Span-ify our homebrew parser's 'public' API.

Avalonia.sln

@@ -149,6 +149,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Props", "Props", "{F3AC8BC1
 		build\SharpDX.props = build\SharpDX.props
 		build\SkiaSharp.props = build\SkiaSharp.props
 		build\Splat.props = build\Splat.props
+		build\System.Memory.props = build\System.Memory.props
 		build\XUnit.props = build\XUnit.props
 	EndProjectSection
 EndProject

build/System.Memory.props

@@ -0,0 +1,5 @@
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <PackageReference Include="System.Memory" Version="4.5.0" />
+  </ItemGroup>
+</Project>

packages.cake

@@ -119,6 +119,7 @@ public class Packages
         var SharpDXDirect3D11Version = packageVersions["SharpDX.Direct3D11"].FirstOrDefault().Item1;
         var SharpDXDirect3D9Version = packageVersions["SharpDX.Direct3D9"].FirstOrDefault().Item1;
         var SharpDXDXGIVersion = packageVersions["SharpDX.DXGI"].FirstOrDefault().Item1;
+        var SystemMemoryVersion = packageVersions["System.Memory"].FirstOrDefault().Item1;
 
         context.Information("Package: Serilog, version: {0}", SerilogVersion);
         context.Information("Package: System.Reactive, version: {0}", SystemReactiveVersion);
@@ -131,6 +132,7 @@ public class Packages
         context.Information("Package: SharpDX.Direct3D11, version: {0}", SharpDXDirect3D11Version);
         context.Information("Package: SharpDX.Direct3D9, version: {0}", SharpDXDirect3D9Version);
         context.Information("Package: SharpDX.DXGI, version: {0}", SharpDXDXGIVersion);
+        context.Information("Package: System.Memory, version: {0}", SystemMemoryVersion);
 
         var nugetPackagesDir = System.Environment.GetEnvironmentVariable("NUGET_HOME")
             ?? System.IO.Path.Combine(System.Environment.GetEnvironmentVariable("USERPROFILE") ?? System.Environment.GetEnvironmentVariable("HOME"), ".nuget");
@@ -235,6 +237,7 @@ public class Packages
                     new NuSpecDependency() { Id = "Serilog.Sinks.Trace", Version = SerilogSinksTraceVersion },
                     new NuSpecDependency() { Id = "System.Reactive", Version = SystemReactiveVersion },
                     new NuSpecDependency() { Id = "Avalonia.Remote.Protocol", Version = parameters.Version },
+                    new NuSpecDependency() { Id = "System.Memory", Version = SystemMemoryVersion },
                     //.NET Core
                     new NuSpecDependency() { Id = "System.Threading.ThreadPool", TargetFramework = "netcoreapp2.0", Version = "4.3.0" },
                     new NuSpecDependency() { Id = "Microsoft.Extensions.DependencyModel", TargetFramework = "netcoreapp2.0", Version = "1.1.0" },
@@ -244,6 +247,7 @@ public class Packages
                     new NuSpecDependency() { Id = "Serilog.Sinks.Trace", TargetFramework = "netcoreapp2.0", Version = SerilogSinksTraceVersion },
                     new NuSpecDependency() { Id = "System.Reactive", TargetFramework = "netcoreapp2.0", Version = SystemReactiveVersion },
                     new NuSpecDependency() { Id = "Avalonia.Remote.Protocol", TargetFramework = "netcoreapp2.0", Version = parameters.Version },
+                    new NuSpecDependency() { Id = "System.Memory", TargetFramework = "netcoreapp2.0", Version = SystemMemoryVersion },
                 }
                 .Deps(new string[]{null, "netcoreapp2.0"},
                     "System.ValueTuple", "System.ComponentModel.TypeConverter", "System.ComponentModel.Primitives",

