Add bank account number formatting

src/Redskap/BankAccountNumber.Formatting.cs

@@ -0,0 +1,36 @@
+using System;
+using static Redskap.FormattingHelpers;
+
+namespace Redskap;
+
+public readonly partial struct BankAccountNumber
+{
+    /// <inheritdoc />
+    public override string ToString()
+    {
+        const int length = Length + 2;
+
+#if NETSTANDARD
+        var buffer = new char[length];
+
+        Format(this, buffer);
+
+        return new string(buffer);
+#else
+        return string.Create(length, this, (span, number) =>
+        {
+            Format(number, span);
+        });
+#endif
+    }
+
+    private static void Format(BankAccountNumber number, Span<char> buffer)
+    {
+        WriteDigit((uint) number.CheckDigit, buffer, 12);
+        WriteFourDecimalDigits((uint) number.CustomerNumber, buffer, 8);
+        buffer[7] = ' ';
+        WriteTwoDecimalDigits((uint) number.AccountGroup, buffer, 5);
+        buffer[4] = ' ';
+        WriteFourDecimalDigits((uint) number.RegisterNumber, buffer, 0);
+    }
+}

src/Redskap/FormattingHelpers.cs

@@ -9,6 +9,14 @@ internal static class FormattingHelpers
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     internal static char GetChar(uint digit) => (char) ('0' + digit);
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    internal static void WriteDigit(uint value, Span<char> destination, int offset)
+    {
+        Debug.Assert(value <= 9);
+
+        destination[offset] = GetChar(value);
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     internal static void WriteTwoDecimalDigits(uint value, Span<char> destination, int offset)
     {
@@ -36,4 +44,24 @@ public static void WriteThreeDecimalDigits(uint value, Span<char> destination, i
 
         destination[offset] = GetChar(value);
     }
-}
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void WriteFourDecimalDigits(uint value, Span<char> destination, int offset)
+    {
+        Debug.Assert(value <= 9999);
+
+        var temp = value;
+        value /= 10;
+        destination[offset + 3] = GetChar(temp - (value * 10));
+
+        temp = value;
+        value /= 10;
+        destination[offset + 2] = GetChar(temp - (value * 10));
+
+        temp = value;
+        value /= 10;
+        destination[offset + 1] = GetChar(temp - (value * 10));
+
+        destination[offset] = GetChar(value);
+    }
+}

src/Redskap/IdentificationNumber.Formatting.cs

@@ -9,11 +9,11 @@ public readonly partial struct IdentificationNumber
     public override string ToString()
     {
 #if NETSTANDARD
-            var buffer = new char[Length];
+        var buffer = new char[Length];
 
-            Format(this, buffer);
+        Format(this, buffer);
 
-            return new string(buffer);
+        return new string(buffer);
 #else
         return string.Create(Length, this, (span, number) =>
         {
@@ -64,4 +64,4 @@ private static void WriteYear(Span<char> destination, DateTime dateOfBirth)
     {
         WriteTwoDecimalDigits((uint) dateOfBirth.Year % 100, destination, 4);
     }
-}
+}

src/Redskap/Redskap.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
-    
+
     <PackageProjectUrl>https://github.com/khellang/Redskap</PackageProjectUrl>
     <RepositoryUrl>https://github.com/khellang/Redskap</RepositoryUrl>
 
@@ -26,10 +26,10 @@
     <PackageTags>norway;norwegian;fødselsnummer;personnummer;parser;validator</PackageTags>
     <PackageIcon>icon.png</PackageIcon>
     <Authors>Kristian Hellang</Authors>
-    
+
     <PolySharpExcludeGeneratedTypes>System.Range</PolySharpExcludeGeneratedTypes>
   </PropertyGroup>
-  
+
   <ItemGroup>
     <InternalsVisibleTo Include="$(AssemblyName).Tests" />
     <None Include="../../icon.png" Pack="true" PackagePath="/" />
@@ -86,14 +86,17 @@
       <DesignTime>True</DesignTime>
       <DependentUpon>FamilyNames.tt</DependentUpon>
     </Compile>
+    <Compile Update="BankAccountNumber.Formatting.cs">
+      <DependentUpon>BankAccountNumber.Parsing.cs</DependentUpon>
+    </Compile>
     <Compile Update="BankAccountNumber.Parsing.cs">
       <DependentUpon>BankAccountNumber.cs</DependentUpon>
     </Compile>
     <Compile Update="BankAccountNumber.Parsing.netstandard.cs">
       <DependentUpon>BankAccountNumber.Parsing.cs</DependentUpon>
     </Compile>
   </ItemGroup>
-  
+
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="Microsoft.Bcl.HashCode" Version="1.1.1" />
     <PackageReference Include="System.Memory" Version="4.5.5" />

test/Redskap.Tests/BankAccountNumberTests.cs

@@ -19,7 +19,7 @@ public void TryParse_Valid_Returns_True(string path)
             Assert.Equal(testData.AccountGroup, result.AccountGroup);
             Assert.Equal(testData.CustomerNumber, result.CustomerNumber);
             Assert.Equal(testData.CheckDigit, result.CheckDigit);
-            // Assert.Equal(testData.Value, result.ToString());
+            Assert.Equal(testData.Value, result.ToString());
         }
     }
 
@@ -60,9 +60,9 @@ public static IEnumerable<TestData> ReadFrom(string fileName)
             foreach (var line in File.ReadLines(fileName))
             {
                 var registerNumber = int.Parse(line.AsSpan().Slice(0, 4));
-                var accountGroup = int.Parse(line.AsSpan().Slice(4, 2));
-                var customerNumber = int.Parse(line.AsSpan().Slice(6, 4));
-                var checkDigit = int.Parse(line.AsSpan().Slice(10, 1));
+                var accountGroup = int.Parse(line.AsSpan().Slice(5, 2));
+                var customerNumber = int.Parse(line.AsSpan().Slice(8, 4));
+                var checkDigit = int.Parse(line.AsSpan().Slice(12, 1));
 
                 yield return new TestData(line, registerNumber, accountGroup, customerNumber, checkDigit);
             }