EscapeProcessor.java

package org.kefirsf.bb;

import java.util.Arrays;

/**
 * Class for escape processing. For example, EscapeXmlProcessorFactory use this class for create EscapeXmlProcessor.
 *
 * @author Kefir
 */
public class EscapeProcessor extends TextProcessorAdapter {
    /**
     * Escape symbols with replacement.
     */
    private final String[][] escape;

    /**
     * Construct the escape processor with special escape symbols.
     *
     * @param escape escape symbols with replacement. This is a array of array wich consist of two strings
     *               the pattern and the replacement
     */
    public EscapeProcessor(String[][] escape) {
        this.escape = escape;
    }

    /**
     * Process the text
     *
     * @param source the sourcetext
     * @return the result of text processing
     * @see TextProcessor#process(CharSequence)
     */
    public CharSequence process(CharSequence source) {
        if (source != null && source.length() > 0) {
            String stringSource = source instanceof String ? (String) source : source.toString();

            // Array to cache founded indexes of sequences
            int[] indexes = new int[escape.length];
            Arrays.fill(indexes, -1);

            int length = source.length();
            int offset = 0;
            StringBuilder result = new StringBuilder(length);
            while (offset < length) {
                // Find next escape sequence
                int escPosition = -1;
                int escIndex = -1;
                for (int i = 0; i < escape.length; i++) {
                    int index;
                    if (indexes[i] < offset) {
                        index = stringSource.indexOf(escape[i][0], offset);
                        indexes[i] = index;
                    } else {
                        index = indexes[i];
                    }

                    if (index >= 0 && (index < escPosition || escPosition < 0)) {
                        escPosition = index;
                        escIndex = i;
                    }
                }

                // If escape sequence is found
                if (escPosition >= 0) {
                    // replace chars before escape sequence
                    result.append(stringSource, offset, escPosition);

                    // Replace sequence
                    result.append(escape[escIndex][1]);
                    offset = escPosition + escape[escIndex][0].length();
                } else {
                    // Put other string to result sequence 
                    result.append(stringSource, offset, length);
                    offset = length;
                }
            }
            return result;
        } else {
            return new StringBuilder(0);
        }
    }
}