/**
* Normalize the given path. The following transformation takes place:
*
* <ol>
* <li>All `.' segments are removed.
* <li>Each `..' segment which can be paired with a prior non-`..' segment is removed along with
* the preceding segment.
* <li>A `.' segment is added to the front if the first segment contains a colon (`:'). This is
* a deviation from the RFC, which prevents confusion between the path and the scheme.
* </ol>
*
* <p>The resulting URI will be free of `.' and `..' segments, barring those that were prepended
* or which couldn't be paired, respectively.
*
* @param relativePath the relative path to be normalized.
* @return the normalized path.
*/
private String normalizePath(String relativePath) {
/*
This follows the algorithm in section 5.2.4. of RFC3986,
but doesn't modify the input buffer.
*/
StringBuilder input = new StringBuilder(relativePath);
StringBuilder output = new StringBuilder();
int start = 0;
while (start < input.length()) {
/* A */
if (input.indexOf("../", start) == start) {
start += 3;
continue;
}
if (input.indexOf("./", start) == start) {
start += 2;
continue;
}
/* B */
if (input.indexOf("/./", start) == start) {
start += 2;
continue;
}
if (input.indexOf("/.", start) == start && input.charAt(start + 2) != '.') {
start += 1;
input.setCharAt(start, '/');
continue;
}
/* C */
if (input.indexOf("/../", start) == start) {
start += 3;
removeLastSegment(output);
continue;
}
if (input.indexOf("/..", start) == start) {
start += 2;
input.setCharAt(start, '/');
removeLastSegment(output);
continue;
}
/* D */
if (start == input.length() - 1 && input.indexOf(".", start) == start) {
input.delete(0, 1);
continue;
}
if (start == input.length() - 2 && input.indexOf("..", start) == start) {
input.delete(0, 2);
continue;
}
/* E */
int indexOfSlash = input.indexOf("/", start);
while (indexOfSlash == start) {
output.append("/");
++start;
indexOfSlash = input.indexOf("/", start);
}
if (indexOfSlash == -1) indexOfSlash = input.length();
output.append(input.substring(start, indexOfSlash));
start = indexOfSlash;
}
return output.toString();
}