src/Markup/Avalonia.Markup/Avalonia.Markup.csproj

@@ -9,4 +9,5 @@
     <ProjectReference Include="..\..\Avalonia.Visuals\Avalonia.Visuals.csproj" />
   </ItemGroup>
   <Import Project="..\..\..\build\Rx.props" />
+  <Import Project="..\..\..\build\System.Memory.props" />
 </Project>

src/Markup/Avalonia.Markup/Markup/Parsers/ArgumentListParser.cs

@@ -20,16 +20,13 @@ namespace Avalonia.Markup.Parsers
 
                 while (!r.End)
                 {
-                    var builder = new StringBuilder();
-                    while (!r.End && r.Peek != ',' && r.Peek != close && !char.IsWhiteSpace(r.Peek))
-                    {
-                        builder.Append(r.Take());
-                    }
-                    if (builder.Length == 0)
+                    var argument = r.TakeUntil(',');
+                    if (argument.IsEmpty)
                     {
                         throw new ExpressionParseException(r.Position, "Expected indexer argument.");
                     }
-                    result.Add(builder.ToString());
+
+                    result.Add(argument.ToString());
 
                     r.SkipWhitespace();
 

src/Markup/Avalonia.Markup/Markup/Parsers/ExpressionParser.cs

@@ -83,9 +83,9 @@ namespace Avalonia.Markup.Parsers
             {
                 var identifier = r.ParseIdentifier();
 
-                if (identifier != null)
+                if (!identifier.IsEmpty)
                 {
-                    nodes.Add(new PropertyAccessorNode(identifier, _enableValidation));
+                    nodes.Add(new PropertyAccessorNode(identifier.ToString(), _enableValidation));
                     return State.AfterMember;
                 }
             }
@@ -122,9 +122,9 @@ namespace Avalonia.Markup.Parsers
             {
                 var identifier = r.ParseIdentifier();
 
-                if (identifier != null)
+                if (!identifier.IsEmpty)
                 {
-                    nodes.Add(new PropertyAccessorNode(identifier, _enableValidation));
+                    nodes.Add(new PropertyAccessorNode(identifier.ToString(), _enableValidation));
                     return State.AfterMember;
                 }
 
@@ -134,8 +134,8 @@ namespace Avalonia.Markup.Parsers
 
         private State ParseAttachedProperty(Reader r, List<ExpressionNode> nodes)
         {
-            string ns = string.Empty;
-            string owner;
+            ReadOnlySpan<char> ns = ReadOnlySpan<char>.Empty;
+            ReadOnlySpan<char> owner;
             var ownerOrNamespace = r.ParseIdentifier();
 
             if (r.TakeIf(':'))
@@ -160,7 +160,7 @@ namespace Avalonia.Markup.Parsers
                 throw new ExpressionParseException(r.Position, "Expected ')'.");
             }
 
-            var property = AvaloniaPropertyRegistry.Instance.FindRegistered(_typeResolver(ns, owner), name);
+            var property = AvaloniaPropertyRegistry.Instance.FindRegistered(_typeResolver(ns.ToString(), owner.ToString()), name.ToString());
 
             nodes.Add(new AvaloniaPropertyAccessorNode(property, _enableValidation));
             return State.AfterMember;

src/Markup/Avalonia.Markup/Markup/Parsers/IdentifierParser.cs

@@ -1,52 +0,0 @@
-// Copyright (c) The Avalonia Project. All rights reserved.
-// Licensed under the MIT license. See licence.md file in the project root for full license information.
-
-using System.Globalization;
-using System.Text;
-
-namespace Avalonia.Markup.Parsers
-{
-    internal static class IdentifierParser
-    {
-        public static string ParseIdentifier(this Reader r)
-        {
-            if (IsValidIdentifierStart(r.Peek))
-            {
-                var result = new StringBuilder();
-
-                while (!r.End && IsValidIdentifierChar(r.Peek))
-                {
-                    result.Append(r.Take());
-                }
-
-                return result.ToString();
-            }
-            else
-            {
-                return null;
-            }
-        }
-
-        private static bool IsValidIdentifierStart(char c)
-        {
-            return char.IsLetter(c) || c == '_';
-        }
-
-        private static bool IsValidIdentifierChar(char c)
-        {
-            if (IsValidIdentifierStart(c))
-            {
-                return true;
-            }
-            else
-            {
-                var cat = CharUnicodeInfo.GetUnicodeCategory(c);
-                return cat == UnicodeCategory.NonSpacingMark ||
-                       cat == UnicodeCategory.SpacingCombiningMark ||
-                       cat == UnicodeCategory.ConnectorPunctuation ||
-                       cat == UnicodeCategory.Format ||
-                       cat == UnicodeCategory.DecimalDigitNumber;
-            }
-        }
-    }
-}

