Added examples for console applications; Minor bugfix

I18Next.Net.sln

@@ -12,10 +12,14 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "I18Next.Net.Tests", "tests\
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "I18Next.Net.AspNetCore", "src\I18Next.Net.AspNetCore\I18Next.Net.AspNetCore.csproj", "{AC1CFDD9-1DBC-4E21-A1CF-F9C154BBF177}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.WebApp", "examples\Example.WebApp\Example.WebApp.csproj", "{7A9BDD90-BC7A-4B7D-A3F0-42A83D04E6C3}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.WebApp", "samples\Example.WebApp\Example.WebApp.csproj", "{7A9BDD90-BC7A-4B7D-A3F0-42A83D04E6C3}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "I18Next.Net.Abstractions", "src\I18Next.Net.Abstractions\I18Next.Net.Abstractions.csproj", "{42AB2562-8DA6-41E1-ABD5-152DDD622E6D}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.ConsoleApp.NetCore", "samples\Example.ConsoleApp.NetCore\Example.ConsoleApp.NetCore.csproj", "{4F2A9939-3351-465F-9E4C-12616F64A0CD}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.ConsoleApp.NetFramework", "samples\Example.ConsoleApp.NetFramework\Example.ConsoleApp.NetFramework.csproj", "{15DAA359-C831-4260-9F6F-6255B7A45110}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -54,5 +58,13 @@ Global
 		{42AB2562-8DA6-41E1-ABD5-152DDD622E6D}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{42AB2562-8DA6-41E1-ABD5-152DDD622E6D}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{42AB2562-8DA6-41E1-ABD5-152DDD622E6D}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4F2A9939-3351-465F-9E4C-12616F64A0CD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4F2A9939-3351-465F-9E4C-12616F64A0CD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4F2A9939-3351-465F-9E4C-12616F64A0CD}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4F2A9939-3351-465F-9E4C-12616F64A0CD}.Release|Any CPU.Build.0 = Release|Any CPU
+		{15DAA359-C831-4260-9F6F-6255B7A45110}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{15DAA359-C831-4260-9F6F-6255B7A45110}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{15DAA359-C831-4260-9F6F-6255B7A45110}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{15DAA359-C831-4260-9F6F-6255B7A45110}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

samples/Example.ConsoleApp.NetCore/Example.ConsoleApp.NetCore.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>netcoreapp2.1</TargetFramework>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\src\I18Next.Net.Extensions\I18Next.Net.Extensions.csproj" />
+      <ProjectReference Include="..\..\src\I18Next.Net\I18Next.Net.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="2.1.1" />
+    </ItemGroup>
+
+</Project>

