done

RecordParser.Benchmark/FixedLengthReaderBenchmark.cs

@@ -4,7 +4,7 @@
 using FlatFiles;
 using FlatFiles.TypeMapping;
 using RecordParser.Builders.Reader;
-using RecordParser.Extensions.FileReader;
+using RecordParser.Extensions;
 using System;
 using System.Globalization;
 using System.IO;

RecordParser.Benchmark/VariableLengthReaderBenchmark.cs

@@ -7,7 +7,7 @@
 using FlatFiles;
 using FlatFiles.TypeMapping;
 using RecordParser.Builders.Reader;
-using RecordParser.Extensions.FileReader;
+using RecordParser.Extensions;
 using System;
 using System.Globalization;
 using System.IO;

RecordParser.Test/SpanExtensions.cs

@@ -25,6 +25,9 @@ public static string ToLower(this ReadOnlySpan<char> value)
         public static StringAssertions Should(this Span<char> value)
             => value.ToString().Should();
 
+        // FluentAssertions does not support ReadOnlySpan yet
+        public static StringAssertions Should(this ReadOnlySpan<char> value)
+            => value.ToString().Should();
 
         public static readonly FuncSpanTIntBool ToUpperInvariant = (Span<char> span, ReadOnlySpan<char> text) =>
             (text.ToUpperInvariant(span) is var written && written == text.Length, Math.Max(0, written));

RecordParser.Test/TextFindHelperTest.cs

@@ -0,0 +1,71 @@
+using FluentAssertions;
+using RecordParser.Engines.Reader;
+using System;
+using Xunit;
+
+namespace RecordParser.Test
+{
+    public class TextFindHelperTest : TestSetup
+    {
+        [Fact]
+        public void Given_column_mapped_more_than_once_should_works()
+        {
+            var id = Guid.NewGuid().ToString();
+            var date = "2020.05.23";
+            var color = "LightBlue";
+
+            var record = $"{id};{date};{color}";
+            var finder = new TextFindHelper(record, ";", ('"', "\""));
+            ;
+            // Act
+
+            var a = finder.GetValue(0);
+            var b = finder.GetValue(0);
+            var c = finder.GetValue(1);
+            var d = finder.GetValue(2);
+            var e = finder.GetValue(2);
+
+            // Assert
+
+            a.Should().Be(id);
+            b.Should().Be(id);
+            c.Should().Be(date);
+            d.Should().Be(color);
+            e.Should().Be(color);
+        }
+
+        [Fact]
+        public void Given_access_to_past_column_should_throw()
+        {
+            var id = Guid.NewGuid().ToString();
+            var date = "2020.05.23";
+            var color = "LightBlue";
+
+            var record = $"{id};{date};{color}";
+
+            string a, b, c, d;
+            a = b = c = d = null;
+
+            // Act
+
+            var action = () =>
+            {
+                var finder = new TextFindHelper(record, ";", ('"', "\""));
+
+                a = finder.GetValue(0).ToString();
+                b = finder.GetValue(1).ToString();
+                c = finder.GetValue(2).ToString();
+                d = finder.GetValue(1).ToString();
+            };
+
+            // Assert
+
+            action.Should().Throw<Exception>().WithMessage("can only be forward");
+
+            a.Should().Be(id);
+            b.Should().Be(date);
+            c.Should().Be(color);
+            d.Should().BeNull();
+        }
+    }
+}

RecordParser/RecordParser.csproj

@@ -30,6 +30,12 @@
       <None Include="..\LICENSE.md" Pack="true" PackagePath="LICENSE.md"/>
   </ItemGroup>
 
+    <ItemGroup>
+        <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute">
+            <_Parameter1>RecordParser.Test</_Parameter1>
+        </AssemblyAttribute>
+    </ItemGroup>
+
   <PropertyGroup Condition="
 		( '$(Configuration)' == 'Debug' OR '$(Configuration)' == 'Release') AND
 		( '$(TargetFramework)' == 'net5.0' OR '$(TargetFramework)' == 'net6.0' OR '$(TargetFramework)' == 'net7.0') AND