92 lines
3.9 KiB
C#
92 lines
3.9 KiB
C#
using System;
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using System.Linq.Expressions;
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using System.Reflection;
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using System.Threading.Tasks;
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using Tapeti.Config;
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namespace Tapeti.Flow.Default
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{
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/// <summary>
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/// Default implementation for IFlowStarter.
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/// </summary>
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internal class FlowStarter : IFlowStarter
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{
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private readonly ITapetiConfig config;
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/// <summary>
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/// </summary>
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public FlowStarter(ITapetiConfig config)
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{
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this.config = config;
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}
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/// <inheritdoc />
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public async Task Start<TController>(Expression<Func<TController, Func<IYieldPoint>>> methodSelector) where TController : class
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{
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await CallControllerMethod<TController>(GetExpressionMethod(methodSelector), value => Task.FromResult((IYieldPoint)value), Array.Empty<object?>());
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}
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/// <inheritdoc />
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public async Task Start<TController>(Expression<Func<TController, Func<Task<IYieldPoint>>>> methodSelector) where TController : class
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{
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await CallControllerMethod<TController>(GetExpressionMethod(methodSelector), value => (Task<IYieldPoint>)value, Array.Empty<object?>());
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}
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/// <inheritdoc />
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public async Task Start<TController, TParameter>(Expression<Func<TController, Func<TParameter, IYieldPoint>>> methodSelector, TParameter parameter) where TController : class
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{
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await CallControllerMethod<TController>(GetExpressionMethod(methodSelector), value => Task.FromResult((IYieldPoint)value), new object?[] {parameter});
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}
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/// <inheritdoc />
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public async Task Start<TController, TParameter>(Expression<Func<TController, Func<TParameter, Task<IYieldPoint>>>> methodSelector, TParameter parameter) where TController : class
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{
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await CallControllerMethod<TController>(GetExpressionMethod(methodSelector), value => (Task<IYieldPoint>)value, new object?[] {parameter});
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}
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private async Task CallControllerMethod<TController>(MethodInfo method, Func<object, Task<IYieldPoint>> getYieldPointResult, object?[] parameters) where TController : class
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{
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var controller = config.DependencyResolver.Resolve<TController>();
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var result = method.Invoke(controller, parameters);
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if (result == null)
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throw new InvalidOperationException($"Method {method.Name} must return an IYieldPoint or Task<IYieldPoint>, got null");
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var yieldPoint = await getYieldPointResult(result);
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var context = new FlowHandlerContext(config, controller, method);
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var flowHandler = config.DependencyResolver.Resolve<IFlowHandler>();
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await flowHandler.Execute(context, yieldPoint);
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}
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private static MethodInfo GetExpressionMethod<TController, TResult>(Expression<Func<TController, Func<TResult>>> methodSelector)
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{
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var callExpression = (methodSelector.Body as UnaryExpression)?.Operand as MethodCallExpression;
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var targetMethodExpression = callExpression?.Object as ConstantExpression;
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var method = targetMethodExpression?.Value as MethodInfo;
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if (method == null)
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throw new ArgumentException("Unable to determine the starting method", nameof(methodSelector));
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return method;
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}
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private static MethodInfo GetExpressionMethod<TController, TResult, TParameter>(Expression<Func<TController, Func<TParameter, TResult>>> methodSelector)
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{
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var callExpression = (methodSelector.Body as UnaryExpression)?.Operand as MethodCallExpression;
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var targetMethodExpression = callExpression?.Object as ConstantExpression;
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var method = targetMethodExpression?.Value as MethodInfo;
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if (method == null)
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throw new ArgumentException("Unable to determine the starting method", nameof(methodSelector));
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return method;
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}
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}
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}
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