Enable nullable reference types for simple values (#840)

src/DocumentFormat.OpenXml/Framework/Validation/StringValidator.cs

@@ -188,7 +188,7 @@ private void Validate(StringValue str, ValidationContext context, in ValidationE
                             errorType: ValidationErrorType.Schema);
                     }
                 }
-                else if (current.Value.InnerText.Length > 255)
+                else if (current.Value.InnerText != null && current.Value.InnerText.Length > 255)
                 {
                     context.CreateError(
                         id: id,

src/DocumentFormat.OpenXml/Resources/SR.cs

@@ -7,22 +7,22 @@ namespace DocumentFormat.OpenXml
 {
     internal static class SR
     {
-        public static string Format(string str, params object[] args)
+        public static string Format(string str, params object?[] args)
         {
             return string.Format(CultureInfo.CurrentUICulture, str, args);
         }
 
-        public static string Format(string str, object arg0)
+        public static string Format(string str, object? arg0)
         {
             return string.Format(CultureInfo.CurrentUICulture, str, arg0);
         }
 
-        public static string Format(string str, object arg0, object arg1)
+        public static string Format(string str, object? arg0, object? arg1)
         {
             return string.Format(CultureInfo.CurrentUICulture, str, arg0, arg1);
         }
 
-        public static string Format(string str, object arg0, object arg1, object arg2)
+        public static string Format(string str, object? arg0, object? arg1, object? arg2)
         {
             return string.Format(CultureInfo.CurrentUICulture, str, arg0, arg1, arg2);
         }

src/DocumentFormat.OpenXml/SimpleTypes/Base64BinaryValue.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-#nullable disable
-
 using System;
 using System.Diagnostics;
 
@@ -15,30 +13,30 @@ namespace DocumentFormat.OpenXml
     public class Base64BinaryValue : StringValue
     {
         /// <summary>
-        /// Initializes a new instance of the Base64BinaryValue class.
+        /// Initializes a new instance of the <see cref="Base64BinaryValue"/> class.
         /// </summary>
         public Base64BinaryValue()
         {
         }
 
         /// <summary>
-        /// Initializes a new instance of the Base64BinaryValue class by deep copying
-        /// the supplied String value.
+        /// Initializes a new instance of the <see cref="Base64BinaryValue"/> class by deep copying
+        /// the supplied <see cref="string"/> value.
         /// </summary>
         /// <param name="base64Binary">
-        /// The String value.
+        /// The <see cref="string"/> value.
         /// </param>
         public Base64BinaryValue(string base64Binary)
         {
             TextValue = base64Binary;
         }
 
         /// <summary>
-        /// Initializes a new instance of the Base64BinaryValue class by deep copying
-        /// the supplied Base64BinaryValue class.
+        /// Initializes a new instance of the <see cref="Base64BinaryValue"/> class by deep copying
+        /// the supplied <see cref="Base64BinaryValue"/> class.
         /// </summary>
         /// <param name="source">
-        /// The source Base64BinaryValue class.
+        /// The source <see cref="Base64BinaryValue"/> class.
         /// </param>
         public Base64BinaryValue(Base64BinaryValue source)
             : base(source?.InnerText)
@@ -48,7 +46,7 @@ public Base64BinaryValue(Base64BinaryValue source)
         /// <summary>
         /// Gets or sets the Base64 binary string value.
         /// </summary>
-        public override string Value
+        public override string? Value
         {
             get => TextValue;
             set => TextValue = value;
@@ -93,50 +91,50 @@ internal override int Length
         }
 
         /// <summary>
-        /// Implicitly converts the specified value to a String value.
+        /// Implicitly converts the specified value to a <see cref="string"/> value.
         /// </summary>
-        /// <param name="xmlAttribute">The Base64BinaryValue object to convert.</param>
-        /// <returns>The base64Binary string. Returns null when xmlAttribute is null.</returns>
-        public static implicit operator string(Base64BinaryValue xmlAttribute)
+        /// <param name="value">The <see cref="Base64BinaryValue"/> object to convert.</param>
+        /// <returns>The base64Binary string. Returns null when <paramref name="value"/> is <c>null</c>.</returns>
+        public static implicit operator string?(Base64BinaryValue value)
         {
-            if (xmlAttribute == null)
+            if (value is null)
             {
                 return null;
             }
 