samples/Example.ConsoleApp.NetCore/Program.cs

@@ -0,0 +1,114 @@
+using System;
+using I18Next.Net;
+using I18Next.Net.Backends;
+using I18Next.Net.Extensions;
+using I18Next.Net.Plugins;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Localization;
+using Console = System.Console; 
+
+namespace Example.ConsoleApp.NetCore
+{
+    class Program
+    {
+        private static ITranslationBackend _backend;
+
+        static void Main(string[] args)
+        {
+            SetupBackend();
+
+            SampleOne();
+
+            SampleTwo();
+
+            Console.ReadKey();
+        }
+
+        private static void SetupBackend()
+        {
+            var backend = new InMemoryBackend();
+
+            backend.AddTranslation("en", "translation", "exampleKey", "My English text.");
+            backend.AddTranslation("de", "translation", "exampleKey", "Mein deutscher text.");
+
+            _backend = backend;
+        }
+
+        private static void SampleOne()
+        {
+            Console.WriteLine("Sample one: Without Microsoft.Extensions.DependencyInjection");
+
+            var translator = new DefaultTranslator(_backend);
+
+            var i18next = new I18NextNet(_backend, translator);
+
+            Console.WriteLine("English translation:");
+            i18next.Language = "en";
+            Console.WriteLine(i18next.T("exampleKey"));
+
+            Console.WriteLine("German translation:");
+            i18next.Language = "de";
+            Console.WriteLine(i18next.T("exampleKey"));
+
+            Console.WriteLine();
+        }
+
+        private static void SampleTwo()
+        {
+            Console.WriteLine("Sample one: Using Microsoft.Extensions.DependencyInjection");
+
+            var services = new ServiceCollection();
+
+            // Register I18Next.Net
+            services.AddI18NextLocalization(builder => builder.AddBackend(_backend));
+
+            using(var serviceProvider = services.BuildServiceProvider())
+            using (var scope = serviceProvider.CreateScope())
+            {
+                var scopeProvider = scope.ServiceProvider;
+
+                Console.WriteLine("The first example uses the II18Next interface for direct access to I18Next");
+
+                var i18next = scopeProvider.GetService<II18Next>();
+
+                Console.WriteLine("English translation:");
+                i18next.Language = "en";
+                Console.WriteLine(i18next.T("exampleKey"));
+
+                Console.WriteLine("German translation:");
+                i18next.Language = "de";
+                Console.WriteLine(i18next.T("exampleKey"));
+
+
+                Console.WriteLine();
+                Console.WriteLine("The second example uses Microsofts IStringLocalizer interface for translations.");
+
+                var localizer = scopeProvider.GetService<IStringLocalizer>();
+
+                Console.WriteLine("English translation:");
+                i18next.Language = "en";
+                Console.WriteLine(localizer["exampleKey"]);
+
+                Console.WriteLine("German translation:");
+                i18next.Language = "de";
+                Console.WriteLine(localizer["exampleKey"]);
+
+
+                Console.WriteLine();
+                Console.WriteLine("It is also possible to use Microsofts IStringLocalizer<T> interface for translations.");
+
+                var localizerGeneric = scopeProvider.GetService<IStringLocalizer<Program>>();
+
+                Console.WriteLine("English translation:");
+                i18next.Language = "en";
+                Console.WriteLine(localizerGeneric["exampleKey"]);
+
+                Console.WriteLine("German translation:");
+                i18next.Language = "de";
+                Console.WriteLine(localizerGeneric["exampleKey"]);
+
+                Console.WriteLine();
+            }
+        }
+    }
+}

samples/Example.ConsoleApp.NetFramework/Example.ConsoleApp.NetFramework.csproj

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{15DAA359-C831-4260-9F6F-6255B7A45110}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Example.ConsoleApp.NetFramework</RootNamespace>
+    <AssemblyName>Example.ConsoleApp.NetFramework</AssemblyName>
+    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Program.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\I18Next.Net.Abstractions\I18Next.Net.Abstractions.csproj">
+      <Project>{42ab2562-8da6-41e1-abd5-152ddd622e6d}</Project>
+      <Name>I18Next.Net.Abstractions</Name>
+    </ProjectReference>
+    <ProjectReference Include="..\..\src\I18Next.Net\I18Next.Net.csproj">
+      <Project>{71f47bec-c9fb-4393-aa78-8d7ad2d51863}</Project>
+      <Name>I18Next.Net</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+         Other similar extension points exist, see Microsoft.Common.targets.
+    <Target Name="BeforeBuild">
+    </Target>
+    <Target Name="AfterBuild">
+    </Target>
+    -->
+</Project>

samples/Example.ConsoleApp.NetFramework/Program.cs

@@ -0,0 +1,41 @@
+using System;
+using I18Next.Net;
+using I18Next.Net.Backends;
+using I18Next.Net.Plugins;
+
+namespace Example.ConsoleApp.NetFramework
+{
+    internal class Program
+    {
+        private static ITranslationBackend _backend;
+
+        public static void Main(string[] args)
+        {
+            SetupBackend();
+
+            var translator = new DefaultTranslator(_backend);
+
+            var i18next = new I18NextNet(_backend, translator);
+
+            Console.WriteLine("English translation:");
+            i18next.Language = "en";
+            Console.WriteLine(i18next.T("exampleKey"));
+
+            Console.WriteLine("German translation:");
+            i18next.Language = "de";
+            Console.WriteLine(i18next.T("exampleKey"));
+
+            Console.ReadKey();
+        }
+
+        private static void SetupBackend()
+        {
+            var backend = new InMemoryBackend();
+
+            backend.AddTranslation("en", "translation", "exampleKey", "My English text.");
+            backend.AddTranslation("de", "translation", "exampleKey", "Mein deutscher text.");
+
+            _backend = backend;
+        }
+    }
+}

samples/Example.ConsoleApp.NetFramework/Properties/AssemblyInfo.cs

@@ -0,0 +1,35 @@
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("Example.ConsoleApp.NetFramework")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("Example.ConsoleApp.NetFramework")]
+[assembly: AssemblyCopyright("Copyright ©  2018")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible 
+// to COM components.  If you need to access a type in this assembly from 
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+// The following GUID is for the ID of the typelib if this project is exposed to COM
+[assembly: Guid("15DAA359-C831-4260-9F6F-6255B7A45110")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers 
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]

src/I18Next.Net.Extensions/Builder/I18NextBuilder.cs

@@ -4,6 +4,7 @@
 using I18Next.Net.Backends;
 using I18Next.Net.Plugins;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Localization;
 using Microsoft.Extensions.Options;
 
