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/**
 * 
 */
package clime.messadmin.utils;

/**
 * Copy of org.apache.commons.lang.StringUtils 2.1
 * @author Cédrik LIME
 */
public class StringUtils {

	private StringUtils() {
	}

	/**
	 * Checks if a String is not empty ("") and not null.
	 * 
	 * @param str  the String to check, may be null
	 * @return true if the String is not empty or null
	 */
	public static boolean isEmpty(String str) {
		return str == null || str.length() == 0;
	}

	/**
	 * Checks if a String is not empty ("") and not null.
	 * 
	 * @param str  the String to check, may be null
	 * @return true if the String is not empty and not null
	 */
	public static boolean isNotEmpty(String str) {
		return str != null && str.length() > 0;
	}

	/**
	 * Checks if a String is whitespace, empty ("") or null.
	 * 
	 * @param str  the String to check, may be null
	 * @return true if the String is null, empty or whitespace
	 */
	public static boolean isBlank(String str) {
		int strLen;
		if (str == null || (strLen = str.length()) == 0) {
			return true;
		}
		for (int i = 0; i < strLen; ++i) {
			if ( ! Character.isWhitespace(str.charAt(i)) ) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Checks if a String is not empty (""), not null and not whitespace only.
	 * 
	 * @param str  the String to check, may be null
	 * @return true if the String is not empty and not null and not whitespace
	 */
	public static boolean isNotBlank(String str) {
		int strLen;
		if (str == null || (strLen = str.length()) == 0) {
			return false;
		}
		for (int i = 0; i < strLen; ++i) {
			if ( ! Character.isWhitespace(str.charAt(i)) ) {
				return true;
			}
		}
		return false;
	}

	private static final int HIGHEST_SPECIAL = '>';
	private static char[][] specialCharactersRepresentation = new char[HIGHEST_SPECIAL + 1][];
	static {
		specialCharactersRepresentation['&'] = "&".toCharArray();//$NON-NLS-1$
		specialCharactersRepresentation['<'] = "<".toCharArray();//$NON-NLS-1$
		specialCharactersRepresentation['>'] = ">".toCharArray();//$NON-NLS-1$
		specialCharactersRepresentation['"'] = """.toCharArray();//$NON-NLS-1$
		specialCharactersRepresentation['\''] = "'".toCharArray();//$NON-NLS-1$
	}
	/**
	 * Copied and adapted from org.apache.taglibs.standard.tag.common.core.Util v1.1.2
	 * 
	 * Performs the following substring replacements
	 * (to facilitate output to XML/HTML pages):
	 *
	 *	& -> &
	 *	< -> <
	 *	> -> >
	 *	" -> "
	 *	' -> '
	 *
	 * See also OutSupport.writeEscapedXml().
	 */
	public static String escapeXml(String buffer) {
		if (null == buffer) {
			return null;
		}
		int start = 0;
		int length = buffer.length();
		char[] arrayBuffer = buffer.toCharArray();
		StringBuffer escapedBuffer = null;
	
		for (int i = 0; i < length; ++i) {
			char c = arrayBuffer[i];
			if (c <= HIGHEST_SPECIAL) {
				char[] escaped = specialCharactersRepresentation[c];
				if (escaped != null) {
					// create StringBuffer to hold escaped xml string
					if (start == 0) {
						escapedBuffer = new StringBuffer(length + 5);
					}
					// add unescaped portion
					if (start < i) {
						escapedBuffer.append(arrayBuffer,start,i-start);
					}
					start = i + 1;
					// add escaped xml
					escapedBuffer.append(escaped);
				}
			}
		}
		// no xml escaping was necessary
		if (start == 0) {
			return buffer;
		}
		// add rest of unescaped portion
		if (start < length) {
			escapedBuffer.append(arrayBuffer,start,length-start);
		}
		return escapedBuffer.toString();
	}
}