Add Visitor.

.gitignore

@@ -396,3 +396,6 @@ FodyWeavers.xsd
 
 # JetBrains Rider
 *.sln.iml
+.DS_Store
+.idea/
+.idea/.DS_Store

DesignPatterns.Visitor/Context.cs

@@ -0,0 +1,30 @@
+using AutoFixture;
+
+namespace DesignPatterns.Visitor;
+
+public class Context
+{
+    private readonly IFixture fixture = new Fixture();
+    private readonly Random random = new Random();
+
+    public (ICollection<ISize> itemsInBytes, ICollection<ISize> itemsInGB) GetData()
+    {
+        var inBytes = GetSizesInBytes().ToList();
+        var inGB = GetSizesInGB().ToList();
+        return (inBytes, inGB);
+    }
+
+    private static IEnumerable<ISize> GetSizesInBytes()
+    {
+        yield return new SizeInBytes { Value = 1073741824 };
+        yield return new SizeInBytes { Value = 2147483648 };
+        yield return new SizeInBytes { Value = 3221225472 };
+    }
+
+    private static IEnumerable<ISize> GetSizesInGB()
+    {
+        yield return new SizeInGB { Value = 10 };
+        yield return new SizeInGB { Value = 20 };
+        yield return new SizeInGB { Value = 30 };
+    }
+}

DesignPatterns.Visitor/DesignPatterns.Visitor.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
+        <RootNamespace>DesignPatterns.Visitor</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <Content Include="..\.dockerignore">
+        <Link>.dockerignore</Link>
+      </Content>
+    </ItemGroup>
+
+    <ItemGroup>
+      <PackageReference Include="AutoFixture" Version="4.18.1" />
+    </ItemGroup>
+
+</Project>

DesignPatterns.Visitor/Dockerfile

@@ -0,0 +1,21 @@
+FROM mcr.microsoft.com/dotnet/runtime:8.0 AS base
+USER $APP_UID
+WORKDIR /app
+
+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+ARG BUILD_CONFIGURATION=Release
+WORKDIR /src
+COPY ["DesignPatterns.Visitor/DesignPatterns.Visitor.csproj", "DesignPatterns.Visitor/"]
+RUN dotnet restore "DesignPatterns.Visitor/DesignPatterns.Visitor.csproj"
+COPY . .
+WORKDIR "/src/DesignPatterns.Visitor"
+RUN dotnet build "DesignPatterns.Visitor.csproj" -c $BUILD_CONFIGURATION -o /app/build
+
+FROM build AS publish
+ARG BUILD_CONFIGURATION=Release
+RUN dotnet publish "DesignPatterns.Visitor.csproj" -c $BUILD_CONFIGURATION -o /app/publish /p:UseAppHost=false
+
+FROM base AS final
+WORKDIR /app
+COPY --from=publish /app/publish .
+ENTRYPOINT ["dotnet", "DesignPatterns.Visitor.dll"]

DesignPatterns.Visitor/Handler.cs

@@ -0,0 +1,15 @@
+namespace DesignPatterns.Visitor;
+
+public class Handler(IEnumerable<IVisitor> visitors)
+{
+    public IEnumerable<ISize> Process(ICollection<ISize> sizes)
+    {
+        var result = new List<ISize>();
+        foreach (var visitor in visitors)
+        {
+            result.AddRange(sizes.Select(size => size.Accept(visitor)));
+        }
+
+        return result;
+    }
+}

DesignPatterns.Visitor/ISize.cs

@@ -0,0 +1,8 @@
+namespace DesignPatterns.Visitor;
+
+public interface ISize
+{
+    double Value { get; }
+    string Unit { get; }
+    ISize Accept(IVisitor visitor);
+}

DesignPatterns.Visitor/IVisitor.cs

@@ -0,0 +1,6 @@
+namespace DesignPatterns.Visitor;
+
+public interface IVisitor
+{
+    ISize Visit(ISize size); 
+}

DesignPatterns.Visitor/Program.cs

@@ -0,0 +1,10 @@
+using DesignPatterns.Visitor;
+
+var context = new Context();
+var discountVisitor = new SizeVisitor();
+var handler = new Handler(new[] { discountVisitor });
+var data = context.GetData();
+var convertedInGB = handler.Process(data.itemsInBytes);
+var convertedInBytes = handler.Process(data.itemsInGB);
+
+Console.WriteLine();

DesignPatterns.Visitor/SizeInBytes.cs

@@ -0,0 +1,12 @@
+namespace DesignPatterns.Visitor;
+
+public record class SizeInBytes : ISize
+{
+    public double Value { get; init; }
+    public string Unit => "Bytes";
+
+    public ISize Accept(IVisitor visitor)
+    {
+        return visitor.Visit(this);
+    }
+}

DesignPatterns.Visitor/SizeInGB.cs

@@ -0,0 +1,12 @@
+namespace DesignPatterns.Visitor;
+
+public record class SizeInGB : ISize
+{
+    public double Value { get; init; }
+    public string Unit => "GB";
+
+    public ISize Accept(IVisitor visitor)
+    {
+        return visitor.Visit(this);
+    }
+}

DesignPatterns.Visitor/SizeVisitor.cs

@@ -0,0 +1,34 @@
+namespace DesignPatterns.Visitor;
+
+public class SizeVisitor : IVisitor
+{
+    public ISize Visit(ISize size)
+    {
+        return size switch
+        {
+            SizeInBytes bytes => ConvertToGb(bytes),
+            SizeInGB gigaBytes => ConvertToBytes(gigaBytes),
+            _ => throw new ArgumentOutOfRangeException(nameof(size), "Could not recognize a unit.")
+        };
+    }
+
+    private static ISize ConvertToGb(SizeInBytes size)
+    {
+        var result = new SizeInGB
+        {
+            Value = size.Value / (1024 * 1024 * 1024.0)
+        };
+
+        return result;
+    }
+
+    private static ISize ConvertToBytes(SizeInGB size)
+    {
+        var result = new SizeInBytes
+        {
+            Value = size.Value * (1024 * 1024 * 1024.0)
+        };
+
+        return result;
+    }
+}

DesignPatterns.sln

@@ -0,0 +1,16 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DesignPatterns.Visitor", "DesignPatterns.Visitor\DesignPatterns.Visitor.csproj", "{DCE06EB6-BAB5-4573-AF67-128DBCCDB90C}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{DCE06EB6-BAB5-4573-AF67-128DBCCDB90C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DCE06EB6-BAB5-4573-AF67-128DBCCDB90C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DCE06EB6-BAB5-4573-AF67-128DBCCDB90C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DCE06EB6-BAB5-4573-AF67-128DBCCDB90C}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal