Fix Scanner.ReadQuotedString

src/Parlot/Scanner.cs

@@ -373,6 +373,7 @@ public bool ReadText(ReadOnlySpan<char> text, StringComparison comparisonType, o
         /// <summary>
         /// Reads the specific expected chars.
         /// </summary>
+        [Obsolete("Prefer bool ReadAnyOf(ReadOnlySpan<char>, out ReadOnlySpan<char>)")]
         public bool ReadAnyOf(ReadOnlySpan<char> chars, StringComparison comparisonType, out ReadOnlySpan<char> result)
         {
             var current = Cursor.Buffer.AsSpan(Cursor.Offset, 1);
@@ -392,6 +393,42 @@ public bool ReadAnyOf(ReadOnlySpan<char> chars, StringComparison comparisonType,
             return true;
         }
 
+        /// <summary>
+        /// Reads the specific expected chars.
+        /// </summary>
+        public bool ReadAnyOf(ReadOnlySpan<char> chars, out ReadOnlySpan<char> result)
+        {
+            var start = Cursor.Offset;
+
+            while (true)
+            {
+                var current = Cursor.Current;
+                var index = chars.IndexOf(current);
+
+                if (index == -1)
+                {
+                    if (Cursor.Offset == start)
+                    {
+                        result = [];
+                        return false;
+                    }
+
+                    var length = Cursor.Offset - start;
+
+                    result = Cursor.Buffer.AsSpan(start, length);
+                    return true;
+                }
+
+                if (Cursor.Eof)
+                {
+                    result = [];
+                    return false;
+                }
+
+                Cursor.Advance(1);
+            }
+        }
+
 #if NET8_0_OR_GREATER
         /// <summary>
         /// Reads the specific expected chars.
@@ -631,7 +668,7 @@ private bool ReadQuotedString(char quoteChar, out ReadOnlySpan<char> result)
                     }
                 }
 
-                nextEscape = Cursor.Buffer.AsSpan(Cursor.Offset).IndexOfAny('\\', startChar);
+                nextEscape = Cursor.Span.IndexOfAny('\\', startChar);
 
                 if (Cursor.Match(startChar))
                 {
@@ -647,7 +684,7 @@ private bool ReadQuotedString(char quoteChar, out ReadOnlySpan<char> result)
                 }
             }
 
-            result = Buffer.AsSpan(start.Offset, Cursor.Offset);
+            result = Buffer.AsSpan(start.Offset, Cursor.Offset - start.Offset);
 
             return true;
         }

test/Parlot.Tests/ScannerTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Buffers;
 using Xunit;
 
 namespace Parlot.Tests
@@ -55,6 +56,47 @@ public void ShouldNotReadStringWithInvalidEscapes(string text)
             Assert.False(s.ReadQuotedString());
         }
 
+        [Fact]
+        public void ShouldReadQuotedStringPartial()
+        {
+            var s = new Scanner("[h a='\\\"']");
+            Assert.True(s.ReadText("[h a="));
+            Assert.True(s.ReadSingleQuotedString(out var result));
+            Assert.Equal("'\\\"'", result);
+        }
+
+        [Theory]
+        [InlineData("hello world", "helo", "hello")]
+        [InlineData("hello world", "helo wrd", "hello world")]
+        [InlineData("hello world", "h", "h")]
+        public void ShouldReadAnyOf(string source, string pattern, string expected)
+        {
+            var s = new Scanner(source);
+            Assert.True(s.ReadAnyOf(pattern, out var result));
+            Assert.Equal(expected, result);
+
+#if NET8_0_OR_GREATER
+            s = new Scanner(source);
+            Assert.True(s.ReadAnyOf(SearchValues.Create(pattern), out result));
+            Assert.Equal(expected, result);
+#endif
+        }
+
+        [Theory]
+        [InlineData("hello world", "wrd")]
+        [InlineData("", "helo wrd")]
+        [InlineData("hello world", "")]
+        public void ShouldNotReadAnyOf(string source, string pattern)
+        {
+            var s = new Scanner(source);
+            Assert.False(s.ReadAnyOf(pattern, out var result));
+
+#if NET8_0_OR_GREATER
+            s = new Scanner(source);
+            Assert.False(s.ReadAnyOf(SearchValues.Create(pattern), out result));
+#endif
+        }
+
         [Fact]
         public void SkipWhitespaceShouldSkipWhitespace()
         {