@@ -205,18 +206,19 @@ public I18NextBuilder AddTranslator<T>(Func<IServiceProvider, T> factory)
 
         public void Build()
         {
-            AddSingletonIfNotPresent<ILogger, DefaultExtensionsLogger>();
+            AddSingletonIfNotPresent(DefaultLoggerFactory);
             AddSingletonIfNotPresent<IPluralResolver, DefaultPluralResolver>();
-            AddSingletonIfNotPresent<ILanguageDetector, DefaultLanguageDetector>(DefaultLanguageDetectorFactory);
+            AddSingletonIfNotPresent<ILanguageDetector>(DefaultLanguageDetectorFactory);
             AddSingletonIfNotPresent<ITranslationBackend, JsonFileBackend>();
-            AddSingletonIfNotPresent<ITranslator, DefaultTranslator>(DefaultTranslatorFactory);
-            AddSingletonIfNotPresent<IInterpolator, DefaultInterpolator>(DefaultInterpolatorFactory);
+            AddSingletonIfNotPresent<ITranslator>(DefaultTranslatorFactory);
+            AddSingletonIfNotPresent<IInterpolator>(DefaultInterpolatorFactory);
 
             Services.AddSingleton<II18NextFactory, I18NextFactory>();
             Services.AddSingleton(c => c.GetRequiredService<II18NextFactory>().CreateInstance());
 
             Services.AddSingleton<IStringLocalizerFactory, I18NextStringLocalizerFactory>();
             Services.AddTransient(typeof(IStringLocalizer<>), typeof(StringLocalizer<>));
+            Services.TryAddTransient(typeof(IStringLocalizer), c => c.GetRequiredService<IStringLocalizerFactory>().Create(null));
         }
 
         public I18NextBuilder Configure(Action<I18NextOptions> configure)
@@ -254,12 +256,11 @@ private void AddSingletonIfNotPresent<TService, TImplementation>()
                 Services.AddSingleton<TService, TImplementation>();
         }
 
-        private void AddSingletonIfNotPresent<TService, TImplementation>(Func<IServiceProvider, TImplementation> factory)
-            where TImplementation : class, TService
+        private void AddSingletonIfNotPresent<TService>(Func<IServiceProvider, TService> factory)
             where TService : class
         {
             if (Services.All(s => s.ServiceType != typeof(TService)))
-                Services.AddSingleton<TService, TImplementation>(factory);
+                Services.AddSingleton(factory);
         }
 
         private DefaultInterpolator DefaultInterpolatorFactory(IServiceProvider c)
@@ -280,6 +281,16 @@ private DefaultLanguageDetector DefaultLanguageDetectorFactory(IServiceProvider
             return new DefaultLanguageDetector(options.Value.DefaultLanguage);
         }
 
+        private ILogger DefaultLoggerFactory(IServiceProvider c)
+        {
+            var msLogger = c.GetService<Microsoft.Extensions.Logging.ILogger>();
+
+            if (msLogger != null)
+                return new DefaultExtensionsLogger(msLogger);
+
+            return new TraceLogger();
+        }
+
         private DefaultTranslator DefaultTranslatorFactory(IServiceProvider c)
         {
             var backend = c.GetRequiredService<ITranslationBackend>();

src/I18Next.Net/Backends/InMemoryBackend.cs

@@ -19,7 +19,7 @@ public Task<ITranslationTree> LoadNamespaceAsync(string language, string @namesp
             treeKey = BackendUtilities.GetLanguagePart(language) + "_" + @namespace;
 
             if (!_namespaces.TryGetValue(treeKey, out tree))
-                return null;
+                return Task.FromResult(default(ITranslationTree));
 
             return Task.FromResult(tree as ITranslationTree);
         }