Add a class that visits the OpenApi operations and returns the search results

Author: MaggieKimani1

src/Microsoft.OpenApi/Services/OperationSearch.cs

@@ -0,0 +1,67 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.OpenApi.Models;
+
+namespace Microsoft.OpenApi.Services
+{
+    public class OperationSearch : OpenApiVisitorBase
+    {
+        private readonly Func<OpenApiOperation, bool> _predicate;
+        private readonly List<SearchResult> _searchResults = new();
+
+        public IList<SearchResult> SearchResults => _searchResults;
+
+        public OperationSearch(Func<OpenApiOperation, bool> predicate)
+        {
+            _predicate = predicate ?? throw new ArgumentNullException(nameof(predicate));
+        }
+
+        /// <summary>
+        /// Visits <see cref="OpenApiOperation"/>.
+        /// </summary>
+        /// <param name="operation">The target <see cref="OpenApiOperation"/>.</param>
+        public override void Visit(OpenApiOperation operation)
+        {
+            if (_predicate(operation))
+            {
+                _searchResults.Add(new SearchResult()
+                {
+                    Operation = operation,
+                    CurrentKeys = CopyCurrentKeys(CurrentKeys)
+                });
+            }
+        }
+
+        /// <summary>
+        /// Visits list of <see cref="OpenApiParameter"/>.
+        /// </summary>
+        /// <param name="parameters">The target list of <see cref="OpenApiParameter"/>.</param>
+        public override void Visit(IList<OpenApiParameter> parameters)
+        {
+            /* The Parameter.Explode property should be true
+             * if Parameter.Style == Form; but OData query params
+             * as used in Microsoft Graph implement explode: false
+             * ex: $select=id,displayName,givenName
+             */
+            foreach (var parameter in parameters.Where(x => x.Style == ParameterStyle.Form))
+            {
+                parameter.Explode = false;
+            }
+
+            base.Visit(parameters);
+        }
+
+        private static CurrentKeys CopyCurrentKeys(CurrentKeys currentKeys)
+        {
+            return new CurrentKeys
+            {
+                Path = currentKeys.Path,
+                Operation = currentKeys.Operation
+            };
+        }
+    }
+}