AbstractLogReader.java

package com.skiwi.hearthmonitor.logreader;

import com.skiwi.hearthmonitor.logapi.LogEntry;

import java.util.*;

/**
 * @author Frank van Heeswijk
 */
public abstract class AbstractLogReader implements LogReader  {
    private final Set<EntryReader> entryReaders = entryReaders();
    private final Deque<String> linesInMemory = new ArrayDeque<>();

    @Override
    public LogEntry readEntry() throws NotReadableException {
        String line = readLineInternal();
        for (EntryReader entryReader : entryReaders) {
            if (!entryReader.isParsable(line)) {
                continue;
            }
            try {
                return entryReader.parse(line, this::readLineInternal);
            } catch (NotParsableException ex) {
                List<String> notReadableLines = new ArrayList<>();
                while (!linesInMemory.isEmpty()) {
                    notReadableLines.add(linesInMemory.pop());
                }
                throw new NotReadableException(notReadableLines);
            }
        }
        throw new IllegalStateException();
    }

    //TODO throw exception if modified after construction
    abstract protected Set<EntryReader> entryReaders();

    abstract protected String readLineFromLog();

    private String readLineInternal() {
        if (!linesInMemory.isEmpty()) {
            return linesInMemory.pop();
        }
        String line = readLineFromLog();
        linesInMemory.push(line);
        return line;
    }
}