StringBuilder.Replace with ReadOnlySpan<char>

src/libraries/System.Private.CoreLib/src/System/Text/StringBuilder.cs

@@ -1841,6 +1841,17 @@ private StringBuilder AppendFormat<TArg0, TArg1, TArg2>(IFormatProvider? provide
         /// </remarks>
         public StringBuilder Replace(string oldValue, string? newValue) => Replace(oldValue, newValue, 0, Length);
 
+        /// <summary>
+        /// Replaces all instances of one read-only character span with another in this builder.
+        /// </summary>
+        /// <param name="oldValue">The read-only character span to replace.</param>
+        /// <param name="newValue">The read-only character span to replace <paramref name="oldValue"/> with.</param>
+        /// <remarks>
+        /// If <paramref name="newValue"/> is <c>null</c>, instances of <paramref name="oldValue"/>
+        /// are removed from this builder.
+        /// </remarks>
+        public StringBuilder Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue) => Replace(oldValue, newValue, 0, Length);
+
         /// <summary>
         /// Determines if the contents of this builder are equal to the contents of another builder.
         /// </summary>
@@ -1950,6 +1961,23 @@ public bool Equals(ReadOnlySpan<char> span)
         /// are removed from this builder.
         /// </remarks>
         public StringBuilder Replace(string oldValue, string? newValue, int startIndex, int count)
+        {
+            ArgumentException.ThrowIfNullOrEmpty(oldValue);
+            return Replace(oldValue.AsSpan(), newValue.AsSpan(), startIndex, count);
+        }
+
+        /// <summary>
+        /// Replaces all instances of one read-only character span with another in part of this builder.
+        /// </summary>
+        /// <param name="oldValue">The read-only character span to replace.</param>
+        /// <param name="newValue">The read-only character span to replace <paramref name="oldValue"/> with.</param>
+        /// <param name="startIndex">The index to start in this builder.</param>
+        /// <param name="count">The number of characters to read in this builder.</param>
+        /// <remarks>
+        /// If <paramref name="newValue"/> is <c>null</c>, instances of <paramref name="oldValue"/>
+        /// are removed from this builder.
+        /// </remarks>
+        public StringBuilder Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue, int startIndex, int count)
         {
             int currentLength = Length;
             if ((uint)startIndex > (uint)currentLength)
@@ -1960,9 +1988,10 @@ public StringBuilder Replace(string oldValue, string? newValue, int startIndex,
             {
                 throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_IndexMustBeLessOrEqual);
             }
-            ArgumentException.ThrowIfNullOrEmpty(oldValue);
-
-            newValue ??= string.Empty;
+            if (oldValue.Length == 0)
+            {
+                throw new ArgumentException(SR.Arg_EmptySpan, nameof(oldValue));
+            }
 
             var replacements = new ValueListBuilder<int>(stackalloc int[128]); // A list of replacement positions in a chunk to apply
 
@@ -2225,7 +2254,7 @@ private void Insert(int index, ref char value, int valueCount)
         /// <remarks>
         /// This routine is very efficient because it does replacements in bulk.
         /// </remarks>
-        private void ReplaceAllInChunk(ReadOnlySpan<int> replacements, StringBuilder sourceChunk, int removeCount, string value)
+        private void ReplaceAllInChunk(ReadOnlySpan<int> replacements, StringBuilder sourceChunk, int removeCount, ReadOnlySpan<char> value)
         {
             Debug.Assert(!replacements.IsEmpty);
 
@@ -2251,7 +2280,7 @@ private void ReplaceAllInChunk(ReadOnlySpan<int> replacements, StringBuilder sou
             while (true)
             {
                 // Copy in the new string for the ith replacement
-                ReplaceInPlaceAtChunk(ref targetChunk!, ref targetIndexInChunk, ref value.GetRawStringData(), value.Length);
+                ReplaceInPlaceAtChunk(ref targetChunk!, ref targetIndexInChunk, ref MemoryMarshal.GetReference<char>(value), value.Length);
                 int gapStart = replacements[i] + removeCount;
                 i++;
                 if ((uint)i >= replacements.Length)
@@ -2289,7 +2318,7 @@ private void ReplaceAllInChunk(ReadOnlySpan<int> replacements, StringBuilder sou
         /// <param name="indexInChunk">The index in <paramref name="chunk"/> at which the substring starts.</param>
         /// <param name="count">The logical count of the substring.</param>
         /// <param name="value">The prefix.</param>
-        private bool StartsWith(StringBuilder chunk, int indexInChunk, int count, string value)
+        private bool StartsWith(StringBuilder chunk, int indexInChunk, int count, ReadOnlySpan<char> value)
         {
             for (int i = 0; i < value.Length; i++)
             {

