Convert CreateString helper to static extension method (#11929)

To improve discoverability, transform Razor's
StringExtensions.CreateString(...) helper to a static extension method
on string.

Author: DustinCampbell

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/CodeGeneration/CodeWriter.cs

@@ -11,7 +11,6 @@
 using System.Text;
 using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.CodeAnalysis.Text;
-using static System.StringExtensions;
 
 namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration;
 
@@ -508,7 +507,7 @@ public override string ReadToEnd()
                 return string.Empty;
             }
 
-            var result = CreateString(_remainingLength, (_page, _chunkIndex, _charIndex), static (destination, state) =>
+            var result = string.Create(_remainingLength, (_page, _chunkIndex, _charIndex), static (destination, state) =>
             {
                 var (page, chunkIndex, charIndex) = state;
 

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/DefaultRazorProjectFileSystem.cs

@@ -127,7 +127,7 @@ protected override string NormalizeAndEnsureValidPath(string path)
         var needsSlash = Root[^1] is not '/' && normalizedPath[0] is not '/';
         var length = Root.Length + normalizedPath.Length + (needsSlash ? 1 : 0);
 
-        return StringExtensions.CreateString(
+        return string.Create(
             length,
             state: (Root, normalizedPath, needsSlash),
             static (span, state) =>

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/RazorProjectFileSystem.cs

@@ -120,7 +120,7 @@ internal ImmutableArray<RazorProjectItem> FindHierarchicalItems(string basePath,
         {
             pathMemory = pathMemory[..(index + 1)];
 
-            var itemPath = StringExtensions.CreateString(
+            var itemPath = string.Create(
                 length: pathMemory.Length + fileName.Length,
                 state: (pathMemory, fileName),
                 static (span, state) =>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Logging/LogMessageFormatter.cs

@@ -5,7 +5,6 @@
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using Microsoft.AspNetCore.Razor;
-using static System.StringExtensions;
 
 namespace Microsoft.CodeAnalysis.Razor.Logging;
 
@@ -23,7 +22,7 @@ public static string FormatMessage(string message, string categoryName, Exceptio
                 ref messageLineRangeBuilder, ref exceptionLineRangeBuilder);
 
             // Create the final string.
-            return CreateString(state.Length, state, static (span, state) =>
+            return string.Create(state.Length, state, static (span, state) =>
             {
                 Write(state.CategoryNamePart, ref span);
 

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/StringExtensions.cs

@@ -555,6 +555,7 @@ public static bool EndsWith(this string text, char value)
 #endif
     }
 
+#if !NET
     /// <summary>
     ///  Encapsulates a method that receives a span of objects of type <typeparamref name="T"/>
     ///  and a state object of type <typeparamref name="TArg"/>.
@@ -573,49 +574,49 @@ public static bool EndsWith(this string text, char value)
     /// </param>
     public delegate void SpanAction<T, in TArg>(Span<T> span, TArg arg);
 
-    /// <summary>
-    ///  Creates a new string with a specific length and initializes it after creation by using the specified callback.
-    /// </summary>
-    /// <typeparam name="TState">
-    ///  The type of the element to pass to <paramref name="action"/>.
-    /// </typeparam>
-    /// <param name="length">
-    ///  The length of the string to create.
-    /// </param>
-    /// <param name="state">
-    ///  The element to pass to <paramref name="action"/>.
-    /// </param>
-    /// <param name="action">
-    ///  A callback to initialize the string
-    /// </param>
-    /// <returns>
-    ///  The created string.
-    /// </returns>
-    /// <remarks>
-    ///  The initial content of the destination span passed to <paramref name="action"/> is undefined.
-    ///  Therefore, it is the delegate's responsibility to ensure that every element of the span is assigned.
-    ///  Otherwise, the resulting string could contain random characters
-    /// </remarks>
-    public unsafe static string CreateString<TState>(int length, TState state, SpanAction<char, TState> action)
+    extension(string)
     {
-#if NET
-        return string.Create(length, (action, state), static (span, state) => state.action(span, state.state));
-#else
-        ArgHelper.ThrowIfNegative(length);
-
-        if (length == 0)
+        /// <summary>
+        ///  Creates a new string with a specific length and initializes it after creation by using the specified callback.
+        /// </summary>
+        /// <typeparam name="TState">
+        ///  The type of the element to pass to <paramref name="action"/>.
+        /// </typeparam>
+        /// <param name="length">
+        ///  The length of the string to create.
+        /// </param>
+        /// <param name="state">
+        ///  The element to pass to <paramref name="action"/>.
+        /// </param>
+        /// <param name="action">
+        ///  A callback to initialize the string
+        /// </param>
+        /// <returns>
+        ///  The created string.
+        /// </returns>
+        /// <remarks>
+        ///  The initial content of the destination span passed to <paramref name="action"/> is undefined.
+        ///  Therefore, it is the delegate's responsibility to ensure that every element of the span is assigned.
+        ///  Otherwise, the resulting string could contain random characters.
+        /// </remarks>
+        public unsafe static string Create<TState>(int length, TState state, SpanAction<char, TState> action)
         {
-            return string.Empty;
-        }
+            ArgHelper.ThrowIfNegative(length);
 
-        var result = new string('\0', length);
+            if (length == 0)
+            {
+                return string.Empty;
+            }
 
-        fixed (char* ptr = result)
-        {
-            action(new Span<char>(ptr, length), state);
-        }
+            var result = new string('\0', length);
 
-        return result;
-#endif
+            fixed (char* ptr = result)
+            {
+                action(new Span<char>(ptr, length), state);
+            }
+
+            return result;
+        }
     }
+#endif
 }