text: from configHandler import idleConf
  
  class History:
  
      def __init__(self, text, output_sep = "\n"):
          self.text = text
          self.history = []
          self.history_prefix = None
          self.history_pointer = None
          self.output_sep = output_sep
          self.cyclic = idleConf.GetOption("main", "History", "cyclic", 1, "bool")
          text.bind("<<history-previous>>", self.history_prev)
          text.bind("<<history-next>>", self.history_next)
  
      def history_next(self, event):
          self.history_do(0)
          return "break"
  
      def history_prev(self, event):
          self.history_do(1)
          return "break"
  
      def _get_source(self, start, end):
          # Get source code from start index to end index.  Lines in the
          # text control may be separated by sys.ps2 .
          lines = self.text.get(start, end).split(self.output_sep)
          return "\n".join(lines)
  
      def _put_source(self, where, source):
          output = self.output_sep.join(source.split("\n"))
          self.text.insert(where, output)
  
      def history_do(self, reverse):
          nhist = len(self.history)
          pointer = self.history_pointer
          prefix = self.history_prefix
          if pointer is not None and prefix is not None:
              if self.text.compare("insert", "!=", "end-1c") or \
                 self._get_source("iomark", "end-1c") != self.history[pointer]:
                  pointer = prefix = None
          if pointer is None or prefix is None:
              prefix = self._get_source("iomark", "end-1c")
              if reverse:
                  pointer = nhist
              else:
                  if self.cyclic:
                      pointer = -1
                  else:
                      self.text.bell()
                      return
          nprefix = len(prefix)
          while 1:
              if reverse:
                  pointer = pointer - 1
              else:
                  pointer = pointer + 1
              if pointer < 0 or pointer >= nhist:
                  self.text.bell()
                  if not self.cyclic and pointer < 0:
                      return
                  else:
                      if self._get_source("iomark", "end-1c") != prefix:
                          self.text.delete("iomark", "end-1c")
                          self._put_source("iomark", prefix)
                      pointer = prefix = None
                  break
              item = self.history[pointer]
              if item[:nprefix] == prefix and len(item) > nprefix:
                  self.text.delete("iomark", "end-1c")
                  self._put_source("iomark", item)
                  break
          self.text.mark_set("insert", "end-1c")
          self.text.see("insert")
          self.text.tag_remove("sel", "1.0", "end")
          self.history_pointer = pointer
          self.history_prefix = prefix
  
      def history_store(self, source):
          source = source.strip()
          if len(source) > 2:
              # avoid duplicates
              try:
                  self.history.remove(source)
              except ValueError:
                  pass
              self.history.append(source)
          self.history_pointer = None
          self.history_prefix = None
  