EscapableRegexReplaceFunction.java

package com.aperture_software.glados_wiki.markdown;

import com.google.common.base.Function;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author jhyun
 * @since 2014. Mar. 12.
 */
public class EscapableRegexReplaceFunction implements Function<String, String> {

    private Pattern pattern;

    private Function<Matcher, String> replacement;

    private boolean removeEscapeBackslash = false;

    public EscapableRegexReplaceFunction(Pattern pattern, Function<Matcher, String> replacement, boolean removeEscapeBackslash) {
        this.pattern = pattern;
        this.replacement = replacement;
        this.removeEscapeBackslash = removeEscapeBackslash;
    }

    public Pattern getPattern() {
        return pattern;
    }

    public void setPattern(Pattern pattern) {
        this.pattern = pattern;
    }

    public Function<Matcher, String> getReplacement() {
        return replacement;
    }

    public void setReplacement(Function<Matcher, String> replacement) {
        this.replacement = replacement;
    }

    @Override
    public String apply(String input) {
        final StringBuffer sbuf = new StringBuffer();
        Matcher m = pattern.matcher(input);
        int pos = 0;
        while (true) {
            if (m.find()) {
                final int start = m.start();
                final int end = m.end();
                if (pos <= start) {
                    final String s = m.group();
                    if (start > 0 && input.charAt(start - 1) == '\\') {
                        if (this.removeEscapeBackslash) {
                            sbuf.append(input.substring(pos, start - 1));
                        } else {
                            sbuf.append(input.substring(pos, start));
                        }
                        pos = end;
                        //
                        sbuf.append(s);
                    } else {
                        sbuf.append(input.substring(pos, start));
                        pos = end;
                        //
                        sbuf.append(replacement.apply(m));
                    }
                }
            } else {
                if (pos < input.length() - 1) {
                    sbuf.append(input.substring(pos));
                }
                break;
            }
        }
        return sbuf.toString();
    }
}