From 29dd0e4953e0c8dc4f7a01117e16f94991eeaa2d Mon Sep 17 00:00:00 2001
From: Marko Urh <urh.marko@gmail.com>
Date: Wed, 12 Jul 2023 15:03:40 +0200
Subject: [PATCH] fix: null check (#9)

---
 source/Directory.Build.props        |  2 +-
 source/Perun.Differ/DifferDotNet.cs | 46 ++++++++++++++---------------
 2 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/source/Directory.Build.props b/source/Directory.Build.props
index 664f411..8fb23bb 100644
--- a/source/Directory.Build.props
+++ b/source/Directory.Build.props
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project>
   <PropertyGroup>
-    <Version>2.1.0</Version>
+    <Version>2.1.1</Version>
     <Authors>Marko Urh</Authors>
     <Company>Perun</Company>
     <Copyright>Copyright (c) 2023 Marko Urh and other authors.</Copyright>
diff --git a/source/Perun.Differ/DifferDotNet.cs b/source/Perun.Differ/DifferDotNet.cs
index 46feb5f..078a637 100644
--- a/source/Perun.Differ/DifferDotNet.cs
+++ b/source/Perun.Differ/DifferDotNet.cs
@@ -7,7 +7,7 @@
 
 namespace Differ.DotNet
 {
-    [PublicAPI]
+    [PublicAPI]
     public sealed class DifferDotNet
     {
         /// <summary>
@@ -21,7 +21,7 @@ public static IEnumerable<Difference> Diff<T>(T left, T right) where T : class
         {
             var differences = DiffRecursive(
                 string.Empty,
-                string.Empty,
+                string.Empty,
                 null,
                 typeof(T),
                 left,
@@ -99,8 +99,8 @@ DiffActions actions
                 // Check for KeepInDiff attribute
                 if (prop.GetCustomAttribute<KeepInDiffAttribute>() is { } keepAtt)
                 {
-                    actions |= keepAtt.IgnoreIfNoSiblingOrChildDiff
-                        ? DiffActions.KeepOptional
+                    actions |= keepAtt.IgnoreIfNoSiblingOrChildDiff
+                        ? DiffActions.KeepOptional
                         : DiffActions.Keep;
                 }
 
@@ -108,7 +108,7 @@ DiffActions actions
                 DiffRecursive(
                     fullPath + ".",
                     customFullPath + ".",
-                    prop,
+                    prop,
                     prop.PropertyType,
                     leftObj != null ? prop.GetValue(leftObj) : null,
                     rightObj != null ? prop.GetValue(rightObj) : null,
@@ -125,7 +125,7 @@ DiffActions actions
         private static bool HandleIterable<T>(
             string path,
             string customPath,
-            PropertyInfo prop,
+            PropertyInfo prop,
             Type type,
             T leftObj, T rightObj,
             DiffCollection diffs,
@@ -145,17 +145,17 @@ DiffActions actions
 
             // Check for DiffArrayIdPropertyName attribute
             PropertyInfo idProperty = null;
-            if (prop.GetCustomAttribute<DiffCollectionId>() is { } idAttr)
+            if (prop != null && prop.GetCustomAttribute<DiffCollectionId>() is { } idAttr)
             {
                 idProperty = underlyingType?.GetProperty(idAttr.Name);
-            }
-
+            }
+
             // key based
             if (idProperty != null)
             {
-                var sortedL = leftArr.OrderBy(x => idProperty?.GetValue(x)).ToArray();
-                var sortedR = rightArr.OrderBy(x => idProperty?.GetValue(x)).ToArray();
-
+                var sortedL = leftArr.OrderBy(x => idProperty?.GetValue(x)).ToArray();
+                var sortedR = rightArr.OrderBy(x => idProperty?.GetValue(x)).ToArray();
+
                 var l = 0;
                 var r = 0;
                 while (l < sortedL.Length || r < sortedR.Length)
@@ -163,7 +163,7 @@ DiffActions actions
                     var curL = l < sortedL.Length ? leftArr[l] : null;
                     var curR = r < sortedR.Length ? rightArr[r] : null;
 
-                    var keyL = curL != null ? idProperty.GetValue(curL) : null;
+                    var keyL = curL != null ? idProperty.GetValue(curL) : null;
                     var keyR = curR != null ? idProperty.GetValue(curR) : null;
 
                     if (keyL != keyR)
@@ -174,7 +174,7 @@ DiffActions actions
                         DiffRecursive(
                             path + $"{nextIdx}.",
                             customPath + $"{nextIdx}.",
-                            prop,
+                            prop,
                             underlyingType,
                             curL,
                             nextR,
@@ -184,8 +184,8 @@ DiffActions actions
 
                         var _ = curL != null ? l++ : r++;
                         continue;
-                    }
-
+                    }
+
                     DiffRecursive(
                         path + $"{l}.",
                         customPath + $"{l}.",
@@ -195,15 +195,15 @@ DiffActions actions
                         curR,
                         diffs,
                         actions
-                    );
+                    );
 
                     l++;
                     r++;
-                }
+                }
 
                 return true;
-            }
-
+            }
+
             // index based
             for (var i = 0; i < Math.Max(leftArr.Length, rightArr.Length); i++)
             {
@@ -244,7 +244,7 @@ DiffActions actions
                 path.Substring(0, path.Length - 1),
                 customPath.Substring(0, customPath.Length - 1),
                 leftObj,
-                rightObj
+                rightObj
             );
 
             if (actions.HasFlag(DiffActions.Keep) || actions.HasFlag(DiffActions.KeepOptional))
@@ -261,8 +261,8 @@ DiffActions actions
             if (exitCond)
             {
                 return true;
-            }
-
+            }
+
             diffs.Diffs.Add(diff.FullPath, diff);
             return true;
         }