code: private int doSearch(final CharBuffer buffer, final int matchedLength,
          final int currentLength, final boolean ignoreCase)
      {
          /*
           * Try and see if there is a possible match here; there is if "fullword"
           * is true, in this case the next "matchedLength" argument to a possible
           * child call will be the current length.
           */
          final int nextLength = fullWord ? currentLength : matchedLength;
  
  
          /*
           * If there is nothing left in the buffer, we have a match.
           */
          if (!buffer.hasRemaining())
              return nextLength;
  
          /*
           * OK, there is at least one character remaining, so pick it up and see
           * whether it is in the list of our children...
           */
          char c = buffer.get();
          int index = Arrays.binarySearch(nextChars, c);
          if (index < 0 && ignoreCase) {
              final boolean isUpper = Character.isUpperCase(c);
              final boolean isLower = Character.isLowerCase(c);
              if (isUpper != isLower) {
                 c = isUpper ? Character.toLowerCase(c)
                     : Character.toUpperCase(c);
                 index = Arrays.binarySearch(nextChars, c);
              }
          }
  
          /*
           * If not, we return the last good match; if yes, we call this same
           * method on the matching child node with the (possibly new) matched
           * length as an argument and a depth increased by 1.
           */
          if (index < 0)
              return nextLength;
          return nextNodes[index].doSearch(buffer, nextLength, currentLength + 1,
              ignoreCase);
      }
docs: Core search method
  
  <p>This method uses a {@link CharBuffer} to perform searches, and changes
  this buffer's position as the match progresses. The two other arguments
  are the depth of the current search (ie the number of nodes visited
  since root) and the index of the last node where a match was found (ie
  the last node where {@link #fullWord} was true.</p>
  
  @param buffer the charbuffer
  @param matchedLength the last matched length (-1 if no match yet)
  @param currentLength the current length walked by the trie
  @return the length of the match found, -1 otherwise