src/Markup/Avalonia.Markup/Markup/Parsers/Reader.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Globalization;
 using System.Text;
 
 namespace Avalonia.Markup.Parsers
@@ -52,14 +53,55 @@ namespace Avalonia.Markup.Parsers
             return false;
         }
 
-        public string TakeUntil(char c)
+        public ReadOnlySpan<char> TakeUntil(char c)
         {
-            var builder = new StringBuilder();
+            int startIndex = Position;
             while (!End && Peek != c)
             {
-                builder.Append(Take());
+                Take();
+            }
+            return _s.AsSpan(startIndex, Position - startIndex);
+        }
+
+        public ReadOnlySpan<char> ParseIdentifier()
+        {
+            if (IsValidIdentifierStart(Peek))
+            {
+                int startIndex = Position;
+
+                while (!End && IsValidIdentifierChar(Peek))
+                {
+                    Take();
+                }
+
+                return _s.AsSpan(startIndex, Position - startIndex);
+            }
+            else
+            {
+                return ReadOnlySpan<char>.Empty;
+            }
+        }
+
+        private static bool IsValidIdentifierStart(char c)
+        {
+            return char.IsLetter(c) || c == '_';
+        }
+
+        private static bool IsValidIdentifierChar(char c)
+        {
+            if (IsValidIdentifierStart(c))
+            {
+                return true;
+            }
+            else
+            {
+                var cat = CharUnicodeInfo.GetUnicodeCategory(c);
+                return cat == UnicodeCategory.NonSpacingMark ||
+                       cat == UnicodeCategory.SpacingCombiningMark ||
+                       cat == UnicodeCategory.ConnectorPunctuation ||
+                       cat == UnicodeCategory.Format ||
+                       cat == UnicodeCategory.DecimalDigitNumber;
             }
-            return builder.ToString();
         }
     }
 }

src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs

@@ -1,6 +1,7 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using System;
 using System.Collections.Generic;
 using System.Globalization;
 using Avalonia.Data.Core;
@@ -139,12 +140,12 @@ namespace Avalonia.Markup.Parsers
         {
             var identifier = r.ParseIdentifier();
 
-            if (string.IsNullOrEmpty(identifier))
+            if (identifier.IsEmpty)
             {
                 throw new ExpressionParseException(r.Position, "Expected class name or is selector after ':'.");
             }
 
-            if (identifier == "is" && r.TakeIf('('))
+            if (identifier.SequenceEqual("is".AsSpan()) && r.TakeIf('('))
             {
                 var syntax = ParseType<IsSyntax>(r);
                 if (r.End || !r.TakeIf(')'))
@@ -160,7 +161,7 @@ namespace Avalonia.Markup.Parsers
                     State.CanHaveType,
                     new ClassSyntax
                     {
-                        Class = ":" + identifier
+                        Class = ":" + identifier.ToString()
                     });
             }
         }
@@ -190,20 +191,20 @@ namespace Avalonia.Markup.Parsers
         private static (State, ISyntax) ParseClass(Reader r)
         {
             var @class = r.ParseIdentifier();
-            if (string.IsNullOrEmpty(@class))
+            if (@class.IsEmpty)
             {
                 throw new ExpressionParseException(r.Position, $"Expected a class name after '.'.");
             }
 