-            return ToString(xmlAttribute);
+            return ToString(value);
         }
 
         /// <summary>
-        /// Initializes a new instance of a Base64BinaryValue class using the
+        /// Initializes a new instance of a <see cref="Base64BinaryValue"/> class using the
         /// supplied string.
         /// </summary>
         /// <param name="value">The specified base64Binary value.</param>
-        /// <returns>A new Base64BinaryValue instance with the value.</returns>
+        /// <returns>A new <see cref="Base64BinaryValue"/> instance with the value.</returns>
         public static implicit operator Base64BinaryValue(string value) => FromString(value);
 
         /// <summary>
-        /// Returns a new Base64BinaryValue object that was created from a String value.
+        /// Returns a new <see cref="Base64BinaryValue"/> object that was created from a <see cref="string"/> value.
         /// </summary>
-        /// <param name="value">A String value to use to create a new Base64BinaryValue object.</param>
-        /// <returns>A Base64BinaryValue that corresponds to the value parameter.</returns>
+        /// <param name="value">A <see cref="string"/> value to use to create a new <see cref="Base64BinaryValue"/> object.</param>
+        /// <returns>A <see cref="Base64BinaryValue"/> that corresponds to the value parameter.</returns>
         public new static Base64BinaryValue FromString(string value) => new Base64BinaryValue(value);
 
         /// <summary>
-        /// Returns the String value representation of a Base64BinaryValue object.
+        /// Returns the <see cref="string"/>  value representation of a <see cref="Base64BinaryValue"/> object.
         /// </summary>
-        /// <param name="xmlAttribute">
-        /// A Base64BinaryValue object used to retrieve a String value representation.
+        /// <param name="value">
+        /// A <see cref="Base64BinaryValue"/> object used to retrieve a <see cref="string"/> value representation.
         /// </param>
-        /// <returns>A String value that represents a Base64BinaryValue object.</returns>
-        public static string ToString(Base64BinaryValue xmlAttribute)
+        /// <returns>A <see cref="string"/> value that represents a <see cref="Base64BinaryValue"/> object.</returns>
+        public static string? ToString(Base64BinaryValue value)
         {
-            if (xmlAttribute == null)
+            if (value is null)
             {
                 throw new InvalidOperationException(ExceptionMessages.ImplicitConversionExceptionOnNull);
             }
 
-            return xmlAttribute.Value;
+            return value.Value;
         }
 
         private protected override OpenXmlSimpleType CloneImpl() => new Base64BinaryValue(this);

src/DocumentFormat.OpenXml/SimpleTypes/BooleanValue.cs

@@ -1,42 +1,40 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-#nullable disable
-
 using System;
 using System.Diagnostics;
 using System.Xml;
 
 namespace DocumentFormat.OpenXml
 {
     /// <summary>
-    /// Represents the Boolean value for attributes.
+    /// Represents the <see cref="bool"/> value for attributes.
     /// </summary>
     [DebuggerDisplay("{InnerText}")]
     public class BooleanValue : OpenXmlComparableSimpleValue<bool>
     {
         /// <summary>
-        /// Initializes a new instance of the BooleanValue class.
+        /// Initializes a new instance of the <see cref="BooleanValue"/> class.
         /// </summary>
         public BooleanValue()
         {
         }
 
         /// <summary>
-        /// Initializes a new instance of the BooleanValue class using the supplied Boolean value.
+        /// Initializes a new instance of the <see cref="BooleanValue"/> class using the supplied <see cref="bool"/> value.
         /// </summary>
-        /// <param name="value">The Boolean value.</param>
+        /// <param name="value">The <see cref="bool"/> value.</param>
         public BooleanValue(bool value)
             : base(value)
         {
         }
 
         /// <summary>
-        /// Initializes a new instance of the BooleanValue class by deep copying
-        /// the supplied BooleanValue class.
+        /// Initializes a new instance of the <see cref="BooleanValue"/> class by deep copying
+        /// the supplied <see cref="BooleanValue"/> class.
         /// </summary>
         /// <param name="source">
-        /// The source BooleanValue class.
+        /// The source <see cref="BooleanValue"/> class.
         /// </param>
         public BooleanValue(BooleanValue source)
             : base(source)
@@ -45,60 +43,54 @@ public BooleanValue(BooleanValue source)
 
         private protected override string GetText(bool input) => input ? "1" : "0";
 
