MBW.Generators.GeneratorHelpers 0.3.0

MBW.Generators.GeneratorHelpers

About

Provides allocation-free extension methods for Roslyn symbols based on predefined type and namespace strings. Annotate a type with constants representing canonical symbols and the generator emits helper methods to quickly compare symbols without allocations or ToDisplayString calls.

Useful when analyzing large code bases where repeated string construction would otherwise hurt performance.

Quick Start

• Install the MBW.Generators.GeneratorHelpers package.
• Apply [GenerateSymbolExtensions] to a class or struct containing annotated const string fields.
• Override the generated extensions class name and namespace via the attribute’s Name and Namespace properties. Defaults to <TypeName>Extensions in Microsoft.CodeAnalysis.
• Per-field MethodName overrides customise the method suffix for [SymbolNameExtension] and [NamespaceNameExtension].
• Fully qualified strings support the global:: prefix, nested types using +, and generic metadata names like Dictionary`2.
• The package includes both the attributes and the source generator.

Example

using MBW.Generators.GeneratorHelpers;
using MBW.Generators.GeneratorHelpers.Attributes;

// Control the generated type, Name and Namespace are optional - the default is 'Microsoft.CodeAnalysis'
[GenerateSymbolExtensions(Name = "KnownExtensions", Namespace = "My.Helpers")]
internal static class Known
{
    // Generate 
    [SymbolNameExtension(MethodName = "Exception")]
    public const string ExceptionType = "global::System.Exception";
}

Generates

// <auto-generated/>
using System;
using Microsoft.CodeAnalysis;

namespace My.Helpers;

internal static class KnownExtensions
{
    public static bool IsNamedExactlyTypeException(this ISymbol? symbol)
    {
        if (symbol is null) return false;
        if (!symbol.Name.Equals("Exception", StringComparison.Ordinal)) return false;
        if (symbol is not INamedTypeSymbol t0) return false;
        if (t0.ContainingType is not null) return false;
        var ns = t0.ContainingNamespace;
        if (ns is null || !ns.Name.Equals("System", StringComparison.Ordinal)) return false;
        ns = ns.ContainingNamespace;
        return ns != null && ns.IsGlobalNamespace;
    }
}

Features

• Generates allocation-free helpers for types and namespaces.
• Handles nested and generic types, including names with global:: and multiple containing types.
• Provides ISymbol and INamespaceSymbol overloads for namespace checks.
• Supports custom extension class name/namespace and per-field method name overrides.
• Benchmarks show this approach is 10 times faster than performing a ToDisplayString() and then string equality

Attributes

• [GenerateSymbolExtensions] – apply to a type to opt in. Controls generated class name and namespace.
• [SymbolNameExtension] – place on a const string field containing a fully qualified type name.
  • Generates:
    • IsNamedExactlyTypeN(this ISymbol) - tests if the symbol is exactly named N
• [NamespaceNameExtension] – place on a const string field containing a fully qualified namespace.
  • Generates:
    • IsInNamespaceN(this ISymbol) - tests if the symbol is in the namespace N, or any namespace under N
    • IsExactlyInNamespaceN(this ISymbol) - tests if the symbol is exactly in the namespace N
    • IsInNamespaceN(this INamespaceSymbol) - tests if the namespace symbol is in the namespace N, or any namespace under N
    • IsExactlyNamespaceN(this INamespaceSymbol) - tests if the namespace symbol is exactly the namespace N

More information

This project is provided as-is without support. Additional examples will be available in the tests.