URLUtil.java

package jetbrains.mps.core.tool.environment.common;

/*Generated by MPS */

import org.jetbrains.annotations.NotNull;
import java.util.List;
import java.util.ArrayList;
import java.io.UnsupportedEncodingException;

public class URLUtil {
  public URLUtil() {
  }
  @NotNull
  public static String unescapePercentSequences(@NotNull String s) {
    if (s.indexOf('%') == -1) {
      return s;
    }
    StringBuilder decoded = new StringBuilder();
    final int len = s.length();
    int i = 0;
    while (i < len) {
      char c = s.charAt(i);
      if (c == '%') {
        List<Integer> bytes = new ArrayList<Integer>();
        while (i + 2 < len && s.charAt(i) == '%') {
          final int d1 = decode(s.charAt(i + 1));
          final int d2 = decode(s.charAt(i + 2));
          if (d1 != -1 && d2 != -1) {
            bytes.add(((d1 & 15) << 4 | d2 & 15));
            i += 3;
          } else {
            break;
          }
        }
        if (!(bytes.isEmpty())) {
          final byte[] bytesArray = new byte[bytes.size()];
          for (int j = 0; j < bytes.size(); j++) {
            bytesArray[j] = (byte) bytes.get(j).intValue();
          }
          try {
            decoded.append(new String(bytesArray, "UTF-8"));
            continue;
          } catch (UnsupportedEncodingException ignored) {
          }
        }
      }
      decoded.append(c);
      i++;
    }
    return decoded.toString();
  }
  private static int decode(char c) {
    if ((c >= '0') && (c <= '9')) {
      return c - '0';
    }
    if ((c >= 'a') && (c <= 'f')) {
      return c - 'a' + 10;
    }
    if ((c >= 'A') && (c <= 'F')) {
      return c - 'A' + 10;
    }
    return -1;
  }
}