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -14925,6 +14925,8 @@ public void CopyTo(int sourceIndex, System.Span<char> destination, int count) {
         public System.Text.StringBuilder Replace(char oldChar, char newChar, int startIndex, int count) { throw null; }
         public System.Text.StringBuilder Replace(string oldValue, string? newValue) { throw null; }
         public System.Text.StringBuilder Replace(string oldValue, string? newValue, int startIndex, int count) { throw null; }
+        public System.Text.StringBuilder Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue) { throw null; }
+        public System.Text.StringBuilder Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue, int startIndex, int count) { throw null; }
         void System.Runtime.Serialization.ISerializable.GetObjectData(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context) { }
         public override string ToString() { throw null; }
         public string ToString(int startIndex, int length) { throw null; }

src/libraries/System.Runtime/tests/NlsTests/System.Runtime.Nls.Tests.csproj

@@ -30,6 +30,8 @@
              Link="System\Text\RuneTests.TestData.cs" />
     <Compile Include="..\System\Text\StringBuilderTests.cs"
              Link="System\Text\StringBuilderTests.cs" />
+    <Compile Include="..\System\Text\StringBuilderReplaceTests.cs"
+             Link="System\Text\StringBuilderReplaceTests.cs" />
     <Compile Include="..\System\Uri.CreateStringTests.cs"
              Link="System\Uri.CreateStringTests.cs" />
     <Compile Include="..\System\Uri.CreateUriTests.cs"

src/libraries/System.Runtime/tests/System.Runtime.Tests.csproj

@@ -153,6 +153,7 @@
     <Compile Include="System\StringTests.cs" />
     <Compile Include="System\SystemExceptionTests.cs" />
     <Compile Include="System\Text\CompositeFormatTests.cs" />
+    <Compile Include="System\Text\StringBuilderReplaceTests.cs" />
     <Compile Include="System\TimeOnlyTests.cs" />
     <Compile Include="System\TimeoutExceptionTests.cs" />
     <Compile Include="System\TimeSpanTests.cs" />

