Closes #216

.editorconfig

@@ -26,9 +26,6 @@ dotnet_diagnostic.CA1707.severity = none
 # CS8618: Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 dotnet_diagnostic.CS8618.severity = none
 
-# IDE0290: Use primary constructor
-dotnet_diagnostic.IDE0290.severity = none
-
 # IDE0301: Simplify collection initialization
 dotnet_diagnostic.IDE0301.severity = none
 

Mjml.Net/Components/RootComponent.cs

@@ -63,12 +63,10 @@ private static void RenderHead(IHtmlRenderer renderer, GlobalContext context)
             {
                 // Already formatted properly.
                 renderer.Plain(head.Buffer);
-                renderer.ReturnStringBuilder(head.Buffer);
             }
         }
 
         renderer.RenderHelpers(HelperTarget.HeadEnd);
-
         renderer.EndElement("head");
     }
 
@@ -86,12 +84,10 @@ private static void RenderBody(IHtmlRenderer renderer, GlobalContext context)
             {
                 // Already formatted properly.
                 renderer.Plain(body.Buffer);
-                renderer.ReturnStringBuilder(body.Buffer);
             }
         }
 
         renderer.RenderHelpers(HelperTarget.BodyEnd);
-
         renderer.EndElement("body");
     }
 }

Mjml.Net/Components/RootData.cs

@@ -1,14 +1,12 @@
-using System.Text;
-
-#pragma warning disable SA1313 // Parameter names should begin with lower-case letter
+#pragma warning disable SA1313 // Parameter names should begin with lower-case letter
 
 namespace Mjml.Net.Components;
 
-public sealed record BodyBuffer(StringBuilder? Buffer) : GlobalData;
+public sealed record BodyBuffer(IBuffer? Buffer) : GlobalData;
 
 public sealed record Background(string Color) : GlobalData;
 
-public sealed record HeadBuffer(StringBuilder? Buffer) : GlobalData;
+public sealed record HeadBuffer(IBuffer? Buffer) : GlobalData;
 
 public sealed record Language(string Value) : GlobalData;
 

Mjml.Net/IBuffer.cs

@@ -0,0 +1,12 @@
+using System.Text;
+
+namespace Mjml.Net;
+
+public interface IBuffer : IDisposable
+{
+    bool IsEmpty { get; }
+
+    int AppendTo(StringBuilder sb);
+
+    string ToText();
+}

Mjml.Net/IHtmlRenderer.cs

@@ -19,12 +19,6 @@ public interface IHtmlRenderer
     /// </returns>
     IHtmlAttrRenderer StartElement(string elementName, bool close = false);
 
-    /// <summary>
-    /// Returns a string builder back to the pool.
-    /// </summary>
-    /// <param name="stringBuilder">The string builder to return.</param>
-    void ReturnStringBuilder(StringBuilder stringBuilder);
-
     /// <summary>
     /// Ends an element.
     /// </summary>
@@ -59,7 +53,7 @@ public interface IHtmlRenderer
     /// Renders a text.
     /// </summary>
     /// <param name="value">The value to render.</param>
-    void Plain(StringBuilder value);
+    void Plain(IBuffer value);
 
     /// <summary>
     /// Renders a text.
@@ -94,7 +88,7 @@ public interface IHtmlRenderer
     /// Removes the buffer from the stack and returns the content.
     /// </summary>
     /// <returns>The buffer content.</returns>
-    StringBuilder? EndBuffer();
+    IBuffer EndBuffer();
 
     internal StringBuilder StringBuilder { get; }
 

Mjml.Net/InMemoryFileLoader.cs

@@ -8,15 +8,9 @@ namespace Tests.Internal;
 /// <remarks>
 /// Useful for preloading.
 /// </remarks>
-public sealed class InMemoryFileLoader : IFileLoader
+public sealed class InMemoryFileLoader(IReadOnlyDictionary<string, string> content) : IFileLoader
 {
     private readonly Stack<string> pathStack = new Stack<string>();
-    private readonly IReadOnlyDictionary<string, string> content;
-
-    public InMemoryFileLoader(IReadOnlyDictionary<string, string> content)
-    {
-        this.content = content;
-    }
 
     /// <inheritdoc />
     public string? LoadText(string path)

Mjml.Net/InnerTextOrHtml.cs

@@ -15,7 +15,7 @@ public InnerTextOrHtml(int capacity = 10)
 
     public InnerTextOrHtml(string input)
     {
-        parts = new List<string>(1) { input };
+        parts = [input];
     }
 
     public void Add(string part)

