Brotli-Builder/BrotliLib/Brotli/Encode/BrotliTransformerBase.cs

using System;
using System.Collections.Generic;
using BrotliLib.Brotli.Components;
using BrotliLib.Brotli.Parameters;

namespace BrotliLib.Brotli.Encode{
    public abstract class BrotliTransformerBase : IBrotliTransformer{
        IList<(MetaBlock MetaBlock, BrotliGlobalState NextState)> IBrotliTransformer.Transform(MetaBlock original, BrotliGlobalState state, BrotliCompressionParameters parameters){
            return original switch{
                MetaBlock.LastEmpty le   => TransformLastEmpty(le, state, parameters),
                MetaBlock.PaddedEmpty pe => TransformPaddedEmpty(pe, state, parameters),
                MetaBlock.Uncompressed u => TransformUncompressed(u, state, parameters),
                MetaBlock.Compressed c   => TransformCompressed(c, state, parameters),
                _ => throw new InvalidOperationException("Unknown meta-block type: " + original.GetType().Name)
            };
        }

        protected virtual IList<(MetaBlock MetaBlock, BrotliGlobalState NextState)> TransformLastEmpty(MetaBlock.LastEmpty original, BrotliGlobalState state, BrotliCompressionParameters parameters){
            original.Decompress(state);
            return Array.Empty<(MetaBlock, BrotliGlobalState)>();
        }

        protected virtual IList<(MetaBlock MetaBlock, BrotliGlobalState NextState)> TransformPaddedEmpty(MetaBlock.PaddedEmpty original, BrotliGlobalState state, BrotliCompressionParameters parameters){
            original.Decompress(state);
            return new (MetaBlock, BrotliGlobalState)[]{ (original, state) };
        }

        protected virtual IList<(MetaBlock MetaBlock, BrotliGlobalState NextState)> TransformUncompressed(MetaBlock.Uncompressed original, BrotliGlobalState state, BrotliCompressionParameters parameters){
            original.Decompress(state);
            return new (MetaBlock, BrotliGlobalState)[]{ (original, state) };
        }

        protected virtual IList<(MetaBlock MetaBlock, BrotliGlobalState NextState)> TransformCompressed(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters){
            original.Decompress(state);
            return new (MetaBlock, BrotliGlobalState)[]{ (original, state) };
        }
    }
}