EmitWriter¶

A C#-aware text writer for source generator output. Replaces SyntaxFactory + NormalizeWhitespace() with ~100-460x better performance and ~36x less memory allocation.

See also: Emit Overview | IWritable | PartialTypeHierarchy

Constructor¶

using var writer = new EmitWriter(indentation: "    ", endOfLine: "\n");

Parameter	Type	Default	Description
`indentation`	`string`	`" "`	Indentation string per level (4 spaces)
`endOfLine`	`string`	`"\n"`	Line ending string

EmitWriter implements IDisposable. Use using var or using blocks.

Core Writing¶

Method	Description
`Write(string text)`	Write text (applies indentation at line start)
`WriteLine(string text)`	Write text followed by a newline
`WriteLine()`	Write an empty line (no indentation)
`Write(IWritable writable)`	Delegate to an IWritable component's `WriteTo` method

All methods return this for fluent chaining.

Indentation¶

Method / Property	Description
`Indent()`	Increase indentation by one level
`Outdent()`	Decrease indentation by one level
`IndentLevel`	`int` — current indentation depth

Indentation is applied automatically when writing at the start of a line.

Block Helpers¶

Method	Description
`Block(bool trailingSemicolon = false)`	Write `{`, indent, return `IDisposable` that writes `}` (or `};`) and outdents
`Block(string declaration, bool trailingSemicolon = false)`	Write declaration, then open block

// Block with declaration
using (writer.Block("public class Foo"))
{
    writer.WriteLine("public int Value { get; set; }");
}
// Produces:
// public class Foo
// {
//     public int Value { get; set; }
// }

// Trailing semicolon (enum, record with body)
using (writer.Block("public enum Status", trailingSemicolon: true))
{
    writer.WriteLine("Active,");
    writer.WriteLine("Inactive,");
}
// Produces:
// public enum Status
// {
//     Active,
//     Inactive,
// };

C# Helpers¶

Method	Description
`Comment(string text)`	Write `// text`
`XmlDoc(string tag, string content)`	Write `/// <tag>content</tag>`
`XmlDocBlock(string tag, IEnumerable<string> lines)`	Write multi-line `/// <tag>` block
`Attribute(string attribute)`	Write `[attribute]`
`NullableEnable()`	Write `#nullable enable`
`IfDirective(string condition)`	Write `#if condition`
`EndIfDirective()`	Write `#endif`
`Region(string name)`	Write `#region name`
`EndRegion()`	Write `#endregion`
`Using(string ns)`	Write `using ns;`
`GlobalUsing(string ns)`	Write `global using ns;`

Fluent Chaining¶

All methods return this:

writer
    .Comment("<auto-generated/>")
    .NullableEnable()
    .WriteLine()
    .Using("System")
    .Using("System.Collections.Generic")
    .WriteLine();

Complete Example¶

using var writer = new EmitWriter();
writer.Comment("<auto-generated/>");
writer.NullableEnable();
writer.WriteLine();

writer.Using("System");
writer.WriteLine();

writer.XmlDoc("summary", "A generated service.");
using (writer.Block("public sealed class MyService"))
{
    writer.XmlDoc("summary", "Gets the name.");
    writer.WriteLine("public string Name { get; }");
    writer.WriteLine();

    writer.XmlDoc("summary", "Creates a new instance.");
    using (writer.Block("public MyService(string name)"))
    {
        writer.WriteLine("Name = name;");
    }
}

context.AddSource("MyService.g.cs", writer.ToString());

Output¶

Member	Description
`ToString()`	Returns the accumulated output as a string
`Dispose()`	Disposes the underlying `StringWriter`

Thread Safety¶

Not thread-safe. Each generator output step should create its own EmitWriter instance.