osu-lazer/osu.Game.Rulesets.Mania/Beatmaps/Patterns/PatternGenerator.cs

// 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.Diagnostics;
using JetBrains.Annotations;
using osu.Framework.Logging;
using osu.Game.Rulesets.Objects;

namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns
{
    /// <summary>
    /// Generator to create a pattern <see cref="Pattern"/> from a hit object.
    /// </summary>
    internal abstract class PatternGenerator
    {
        /// <summary>
        /// An arbitrary maximum amount of iterations to perform in <see cref="RunWhile"/>.
        /// The specific value is not super important - enough such that no false-positives occur.
        /// </summary>
        private const int max_rng_iterations = 20;

        /// <summary>
        /// The last pattern.
        /// </summary>
        protected readonly Pattern PreviousPattern;

        /// <summary>
        /// The hit object to create the pattern for.
        /// </summary>
        protected readonly HitObject HitObject;

        /// <summary>
        /// The beatmap which <see cref="HitObject"/> is a part of.
        /// </summary>
        protected readonly ManiaBeatmap Beatmap;

        protected readonly int TotalColumns;

        protected PatternGenerator(HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern)
        {
            if (hitObject == null) throw new ArgumentNullException(nameof(hitObject));
            if (beatmap == null) throw new ArgumentNullException(nameof(beatmap));
            if (previousPattern == null) throw new ArgumentNullException(nameof(previousPattern));

            HitObject = hitObject;
            Beatmap = beatmap;
            PreviousPattern = previousPattern;

            TotalColumns = Beatmap.TotalColumns;
        }

        protected void RunWhile([InstantHandle] Func<bool> condition, Action action)
        {
            int iterations = 0;

            while (condition() && iterations++ < max_rng_iterations)
                action();

            if (iterations < max_rng_iterations)
                return;

            // Generate + log an error/stacktrace

            Logger.Log($"Allowable iterations ({max_rng_iterations}) exceeded:\n{new StackTrace(0)}", level: LogLevel.Error);
        }

        /// <summary>
        /// Generates the patterns for <see cref="HitObject"/>, each filled with hit objects.
        /// </summary>
        /// <returns>The <see cref="Pattern"/>s containing the hit objects.</returns>
        public abstract IEnumerable<Pattern> Generate();
    }
}