-        private protected override bool Parse(string input) => XmlConvert.ToBoolean(input);
+        private protected override bool Parse(string? input) => XmlConvert.ToBoolean(input);
 
         /// <summary>
-        /// Implicitly converts the specified value to a Boolean value.
+        /// Implicitly converts the specified value to a <see cref="bool"/> value.
         /// </summary>
-        /// <param name="xmlAttribute">The BooleanValue to convert.</param>
-        /// <returns>The converted Boolean value.</returns>
-        /// <exception cref="InvalidOperationException">Thrown when xmlAttribute is null.</exception>
-        public static implicit operator bool(BooleanValue xmlAttribute)
+        /// <param name="value">The <see cref="BooleanValue"/> to convert.</param>
+        /// <returns>The converted <see cref="bool"/> value.</returns>
+        /// <exception cref="InvalidOperationException">Thrown when <paramref name="value"/> is null.</exception>
+        public static implicit operator bool(BooleanValue value)
         {
-            if (xmlAttribute == null)
+            if (value is null)
             {
                 throw new InvalidOperationException(ExceptionMessages.ImplicitConversionExceptionOnNull);
             }
 
-            return ToBoolean(xmlAttribute);
+            return ToBoolean(value);
         }
 
         /// <summary>
-        /// Initializes a new instance of the BooleanValue class by implicitly
-        /// converting the supplied Boolean value.
+        /// Initializes a new instance of the <see cref="BooleanValue"/> class by implicitly
+        /// converting the supplied <see cref="bool"/> value.
         /// </summary>
-        /// <param name="value">The Boolean value.</param>
-        /// <returns>A new BooleanValue instance with the value.</returns>
-        public static implicit operator BooleanValue(bool value)
-        {
-            return FromBoolean(value);
-        }
+        /// <param name="value">The <see cref="bool"/> value.</param>
+        /// <returns>A new <see cref="BooleanValue"/> instance with the value.</returns>
+        public static implicit operator BooleanValue(bool value) => FromBoolean(value);
 
         /// <summary>
-        /// Returns a new BooleanValue object that was created by using the supplied Boolean value.
+        /// Returns a new <see cref="BooleanValue"/> object that was created by using the supplied <see cref="bool"/> value.
         /// </summary>
-        /// <param name="value">A Boolean value to use to create a new BooleanValue object.</param>
-        /// <returns>A BooleanValue that corresponds to the value parameter.</returns>
-        public static BooleanValue FromBoolean(bool value)
-        {
-            return new BooleanValue(value);
-        }
+        /// <param name="value">A <see cref="bool"/> value to use to create a new <see cref="BooleanValue"/> object.</param>
+        /// <returns>A <see cref="BooleanValue"/> that corresponds to the value parameter.</returns>
+        public static BooleanValue FromBoolean(bool value) => new BooleanValue(value);
 
         /// <summary>
-        /// Returns the Boolean representation of a BooleanValue object.
+        /// Returns the <see cref="bool"/> representation of a <see cref="BooleanValue"/> object.
         /// </summary>
-        /// <param name="xmlAttribute">
-        /// A BooleanValue object to retrieve a Boolean representation.
+        /// <param name="value">
+        /// A <see cref="BooleanValue"/> object to retrieve a <see cref="bool"/> representation.
         /// </param>
-        /// <returns>A Boolean value that represents a BooleanValue object.</returns>
-        public static bool ToBoolean(BooleanValue xmlAttribute)
+        /// <returns>A <see cref="bool"/> value that represents a <see cref="BooleanValue"/> object.</returns>
+        public static bool ToBoolean(BooleanValue value)
         {
-            if (xmlAttribute == null)
+            if (value is null)
             {
                 throw new InvalidOperationException(ExceptionMessages.ImplicitConversionExceptionOnNull);
             }
 
-            return xmlAttribute.Value;
+            return value.Value;
         }
 
         private protected override OpenXmlSimpleType CloneImpl() => new BooleanValue(this);