110 lines
4.3 KiB
C#
110 lines
4.3 KiB
C#
using System.Collections.Generic;
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using System.Linq;
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using System.Threading.Tasks;
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using MfGames.Gallium;
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using MfGames.Nitride;
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using MfGames.Nitride.IO.Contents;
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using MfGames.Nitride.IO.Directories;
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using MfGames.Nitride.IO.Paths;
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using MfGames.Nitride.Pipelines;
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namespace CopyFiles;
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/// <summary>
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/// The single pipeline used by the CopyFiles project.
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/// </summary>
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public class CopyFilesPipeline : PipelineBase
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{
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private readonly AddPathPrefix addPathPrefix;
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private readonly ClearDirectory clearDirectory;
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private readonly ReadFiles readFiles;
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private readonly RemovePathPrefix removePathPrefix;
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private readonly WriteFiles writeFiles;
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public CopyFilesPipeline(
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ReadFiles readFiles,
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ClearDirectory clearDirectory,
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WriteFiles writeFiles,
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RemovePathPrefix removePathPrefix,
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AddPathPrefix addPathPrefix)
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{
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// While we can configure these during runtime, it seems cleaner to
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// build them up during the constructor to call out the ones that
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// require runtime data.
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this.readFiles = readFiles.WithPattern("/input/**/*.txt");
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this.clearDirectory = clearDirectory.WithPath("/output");
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this.writeFiles = writeFiles;
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this.removePathPrefix = removePathPrefix.WithPathPrefix("/input");
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this.addPathPrefix = addPathPrefix.WithPathPrefix("/output");
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}
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/// <inheritdoc />
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public override IAsyncEnumerable<Entity> RunAsync(IEnumerable<Entity> _)
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{
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// We don't care about the incoming entities which means we can
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// ignore them and use the entities from the ReadFiles operation
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// or we can union the entities pass in with the ReadFiles in case
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// we want to merge them.
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//
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// This will read all the files of the given pattern and return them
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// as an IEnumerable<Entity> with the Zio components (UPath and
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// binary contents) set. As a note, this doesn't actually read the
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// file, just create a pointer to where the file could be read from.
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//
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// The path component will always be the relative path to the root,
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// so `/input/a.txt` in this case since we only have one file.
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IEnumerable<Entity> entities = this.readFiles.Run();
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// Change the path. The path (Zio.UPath component) stays with the
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// entity which is why there is no root directory in the writeFiles
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// operation. Instead, we need to remove the `/input` and replace it
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// with the `/output`.
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//
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// We can do that with a RemovePathPrefix followed by an
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// AddPathPrefix, or use the more complex version of ChangePaths.
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// In this case, we are going for easy to learn, so we'll do the
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// pair.
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//
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// We are going to use the chain extension to make it easier to
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// read. Coming out of this, we will have one entity that fulfills:
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//
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// entity.Get<UPath> == "/output/a.txt"
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entities = entities.Run(this.removePathPrefix)
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.Run(this.addPathPrefix);
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// Then we write out the files to the output. First we make sure we
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// clear out the output. This operation performs an action when it
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// it is first entered, but otherwise passes all the inputs through.
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//
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// We can call the clear directory in three ways. The first is to call
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// the operation with:
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//
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// this.clearDirectory.Run()
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//
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// The other is to pass in the entities and get a new list of
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// modified ones out. In this case, clear doesn't make any changes,
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// but Entity objects are immutable, so we always work on the list
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// returned.
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//
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// entities = this.clearDirectory.Run(entity)
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//
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// The third way is to use an extension on entities which lets us
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// chain calls, ala Gulp's pipelines. The below code does this along
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// with writing the files to the output.
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entities = entities.Run(this.clearDirectory)
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.Run(this.writeFiles);
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// If we are chaining this pipeline into another, we return the
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// entities. Otherwise, we can just return an empty list. The
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// pipeline is async, so it is wrapped in a task, but most
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// operations are not (or are both).
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return entities.ToAsyncEnumerable();
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}
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}
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