Add SuffixExpressionVisitor to support appending suffixes to lambda expressions

Add documentation to demonstrate usage
Closes #1795

Author: russcam

docs/asciidoc/ClientConcepts/HighLevel/Inferrence/FieldInference.doc.asciidoc

@@ -23,7 +23,7 @@ Expect("name")
 				.WhenSerializing(fieldExpression)
 				.WhenSerializing(fieldString);
 ----
-Therefor you can also implicitly convert strings and expressions to Field's 
+Therefore you can also implicitly convert strings and expressions to Field's 
 
 [source, csharp]
 ----
@@ -52,7 +52,7 @@ but for expressions this is still rather involved
 
 [source, csharp]
 ----
-var fieldExpression = Field<Project>(p => p.Name);
+var fieldExpression = Infer.Field<Project>(p => p.Name);
 ----
 Using static imports in c# 6 this can be even shortened:
 using static Nest.Static; 
@@ -175,6 +175,36 @@ var suffix = "unanalyzed";
 Expect("metadata.var.unanalyzed").WhenSerializing(Field<Project>(p => p.Metadata[variable].Suffix(suffix)));
 Expect("metadata.var.created.unanalyzed").WhenSerializing(Field<Project>(p => p.Metadata[variable].Created.Suffix(suffix)));
 ----
+
+Suffixes can be appended to expressions. This is useful in cases where you want to apply the same suffix
+to a list of fields 
+
+
+
+[source, csharp]
+----
+var expressions = new List<Expression<Func<Project, object>>>
+{
+	p => p.Name,
+	p => p.Description,
+	p => p.CuratedTags.First().Name,
+	p => p.LeadDeveloper.FirstName
+};
+----
+append the suffix "raw" to each expression 
+
+[source, csharp]
+----
+var fieldExpressions = 
+	expressions.Select<Expression<Func<Project, object>>, Field>(e => e.AppendSuffix("raw")).ToList();
+----
+[source, csharp]
+----
+Expect("name.raw").WhenSerializing(fieldExpressions[0]);
+Expect("description.raw").WhenSerializing(fieldExpressions[1]);
+Expect("curatedTags.name.raw").WhenSerializing(fieldExpressions[2]);
+Expect("leadDeveloper.firstName.raw").WhenSerializing(fieldExpressions[3]);
+----
 Annotations 
 
 When using NEST's property attributes you can specify a new name for the properties

src/Benchmarking/project.lock.json

@@ -2025,7 +2025,7 @@
     "System.Dynamic.Runtime/4.0.11-beta-23516": {
       "type": "package",
       "serviceable": true,
-      "sha512": "ypkxS0e+yUw7F6JEwuB22u0qqruMeZFOmtcImh2efDHpTAuhF2FOqCDJ7f4qLf9yomVvB4kjkZ6xGunbIQryxQ==",
+      "sha512": "C2GXB20I5vMcO4wemZr5pEjwwEb6H6zVkwF12JSUhripKBIKgI0YKpfp9glyDSL903cYgIXAztMQDajwCR0PmA==",
       "files": [
         "lib/DNXCore50/System.Dynamic.Runtime.dll",
         "lib/MonoAndroid10/_._",

src/Elasticsearch.Net/project.lock.json

@@ -0,0 +1,48 @@
+using System;
+using System.Linq.Expressions;
+
+namespace Nest
+{
+	public static class ExpressionExtensions
+	{
+		/// <summary>
+		/// Appends <paramref name="suffix"/> to the path separating it with a dot.
+		/// This is especially useful with multi fields.
+		/// </summary>
+		/// <param name="expression">the expression to which the suffix should be applied</param>
+		/// <param name="suffix">the suffix</param>
+		public static Expression<Func<T, object>> AppendSuffix<T>(this Expression<Func<T, object>> expression, string suffix)
+		{
+			var newBody = new SuffixExpressionVisitor(suffix).Visit(expression.Body);
+			return Expression.Lambda<Func<T, object>>(newBody, expression.Parameters[0]);
+		}
+
+		/// <summary>
+		/// Calls <see cref="SuffixExtensions.Suffix"/> on a member expression.
+		/// </summary>
+		private class SuffixExpressionVisitor : ExpressionVisitor
+		{
+			private readonly string suffix;
+
+			public SuffixExpressionVisitor(string suffix)
+			{
+				this.suffix = suffix;
+			}
+
+			protected override Expression VisitMember(MemberExpression node)
+			{
+				return Expression.Call(
+					typeof(SuffixExtensions),
+					nameof(SuffixExtensions.Suffix),
+					null,
+					node,
+					Expression.Constant(suffix));
+			}
+
+			protected override Expression VisitUnary(UnaryExpression node)
+			{
+				return node;
+			}
+		}
+	}
+}

