Alternative to package-private threetenbp apis about lazythreetenbp

[gabrielittner]

I don't think it's worth to copy the compiler code. It uses a lot of other package-private code and in the end it's not important how the data was written.

For the runtime copying the deserialization code has the advantage that consumers can safely upgrade threetenbp itself without fearing any breakage. Even when copying all the serialization code (see below) it would still need to either access a private constructor of the already package-private StandardZoneRules or go through a lot of conversion to use the public ZoneRules.of(...) (the opposite of this) only to get converted back immediately. Copying StandardZoneRules completely wouldn't help because ZoneRules (the super class) has a package-private constructor and needs access to other package-private classes/methods in threetenbp.

package com.gabrielittner.threetenbp;

import org.threeten.bp.DayOfWeek;
import org.threeten.bp.LocalTime;
import org.threeten.bp.Month;
import org.threeten.bp.ZoneOffset;
import org.threeten.bp.zone.ZoneOffsetTransitionRule;
import org.threeten.bp.zone.ZoneOffsetTransitionRule.TimeDefinition;
import org.threeten.bp.zone.ZoneRules;
import java.io.DataInput;
import java.io.IOException;

import static org.threeten.bp.ZoneOffset.ofTotalSeconds;

class ZoneRulesReader {

    static ZoneRules readZoneRules(DataInput in) throws IOException, ClassNotFoundException {
        int stdSize = in.readInt();
        long[] stdTrans = new long[stdSize];
        for (int i = 0; i < stdSize; i++) {
            stdTrans[i] = readEpochSec(in);
        }
        ZoneOffset[] stdOffsets = new ZoneOffset[stdSize + 1];
        for (int i = 0; i < stdOffsets.length; i++) {
            stdOffsets[i] = readOffset(in);
        }
        int savSize = in.readInt();
        long[] savTrans = new long[savSize];
        for (int i = 0; i < savSize; i++) {
            savTrans[i] = readEpochSec(in);
        }
        ZoneOffset[] savOffsets = new ZoneOffset[savSize + 1];
        for (int i = 0; i < savOffsets.length; i++) {
            savOffsets[i] = readOffset(in);
        }
        int ruleSize = in.readByte();
        ZoneOffsetTransitionRule[] rules = new ZoneOffsetTransitionRule[ruleSize];
        for (int i = 0; i < ruleSize; i++) {
            rules[i] = readZoneOffsetTransitionRule(in);
        }
        return new StandardZoneRules(stdTrans, stdOffsets, savTrans, savOffsets, rules);
    }

    private static long readEpochSec(DataInput in) throws IOException {
        int hiByte = in.readByte() & 255;
        if (hiByte == 255) {
            return in.readLong();
        } else {
            int midByte = in.readByte() & 255;
            int loByte = in.readByte() & 255;
            long tot = ((hiByte << 16) + (midByte << 8) + loByte);
            return (tot * 900) - 4575744000L;
        }
    }

    private static ZoneOffset readOffset(DataInput in) throws IOException {
        int offsetByte = in.readByte();
        return (offsetByte == 127 ? ofTotalSeconds(in.readInt()) : ofTotalSeconds(offsetByte * 900));
    }

    private static ZoneOffsetTransitionRule readZoneOffsetTransitionRule(DataInput in) throws IOException {
        int data = in.readInt();
        Month month = Month.of(data >>> 28);
        int dom = ((data & (63 << 22)) >>> 22) - 32;
        int dowByte = (data & (7 << 19)) >>> 19;
        DayOfWeek dow = dowByte == 0 ? null : DayOfWeek.of(dowByte);
        int timeByte = (data & (31 << 14)) >>> 14;
        TimeDefinition defn = TimeDefinition.values()[(data & (3 << 12)) >>> 12];
        int stdByte = (data & (255 << 4)) >>> 4;
        int beforeByte = (data & (3 << 2)) >>> 2;
        int afterByte = (data & 3);
        LocalTime time = (timeByte == 31 ? LocalTime.ofSecondOfDay(in.readInt()) : LocalTime.of(timeByte % 24, 0));
        ZoneOffset std = (stdByte == 255 ? ofTotalSeconds(in.readInt()) : ofTotalSeconds((stdByte - 128) * 900));
        ZoneOffset before = (beforeByte == 3 ? ofTotalSeconds(in.readInt()) : ofTotalSeconds(std.getTotalSeconds() + beforeByte * 1800));
        ZoneOffset after = (afterByte == 3 ? ofTotalSeconds(in.readInt()) : ofTotalSeconds(std.getTotalSeconds() + afterByte * 1800));
        return ZoneOffsetTransitionRule.of(month, dom, dow, time, timeByte == 24, defn, std, before, after);
    }

    private ZoneRulesReader() {
        throw new AssertionError("No instances");
    }
}