Improved some of the exceptions thrown during deserialization.

Author: StringEpsilon

PhpSerializerNET.Test/TestDeserializeErrors.cs

@@ -54,10 +54,10 @@ public void DeserializeMalformedString() {
 			Assert.AreEqual("Malformed string at position 0", ex.Message);
 
 			ex = Assert.ThrowsException<DeserializationException>(() => PhpSerialization.Deserialize("s:30:\"\";"));
-			Assert.AreEqual("Unexpected end of data at position. The string at position 0 pointed to out of bounds index 36.", ex.Message);
+			Assert.AreEqual("Illegal length of 30. The string at position 0 pointed to out of bounds index 36.", ex.Message);
 
 			ex = Assert.ThrowsException<DeserializationException>(() => PhpSerialization.Deserialize("s:1:\"\";"));
-			Assert.AreEqual("String at position 0 has an incorrect length.", ex.Message);
+			Assert.AreEqual("String at position 0 has an incorrect length of 1: Expected double quote at position 6, found ';' instead.", ex.Message);
 
 			ex = Assert.ThrowsException<DeserializationException>(() => PhpSerialization.Deserialize("s:a:\"\";"));
 			Assert.AreEqual("Malformed string at position 0", ex.Message);

PhpSerializerNET/PhpDeserializer.cs

@@ -174,7 +174,7 @@ private object DeserializeToken(Type targetType, PhpSerializeToken token) {
 						return this.MakeStruct(targetType, token);
 					}
 				default:
-					throw new Exception("Unsupported datatype.");
+					throw new DeserializationException($"Unsupported datatype {targetType.Name}.");
 			}
 		}
 
@@ -199,7 +199,14 @@ private object MakeStruct(Type targetType, PhpSerializeToken token) {
 				if (field.GetCustomAttribute<PhpIgnoreAttribute>() != null) {
 					break;
 				}
-				field.SetValue(result, this.DeserializeToken(field.FieldType, valueToken));
+				try{
+					field.SetValue(result, this.DeserializeToken(field.FieldType, valueToken));
+				} catch(Exception exception){
+					throw new DeserializationException(
+						$"Exception encountered while trying to assign '{token.Value}' to {targetType.Name}.{field.Name}. See inner exception for details.",
+						exception
+					);
+				}
 			}
 			return result;
 		}
@@ -226,7 +233,14 @@ private object MakeObject(Type targetType, PhpSerializeToken token) {
 				if (property.GetCustomAttribute<PhpIgnoreAttribute>() != null) {
 					break;
 				}
-				property.SetValue(result, this.DeserializeToken(property.PropertyType, valueToken));
+				try{
+					property.SetValue(result, this.DeserializeToken(property.PropertyType, valueToken));
+				} catch(Exception exception){
+					throw new DeserializationException(
+						$"Exception encountered while trying to assign '{token.Value}' to {targetType.Name}.{property.Name}. See inner exception for details.",
+						exception
+					);
+				}
 			}
 			return result;
 		}
@@ -243,7 +257,7 @@ private object MakeList(Type targetType, PhpSerializeToken token) {
 				if (token.Children[i].Type != PhpSerializerType.Integer) {
 					throw new DeserializationException(
 						$"Can not deserialize array at position {token.Position} to list: " +
-						$"It has a non-integer key at element {i} (position {token.Children[i].Position})."
+						$"It has a non-integer key '{token.Value}' at element {i} (position {token.Children[i].Position})."
 					);
 				}
 			}

PhpSerializerNET/PhpSerializationException.cs

@@ -10,5 +10,8 @@ namespace PhpSerializerNET {
 	public class DeserializationException : Exception {
 		public DeserializationException(string message) : base(message) {
 		}
+
+		public DeserializationException(string message, Exception innerException) : base(message, innerException) {
+		}
 	}
 }

PhpSerializerNET/PhpTokenizer.cs

@@ -113,7 +113,7 @@ internal List<PhpSerializeToken> Tokenize() {
 					return tokens;
 				}
 				if (_inputBytes.Length - 1 <= _position) {
-					throw new DeserializationException($"Unexpected end of data at position { _position + 1}");
+					throw new DeserializationException($"Unexpected end of data at position { _position}");
 				}
 				switch ((char)_inputBytes[_position]) {
 					case 'N': {
@@ -163,12 +163,15 @@ internal List<PhpSerializeToken> Tokenize() {
 
 							if (valueStart + length >= _inputBytes.Length) {
 								throw new DeserializationException(
-									$"Unexpected end of data at position. The string at position {_position} pointed to out of bounds index {valueStart + length}."
+									$"Illegal length of {length}. " +
+									$"The string at position {_position} points to out of bounds index {valueStart + length}."
 								);
 							}
-							if (_inputBytes[valueStart + length] != '"') {
+							char stringEnd = (char)_inputBytes[valueStart + length];
+							if (stringEnd != '"') {
 								throw new DeserializationException(
-									$"String at position {_position} has an incorrect length."
+									$"String at position {_position} has an incorrect length of {length}: "+
+									$"Expected double quote at position {valueStart + length}, found '{stringEnd}' instead."
 								);
 							}
 
@@ -223,7 +226,8 @@ internal List<PhpSerializeToken> Tokenize() {
 							};
 							if (arrayToken.Length != arrayToken.Children.Count / 2) {
 								throw new DeserializationException(
-									$"Array at position {arrayToken.Position} should be of length {arrayToken.Length}, but actual length is {arrayToken.Children.Count / 2}."
+									$"Array at position {arrayToken.Position} should be of length {arrayToken.Length}, " +
+									$"but actual length is {arrayToken.Children.Count / 2}."
 								);
 							}
 							tokens.Add(arrayToken);