src/libraries/System.Runtime/tests/System/Text/StringBuilderReplaceTests.cs

@@ -0,0 +1,117 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Xunit;
+
+namespace System.Text.Tests
+{
+    public abstract class StringBuilderReplaceTests
+    {
+        [Theory]
+        [InlineData("", "a", "!", 0, 0, "")]
+        [InlineData("aaaabbbbccccdddd", "a", "!", 0, 16, "!!!!bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "a", "!", 2, 3, "aa!!bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "a", "!", 4, 1, "aaaabbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aab", "!", 2, 2, "aaaabbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aab", "!", 2, 3, "aa!bbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aa", "!", 0, 16, "!!bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aa", "$!", 0, 16, "$!$!bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aa", "$!$", 0, 16, "$!$$!$bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aaaa", "!", 0, 16, "!bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aaaa", "$!", 0, 16, "$!bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "a", "", 0, 16, "bbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "b", null, 0, 16, "aaaaccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aaaabbbbccccdddd", "", 0, 16, "")]
+        [InlineData("aaaabbbbccccdddd", "aaaabbbbccccdddd", "", 16, 0, "aaaabbbbccccdddd")]
+        [InlineData("aaaabbbbccccdddd", "aaaabbbbccccdddde", "", 0, 16, "aaaabbbbccccdddd")]
+        [InlineData("aaaaaaaaaaaaaaaa", "a", "b", 0, 16, "bbbbbbbbbbbbbbbb")]
+        public void Replace_StringBuilder(string value, string oldValue, string newValue, int startIndex, int count, string expected)
+        {
+            StringBuilder builder;
+            if (startIndex == 0 && count == value.Length)
+            {
+                // Use Replace(string, string) / Replace(ReadOnlySpan<char>, ReadOnlySpan<char>)
+                builder = new StringBuilder(value);
+                Replace(builder, oldValue, newValue);
+                Assert.Equal(expected, builder.ToString());
+            }
+
+            // Use Replace(string, string, int, int) / Replace(ReadOnlySpan<char>, ReadOnlySpan<char>, int, int)
+            builder = new StringBuilder(value);
+            Replace(builder, oldValue, newValue, startIndex, count);
+            Assert.Equal(expected, builder.ToString());
+        }
+
+        [Fact]
+        public void Replace_StringBuilderWithMultipleChunks()
+        {
+            StringBuilder builder = StringBuilderTests.StringBuilderWithMultipleChunks();
+            Replace(builder, "a", "b", builder.Length - 10, 10);
+            Assert.Equal(new string('a', builder.Length - 10) + new string('b', 10), builder.ToString());
+        }
+
+        [Fact]
+        public void Replace_StringBuilderWithMultipleChunks_WholeString()
+        {
+            StringBuilder builder = StringBuilderTests.StringBuilderWithMultipleChunks();
+            Replace(builder, builder.ToString(), "");
+            Assert.Same(string.Empty, builder.ToString());
+        }
+
+        [Fact]
+        public void Replace_StringBuilderWithMultipleChunks_LongString()
+        {
+            StringBuilder builder = StringBuilderTests.StringBuilderWithMultipleChunks();
+            Replace(builder, builder.ToString() + "b", "");
+            Assert.Equal(StringBuilderTests.s_chunkSplitSource, builder.ToString());
+        }
+
+        [Fact]
+        public void Replace_Invalid()
+        {
+            var builder = new StringBuilder(0, 5);
+            builder.Append("Hello");
+
+            AssertExtensions.Throws<ArgumentException>("oldValue", () => Replace(builder, "", "a")); // Old value is empty
+            AssertExtensions.Throws<ArgumentException>("oldValue", () => Replace(builder, "", "a", 0, 0)); // Old value is empty
+
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("requiredLength", () => Replace(builder, "o", "oo")); // New length > builder.MaxCapacity
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("requiredLength", () => Replace(builder, "o", "oo", 0, 5)); // New length > builder.MaxCapacity
+
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => Replace(builder, "a", "b", -1, 0)); // Start index < 0
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => Replace(builder, "a", "b", 0, -1)); // Count < 0
+
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => Replace(builder, "a", "b", 6, 0)); // Count + start index > builder.Length
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => Replace(builder, "a", "b", 5, 1)); // Count + start index > builder.Length
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => Replace(builder, "a", "b", 4, 2)); // Count + start index > builder.Length
+        }
+
+        protected virtual StringBuilder Replace(StringBuilder builder, string oldValue, string newValue)
+            => builder.Replace(oldValue, newValue);
+
+        protected virtual StringBuilder Replace(StringBuilder builder, string oldValue, string newValue, int startIndex, int count)
+            => builder.Replace(oldValue, newValue, startIndex, count);
+    }
+
+    public class StringBuilderReplaceTests_String : StringBuilderReplaceTests
+    {
+        [Fact]
+        public void Replace_String_Invalid()
+        {
+            var builder = new StringBuilder(0, 5);
+            builder.Append("Hello");
+
+            AssertExtensions.Throws<ArgumentNullException>("oldValue", () => Replace(builder, null, "")); // Old value is null
+            AssertExtensions.Throws<ArgumentNullException>("oldValue", () => Replace(builder, null, "a", 0, 0)); // Old value is null
+        }
+    }
+
+    public class StringBuilderReplaceTests_Span : StringBuilderReplaceTests
+    {
+        protected override StringBuilder Replace(StringBuilder builder, string oldValue, string newValue)
+            => builder.Replace(oldValue.AsSpan(), newValue.AsSpan());
+
+        protected override StringBuilder Replace(StringBuilder builder, string oldValue, string newValue, int startIndex, int count)
+            => builder.Replace(oldValue.AsSpan(), newValue.AsSpan(), startIndex, count);
+    }
+}

src/libraries/System.Runtime/tests/System/Text/StringBuilderTests.cs

@@ -13,10 +13,10 @@ namespace System.Text.Tests
 {
     public partial class StringBuilderTests
     {
-        private static readonly string s_chunkSplitSource = new string('a', 30);
         private static readonly string s_noCapacityParamName = "valueCount";
 
-        private static StringBuilder StringBuilderWithMultipleChunks() => new StringBuilder(20).Append(s_chunkSplitSource);
+        internal static readonly string s_chunkSplitSource = new string('a', 30);
+        internal static StringBuilder StringBuilderWithMultipleChunks() => new StringBuilder(20).Append(s_chunkSplitSource);
 