-            return (State.CanHaveType, new ClassSyntax { Class = @class });
+            return (State.CanHaveType, new ClassSyntax { Class = @class.ToString() });
         }
 
         private static (State, ISyntax) ParseTemplate(Reader r)
         {
             var template = r.ParseIdentifier();
-            if (template != nameof(template))
+            if (!template.SequenceEqual(nameof(template).AsSpan()))
             {
-                throw new ExpressionParseException(r.Position, $"Expected 'template', got {template}");
+                throw new ExpressionParseException(r.Position, $"Expected 'template', got '{template.ToString()}'");
             }
             else if (!r.TakeIf('/'))
             {
@@ -215,11 +216,11 @@ namespace Avalonia.Markup.Parsers
         private static (State, ISyntax) ParseName(Reader r)
         {
             var name = r.ParseIdentifier();
-            if (string.IsNullOrEmpty(name))
+            if (name.IsEmpty)
             {
                 throw new ExpressionParseException(r.Position, $"Expected a name after '#'.");
             }
-            return (State.CanHaveType, new NameSyntax { Name = name });
+            return (State.CanHaveType, new NameSyntax { Name = name.ToString() });
         }
 
         private static (State, ISyntax) ParseTypeName(Reader r)
@@ -240,17 +241,17 @@ namespace Avalonia.Markup.Parsers
 
             r.Take();
 
-            return (State.CanHaveType, new PropertySyntax { Property = property, Value = value });
+            return (State.CanHaveType, new PropertySyntax { Property = property.ToString(), Value = value.ToString() });
         }
 
         private static TSyntax ParseType<TSyntax>(Reader r)
             where TSyntax : ITypeSyntax, new()
         {
-            string ns = null;
-            string type;
+            ReadOnlySpan<char> ns = null;
+            ReadOnlySpan<char> type;
             var namespaceOrTypeName = r.ParseIdentifier();
 
-            if (string.IsNullOrEmpty(namespaceOrTypeName))
+            if (namespaceOrTypeName.IsEmpty)
             {
                 throw new ExpressionParseException(r.Position, $"Expected an identifier, got '{r.Peek}");
             }
@@ -270,8 +271,8 @@ namespace Avalonia.Markup.Parsers
             }
             return new TSyntax
             {
-                Xmlns = ns,
-                TypeName = type
+                Xmlns = ns.ToString(),
+                TypeName = type.ToString()
             };
         }
 
@@ -290,7 +291,7 @@ namespace Avalonia.Markup.Parsers
         {
             public string TypeName { get; set; }
 
-            public string Xmlns { get; set; }
+            public string Xmlns { get; set; } = string.Empty;
 
             public override bool Equals(object obj)
             {
@@ -303,7 +304,7 @@ namespace Avalonia.Markup.Parsers
         {
             public string TypeName { get; set; }
 
-            public string Xmlns { get; set; }
+            public string Xmlns { get; set; } = string.Empty;
 
             public override bool Equals(object obj)
             {

tests/Avalonia.Markup.UnitTests/Parsers/SelectorGrammarTests.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Markup.UnitTests.Parsers
             var result = SelectorGrammar.Parse("Button");
 
             Assert.Equal(
-                new[] { new SelectorGrammar.OfTypeSyntax { TypeName = "Button", Xmlns = null } },
+                new[] { new SelectorGrammar.OfTypeSyntax { TypeName = "Button", Xmlns = "" } },
                 result);
         }
 
@@ -60,7 +60,7 @@ namespace Avalonia.Markup.UnitTests.Parsers
             var result = SelectorGrammar.Parse(":is(Button)");
 
             Assert.Equal(
-                new[] { new SelectorGrammar.IsSyntax { TypeName = "Button", Xmlns = null } },
+                new[] { new SelectorGrammar.IsSyntax { TypeName = "Button", Xmlns = "" } },
                 result);
         }