lib/readline-native.rb

   1 module Readline
   2
   3   module ASCII
   4     Home = 1
   5     ControlC = 3
   6     ControlD = 4
   7     End = 5
   8     Erase = 8
   9     Tab = 9
  10     Return = 10
  11     Escape = 27
  12     Backspace = 127
  13   end
  14
  15   @history = []
  16   @history_idx = 0
  17
  18   def self.readline(prompt)
  19     str = []
  20     idx = 0
  21
  22     begin
  23       @c_erase, @c_kill, @c_quit, @c_intr = _terminal_raw
  24
  25       print prompt
  26
  27       while true
  28         cur = STDIN.read(1)
  29
  30         if cur.nil? then
  31           print "\n"
  32           return nil
  33         end
  34
  35         code = cur[0]
  36         code = ASCII::Erase if code == @c_erase
  37
  38         cur = code.chr
  39
  40         if code == ASCII::Return
  41           print "\n"
  42           break
  43         elsif code == ASCII::ControlD
  44           print "\n"
  45           return nil
  46         elsif code == @c_intr
  47           puts "", "<Control-C>"
  48           raise Interrupt, "User requested termination with Control-C"
  49         elsif code == ASCII::Erase
  50           if str.size > 0
  51             print "\b" * idx
  52             idx -= 1
  53             str.slice!(idx)
  54             print str.join(""), " ", "\b" * (str.size + 1 - idx)
  55           end
  56         elsif code == ASCII::Escape
  57           STDIN.read(1) # eat the [
  58           command = STDIN.read(1)
  59           input = "\e[" + command
  60
  61           if command == "A"
  62             # history up
  63             if @history_idx > 0
  64               if @history_idx == @history.size && str.size > 0
  65                 @history << str
  66               end
  67
  68               @history_idx -= 1
  69
  70               print "\b" * idx, " " * str.size, "\b" * str.size
  71               str = @history[@history_idx].dup
  72               idx = str.size
  73               print str.join("")
  74             end
  75           elsif command == "B"
  76             # history down
  77             if @history_idx < @history.size
  78               @history_idx += 1
  79
  80               print "\b" * idx, " " * str.size, "\b" * str.size
  81               str = (@history[@history_idx] || []).dup
  82               idx = str.size
  83               print str.join("")
  84             end
  85           elsif command == "C"
  86             # cursor right
  87             if idx < str.size
  88               idx += 1
  89               print input
  90             end
  91           elsif command == "D"
  92             # cursor left
  93             if idx > 0
  94               idx -= 1
  95               print input
  96             end
  97           else
  98             print input
  99           end
 100         elsif code == ASCII::Home
 101           print "\b" * idx
 102           idx = 0
 103         elsif code == ASCII::End
 104           print "\b" * idx, str.join("")
 105           idx = str.size
 106         else
 107           str.insert(idx, cur)
 108           print "\b" * idx, str.join(""), "\b" * (str.size - idx - 1)
 109           idx += 1
 110         end
 111       end
 112     ensure
 113       _terminal_normal
 114     end
 115
 116     @history << str
 117     @history_idx = @history.size
 118
 119     out = str.join("")
 120     return out
 121   end
 122 end