         [Fact]
         public static void Ctor_Empty()
@@ -1694,87 +1694,6 @@ public static void Replace_Char_Invalid()
             AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => builder.Replace('a', 'b', 4, 2)); // Count + start index > builder.Length
         }
 
-        [Theory]
-        [InlineData("", "a", "!", 0, 0, "")]
-        [InlineData("aaaabbbbccccdddd", "a", "!", 0, 16, "!!!!bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "a", "!", 2, 3, "aa!!bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "a", "!", 4, 1, "aaaabbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aab", "!", 2, 2, "aaaabbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aab", "!", 2, 3, "aa!bbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aa", "!", 0, 16, "!!bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aa", "$!", 0, 16, "$!$!bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aa", "$!$", 0, 16, "$!$$!$bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aaaa", "!", 0, 16, "!bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aaaa", "$!", 0, 16, "$!bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "a", "", 0, 16, "bbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "b", null, 0, 16, "aaaaccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aaaabbbbccccdddd", "", 0, 16, "")]
-        [InlineData("aaaabbbbccccdddd", "aaaabbbbccccdddd", "", 16, 0, "aaaabbbbccccdddd")]
-        [InlineData("aaaabbbbccccdddd", "aaaabbbbccccdddde", "", 0, 16, "aaaabbbbccccdddd")]
-        [InlineData("aaaaaaaaaaaaaaaa", "a", "b", 0, 16, "bbbbbbbbbbbbbbbb")]
-        public static void Replace_String(string value, string oldValue, string newValue, int startIndex, int count, string expected)
-        {
-            StringBuilder builder;
-            if (startIndex == 0 && count == value.Length)
-            {
-                // Use Replace(string, string)
-                builder = new StringBuilder(value);
-                builder.Replace(oldValue, newValue);
-                Assert.Equal(expected, builder.ToString());
-            }
-            // Use Replace(string, string, int, int)
-            builder = new StringBuilder(value);
-            builder.Replace(oldValue, newValue, startIndex, count);
-            Assert.Equal(expected, builder.ToString());
-        }
-
-        [Fact]
-        public static void Replace_String_StringBuilderWithMultipleChunks()
-        {
-            StringBuilder builder = StringBuilderWithMultipleChunks();
-            builder.Replace("a", "b", builder.Length - 10, 10);
-            Assert.Equal(new string('a', builder.Length - 10) + new string('b', 10), builder.ToString());
-        }
-
-        [Fact]
-        public static void Replace_String_StringBuilderWithMultipleChunks_WholeString()
-        {
-            StringBuilder builder = StringBuilderWithMultipleChunks();
-            builder.Replace(builder.ToString(), "");
-            Assert.Same(string.Empty, builder.ToString());
-        }
-
-        [Fact]
-        public static void Replace_String_StringBuilderWithMultipleChunks_LongString()
-        {
-            StringBuilder builder = StringBuilderWithMultipleChunks();
-            builder.Replace(builder.ToString() + "b", "");
-            Assert.Equal(s_chunkSplitSource, builder.ToString());
-        }
-
-        [Fact]
-        public static void Replace_String_Invalid()
-        {
-            var builder = new StringBuilder(0, 5);
-            builder.Append("Hello");
-
-            AssertExtensions.Throws<ArgumentNullException>("oldValue", () => builder.Replace(null, "")); // Old value is null
-            AssertExtensions.Throws<ArgumentNullException>("oldValue", () => builder.Replace(null, "a", 0, 0)); // Old value is null
-
-            AssertExtensions.Throws<ArgumentException>("oldValue", () => builder.Replace("", "a")); // Old value is empty
-            AssertExtensions.Throws<ArgumentException>("oldValue", () => builder.Replace("", "a", 0, 0)); // Old value is empty
-
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("requiredLength", () => builder.Replace("o", "oo")); // New length > builder.MaxCapacity
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("requiredLength", () => builder.Replace("o", "oo", 0, 5)); // New length > builder.MaxCapacity
-
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => builder.Replace("a", "b", -1, 0)); // Start index < 0
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => builder.Replace("a", "b", 0, -1)); // Count < 0
-
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => builder.Replace("a", "b", 6, 0)); // Count + start index > builder.Length
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => builder.Replace("a", "b", 5, 1)); // Count + start index > builder.Length
-            AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => builder.Replace("a", "b", 4, 2)); // Count + start index > builder.Length
-        }
-
         [Theory]
         [InlineData("Hello", 0, 5, "Hello")]
         [InlineData("Hello", 2, 3, "llo")]