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/**
*
*/
package cgeo.geocaching.utils;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import org.eclipse.jdt.annotation.Nullable;
import java.nio.charset.Charset;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.zip.CRC32;
/**
* Misc. utils. All methods don't use Android specific stuff to use these methods in plain JUnit tests.
*/
public final class TextUtils {
public static final Charset CHARSET_UTF8 = Charset.forName("UTF-8");
public static final Charset CHARSET_ASCII = Charset.forName("US-ASCII");
private static final Pattern PATTERN_REMOVE_NONPRINTABLE = Pattern.compile("\\p{Cntrl}");
private TextUtils() {
// utility class
}
/**
* Searches for the pattern p in the data. If the pattern is not found defaultValue is returned
*
* @param data
* Data to search in
* @param p
* Pattern to search for
* @param trim
* Set to true if the group found should be trim'ed
* @param group
* Number of the group to return if found
* @param defaultValue
* Value to return if the pattern is not found
* @param last
* Find the last occurring value
* @return defaultValue or the n-th group if the pattern matches (trimmed if wanted)
*/
@SuppressFBWarnings("DM_STRING_CTOR")
public static String getMatch(@Nullable final String data, final Pattern p, final boolean trim, final int group, final String defaultValue, final boolean last) {
if (data != null) {
String result = null;
final Matcher matcher = p.matcher(data);
if (matcher.find()) {
result = matcher.group(group);
}
if (null != result) {
final Matcher remover = PATTERN_REMOVE_NONPRINTABLE.matcher(result);
result = remover.replaceAll(" ");
return trim ? new String(result).trim() : new String(result);
// Java copies the whole page String, when matching with regular expressions
// later this would block the garbage collector, as we only need tiny parts of the page
// see http://developer.android.com/reference/java/lang/String.html#backing_array
// Thus the creating of a new String via String constructor is necessary here!!
// And BTW: You cannot even see that effect in the debugger, but must use a separate memory profiler!
}
}
return defaultValue;
}
/**
* Searches for the pattern p in the data. If the pattern is not found defaultValue is returned
*
* @param data
* Data to search in
* @param p
* Pattern to search for
* @param trim
* Set to true if the group found should be trim'ed
* @param defaultValue
* Value to return if the pattern is not found
* @return defaultValue or the first group if the pattern matches (trimmed if wanted)
*/
public static String getMatch(final String data, final Pattern p, final boolean trim, final String defaultValue) {
return TextUtils.getMatch(data, p, trim, 1, defaultValue, false);
}
/**
* Searches for the pattern p in the data. If the pattern is not found defaultValue is returned
*
* @param data
* Data to search in
* @param p
* Pattern to search for
* @param defaultValue
* Value to return if the pattern is not found
* @return defaultValue or the first group if the pattern matches (trimmed)
*/
public static String getMatch(@Nullable final String data, final Pattern p, final String defaultValue) {
return TextUtils.getMatch(data, p, true, 1, defaultValue, false);
}
/**
* Searches for the pattern p in the data.
*
* @param data
* @param p
* @return true if data contains the pattern p
*/
public static boolean matches(final String data, final Pattern p) {
if (data == null) {
return false;
}
// matcher is faster than String.contains() and more flexible - it takes patterns instead of fixed texts
return p.matcher(data).find();
}
/**
* Replaces every \n, \r and \t with a single space. Afterwards multiple spaces
* are merged into a single space. Finally leading spaces are deleted.
*
* This method must be fast, but may not lead to the shortest replacement String.
*
* You are only allowed to change this code if you can prove it became faster on a device.
* see cgeo.geocaching.test.WhiteSpaceTest#replaceWhitespaceManually in the test project.
*
* @param data
* complete HTML page
* @return the HTML page as a very long single "line"
*/
public static String replaceWhitespace(final String data) {
final int length = data.length();
final char[] chars = new char[length];
data.getChars(0, length, chars, 0);
int resultSize = 0;
boolean lastWasWhitespace = true;
for (final char c : chars) {
if (c == ' ' || c == '\n' || c == '\r' || c == '\t') {
if (!lastWasWhitespace) {
chars[resultSize++] = ' ';
}
lastWasWhitespace = true;
} else {
chars[resultSize++] = c;
lastWasWhitespace = false;
}
}
return String.valueOf(chars, 0, resultSize);
}
/**
* Quick and naive check for possible rich HTML content in a string.
*
* @param str A string containing HTML code.
* @return <tt>true</tt> if <tt>str</tt> contains HTML code that needs to go through a HTML renderer before
* being displayed, <tt>false</tt> if it can be displayed as-is without any loss
*/
public static boolean containsHtml(final String str) {
return str.indexOf('<') != -1 || str.indexOf('&') != -1;
}
/**
* Remove all control characters (which are not valid in XML or HTML), as those should not appear in cache texts
* anyway
*
* @param input
* @return
*/
public static String removeControlCharacters(final String input) {
final Matcher remover = PATTERN_REMOVE_NONPRINTABLE.matcher(input);
return remover.replaceAll(" ").trim();
}
/**
* Calculate a simple checksum for change-checking (not usable for security/cryptography!)
*
* @param input
* String to check
* @return resulting checksum
*/
public static long checksum(final String input) {
final CRC32 checksum = new CRC32();
checksum.update(input.getBytes());
return checksum.getValue();
}
}
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