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osu-lazer/osu.Game/Beatmaps/Formats/Decoder.cs
2018-01-05 20:21:19 +09:00

83 lines
2.8 KiB
C#

// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
using System;
using System.Collections.Generic;
using System.IO;
using osu.Game.Storyboards;
namespace osu.Game.Beatmaps.Formats
{
public abstract class Decoder
{
private static readonly Dictionary<string, Func<string, Decoder>> decoders = new Dictionary<string, Func<string, Decoder>>();
static Decoder()
{
LegacyDecoder.Register();
JsonBeatmapDecoder.Register();
}
/// <summary>
/// Retrieves a <see cref="Decoder"/> to parse a <see cref="Beatmap"/>.
/// </summary>
/// <param name="stream">A stream pointing to the <see cref="Beatmap"/>.</param>
public static Decoder GetDecoder(StreamReader stream)
{
if (stream == null)
throw new ArgumentNullException(nameof(stream));
string line;
do
{ line = stream.ReadLine()?.Trim(); }
while (line != null && line.Length == 0);
if (line == null || !decoders.ContainsKey(line))
throw new IOException(@"Unknown file format");
return decoders[line](line);
}
/// <summary>
/// Registers an instantiation function for a <see cref="Decoder"/>.
/// </summary>
/// <param name="magic">A string in the file which triggers this decoder to be used.</param>
/// <param name="constructor">A function which constructs the <see cref="Decoder"/> given <paramref name="magic"/>.</param>
protected static void AddDecoder(string magic, Func<string, Decoder> constructor)
{
decoders[magic] = constructor;
}
/// <summary>
/// Retrieves a <see cref="Decoder"/> to parse a <see cref="Storyboard"/>
/// </summary>
public abstract Decoder GetStoryboardDecoder();
public virtual Beatmap DecodeBeatmap(StreamReader stream)
{
var beatmap = new Beatmap
{
BeatmapInfo = new BeatmapInfo
{
Metadata = new BeatmapMetadata(),
BaseDifficulty = new BeatmapDifficulty(),
},
};
ParseBeatmap(stream, beatmap);
return beatmap;
}
protected abstract void ParseBeatmap(StreamReader stream, Beatmap beatmap);
public virtual Storyboard DecodeStoryboard(StreamReader stream)
{
var storyboard = new Storyboard();
ParseStoryboard(stream, storyboard);
return storyboard;
}
protected abstract void ParseStoryboard(StreamReader stream, Storyboard storyboard);
}
}