118 lines
4.2 KiB
C#
118 lines
4.2 KiB
C#
using System.Net;
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using System.Reflection;
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namespace SimpleHttpServer.Types;
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public abstract class InternalEndpointCheckAttribute : Attribute {
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public InternalEndpointCheckAttribute() {
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CheckSharedVariables();
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}
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private void CheckSharedVariables() {
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foreach (var f in GetType().GetRuntimeFields()) {
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if (f.FieldType.IsAssignableTo(typeof(SharedVariable))) {
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if (!f.IsInitOnly) {
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throw new Exception($"Found non-readonly global field {f}!");
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}
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if (f.GetValue(this) == null) {
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throw new Exception("Global fields must be assigned in the CCTOR!");
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}
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}
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}
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}
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private void Initialize(object? instance, Dictionary<FieldInfo, List<(InternalEndpointCheckAttribute, SharedVariable)>> globals) {
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SetInstance(instance);
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foreach (var f in GetType().GetRuntimeFields()) {
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if (f.FieldType.IsAssignableTo(typeof(SharedVariable))) {
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SharedVariable origVal = (SharedVariable) f.GetValue(this)!;
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if (globals.TryGetValue(f, out var options)) {
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bool foundMatch = false;
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foreach ((var checker, var gv) in options) {
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if (Match(checker)) {
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foundMatch = true;
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// we need to unify their global variables
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f.SetValue(this, gv);
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}
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}
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if (!foundMatch) {
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options.Add((this, origVal));
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}
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} else {
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globals.Add(f, new List<(InternalEndpointCheckAttribute, SharedVariable)>() { (this, origVal) });
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}
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}
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}
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}
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public static void Initialize(object? instance, IEnumerable<InternalEndpointCheckAttribute> endPointChecks) {
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Dictionary<FieldInfo, List<(InternalEndpointCheckAttribute, SharedVariable)>> globals = new();
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foreach (var check in endPointChecks) {
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check.Initialize(instance, globals);
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}
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}
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private interface SharedVariable {
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// Tagging interface
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}
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/// <summary>
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/// Represents a Mutable Shared Variable. Fields of this type need to be initialized in the CCtor.
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/// </summary>
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protected sealed class MSV<V> : SharedVariable {
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private readonly V __default;
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public V Val { get; set; } = default!;
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public MSV() : this(default!) { }
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public MSV(V _default) {
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__default = _default;
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}
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public static implicit operator V(MSV<V> v) => v.Val;
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}
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/// <summary>
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/// Represents an Immutable Shared Variable. Fields of this type need to be initialized in the CCtor.
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/// </summary>
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protected sealed class ISV<V> : SharedVariable {
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private readonly V __default;
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public V Val { get; } = default!;
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public ISV() : this(default!) { }
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public ISV(V _default) {
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__default = _default;
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}
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public static implicit operator V(ISV<V> v) => v.Val;
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}
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/// <summary>
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/// Executed when the endpoint is invoked. The endpoint invocation is skipped if any of the checks fail.
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/// </summary>
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/// <returns>True to allow invocation, false to prevent.</returns>
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public abstract bool Check(HttpListenerRequest req);
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protected virtual bool Match(InternalEndpointCheckAttribute other) => true;
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internal abstract void SetInstance(object? instance);
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}
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[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, Inherited = true, AllowMultiple = true)]
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public abstract class BaseEndpointCheckAttribute<T> : InternalEndpointCheckAttribute {
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/// <summary>
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/// A reference to the instance of the class that this attribute is attached to.
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/// Will be null iff an class factory was passed in <see cref="HttpServer.RegisterEndpointsFromType{T}(Func{T}?)"/>.
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/// </summary>
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protected internal T? EndpointClassInstance { get; internal set; } = default;
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public BaseEndpointCheckAttribute() : base() { }
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internal override void SetInstance(object? instance) {
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if (instance != null)
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EndpointClassInstance = (T?) instance;
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}
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} |