| | | 1 | | using System; |
| | | 2 | | |
| | | 3 | | namespace NexusLabs.Needlr.Generators; |
| | | 4 | | |
| | | 5 | | /// <summary> |
| | | 6 | | /// Generates a public constructor for a partial class from its eligible private |
| | | 7 | | /// instance <see langword="readonly"/> fields, eliminating hand-written constructor, |
| | | 8 | | /// field-assignment, and guard-clause boilerplate. |
| | | 9 | | /// </summary> |
| | | 10 | | /// <remarks> |
| | | 11 | | /// <para> |
| | | 12 | | /// The generator produces exactly one public constructor whose parameters are derived, |
| | | 13 | | /// in declaration order, from every eligible field: a private, instance, |
| | | 14 | | /// <see langword="readonly"/> field without an initializer, unless the field carries |
| | | 15 | | /// <see cref="ConstructorIgnoreAttribute"/>. Field names using the <c>_camelCase</c> |
| | | 16 | | /// convention are mapped to <c>camelCase</c> parameter names. |
| | | 17 | | /// </para> |
| | | 18 | | /// <para> |
| | | 19 | | /// This attribute never introduces optional parameters or overloads on the generated |
| | | 20 | | /// constructor itself. Use an explicit hand-written constructor overload, or a |
| | | 21 | | /// get-only property with its own initialization logic, when optional construction |
| | | 22 | | /// paths are required. |
| | | 23 | | /// </para> |
| | | 24 | | /// <para> |
| | | 25 | | /// The containing class must be declared <see langword="partial"/> and must not |
| | | 26 | | /// declare its own instance constructor, because Roslyn source generators can only add |
| | | 27 | | /// new members to a partial type -- they cannot rewrite or inject statements into a |
| | | 28 | | /// user-authored constructor. The containing type must also not be nested. It may |
| | | 29 | | /// derive from <see cref="object"/> directly, or from any base type that itself has an |
| | | 30 | | /// accessible (public or protected) parameterless constructor -- including the common |
| | | 31 | | /// case of a base type with no explicit constructors at all -- since the generated |
| | | 32 | | /// constructor relies on the implicit <c>: base()</c> call. This supports common |
| | | 33 | | /// framework base types such as <c>BackgroundService</c>. A base type that requires |
| | | 34 | | /// constructor arguments is unsupported: no source is emitted, and an analyzer reports |
| | | 35 | | /// the requirement at compile time instead. |
| | | 36 | | /// </para> |
| | | 37 | | /// <para> |
| | | 38 | | /// A field-level positive guard attribute -- a built-in or custom |
| | | 39 | | /// <see cref="ConstructorGuardAttribute"/>, or a custom alias attribute defined with |
| | | 40 | | /// <see cref="ConstructorGuardDefinitionAttribute"/> -- also enables constructor |
| | | 41 | | /// generation with <see cref="ConstructorNullGuardMode.None"/>, even when this |
| | | 42 | | /// attribute is not applied to the class. |
| | | 43 | | /// </para> |
| | | 44 | | /// </remarks> |
| | | 45 | | /// <example> |
| | | 46 | | /// <code> |
| | | 47 | | /// [GenerateConstructor] |
| | | 48 | | /// public partial class UserService |
| | | 49 | | /// { |
| | | 50 | | /// private readonly IRepository _repository; |
| | | 51 | | /// } |
| | | 52 | | /// |
| | | 53 | | /// // Generated: |
| | | 54 | | /// // public UserService(IRepository repository) |
| | | 55 | | /// // { |
| | | 56 | | /// // _repository = repository; |
| | | 57 | | /// // } |
| | | 58 | | /// </code> |
| | | 59 | | /// <code> |
| | | 60 | | /// [GenerateConstructor] |
| | | 61 | | /// public partial class MyWorker : BackgroundService |
| | | 62 | | /// { |
| | | 63 | | /// private readonly IRepository _repository; |
| | | 64 | | /// |
| | | 65 | | /// protected override Task ExecuteAsync(CancellationToken stoppingToken) |
| | | 66 | | /// { |
| | | 67 | | /// return Task.CompletedTask; |
| | | 68 | | /// } |
| | | 69 | | /// } |
| | | 70 | | /// |
| | | 71 | | /// // BackgroundService has an accessible parameterless constructor, so the generated |
| | | 72 | | /// // constructor relies on the implicit base() call: |
| | | 73 | | /// // public MyWorker(IRepository repository) |
| | | 74 | | /// // { |
| | | 75 | | /// // _repository = repository; |
| | | 76 | | /// // } |
| | | 77 | | /// </code> |
| | | 78 | | /// </example> |
| | | 79 | | [AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)] |
| | | 80 | | public sealed class GenerateConstructorAttribute : Attribute |
| | | 81 | | { |
| | | 82 | | /// <summary> |
| | | 83 | | /// Initializes a new instance of the <see cref="GenerateConstructorAttribute"/> |
| | | 84 | | /// class with <see cref="ConstructorNullGuardMode.None"/>. No automatic null |
| | | 85 | | /// guards are emitted. |
| | | 86 | | /// </summary> |
| | | 87 | | public GenerateConstructorAttribute() |
| | 5740 | 88 | | : this(ConstructorNullGuardMode.None) |
| | | 89 | | { |
| | 5740 | 90 | | } |
| | | 91 | | |
| | | 92 | | /// <summary> |
| | | 93 | | /// Initializes a new instance of the <see cref="GenerateConstructorAttribute"/> |
| | | 94 | | /// class with an explicit null-guard mode. |
| | | 95 | | /// </summary> |
| | | 96 | | /// <param name="mode"> |
| | | 97 | | /// Controls whether the generator automatically emits null guards for eligible |
| | | 98 | | /// non-nullable reference-type fields. |
| | | 99 | | /// </param> |
| | 7380 | 100 | | public GenerateConstructorAttribute(ConstructorNullGuardMode mode) |
| | | 101 | | { |
| | 7380 | 102 | | Mode = mode; |
| | 7380 | 103 | | } |
| | | 104 | | |
| | | 105 | | /// <summary> |
| | | 106 | | /// Gets the configured null-guard mode for the generated constructor. |
| | | 107 | | /// </summary> |
| | 0 | 108 | | public ConstructorNullGuardMode Mode { get; } |
| | | 109 | | } |