Function indexOf

src/searching/knuth-morris-pratt.js:48–73

* Knuth–Morris–Pratt algorithm. Searches for the position of * the first occurrence of a specified value in a string. * * @example * * var indexOf = require('path-to-algorithm/src/searching/'+ * 'knuth-morris-pratt').kmp; * console.log(indexOf('hello', 'll')); // 2

(str, substr)

     * time, or -1 if it never occurs.
     */
    function indexOf(str, substr) {
      if (str === substr) {
        return 0;
      }
      var table = builtKMPTable(substr);
      var i = 0;
      var j = 0;
      while (i < str.length) {
        if (str[i] === substr[j]) {
          i += 1;
          j += 1;
        }
        if (j === substr.length) {
          return i - j;
        }
        if (i < str.length && str[i] !== substr[j]) {
          if (j > 0 && table[j - 1] !== 0) {
            j = table[j - 1];
          } else {
            i += 1;
            j = 0;
          }
        }
      }
      return -1;
    }
    return indexOf;
  }());