IPython/frontend/html/notebook/static/codemirror/lib/util/match-highlighter.js

// Define match-highlighter commands. Depends on searchcursor.js
// Use by attaching the following function call to the onCursorActivity event:
	//myCodeMirror.matchHighlight(minChars);
// And including a special span.CodeMirror-matchhighlight css class (also optionally a separate one for .CodeMirror-focused -- see demo matchhighlighter.html)

(function() {
  var DEFAULT_MIN_CHARS = 2;
  
  function MatchHighlightState() {
	this.marked = [];
  }
  function getMatchHighlightState(cm) {
	return cm._matchHighlightState || (cm._matchHighlightState = new MatchHighlightState());
  }
  
  function clearMarks(cm) {
	var state = getMatchHighlightState(cm);
	for (var i = 0; i < state.marked.length; ++i)
		state.marked[i].clear();
	state.marked = [];
  }
  
  function markDocument(cm, className, minChars) {
    clearMarks(cm);
	minChars = (typeof minChars !== 'undefined' ? minChars : DEFAULT_MIN_CHARS);
	if (cm.somethingSelected() && cm.getSelection().replace(/^\s+|\s+$/g, "").length >= minChars) {
		var state = getMatchHighlightState(cm);
		var query = cm.getSelection();
		cm.operation(function() {
			if (cm.lineCount() < 2000) { // This is too expensive on big documents.
			  for (var cursor = cm.getSearchCursor(query); cursor.findNext();) {
				//Only apply matchhighlight to the matches other than the one actually selected
				if (!(cursor.from().line === cm.getCursor(true).line && cursor.from().ch === cm.getCursor(true).ch))
					state.marked.push(cm.markText(cursor.from(), cursor.to(), className));
			  }
			}
		  });
	}
  }

  CodeMirror.defineExtension("matchHighlight", function(className, minChars) {
    markDocument(this, className, minChars);
  });
})();