SymbolExtensions

Extension methods for working with symbols.

C# Signature

internal static class SymbolExtensions

Examples

The following example checks a symbol for an attribute and gets its declaration string.

C#

using System;
using Hertzole.SourceGen;
using Microsoft.CodeAnalysis;

public static class SymbolInspector
{
    public static void Inspect(INamedTypeSymbol symbol)
    {
        // Checks for the fully qualified attribute name.
        if (symbol.HasAttribute("My.Namespace.MyAttribute"))
        {
            Console.WriteLine("The type has the attribute.");
        }

        // Gets the attribute data if the attribute exists.
        if (symbol.TryGetAttribute("My.Namespace.MyAttribute", out AttributeData? attribute))
        {
            Console.WriteLine(attribute);
        }

        // Returns e.g. "partial class" for a partial class symbol.
        string declaration = symbol.GetDeclarationString(isPartial: true);
        Console.WriteLine(declaration);
    }
}

Methods

GetDeclarationString(ITypeSymbol, bool)

Gets the type declaration, without access modifiers, for the provided symbol.

If isPartial is true then the type declaration will include the partial keyword.

C# Signature

public static string GetDeclarationString(this ITypeSymbol symbol, bool isPartial);

symbol

The symbol to get the declaration from.

isPartial

Whether the type declaration should include the partial keyword.

Examples

The following example shows how to get the declaration string of a symbol.

C#

using Hertzole.SourceGen;
using Microsoft.CodeAnalysis;

internal static class CodeHelper
{
    public static void AppendDeclaration(CodeWriter writer, ITypeSymbol symbol, bool isPartial)
    {
        writer.Append(symbol.GetDeclarationString(isPartial));

        // If the symbol is...
        //   an interface -> "interface"
        //   a class -> "class"
        //   a static class -> "static class"
        //   a record -> "record"
        //   a struct -> "struct"
        //   a readonly struct -> "readonly struct"
        //   a record struct -> "record struct"
        //   a readonly record struct -> "readonly record struct"
        // If partial is true, then the declaration will include the "partial" keyword.
    }
}

Returns

The type declaration.

HasAttribute(ISymbol, string)

Determines whether the given symbol has the specified attribute.

C# Signature

public static bool HasAttribute(this ISymbol symbol, string fullAttributeTypeName);

symbol

The symbol to check.

fullAttributeTypeName

The name of the attribute to check for. It needs to include the full namespace and type name. E.g My.Namespace.MyAttribute. It may also include the global:: prefix.

Returns

true if the symbol has the specified attribute; otherwise false.

HasAttribute(ISymbol, ReadOnlySpan<char>)

Determines whether the given symbol has the specified attribute.

C# Signature

public static bool HasAttribute(this ISymbol symbol, ReadOnlySpan<char> fullAttributeTypeName);

symbol

The symbol to check.

fullAttributeTypeName

The name of the attribute to check for. It needs to include the full namespace and type name. E.g My.Namespace.MyAttribute. It may also include the global:: prefix.

Returns

true if the symbol has the specified attribute; otherwise false.

TryGetAttribute(ISymbol, string, out AttributeData?)

Determines whether the given symbol has the specified attribute, and returns the attribute if it does.

C# Signature

public static bool TryGetAttribute(this ISymbol symbol, string fullAttributeTypeName, out AttributeData? attribute);

symbol

The symbol to check.

fullAttributeTypeName

The name of the attribute to check for. It needs to include the full namespace and type name. E.g My.Namespace.MyAttribute. It may also include the global:: prefix.

attribute

When this method returns, contains the attribute with the specified name, if the attribute was found; otherwise, null. This parameter is passed uninitialized.

Returns

true if the symbol has the specified attribute; otherwise false.

TryGetAttribute(ISymbol, ReadOnlySpan<char>, out AttributeData?)

Determines whether the given symbol has the specified attribute, and returns the attribute if it does.

C# Signature

public static bool TryGetAttribute(this ISymbol symbol, ReadOnlySpan<char> fullAttributeTypeName, out AttributeData? attribute);

symbol

The symbol to check.

fullAttributeTypeName

The name of the attribute to check for. It needs to include the full namespace and type name. E.g My.Namespace.MyAttribute. It may also include the global:: prefix.

attribute

When this method returns, contains the attribute with the specified name, if the attribute was found; otherwise, null. This parameter is passed uninitialized.

Returns

true if the symbol has the specified attribute; otherwise false.