "store"=>
+  {"find"=>{"by_name"=>nil, "by_tag"=>nil, "by_address"=>nil}, "list"=>nil},
+ "user"=>{"login"=>nil, "logout"=>nil, "sign_up"=>nil},
+ "petGroup"=>{"login"=>nil, "loout"=>nil, "sign_up"=>nil},
+}
+
+pp command_tree
+
+def get_current_option(command_tree, line_buffer)
+  current_option = command_tree.keys
+  commands = line_buffer.split
+
+  commands.each_with_index do |command, i|
+
+    # Don't go down to the lower level(and return current_option) in case current command matches two candidates such as "pet" and "petGroup" 
+    return current_option if i == commands.size-1 and !line_buffer.end_with?("\s")
+
+    # Go down  
+    if command_tree.has_key?(command) 
+      if command_tree[command].nil? # invalid command or key at leaf
+        current_option = []
+      else
+        command_tree = command_tree[command] 
+        current_option = command_tree.keys
+      end
+    end
+  end
+  current_option
+end
+
+# Evaluate the proc when pressing <tab>
+comp = proc do |input|
+  get_current_option(command_tree, Readline.line_buffer).select { |name| name.to_s.start_with?(input) }
+end
+
+Readline.completion_proc = comp
+#Readline.completion_append_character = " "
+
+while input = Readline.readline("$ ", true)
+  break if input == "q"
+  p Readline.line_buffer.split if !input.empty?
+end