package constraint_gen;

public class EscapeXml {
    
    private static final String[] ESCAPES;

    static {
        int size = '>' + 1; // '>' is the largest escaped value
        ESCAPES = new String[size];
        ESCAPES['<'] = "&lt;";
        ESCAPES['>'] = "&gt;";
        ESCAPES['&'] = "&amp;";
        ESCAPES['\''] = "&#039;";
        ESCAPES['"'] = "&#034;";
    }

    private static String getEscape(char c) {
        if (c < ESCAPES.length) {
            return ESCAPES[c];
        } else {
            return null;
        }
    }
    
    /**
* Escape a string.
*
* @param src
* the string to escape; must not be null
* @return the escaped string
*/
    public static String escape(String src) {
        // first pass to determine the length of the buffer so we only allocate once
        int length = 0;
        for (int i = 0; i < src.length(); i++) {
            char c = src.charAt(i);
            String escape = getEscape(c);
            if (escape != null) {
                length += escape.length();
            } else {
                length += 1;
            }
        }

        // skip copy if no escaping is needed
        if (length == src.length()) {
            return src;
        }

        // second pass to build the escaped string
        StringBuilder buf = new StringBuilder(length);
        for (int i = 0; i < src.length(); i++) {
            char c = src.charAt(i);
            String escape = getEscape(c);
            if (escape != null) {
                buf.append(escape);
            } else {
                buf.append(c);
            }
        }
        return buf.toString();
    }
}