Use SearchValues for identitifers

src/Parlot/Character.Mask.cs

@@ -0,0 +1,37 @@
+using System;
+#if !NET8_0_OR_GREATER
+using System.Runtime.CompilerServices;
+#endif
+
+namespace Parlot;
+
+[Flags]
+internal enum CharacterMask : byte
+{
+    None = 0,
+    IdentifierStart = 1,
+    IdentifierPart = 2,
+    WhiteSpace = 4,
+    WhiteSpaceOrNewLine = 8
+}
+
+#if !NET8_0_OR_GREATER
+public static partial class Character
+{
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsDecimalDigit(char ch) => IsInRange(ch, '0', '9');
+
+    public static bool IsIdentifierStart(char ch)
+    {
+        return (_characterData[ch] & (byte)CharacterMask.IdentifierStart) != 0;
+    }
+
+    public static bool IsIdentifierPart(char ch)
+    {
+        return (_characterData[ch] & (byte)CharacterMask.IdentifierPart) != 0;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsHexDigit(char ch) => HexConverter.IsHexChar(ch);
+}
+#endif

src/Parlot/Character.SearchValues.cs

@@ -0,0 +1,35 @@
+#if NET8_0_OR_GREATER
+using System.Buffers;
+using System.Runtime.CompilerServices;
+
+namespace Parlot;
+
+public static partial class Character
+{
+    internal const string DecimalDigits = "0123456789";
+    internal const string Alpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    internal const string AlphaNumeric = Alpha + DecimalDigits;
+    internal const string DefaultIdentifierStart = "$_" + Alpha;
+    internal const string DefaultIdentifierPart = "$_" + AlphaNumeric;
+    internal const string HexDigits = "0123456789abcdefABCDEF";
+    internal const string NewLines = "\n\r\v";
+
+    internal static readonly SearchValues<char> _decimalDigits = SearchValues.Create(DecimalDigits);
+    internal static readonly SearchValues<char> _hexDigits = SearchValues.Create(HexDigits);
+    internal static readonly SearchValues<char> _identifierStart = SearchValues.Create(DefaultIdentifierStart);
+    internal static readonly SearchValues<char> _identifierPart = SearchValues.Create(DefaultIdentifierPart);
+    internal static readonly SearchValues<char> _newLines = SearchValues.Create(NewLines);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsDecimalDigit(char ch) => _decimalDigits.Contains(ch);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsIdentifierStart(char ch) => _identifierStart.Contains(ch);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsIdentifierPart(char ch) => _identifierPart.Contains(ch);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsHexDigit(char ch) => _hexDigits.Contains(ch);
+}
+#endif

src/Parlot/Character.cs

@@ -1,51 +1,15 @@
-using System;
+using System;
 using System.Buffers;
 using System.Runtime.CompilerServices;
 
 namespace Parlot;
 
-[Flags]
-internal enum CharacterMask : byte
-{
-    None = 0,
-    IdentifierStart = 1,
-    IdentifierPart = 2,
-    WhiteSpace = 4,
-    WhiteSpaceOrNewLine = 8
-}
-
 public static partial class Character
 {
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static bool IsDecimalDigit(char ch) => IsInRange(ch, '0', '9');
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static bool IsInRange(char ch, char min, char max) => ch - (uint)min <= max - (uint)min;
 
-    public static bool IsHexDigit(char ch) => HexConverter.IsHexChar(ch);
-
-    public static bool IsIdentifierStart(char ch)
-    {
-        return (_characterData[ch] & (byte)CharacterMask.IdentifierStart) != 0;
-    }
-
-    public static bool IsIdentifierPart(char ch)
-    {
-        return (_characterData[ch] & (byte)CharacterMask.IdentifierPart) != 0;
-    }
-
-    public static bool IsWhiteSpace(char ch)
-    {
-        return (_characterData[ch] & (byte)CharacterMask.WhiteSpace) != 0;
-    }
-
-    public static bool IsWhiteSpaceOrNewLine(char ch)
-    {
-        return (_characterData[ch] & (byte)CharacterMask.WhiteSpaceOrNewLine) != 0;
-    }
-
-    public static bool IsNewLine(char ch) => ch is '\n' or '\r' or '\v';
-
     public static char ScanHexEscape(string text, int index, out int length)
     {
         return ScanHexEscape(text.AsSpan(index), out length);
@@ -156,4 +120,16 @@ public static TextSpan DecodeString(TextSpan span)
     }
 
