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KefirBB is a Java-library for text processing. Initially it was developed for BB2HTML translation. But flexible configuration allows to use it in different cases. For example for parsing Markdown, Textile, and for HTML filtration.

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package org.kefirsf.bb.proc;

/**
 * @author kefir
 */
public abstract class AbstractEol implements ProcPatternElement {

    protected static final char[] AN = new char[]{'\n'};
    protected static final char[] AR = new char[]{'\r'};

    protected final boolean ghost;

    public AbstractEol(boolean ghost) {
        this.ghost = ghost;
    }

    public boolean parse(Context context, ProcPatternElement terminator) throws NestingException {
        Source source = context.getSource();
        int len = match(source);
        if (len >= 0) {
            if(!ghost) {
                source.incOffset(len);
            }
            return true;
        } else {
            return false;
        }
    }

    private int match(Source source) {
        return match(source, source.getOffset());
    }

    public boolean isNextIn(Context context) {
        return match(context.getSource()) >= 0;
    }

    public int findIn(Source source) {
        int index = source.getOffset()-1;
        do {
            index++;
            int n = source.findFrom(index, AN, false);
            int r = source.findFrom(index, AR, false);
            if (n >= 0 && r >= 0) {
                index = Math.min(n, r);
            } else if (n >= 0) {
                index = n;
            } else if (r >= 0) {
                index = r;
            } else {
                index = source.length();
            }
        } while (match(source, index) < 0);

        return index;
    }

    protected abstract int match(Source source, int index);

    /**
     * @param source the soruce text
     * @param index current cursor position
     * @return -1 if at the index there is not end of line
     * 0 if it's end of text
     * 1 if it's single \n or \r
     * 2 if it's pair \n\r or \r\n
     */
    protected int calcLength(Source source, int index) {
        if (index >= source.length()) {
            return 0;
        } else {
            char c = source.charAt(index);
            if (c == '\n' || c == '\r') {
                if (index + 1 < source.length()) {
                    char nc = source.charAt(index + 1);
                    if (c == '\n' && nc == '\r' || c == '\r' && nc == '\n') {
                        return 2;
                    }
                }
                return 1;
            } else {
                return -1;
            }
        }
    }
}