Java String Unescape unescape(String elt)

Description

unescape

License

Open Source License

Declaration

private static String unescape(String elt) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

public class Main {
    private static String unescape(String elt) {
        if (elt.length() == 0 || (elt.indexOf('\\') < 0 && elt.indexOf('"') < 0)) {
            return elt.trim();
        }/*from  w  w w.ja  va  2 s  . c  o  m*/

        char[] elts = elt.toCharArray();
        boolean escaped = false;
        boolean quoted = false;
        StringBuffer buf = new StringBuffer(elt.length());
        int start = 0;

        // if it's an escaped hash string and not an actual encoding in string form
        // we need to leave it escaped.
        if (elts[0] == '\\') {
            if (elts[1] == '#') {
                start = 2;
                buf.append("\\#");
            }
        }

        boolean nonWhiteSpaceEncountered = false;
        int lastEscaped = 0;
        char hex1 = 0;

        for (int i = start; i != elts.length; i++) {
            char c = elts[i];

            if (c != ' ') {
                nonWhiteSpaceEncountered = true;
            }

            if (c == '"') {
                if (!escaped) {
                    quoted = !quoted;
                } else {
                    buf.append(c);
                }
                escaped = false;
            } else if (c == '\\' && !(escaped || quoted)) {
                escaped = true;
                lastEscaped = buf.length();
            } else {
                if (c == ' ' && !escaped && !nonWhiteSpaceEncountered) {
                    continue;
                }
                if (escaped && isHexDigit(c)) {
                    if (hex1 != 0) {
                        buf.append((char) (convertHex(hex1) * 16 + convertHex(c)));
                        escaped = false;
                        hex1 = 0;
                        continue;
                    }
                    hex1 = c;
                    continue;
                }
                buf.append(c);
                escaped = false;
            }
        }

        if (buf.length() > 0) {
            while (buf.charAt(buf.length() - 1) == ' ' && lastEscaped != (buf.length() - 1)) {
                buf.setLength(buf.length() - 1);
            }
        }

        return buf.toString();
    }

    private static boolean isHexDigit(char c) {
        return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F');
    }

    private static int convertHex(char c) {
        if ('0' <= c && c <= '9') {
            return c - '0';
        }
        if ('a' <= c && c <= 'f') {
            return c - 'a' + 10;
        }
        return c - 'A' + 10;
    }
}

Related

1. unescape(final String text)
2. unescape(final String[] inval, final Character escapeChar)
3. unescape(String aString)
4. unescape(String aValue)
5. unescape(String data)
6. unescape(String entry)
7. unescape(String escaped)
8. unescape(String escaped)
9. unescape(String escaped, char escape)