Sublime Plugin to Highlight the Current Word

currentWord.py

import sublime, sublime_plugin
import time

key = "HighlightCurrentWord"

# The search is performed half a second after the most recent event in order to prevent the search hapenning on every keypress.
# Each of the event handlers simply marks the time of the most recent event and a timer periodically executes doSearch
class HighlightCurrentWord(sublime_plugin.EventListener):
  def __init__(self):
    self.previousRegion = sublime.Region(0, 0)
    sublime.set_timeout(self.on_timer, 50)

  def on_timer(self):
    sublime.set_timeout(self.on_timer, 50)
    self.doSearch(sublime.active_window().active_view(), False)

  def doSearch(self, view, force=True):
    if view == None:
      return

    selections = view.sel()
    if len(selections) == 0:
      view.erase_regions(key)
      return

    visibleRegion = view.visible_region()
    if force or (self.previousRegion != visibleRegion):
      self.previousRegion = visibleRegion
      view.erase_regions(key)
    else:
      return

    # The default separator does not include whitespace, so I add that here no matter what
    separatorString = view.settings().get('word_separators') + u" \n\r"
    themeSelector = view.settings().get('highlight_word_theme_selector', 'comment')

    currentRegion = view.word(selections[0])
    currentWord = view.substr(currentRegion).strip(separatorString) # remove leading/trailing separator characters just in case

    #print u"|%s|" % currentWord
    if(len(currentWord) == 0):
      view.erase_regions(key)
      return

    searchStart = self.previousRegion.a - len(currentWord)
    searchEnd = self.previousRegion.b + len(currentWord)

    # Reduce m*n search to just n by mapping each word separator character into a dictionary
    separators = {}
    for c in separatorString:
      separators[c] = True

    # ignore the selection if it spans multiple words
    for c in currentWord:
      if c in separators:
        return

    # If we are multi-selecting and all the words are the same, then we should still highlight
    if len(selections) > 1:
      for region in selections:
        word = view.substr(region).strip(separatorString)
        if word != currentWord:
          return

    validRegions = []
    while True:
      foundRegion = view.find(currentWord, searchStart, sublime.LITERAL)
      if foundRegion == None:
        break

      # regions can have reversed start/ends so normalize them
      start = min(foundRegion.a, foundRegion.b)
      end = max(foundRegion.a, foundRegion.b)
      searchStart = end

      if foundRegion.empty() or foundRegion.intersects(currentRegion):
        continue

      # check if the character before and after the region is a separator character
      # if it is not, then the region is part of a larger word and shouldn't match
      # this can't be done in a regex because we would be unable to use the word_separators setting string
      leadingCharacter = view.substr(sublime.Region(start-1, start))
      followingCharacter = view.substr(sublime.Region(end, end+1))
      if start == 0 or leadingCharacter in separators:
        if end == view.size()-1 or followingCharacter in separators:
          validRegions.append(foundRegion)

      if searchStart > searchEnd:
        break
    view.add_regions(key, validRegions, themeSelector)

  def on_selection_modified(self, view):
    self.doSearch(view)

  def on_close(self, view):
    self.doSearch(view)

  def on_activated(self, view):
    self.doSearch(view)