Reduce allocations in TokenSegment.TryMatch

src/NuGet.Core/NuGet.Packaging/ContentModel/ContentPropertyDefinition.cs

@@ -15,76 +15,40 @@ public class ContentPropertyDefinition
     {
         private static readonly Func<object, object, bool> EqualsTest = (left, right) => Equals(left, right);
 
-        public ContentPropertyDefinition(string name)
-            : this(name, null, null, null, null, false)
-        {
-        }
-
-        public ContentPropertyDefinition(
+        internal ContentPropertyDefinition(
             string name,
-            Func<string, PatternTable, object> parser)
+            Func<ReadOnlyMemory<char>, PatternTable, object> parser)
             : this(name, parser, null, null, null, false)
         {
         }
 
-        public ContentPropertyDefinition(
+        internal ContentPropertyDefinition(
             string name,
-            Func<object, object, bool> compatibilityTest)
-            : this(name, null, compatibilityTest, null, null, false)
-        {
-        }
-
-        public ContentPropertyDefinition(
-            string name,
-            Func<string, PatternTable, object> parser,
+            Func<ReadOnlyMemory<char>, PatternTable, object> parser,
             Func<object, object, bool> compatibilityTest)
             : this(name, parser, compatibilityTest, null, null, false)
         {
         }
 
-        public ContentPropertyDefinition(string name,
-            Func<string, PatternTable, object> parser,
+        internal ContentPropertyDefinition(string name,
+            Func<ReadOnlyMemory<char>, PatternTable, object> parser,
             Func<object, object, bool> compatibilityTest,
             Func<object, object, object, int> compareTest)
             : this(name, parser, compatibilityTest, compareTest, null, false)
         {
         }
 
-        public ContentPropertyDefinition(
-            string name,
-            IEnumerable<string> fileExtensions)
-            : this(name, null, null, null, fileExtensions, false)
-        {
-        }
-
-        public ContentPropertyDefinition(
+        internal ContentPropertyDefinition(
             string name,
-            Func<string, PatternTable, object> parser,
+            Func<ReadOnlyMemory<char>, PatternTable, object> parser,
             IEnumerable<string> fileExtensions)
             : this(name, parser, null, null, fileExtensions, false)
         {
         }
 
-        public ContentPropertyDefinition(
-            string name,
-            IEnumerable<string> fileExtensions,
-            bool allowSubfolders)
-            : this(name, null, null, null, fileExtensions, allowSubfolders)
-        {
-        }
-
-        public ContentPropertyDefinition(
-            string name,
-            Func<string, PatternTable, object> parser,
-            IEnumerable<string> fileExtensions,
-            bool allowSubfolders)
-            : this(name, parser, null, null, fileExtensions, allowSubfolders)
-        {
-        }
-
-        public ContentPropertyDefinition(
+        internal ContentPropertyDefinition(
             string name,
-            Func<string, PatternTable, object> parser,
+            Func<ReadOnlyMemory<char>, PatternTable, object> parser,
             Func<object, object, bool> compatibilityTest,
             Func<object, object, object, int> compareTest,
             IEnumerable<string> fileExtensions,
@@ -104,11 +68,11 @@ public ContentPropertyDefinition(
 
         public bool FileExtensionAllowSubFolders { get; }
 
-        public Func<string, PatternTable, object> Parser { get; }
+        internal Func<ReadOnlyMemory<char>, PatternTable, object> Parser { get; }
 
-        public virtual bool TryLookup(string name, PatternTable table, out object value)
+        internal virtual bool TryLookup(ReadOnlyMemory<char> name, PatternTable table, out object value)
         {
-            if (name == null)
+            if (name.IsEmpty)
             {
                 value = null;
                 return false;
@@ -120,9 +84,9 @@ public virtual bool TryLookup(string name, PatternTable table, out object value)
                 {
                     foreach (var fileExtension in FileExtensions)
                     {
-                        if (name.EndsWith(fileExtension, StringComparison.OrdinalIgnoreCase))
+                        if (name.Span.EndsWith(fileExtension.AsSpan(), StringComparison.OrdinalIgnoreCase))
                         {
-                            value = name;
+                            value = name.ToString();
                             return true;
                         }
                     }
@@ -142,10 +106,10 @@ public virtual bool TryLookup(string name, PatternTable table, out object value)
             return false;
         }
 
-        private static bool ContainsSlash(string name)
+        private static bool ContainsSlash(ReadOnlyMemory<char> name)
         {
             var containsSlash = false;
-            foreach (var ch in name)
+            foreach (var ch in name.Span)
             {
                 if (ch == '/' || ch == '\\')
                 {

src/NuGet.Core/NuGet.Packaging/ContentModel/Infrastructure/Parser.cs

@@ -190,7 +190,7 @@ internal override bool TryMatch(
                     {
                         break;
                     }
-                    var substring = path.Substring(startIndex, delimiterIndex - startIndex);
+                    ReadOnlyMemory<char> substring = path.AsMemory(startIndex, delimiterIndex - startIndex);
                     object value;
                     if (propertyDefinition.TryLookup(substring, _table, out value))
                     {
@@ -206,7 +206,7 @@ internal override bool TryMatch(
                             }
                             if (StringComparer.Ordinal.Equals(_token, "tfm"))
                             {
-                                item.Properties.Add("tfm_raw", substring);
+                                item.Properties.Add("tfm_raw", substring.ToString());
                             }
                             item.Properties.Add(_token, value);
                         }