     private static int HexValue(char ch) => HexConverter.FromChar(ch);
+
+    public static bool IsWhiteSpace(char ch)
+    {
+        return (_characterData[ch] & (byte)CharacterMask.WhiteSpace) != 0;
+    }
+
+    public static bool IsWhiteSpaceOrNewLine(char ch)
+    {
+        return (_characterData[ch] & (byte)CharacterMask.WhiteSpaceOrNewLine) != 0;
+    }
+
+    public static bool IsNewLine(char ch) => ch is '\n' or '\r' or '\v';
 }

src/Parlot/Cursor.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Runtime.CompilerServices;
 
 namespace Parlot;
@@ -67,7 +67,7 @@ public void Advance()
     }
 
     /// <summary>
-    /// Advances the cursor.
+    /// Advances the cursor and tracks its current location (line and column).
     /// </summary>
     public void Advance(int count)
     {
@@ -115,7 +115,7 @@ public void Advance(int count)
     }
 
     /// <summary>
-    /// Advances the cursor with the knowledge there are no new lines.
+    /// Advances the cursor and tracks its current location (line and column) with the knowledge there are no new lines (\r or \n).
     /// </summary>
     public void AdvanceNoNewLines(int offset)
     {

src/Parlot/Fluent/IdentifierLiteral.cs

@@ -0,0 +1,46 @@
+#if NET8_0_OR_GREATER
+using System;
+using System.Buffers;
+
+namespace Parlot.Fluent;
+
+internal sealed class IdentifierLiteral : Parser<TextSpan>
+{
+    private readonly SearchValues<char> _startSearchValues;
+    private readonly SearchValues<char> _partSearchValues;
+
+    public IdentifierLiteral(SearchValues<char> startSearchValues, SearchValues<char> partSearchValues)
+    {
+        _startSearchValues = startSearchValues;
+        _partSearchValues = partSearchValues;
+
+        // Since we assume these can't container new lines, we can check this here.
+        if (partSearchValues.Contains('\n') || startSearchValues.Contains('\r'))
+        {
+            throw new InvalidOperationException("Identifiers cannot contain new lines.");
+        }
+    }
+
+    public override bool Parse(ParseContext context, ref ParseResult<TextSpan> result)
+    {
+        context.EnterParser(this);
+
+        var span = context.Scanner.Cursor.Span;
+
+        if (span.Length == 0 || !_startSearchValues.Contains(span[0]))
+        {
+            return false;
+        }
+
+        var index = span.Slice(1).IndexOfAnyExcept(_partSearchValues);
+
+        // If index == -1 the whole input is a match
+        var size = index == -1 ? span.Length : index + 1;
+
+        var start = context.Scanner.Cursor.Position.Offset;
+        context.Scanner.Cursor.AdvanceNoNewLines(size);
+        result.Set(start, start + size, new TextSpan(context.Scanner.Buffer, start, size));
+        return true;
+    }
+}
+#endif

src/Parlot/Fluent/NumberLiteral.cs

@@ -98,10 +98,8 @@ public CompilationResult Compile(CompilationContext context)
     {
         var result = context.CreateCompilationResult<T>();
 
-        // var start = context.Scanner.Cursor.Offset;
         // var reset = context.Scanner.Cursor.Position;
 
-        var start = context.DeclareOffsetVariable(result);
         var reset = context.DeclarePositionVariable(result);
 
         var numberStyles = result.DeclareVariable<NumberStyles>($"numberStyles{context.NextNumber}", Expression.Constant(_numberStyles));