.NET Samples - Create 03-workflows learning path step (#4102)

dotnet/samples/03-workflows/Loop/Program.cs

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+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Agents.AI.Workflows;
+
+namespace WorkflowLoopSample;
+
+/// <summary>
+/// This sample demonstrates a simple number guessing game using a workflow with looping behavior.
+///
+/// The workflow consists of two executors that are connected in a feedback loop:
+/// 1. GuessNumberExecutor: Makes a guess based on the current known bounds.
+/// 2. JudgeExecutor: Evaluates the guess and provides feedback.
+/// The workflow continues until the correct number is guessed.
+/// </summary>
+/// <remarks>
+/// Pre-requisites:
+/// - Foundational samples should be completed first.
+/// </remarks>
+public static class Program
+{
+    private static async Task Main()
+    {
+        // Create the executors
+        GuessNumberExecutor guessNumberExecutor = new("GuessNumber", 1, 100);
+        JudgeExecutor judgeExecutor = new("Judge", 42);
+
+        // Build the workflow by connecting executors in a loop
+        var workflow = new WorkflowBuilder(guessNumberExecutor)
+            .AddEdge(guessNumberExecutor, judgeExecutor)
+            .AddEdge(judgeExecutor, guessNumberExecutor)
+            .WithOutputFrom(judgeExecutor)
+            .Build();
+
+        // Execute the workflow
+        await using StreamingRun run = await InProcessExecution.StreamAsync(workflow, NumberSignal.Init);
+        await foreach (WorkflowEvent evt in run.WatchStreamAsync())
+        {
+            if (evt is WorkflowOutputEvent outputEvent)
+            {
+                Console.WriteLine($"Result: {outputEvent}");
+            }
+        }
+    }
+}
+
+/// <summary>
+/// Signals used for communication between GuessNumberExecutor and JudgeExecutor.
+/// </summary>
+internal enum NumberSignal
+{
+    Init,
+    Above,
+    Below,
+}
+
+/// <summary>
+/// Executor that makes a guess based on the current bounds.
+/// </summary>
+internal sealed class GuessNumberExecutor : Executor<NumberSignal>
+{
+    /// <summary>
+    /// The lower bound of the guessing range.
+    /// </summary>
+    public int LowerBound { get; private set; }
+
+    /// <summary>
+    /// The upper bound of the guessing range.
+    /// </summary>
+    public int UpperBound { get; private set; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="GuessNumberExecutor"/> class.
+    /// </summary>
+    /// <param name="id">A unique identifier for the executor.</param>
+    /// <param name="lowerBound">The initial lower bound of the guessing range.</param>
+    /// <param name="upperBound">The initial upper bound of the guessing range.</param>
+    public GuessNumberExecutor(string id, int lowerBound, int upperBound) : base(id)
+    {
+        this.LowerBound = lowerBound;
+        this.UpperBound = upperBound;
+    }
+
+    private int NextGuess => (this.LowerBound + this.UpperBound) / 2;
+
+    public override async ValueTask HandleAsync(NumberSignal message, IWorkflowContext context, CancellationToken cancellationToken = default)
+    {
+        switch (message)
+        {
+            case NumberSignal.Init:
+                await context.SendMessageAsync(this.NextGuess, cancellationToken: cancellationToken);
+                break;
+            case NumberSignal.Above:
+                this.UpperBound = this.NextGuess - 1;
+                await context.SendMessageAsync(this.NextGuess, cancellationToken: cancellationToken);
+                break;
+            case NumberSignal.Below:
+                this.LowerBound = this.NextGuess + 1;
+                await context.SendMessageAsync(this.NextGuess, cancellationToken: cancellationToken);
+                break;
+        }
+    }
+}
+
+/// <summary>
+/// Executor that judges the guess and provides feedback.
+/// </summary>
+internal sealed class JudgeExecutor : Executor<int>
+{
+    private readonly int _targetNumber;
+    private int _tries;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="JudgeExecutor"/> class.
+    /// </summary>
+    /// <param name="id">A unique identifier for the executor.</param>
+    /// <param name="targetNumber">The number to be guessed.</param>
+    public JudgeExecutor(string id, int targetNumber) : base(id)
+    {
+        this._targetNumber = targetNumber;
+    }
+
+    public override async ValueTask HandleAsync(int message, IWorkflowContext context, CancellationToken cancellationToken = default)
+    {
+        this._tries++;
+        if (message == this._targetNumber)
+        {
+            await context.YieldOutputAsync($"{this._targetNumber} found in {this._tries} tries!", cancellationToken)
+                         ;
+        }
+        else if (message < this._targetNumber)
+        {
+            await context.SendMessageAsync(NumberSignal.Below, cancellationToken: cancellationToken);
+        }
+        else
+        {
+            await context.SendMessageAsync(NumberSignal.Above, cancellationToken: cancellationToken);
+        }
+    }
+}