src/NuGet.Core/NuGet.Packaging/ContentModel/ManagedCodeConventions.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
-using System.Linq;
 using NuGet.ContentModel;
 using NuGet.Frameworks;
 using NuGet.Packaging.Core;
@@ -22,7 +21,7 @@ public class ManagedCodeConventions
 
         private static readonly ContentPropertyDefinition AnyProperty = new ContentPropertyDefinition(
             PropertyNames.AnyValue,
-            parser: (o, t) => o); // Identity parser, all strings are valid for any
+            parser: (o, t) => o.ToString()); // Identity parser, all strings are valid for any
         private static readonly ContentPropertyDefinition AssemblyProperty = new ContentPropertyDefinition(PropertyNames.ManagedAssembly,
             parser: AllowEmptyFolderParser,
             fileExtensions: new[] { ".dll", ".winmd", ".exe" });
@@ -69,8 +68,7 @@ public class ManagedCodeConventions
 
         private RuntimeGraph _runtimeGraph;
 
-        private Dictionary<string, NuGetFramework> _frameworkCache
-            = new Dictionary<string, NuGetFramework>(StringComparer.Ordinal);
+        private Dictionary<ReadOnlyMemory<char>, NuGetFramework> _frameworkCache = new(ReadOnlyMemoryCharComparerOrdinal.Instance);
 
         public ManagedCodeCriteria Criteria { get; }
         public IReadOnlyDictionary<string, ContentPropertyDefinition> Properties { get; }
@@ -90,7 +88,7 @@ public ManagedCodeConventions(RuntimeGraph runtimeGraph)
 
             props[PropertyNames.RuntimeIdentifier] = new ContentPropertyDefinition(
                 PropertyNames.RuntimeIdentifier,
-                parser: (o, t) => o, // Identity parser, all strings are valid runtime ids :)
+                parser: (o, t) => o.ToString(), // Identity parser, all strings are valid runtime ids
                 compatibilityTest: RuntimeIdentifier_CompatibilityTest);
 
             props[PropertyNames.TargetFrameworkMoniker] = new ContentPropertyDefinition(
@@ -125,7 +123,7 @@ private bool RuntimeIdentifier_CompatibilityTest(object criteria, object availab
             }
         }
 
-        private static object CodeLanguage_Parser(string name, PatternTable table)
+        private static object CodeLanguage_Parser(ReadOnlyMemory<char> name, PatternTable table)
         {
             if (table != null)
             {
@@ -138,17 +136,17 @@ private static object CodeLanguage_Parser(string name, PatternTable table)
 
             // Code language values must be alpha numeric.
             // PERF: use foreach to avoid CharEnumerator allocation
-            foreach (char c in name)
+            foreach (char c in name.Span)
             {
                 if (!char.IsLetterOrDigit(c))
                 {
                     return null;
                 }
             }
-            return name;
+            return name.ToString();
         }
 
-        private static object Locale_Parser(string name, PatternTable table)
+        private static object Locale_Parser(ReadOnlyMemory<char> name, PatternTable table)
         {
             if (table != null)
             {
@@ -161,18 +159,18 @@ private static object Locale_Parser(string name, PatternTable table)
 
             if (name.Length == 2)
             {
-                return name;
+                return name.ToString();
             }
-            else if (name.Length >= 4 && name[2] == '-')
+            else if (name.Length >= 4 && name.Span[2] == '-')
             {
-                return name;
+                return name.ToString();
             }
 
             return null;
         }
 
         private object TargetFrameworkName_Parser(
-            string name,
+            ReadOnlyMemory<char> name,
             PatternTable table)
         {
             object obj = null;
@@ -187,21 +185,21 @@ private object TargetFrameworkName_Parser(
             }
 
             // Check the cache for an exact match
-            if (!string.IsNullOrEmpty(name))
+            if (!name.IsEmpty)
             {
                 NuGetFramework cachedResult;
                 if (!_frameworkCache.TryGetValue(name, out cachedResult))
                 {
                     // Parse and add the framework to the cache
-                    cachedResult = TargetFrameworkName_ParserCore(name);
+                    cachedResult = TargetFrameworkName_ParserCore(name.ToString());
                     _frameworkCache.Add(name, cachedResult);
                 }
 
                 return cachedResult;
             }
 
             // Let the framework parser handle null/empty and create the error message.
-            return TargetFrameworkName_ParserCore(name);
+            return TargetFrameworkName_ParserCore(name.ToString());
         }
 
         private static NuGetFramework TargetFrameworkName_ParserCore(string name)
@@ -226,10 +224,15 @@ private static NuGetFramework TargetFrameworkName_ParserCore(string name)
             return new NuGetFramework(name, FrameworkConstants.EmptyVersion);
         }
 
-        private static object AllowEmptyFolderParser(string s, PatternTable table)
+        private static object AllowEmptyFolderParser(ReadOnlyMemory<char> s, PatternTable table)
         {
             // Accept "_._" as a pseudo-assembly
-            return PackagingCoreConstants.EmptyFolder.Equals(s, StringComparison.Ordinal) ? s : null;
+            if (MemoryExtensions.Equals(PackagingCoreConstants.EmptyFolder.AsSpan(), s.Span, StringComparison.Ordinal))
+            {
+                return s.ToString();
+            }
+
+            return null;
         }
 
         private static bool TargetFrameworkName_CompatibilityTest(object criteria, object available)