src/Nest/CommonAbstractions/Extensions/ExpressionExtensions.cs

@@ -2037,7 +2037,7 @@
     "runtime.any.System.Linq.Expressions/4.0.11-beta-23516": {
       "type": "package",
       "serviceable": true,
-      "sha512": "4sPxQCjllMJ1uZNlwz/EataPyHSH+AqSDlOIPPqcy/88R2B+abfhPPC78rd7gvHp8KmMX4qbJF6lcCeDIQpmVg==",
+      "sha512": "P5nzo1Ye0GxB4BYdWian6Y427eTrhn1JS3jLWZq5bMWVn8hS/OIfyylASN0A/qqeLn4rGA0fOzmJSYqFSKvxgQ==",
       "files": [
         "lib/DNXCore50/System.Linq.Expressions.dll",
         "lib/MonoAndroid10/_._",
@@ -2345,7 +2345,7 @@
     "System.Dynamic.Runtime/4.0.11-beta-23516": {
       "type": "package",
       "serviceable": true,
-      "sha512": "ypkxS0e+yUw7F6JEwuB22u0qqruMeZFOmtcImh2efDHpTAuhF2FOqCDJ7f4qLf9yomVvB4kjkZ6xGunbIQryxQ==",
+      "sha512": "C2GXB20I5vMcO4wemZr5pEjwwEb6H6zVkwF12JSUhripKBIKgI0YKpfp9glyDSL903cYgIXAztMQDajwCR0PmA==",
       "files": [
         "lib/DNXCore50/System.Dynamic.Runtime.dll",
         "lib/MonoAndroid10/_._",
@@ -2599,7 +2599,7 @@
     "System.Linq.Expressions/4.0.11-beta-23516": {
       "type": "package",
       "serviceable": true,
-      "sha512": "YEl5oyF5fifLbHHP099cvb/6f2r2h1QVHzoaoINPHOZtpNec+RfqvzETXcYDIdHT7l+bBAYsBuVUkBgfQEoYfQ==",
+      "sha512": "FtKytB13HabzrSvrAgBgOOnG2uxJO4s7zvP5Sk0NS3bwbJUyb5AP1p4897UWnLiB6C95jI4nIkZps51sa9In8g==",
       "files": [
         "lib/MonoAndroid10/_._",
         "lib/MonoTouch10/_._",

src/Nest/project.lock.json

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -41,7 +42,7 @@ public void UsingConstructors()
 				.WhenSerializing(fieldString);
 		}
 
-		/** Therefor you can also implicitly convert strings and expressions to Field's */
+		/** Therefore you can also implicitly convert strings and expressions to Field's */
 		[U]
 		public void ImplicitConversion()
 		{
@@ -63,7 +64,7 @@ public void UsingStaticPropertyField()
 			Field fieldString = "name";
 
 			/** but for expressions this is still rather involved */
-			var fieldExpression = Field<Project>(p => p.Name);
+			var fieldExpression = Infer.Field<Project>(p => p.Name);
 
 			/** Using static imports in c# 6 this can be even shortened:
 				using static Nest.Static; 
@@ -139,6 +140,32 @@ public void ComplexFieldNameExpressions()
 			Expect("metadata.var.created.unanalyzed").WhenSerializing(Field<Project>(p => p.Metadata[variable].Created.Suffix(suffix)));
 		}
 
+		/** 
+		* Suffixes can be appended to expressions. This is useful in cases where you want to apply the same suffix
+		* to a list of fields 
+		*/
+		[U]
+		public void AppendingSuffixToExpressions()
+		{
+			/**  */
+			var expressions = new List<Expression<Func<Project, object>>>
+			{
+				p => p.Name,
+				p => p.Description,
+				p => p.CuratedTags.First().Name,
+				p => p.LeadDeveloper.FirstName
+			};
+
+			/** append the suffix "raw" to each expression */
+			var fieldExpressions = 
+				expressions.Select<Expression<Func<Project, object>>, Field>(e => e.AppendSuffix("raw")).ToList();
+
+			Expect("name.raw").WhenSerializing(fieldExpressions[0]);
+			Expect("description.raw").WhenSerializing(fieldExpressions[1]);
+			Expect("curatedTags.name.raw").WhenSerializing(fieldExpressions[2]);
+			Expect("leadDeveloper.firstName.raw").WhenSerializing(fieldExpressions[3]);
+		}
+
 		/** Annotations 
 		* 
 		* When using NEST's property attributes you can specify a new name for the properties