Improve exception throwing implementation in collections

csharp/src/Google.Protobuf/Collections/MapField.cs

@@ -30,14 +30,13 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endregion
 
+using Google.Protobuf.Compatibility;
 using Google.Protobuf.Reflection;
 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Text;
-using Google.Protobuf.Compatibility;
 
 namespace Google.Protobuf.Collections
 {
@@ -113,7 +112,7 @@ namespace Google.Protobuf.Collections
             // Validation of arguments happens in ContainsKey and the indexer
             if (ContainsKey(key))
             {
-                throw new ArgumentException("Key already exists in map", "key");
+                throw new ArgumentException("Key already exists in map", nameof(key));
             }
             this[key] = value;
         }
@@ -125,7 +124,7 @@ namespace Google.Protobuf.Collections
         /// <returns><c>true</c> if the map contains the given key; <c>false</c> otherwise.</returns>
         public bool ContainsKey(TKey key)
         {
-            ProtoPreconditions.CheckNotNullUnconstrained(key, "key");
+            ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
             return map.ContainsKey(key);
         }
 
@@ -142,7 +141,7 @@ namespace Google.Protobuf.Collections
         /// <returns><c>true</c> if the map contained the given key before the entry was removed; <c>false</c> otherwise.</returns>
         public bool Remove(TKey key)
         {
-            ProtoPreconditions.CheckNotNullUnconstrained(key, "key");
+            ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
             LinkedListNode<KeyValuePair<TKey, TValue>> node;
             if (map.TryGetValue(key, out node))
             {
@@ -190,7 +189,7 @@ namespace Google.Protobuf.Collections
         {
             get
             {
-                ProtoPreconditions.CheckNotNullUnconstrained(key, "key");
+                ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
                 TValue value;
                 if (TryGetValue(key, out value))
                 {
@@ -200,11 +199,11 @@ namespace Google.Protobuf.Collections
             }
             set
             {
-                ProtoPreconditions.CheckNotNullUnconstrained(key, "key");
+                ProtoPreconditions.CheckNotNullUnconstrained(key, nameof(key));
                 // value == null check here is redundant, but avoids boxing.
                 if (value == null)
                 {
-                    ProtoPreconditions.CheckNotNullUnconstrained(value, "value");
+                    ProtoPreconditions.CheckNotNullUnconstrained(value, nameof(value));
                 }
                 LinkedListNode<KeyValuePair<TKey, TValue>> node;
                 var pair = new KeyValuePair<TKey, TValue>(key, value);
@@ -236,7 +235,7 @@ namespace Google.Protobuf.Collections
         /// <param name="entries">The entries to add to the map.</param>
         public void Add(IDictionary<TKey, TValue> entries)
         {
-            ProtoPreconditions.CheckNotNull(entries, "entries");
+            ProtoPreconditions.CheckNotNull(entries, nameof(entries));
             foreach (var pair in entries)
             {
                 Add(pair.Key, pair.Value);
@@ -315,7 +314,7 @@ namespace Google.Protobuf.Collections
         {
             if (item.Key == null)
             {
-                throw new ArgumentException("Key is null", "item");
+                throw new ArgumentException("Key is null", nameof(item));
             }
             LinkedListNode<KeyValuePair<TKey, TValue>> node;
             if (map.TryGetValue(item.Key, out node) &&
@@ -503,7 +502,7 @@ namespace Google.Protobuf.Collections
 
         void IDictionary.Remove(object key)
         {
-            ProtoPreconditions.CheckNotNull(key, "key");
+            ProtoPreconditions.CheckNotNull(key, nameof(key));
             if (!(key is TKey))
             {
                 return;
@@ -532,7 +531,7 @@ namespace Google.Protobuf.Collections
         {
             get
             {
-                ProtoPreconditions.CheckNotNull(key, "key");
+                ProtoPreconditions.CheckNotNull(key, nameof(key));
                 if (!(key is TKey))
                 {
                     return null;
@@ -714,11 +713,11 @@ namespace Google.Protobuf.Collections
             {
                 if (arrayIndex < 0)
                 {
-                    throw new ArgumentOutOfRangeException("arrayIndex");
+                    throw new ArgumentOutOfRangeException(nameof(arrayIndex));
                 }
                 if (arrayIndex + Count  >= array.Length)
                 {
-                    throw new ArgumentException("Not enough space in the array", "array");
+                    throw new ArgumentException("Not enough space in the array", nameof(array));
                 }
                 foreach (var item in this)
                 {
@@ -745,11 +744,11 @@ namespace Google.Protobuf.Collections
             {
                 if (index < 0)
                 {
-                    throw new ArgumentOutOfRangeException("index");
+                    throw new ArgumentOutOfRangeException(nameof(index));
                 }
                 if (index + Count >= array.Length)
                 {
-                    throw new ArgumentException("Not enough space in the array", "array");
+                    throw new ArgumentException("Not enough space in the array", nameof(array));
                 }
                 foreach (var item in this)
                 {

