SeleniumHQ · TikhomirovSergey · Dec 21, 2014 · Dec 21, 2014 · Jan 3, 2015 · Jan 3, 2015
diff --git a/dotnet/src/support/PageObjects/DefaultElementLocator.cs b/dotnet/src/support/PageObjects/DefaultElementLocator.cs
@@ -0,0 +1,252 @@
+using OpenQA.Selenium.Internal;
+using OpenQA.Selenium.Support.PageObjects.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using System.Reflection;
+using OpenQA.Selenium.Support.UI;
+using System.Text;
+
+namespace OpenQA.Selenium.Support.PageObjects
+{
+    /// <summary>
+    /// The default element locator, which will lazily locate an element or an element list on a page. This class is
+    /// designed for use with the <see cref="PageFactory"/> and uses
+    /// attributes <see cref="FindsByAttribute"/> and <see cref="CacheLookupAttribute"/>.
+    /// </summary>
+    public class DefaultElementLocator: IElementLocator, IWrapsDriver
+    {
+        protected readonly MemberInfo Member;
+        protected readonly ISearchContext SearchContext;
+        protected readonly SearchParameterContainer SearchParameters;
+        private readonly IAdjustableByTimeSpan TimeOutContainer;
+        private IWebElement CachedElement;
+        private ReadOnlyCollection<IWebElement> CachedElementCollection;
+        private readonly bool ShouldCacheLookUp;
+
+
+        public DefaultElementLocator(MemberInfo member, ISearchContext searchContext, IAdjustableByTimeSpan timeOutContainer)
+        {
+            this.Member = member;
+            this.SearchContext = searchContext;
+            this.TimeOutContainer = timeOutContainer;
+            this.SearchParameters = new SearchParameterContainer();
+            this.SearchParameters.Context = this.SearchContext;
+            this.SearchParameters.TheGivenBys = CreateBys();
+            ShouldCacheLookUp = ShouldCacheLookup();
+        }
+
+        /// <summary>
+        /// An algorimthm which describes the waiting mechanism
+        /// </summary>
+        /// <returns>A read only collection of <see cref="IWebElement"/>s which are found. 
+        /// If there is no relevant elements when the result is null</returns>
+        private static Func<SearchParameterContainer, ReadOnlyCollection<IWebElement>> FindElements()
+        {
+            return (parameterContainer) => {
+                ISearchContext context = parameterContainer.Context;
+                ReadOnlyCollection<By> bys = parameterContainer.TheGivenBys;
+                try
+                {
+                    List<IWebElement> collection = new List<IWebElement>();
+                    foreach (var by in bys)
+                    {
+                        ReadOnlyCollection<IWebElement> list = context.FindElements(by);
+                        collection.AddRange(list);
+                    }
+                    if (collection.Count > 0)
+                    {
+                        return collection.AsReadOnly();
+                    }
+                    return null;
+                }
+                catch (StaleElementReferenceException)
+                {
+                    return null;
+                }
+
+            };
+        }
+
+        /// <summary>
+        /// </summary>
+        /// <returns>IWebdriver instatnce which is wrapped by the given search context. This method could be overriden</returns>
+        public IWebDriver WrappedDriver
+        {
+	        get { 
+                    IWebDriver driver = SearchContext as IWebDriver;
+                    if (driver != null)
+                    {
+                        return driver;
+                    }
+                    //RemoteWebElement implements IWrapsDriver and it is ISearchContext too
+                    //So we can get IWebDriver from the element
+                    //There can be something that wraps the original element
+                    IWrapsElement wrapsElement = SearchContext as IWrapsElement;
+                    IWebElement   element = SearchContext as IWebElement;
+
+                    while (wrapsElement != null)
+                    {
+                        element = ((IWrapsElement) element).WrappedElement;
+                        wrapsElement = element as IWrapsElement;
+                    }
+
+                    //so we get to the original RemoteWebElement instance
+                    return ((IWrapsDriver) element).WrappedDriver;
+            }
+        }
+
+        /// <summary>
+        /// This method creates <see cref="By"/> strategies according to attributes
+        /// which mark the target field. If it is nesessary you can make your own 
+        /// subclass of DefaultElementLocator and override this method
+        /// </summary>
+        /// <returns></returns>
+        protected virtual ReadOnlyCollection<By> CreateBys()
+        {
+            var useSequenceAttributes = Attribute.GetCustomAttributes(Member, typeof(FindsBySequenceAttribute), true);