Mjml.Net/Internal/Binder.cs

@@ -1,7 +1,4 @@
-using System.Runtime.Intrinsics.X86;
-using System.Xml.Linq;
-
-namespace Mjml.Net.Internal;
+namespace Mjml.Net.Internal;
 
 internal sealed class Binder : IBinder
 {

Mjml.Net/Internal/SubtreeReader.cs

@@ -2,7 +2,7 @@
 
 namespace Mjml.Net.Internal;
 
-internal sealed class SubtreeReader : HtmlReaderWrapper
+internal sealed class SubtreeReader(HtmlReaderWrapper inner) : HtmlReaderWrapper(inner.Impl)
 {
     private static readonly HashSet<string> VoidTags = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
     {
@@ -21,16 +21,8 @@ internal sealed class SubtreeReader : HtmlReaderWrapper
         "track",
         "wbr",
     };
-
-    private readonly HtmlReaderWrapper inner;
     private int depth = 1;
 
-    public SubtreeReader(HtmlReaderWrapper inner)
-        : base(inner.Impl)
-    {
-        this.inner = inner;
-    }
-
     public override bool Read()
     {
         if (depth == 0)

Mjml.Net/MjmlRenderContext.Rendering.cs

@@ -22,33 +22,19 @@ public StringBuilder StringBuilder
     private void ClearRenderData()
     {
         analyzedFonts.Clear();
-
+        // Some buffers might get lost.
         buffers.Clear();
     }
 
-    public void ReturnStringBuilder(StringBuilder stringBuilder)
-    {
-        DefaultPools.StringBuilders.Return(stringBuilder);
-    }
-
     public void StartBuffer()
     {
-        buffers.Push(new RenderBuffer(DefaultPools.StringBuilders.Get(), mjmlOptions.Beautify));
+        buffers.Push(new RenderBuffer(mjmlOptions.Beautify));
     }
 
-    public StringBuilder? EndBuffer()
+    public IBuffer EndBuffer()
     {
         Buffer.FlushAll();
-
-        return buffers.Pop()?.StringBuilder;
-    }
-
-    public void RenderHelpers(HelperTarget target)
-    {
-        foreach (var helper in mjmlRenderer.Helpers)
-        {
-            helper.Render(this, target, context);
-        }
+        return buffers.Pop()!;
     }
 
     public IHtmlAttrRenderer StartElement(string elementName, bool close = false)
@@ -142,7 +128,7 @@ public void StartText()
         Buffer.StartText();
     }
 
-    public void Plain(StringBuilder? value)
+    public void Plain(IBuffer value)
     {
         Buffer.Plain(value);
     }
@@ -201,4 +187,12 @@ private void DetectFontFamily(string name, string? value)
             }
         }
     }
+
+    public void RenderHelpers(HelperTarget target)
+    {
+        foreach (var helper in mjmlRenderer.Helpers)
+        {
+            helper.Render(this, target, context);
+        }
+    }
 }

Mjml.Net/MjmlRenderer.cs

@@ -1,5 +1,4 @@
-using System.Text;
-using Mjml.Net.Components;
+using Mjml.Net.Components;
 using Mjml.Net.Components.Body;
 using Mjml.Net.Components.Head;
 using Mjml.Net.Helpers;
@@ -136,7 +135,7 @@ public async ValueTask<RenderResult> RenderAsync(Stream mjml, MjmlOptions? optio
     public async ValueTask<RenderResult> RenderAsync(TextReader mjml, MjmlOptions? options = null,
         CancellationToken ct = default)
     {
-#if NET8_0_OR_GREATER
+#if NET7_0_OR_GREATER
         return await RenderCoreAsync(await mjml.ReadToEndAsync(ct), options, ct);
 #else
         return await RenderCoreAsync(await mjml.ReadToEndAsync(), options, ct);
@@ -170,25 +169,16 @@ private async ValueTask<RenderResult> RenderCoreAsync(string mjml, MjmlOptions?
         options ??= new MjmlOptions();
 
         var reader = new HtmlReaderWrapper(mjml);
-
         var context = DefaultPools.RenderContexts.Get();
         try
         {
             context.Setup(this, isAsync, options);
             context.StartBuffer();
             context.Read(reader, null, null);
 
-            StringBuilder? buffer = null;
-            try
-            {
-                buffer = context.EndBuffer()!;
+            using var buffer = context.EndBuffer();
 
-                return (new RenderResult(buffer.ToString()!, context.Validate()), options);
-            }
-            finally
-            {
-                DefaultPools.StringBuilders.Return(buffer!);
-            }
+            return (new RenderResult(buffer.ToText(), context.Validate()), options);
         }
         finally
         {