dcparker / jquery_plugins

// qs_score - Quicksilver Score
// 
// A port of the Quicksilver string ranking algorithm
// 
// "hello world".score("axl") //=> 0.0
// "hello world".score("ow") //=> 0.6
// "hello world".score("hello world") //=> 1.0
//
// Tested in Firefox 2 and Safari 3
//
// The Quicksilver code is available here
// http://code.google.com/p/blacktree-alchemy/
// http://blacktree-alchemy.googlecode.com/svn/trunk/Crucible/Code/NSString+BLTRRanking.m
//
// The MIT License
// 
// Copyright (c) 2008 Lachie Cox
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
 
 
String.prototype.score = function(abbreviation,offset) {
  offset = offset || 0 // TODO: I think this is unused... remove
 
  if(abbreviation.length == 0) return 0.9
  if(abbreviation.length > this.length) return 0.0
 
  for (var i = abbreviation.length; i > 0; i--) {
    var sub_abbreviation = abbreviation.substring(0,i)
    var index = this.indexOf(sub_abbreviation)
 
 
    if(index < 0) continue;
    if(index + abbreviation.length > this.length + offset) continue;
 
    var next_string       = this.substring(index+sub_abbreviation.length)
    var next_abbreviation = null
 
    if(i >= abbreviation.length)
      next_abbreviation = ''
    else
      next_abbreviation = abbreviation.substring(i)
 
    var remaining_score   = next_string.score(next_abbreviation,offset+index)
 
    if (remaining_score > 0) {
      var score = this.length-next_string.length;
 
      if(index != 0) {
        var j = 0;
 
        var c = this.charCodeAt(index-1)
        if(c==32 || c == 9) {
          for(var j=(index-2); j >= 0; j--) {
            c = this.charCodeAt(j)
            score -= ((c == 32 || c == 9) ? 1 : 0.15)
          }
 
          // XXX maybe not port this heuristic
          // 
          //          } else if ([[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[self characterAtIndex:matchedRange.location]]) {
          //            for (j = matchedRange.location-1; j >= (int) searchRange.location; j--) {
          //              if ([[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[self characterAtIndex:j]])
          //                score--;
          //              else
          //                score -= 0.15;
          //            }
        } else {
          score -= index
        }
      }
   
      score += remaining_score * next_string.length
      score /= this.length;
      return score
    }
  }
  return 0.0
}