+            bool useSequence = useSequenceAttributes.Length > 0;
+
+            List<By> bys = new List<By>();
+            var attributes = Attribute.GetCustomAttributes(Member, typeof(FindsByAttribute), true);
+            if (attributes.Length > 0)
+            {
+                Array.Sort(attributes);
+                foreach (var attribute in attributes)
+                {
+                    var castedAttribute = (FindsByAttribute)attribute;
+                    if (castedAttribute.Using == null)
+                    {
+                        castedAttribute.Using = Member.Name;
+                    }
+
+                    bys.Add(castedAttribute.Finder);
+                }
+
+                if (useSequence)
+                {
+                    ByChained chained = new ByChained(bys.ToArray());
+                    bys.Clear();
+                    bys.Add(chained);
+                }
+            }
+
+            if (attributes.Length == 0)
+            {
+                bys.Add(new ByIdOrName(Member.Name));
+            }
+            return bys.AsReadOnly();
+        }
+
+        public IWebElement Element
+        {
+            get 
+            {
+                if (CachedElement != null && ShouldCacheLookUp)
+                {
+                    return CachedElement;
+                }
+                ReadOnlyCollection<IWebElement> result = WaitFor();
+                if (result.Count == 0)
+                {
+                    throw new NoSuchElementException("Cann't locate an element by this strategies: " + SearchParameters.TheGivenBys.ToString());
+                }
+
+                if (ShouldCacheLookUp)
+                {
+                    CachedElement = result[0];
+                }
+                return result[0];
+            }
+        }
+
+        /// <summary>
+        /// This method checks the presence of <see cref="CacheLookupAttribute"/>
+        /// attribute. Field or class are checked. 
+        /// </summary>
+        /// <returns>true if the given field or declaring class have attribute <see cref="CacheLookupAttribute"/>. False is returned otherwise.</returns>
+        private bool ShouldCacheLookup()
+        {
+            var cacheAttributeType = typeof(CacheLookupAttribute);
+            bool cache = Member.GetCustomAttributes(cacheAttributeType, true).Length != 0 ||
+                Member.DeclaringType.GetCustomAttributes(cacheAttributeType, true).Length != 0;
+            return cache;
+        }
+
+        private ReadOnlyCollection<IWebElement> WaitFor()
+        {
+            IWebDriver driver = WrappedDriver;
+            ITimeouts timeOuts = driver.Manage().Timeouts();
+
+            DefaultWait<SearchParameterContainer> wait = new DefaultWait<SearchParameterContainer>(SearchParameters);
+            wait.Timeout = TimeOutContainer.WaitingTimeSpan;
+            wait.PollingInterval = TimeOutContainer.TimeForSleeping;
+
+            timeOuts.ImplicitlyWait(TimeSpan.MinValue);
+            ReadOnlyCollection<IWebElement> result;
+            try
+            {
+                result = wait.Until(FindElements());
+            }
+            catch (WebDriverTimeoutException)
+            {
+                result = new ReadOnlyCollection<IWebElement>(new List<IWebElement>());
+            }
+            finally
+            {
+                timeOuts.ImplicitlyWait(TimeOutContainer.WaitingTimeSpan);
+            }
+            return result;
+        }
+
+        public ReadOnlyCollection<IWebElement> Elements
+        {
+            get 
+            {
+                if (CachedElementCollection != null && ShouldCacheLookUp)
+                {
+                    return CachedElementCollection;
+                }
+
+                ReadOnlyCollection<IWebElement> result = WaitFor();
+
+                if (ShouldCacheLookUp)
+                {
+                    CachedElementCollection = result;
+                }
+                return result;
+            }
+
+        }
+
+        public class SearchParameterContainer
+        {
+            private ReadOnlyCollection<By> Bys;
+            private ISearchContext SearchContext;
+
+            public ReadOnlyCollection<By> TheGivenBys
+            { 
+                set 
+                {
+                    Bys = value;
+                }
+                get 
+                {
+                    return Bys;
+                }
+            }
+            public ISearchContext Context
+            {
+                set
+                {
+                    SearchContext = value;
+                }
+                get
+                {
+                    return SearchContext;
+                }
+            }
+        }
+}
+}
diff --git a/dotnet/src/support/PageObjects/DefaultElementLocatorFactory.cs b/dotnet/src/support/PageObjects/DefaultElementLocatorFactory.cs