csharp/src/Google.Protobuf/Collections/RepeatedField.cs

@@ -34,7 +34,6 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.IO;
-using System.Text;
 
 namespace Google.Protobuf.Collections
 {
@@ -227,10 +226,7 @@ namespace Google.Protobuf.Collections
         /// <param name="item">The item to add.</param>
         public void Add(T item)
         {
-            if (item == null)
-            {
-                throw new ArgumentNullException("item");
-            }
+            ProtoPreconditions.CheckNotNullUnconstrained(item, nameof(item));
             EnsureSize(count + 1);
             array[count++] = item;
         }
@@ -300,10 +296,7 @@ namespace Google.Protobuf.Collections
         /// <param name="values">The values to add to this collection.</param>
         public void Add(RepeatedField<T> values)
         {
-            if (values == null)
-            {
-                throw new ArgumentNullException("values");
-            }
+            ProtoPreconditions.CheckNotNull(values, nameof(values));
             EnsureSize(count + values.count);
             // We know that all the values will be valid, because it's a RepeatedField.
             Array.Copy(values.array, 0, array, count, values.count);
@@ -316,10 +309,7 @@ namespace Google.Protobuf.Collections
         /// <param name="values">The values to add to this collection.</param>
         public void Add(IEnumerable<T> values)
         {
-            if (values == null)
-            {
-                throw new ArgumentNullException("values");
-            }
+            ProtoPreconditions.CheckNotNull(values, nameof(values));
             // TODO: Check for ICollection and get the Count, to optimize?
             foreach (T item in values)
             {
@@ -418,10 +408,7 @@ namespace Google.Protobuf.Collections
         /// <returns>The zero-based index of the item, or -1 if it is not found.</returns>
         public int IndexOf(T item)
         {
-            if (item == null)
-            {
-                throw new ArgumentNullException("item");
-            }
+            ProtoPreconditions.CheckNotNullUnconstrained(item, nameof(item));
             EqualityComparer<T> comparer = EqualityComparer<T>.Default;
             for (int i = 0; i < count; i++)
             {
@@ -440,13 +427,10 @@ namespace Google.Protobuf.Collections
         /// <param name="item">The item to insert.</param>
         public void Insert(int index, T item)
         {
-            if (item == null)
-            {
-                throw new ArgumentNullException("item");
-            }
+            ProtoPreconditions.CheckNotNullUnconstrained(item, nameof(item));
             if (index < 0 || index > count)
             {
-                throw new ArgumentOutOfRangeException("index");
+                throw new ArgumentOutOfRangeException(nameof(index));
             }
             EnsureSize(count + 1);
             Array.Copy(array, index, array, index + 1, count - index);
@@ -462,7 +446,7 @@ namespace Google.Protobuf.Collections
         {
             if (index < 0 || index >= count)
             {
-                throw new ArgumentOutOfRangeException("index");
+                throw new ArgumentOutOfRangeException(nameof(index));
             }
             Array.Copy(array, index + 1, array, index, count - index - 1);
             count--;
@@ -494,7 +478,7 @@ namespace Google.Protobuf.Collections
             {
                 if (index < 0 || index >= count)
                 {
-                    throw new ArgumentOutOfRangeException("index");
+                    throw new ArgumentOutOfRangeException(nameof(index));
                 }
                 return array[index];
             }
@@ -502,12 +486,9 @@ namespace Google.Protobuf.Collections
             {
                 if (index < 0 || index >= count)
                 {
-                    throw new ArgumentOutOfRangeException("index");
-                }
-                if (value == null)
-                {
-                    throw new ArgumentNullException("value");
+                    throw new ArgumentOutOfRangeException(nameof(index));
                 }
+                ProtoPreconditions.CheckNotNullUnconstrained(value, nameof(value));
                 array[index] = value;
             }
         }