feat: add a method called ExtractPath to extract path from lamda expr…

src/Pather.CSharp/IResolver.cs

@@ -1,4 +1,6 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
+using System.Linq.Expressions;
 using Pather.CSharp.PathElements;
 
 namespace Pather.CSharp
@@ -41,5 +43,14 @@ public interface IResolver
         /// <param name="path"></param>
         /// <returns></returns>
         object ResolveSafe(object target, string path);
+
+        /// <summary>
+        /// extract field path by a  lambda expression<br/>
+        /// usage example: ExtractPath(()=>student.subjects[0].score) returns "student.subjects[0].score"
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="lambdaExpression"></param>
+        /// <returns></returns>
+        string ExtractPath<T>(Expression<Func<T>> lambdaExpression);
     }
 }

src/Pather.CSharp/Pather.CSharp.csproj

@@ -21,6 +21,7 @@
 
   <ItemGroup>
     <PackageReference Include="System.Linq" Version="4.3.0" />
+    <PackageReference Include="System.Linq.Expressions" Version="4.3.0" />
     <PackageReference Include="System.Reflection" Version="4.3.0" />
     <PackageReference Include="System.Reflection.Extensions" Version="4.3.0" />
     <PackageReference Include="System.Runtime" Version="4.3.0" />

src/Pather.CSharp/Resolver.cs

@@ -4,7 +4,9 @@
 using System.Threading.Tasks;
 using System.Reflection;
 using Pather.CSharp.PathElements;
-
+using System.Linq.Expressions;
+using System.Text.RegularExpressions;
+
 namespace Pather.CSharp
 {
     public class Resolver : IResolver
@@ -40,7 +42,7 @@ public IList<IPathElement> CreatePath(string path)
             var tempPath = path;
             while (tempPath.Length > 0)
             {
-                var pathElement = createPathElement(tempPath, out tempPath);
+                var pathElement = CreatePathElement(tempPath, out tempPath);
                 pathElements.Add(pathElement);
                 //remove the dots chaining properties 
                 //no PathElement could do this reliably
@@ -76,7 +78,7 @@ public object Resolve(object target, IList<IPathElement> pathElements)
                 return result;
         }
 
-        private IPathElement createPathElement(string path, out string newPath)
+        private IPathElement CreatePathElement(string path, out string newPath)
         {
             //get the first applicable path element type
             var pathElementFactory = PathElementFactories.Where(f => f.IsApplicable(path)).FirstOrDefault();
@@ -111,5 +113,20 @@ public object ResolveSafe(object target, string path)
                 return null;
             }
         }
+
+        public string ExtractPath<T>(Expression<Func<T>> lambdaExpression)
+        {
+            var expressionStr = lambdaExpression.ToString();
+
+            string pattern = @"\bvalue\([^)]*\)\.(.+)";
+            var match = Regex.Match(expressionStr, pattern);
+            if (match.Success)
+            {
+                var result = match.Groups[1].Value.Replace(".get_Item(", "[").Replace(")", "]");
+                return result;
+            }
+
+            throw new ArgumentException($"can not extract path from {expressionStr}");
+        }
     }
 }

test/Pather.CSharp.UnitTests/Pather.CSharp.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.0</TargetFramework>

test/Pather.CSharp.UnitTests/ResolveTests.cs

@@ -1,6 +1,7 @@
 using FluentAssertions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Pather.CSharp.UnitTests.TestHelper;
+using Pather.CSharp.UnitTests.TestModels;
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -274,6 +275,74 @@ public void IndexerResolution_String_Success()
 
             var res = resolver.Resolve(target, path);
             res.Should().Be("Testabc");
+        }
+
+        [TestMethod]
+        public void ExtractPath_Success()
+        {
+            var myclass = new Class()
+            {
+                Name = "class 1",
+                Address = new Address()
+                {
+                    Email = "[email protected]"
+                },
+                Students = new List<Student>()
+                {
+                   new Student(){ Name = "Jack",
+                       Subjects = new Subject[] {
+                            new Subject(){Name = "English",Score = 80},
+                            new Subject(){Name = "Math",Score=90}
+                       },
+                       Skills = new Dictionary<string, double>()
+                       {
+                           { "cook",80 },
+                           { "football",60}
+                       },
+                       Scores = new Dictionary<string, Subject>()
+                       {
+                           {"English", new Subject(){Score = 80} },
+                           {"Math", new Subject(){Score=90} }
+                       }
+                   },
+                   new Student(){ Name = "Timi",
+                       Subjects = new Subject[] {
+                            new Subject(){Name = "English",Score = 80},
+                            new Subject(){Name = "Math",Score=90}
+                       },
+                       Skills = new Dictionary<string, double>()
+                       {
+                           { "cook",80 },
+                           { "football",60}
+                       },
+                        Scores = new Dictionary<string, Subject>()
+                       {
+                           {"English", new Subject(){Score = 80} },
+                           {"Math", new Subject(){Score=90} }
+                       }
+                   }
+                }
+            };
+
+            IResolver resolver = new Resolver();
+
+            var case1 = resolver.ExtractPath(() => myclass.Name);
+            case1.Should().Be("myclass.Name");
+
+            var case2 = resolver.ExtractPath(() => myclass.Address.Email);
+            case2.Should().Be("myclass.Address.Email");           
+
+            var case3 = resolver.ExtractPath(() => myclass.Students);
+            case3.Should().Be("myclass.Students");
+
+            var case4 = resolver.ExtractPath(() => myclass.Students[0].Name);
+            case4.Should().Be("myclass.Students[0].Name");
+
+            var case5 = resolver.ExtractPath(() => myclass.Students[0].Subjects[0].Name);
+            case5.Should().Be("myclass.Students[0].Subjects[0].Name");
+
+            var case6 = resolver.ExtractPath(() => myclass.Students[0].Scores["Math"].Score);
+            case6.Should().Be("myclass.Students[0].Scores[\"Math\"].Score");           
         }
     }
 }

test/Pather.CSharp.UnitTests/TestModels/Address.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pather.CSharp.UnitTests.TestModels
+{
+    internal class Address
+    {
+        public string Email { get; set; }
+    }
+}

test/Pather.CSharp.UnitTests/TestModels/Class.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pather.CSharp.UnitTests.TestModels
+{
+    internal class Class
+    {
+        public string Name { get; set; }
+
+        public List<Student> Students { get; set; }
+
+        public Address Address { get; set; }
+    }
+}

test/Pather.CSharp.UnitTests/TestModels/Student.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pather.CSharp.UnitTests.TestModels
+{
+    internal class Student
+    {
+        // 姓名
+        public string Name { get; set; }
+
+        public Subject[] Subjects { get; set; }
+
+        public Dictionary<string,double> Skills { get; set; }
+
+        public Dictionary<string,Subject> Scores { get; set; }
+    }
+}

test/Pather.CSharp.UnitTests/TestModels/Subject.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pather.CSharp.UnitTests.TestModels
+{
+    internal class Subject
+    {
+        public string Name { get; set; }
+        public double Score { get; set; }   
+    }
+}