Initial commit

`Tokenizer` can _just barely_ parse a basic, well-formed move list.

Initially, I wanted to provide the movetext as a `Stream` rather than a
string, the idea being that it could be processed as it was being read
from a file without having to read the entire file into memory first. I
had difficulties with the stream being unreadable in
`Tokenizer.ParseMoves()`, so I switched to a string in order to get the
actual parsing logic down first.

Because of the `yield return` strategy, the debug console output
includes all of the expected halfmoves multiple times in various orders.
After running a test, generally the full, in-order list seems to exist
at the bottom of the output.

13 files changed, 760 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3524b8a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,363 @@
+## Ignore Visual Studio temporary files, build results, and
+## files generated by popular Visual Studio add-ons.
+##
+## Get latest from https://github.com/github/gitignore/blob/master/VisualStudio.gitignore
+
+# User-specific files
+*.rsuser
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
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+# User-specific files (MonoDevelop/Xamarin Studio)
+*.userprefs
+
+# Mono auto generated files
+mono_crash.*
+
+# Build results
+[Dd]ebug/
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+[Rr]eleases/
+x64/
+x86/
+[Ww][Ii][Nn]32/
+[Aa][Rr][Mm]/
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+bld/
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+[Ll]ogs/
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+# Visual Studio 2015/2017 cache/options directory
+.vs/
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+# Visual Studio 2017 auto generated files
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+# MSTest test Results
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+# Build Results of an ATL Project
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+# Benchmark Results
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+# .NET Core
+project.lock.json
+project.fragment.lock.json
+artifacts/
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+# ASP.NET Scaffolding
+ScaffoldingReadMe.txt
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+# StyleCop
+StyleCopReport.xml
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+# Files built by Visual Studio
+*_i.c
+*_p.c
+*_h.h
+*.ilk
+*.meta
+*.obj
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+*.pch
+*.pdb
+*.ipdb
+*.pgc
+*.pgd
+*.rsp
+*.sbr
+*.tlb
+*.tli
+*.tlh
+*.tmp
+*.tmp_proj
+*_wpftmp.csproj
+*.log
+*.vspscc
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+.builds
+*.pidb
+*.svclog
+*.scc
+
+# Chutzpah Test files
+_Chutzpah*
+
+# Visual C++ cache files
+ipch/
+*.aps
+*.ncb
+*.opendb
+*.opensdf
+*.sdf
+*.cachefile
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+
+# Visual Studio profiler
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+# Visual Studio Trace Files
+*.e2e
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+# TFS 2012 Local Workspace
+$tf/
+
+# Guidance Automation Toolkit
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+# ReSharper is a .NET coding add-in
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+*.[Rr]e[Ss]harper
+*.DotSettings.user
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+# TeamCity is a build add-in
+_TeamCity*
+
+# DotCover is a Code Coverage Tool
+*.dotCover
+
+# AxoCover is a Code Coverage Tool
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+# Coverlet is a free, cross platform Code Coverage Tool
+coverage*.json
+coverage*.xml
+coverage*.info
+
+# Visual Studio code coverage results
+*.coverage
+*.coveragexml
+
+# NCrunch
+_NCrunch_*
+.*crunch*.local.xml
+nCrunchTemp_*
+
+# MightyMoose
+*.mm.*
+AutoTest.Net/
+
+# Web workbench (sass)
+.sass-cache/
+
+# Installshield output folder
+[Ee]xpress/
+
+# DocProject is a documentation generator add-in
+DocProject/buildhelp/
+DocProject/Help/*.HxT
+DocProject/Help/*.HxC
+DocProject/Help/*.hhc
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+DocProject/Help/*.hhp
+DocProject/Help/Html2
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+
+# Click-Once directory
+publish/
+
+# Publish Web Output
+*.[Pp]ublish.xml
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+# Note: Comment the next line if you want to checkin your web deploy settings,
+# but database connection strings (with potential passwords) will be unencrypted
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+*.publishproj
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+# Microsoft Azure Web App publish settings. Comment the next line if you want to
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+# NuGet Packages
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+*.snupkg
+# The packages folder can be ignored because of Package Restore
+**/[Pp]ackages/*
+# except build/, which is used as an MSBuild target.
+!**/[Pp]ackages/build/
+# Uncomment if necessary however generally it will be regenerated when needed
+#!**/[Pp]ackages/repositories.config
+# NuGet v3's project.json files produces more ignorable files
+*.nuget.props
+*.nuget.targets
+
+# Microsoft Azure Build Output
+csx/
+*.build.csdef
+
+# Microsoft Azure Emulator
+ecf/
+rcf/
+
+# Windows Store app package directories and files
+AppPackages/
+BundleArtifacts/
+Package.StoreAssociation.xml
+_pkginfo.txt
+*.appx
+*.appxbundle
+*.appxupload
+
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!?*.[Cc]ache/
+
+# Others
+ClientBin/
+~$*
+*~
+*.dbmdl
+*.dbproj.schemaview
+*.jfm
+*.pfx
+*.publishsettings
+orleans.codegen.cs
+
+# Including strong name files can present a security risk
+# (https://github.com/github/gitignore/pull/2483#issue-259490424)
+#*.snk
+
+# Since there are multiple workflows, uncomment next line to ignore bower_components
+# (https://github.com/github/gitignore/pull/1529#issuecomment-104372622)
+#bower_components/
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+# RIA/Silverlight projects
+Generated_Code/
+
+# Backup & report files from converting an old project file
+# to a newer Visual Studio version. Backup files are not needed,
+# because we have git ;-)
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+Backup*/
+UpgradeLog*.XML
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+# Business Intelligence projects
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+*.rptproj.rsuser
+*- [Bb]ackup.rdl
+*- [Bb]ackup ([0-9]).rdl
+*- [Bb]ackup ([0-9][0-9]).rdl
+
+# Microsoft Fakes
+FakesAssemblies/
+
+# GhostDoc plugin setting file
+*.GhostDoc.xml
+
+# Node.js Tools for Visual Studio
+.ntvs_analysis.dat
+node_modules/
+
+# Visual Studio 6 build log
+*.plg
+
+# Visual Studio 6 workspace options file
+*.opt
+
+# Visual Studio 6 auto-generated workspace file (contains which files were open etc.)
+*.vbw
+
+# Visual Studio LightSwitch build output
+**/*.HTMLClient/GeneratedArtifacts
+**/*.DesktopClient/GeneratedArtifacts
+**/*.DesktopClient/ModelManifest.xml
+**/*.Server/GeneratedArtifacts
+**/*.Server/ModelManifest.xml
+_Pvt_Extensions
+
+# Paket dependency manager
+.paket/paket.exe
+paket-files/
+
+# FAKE - F# Make
+.fake/
+
+# CodeRush personal settings
+.cr/personal
+
+# Python Tools for Visual Studio (PTVS)
+__pycache__/
+*.pyc
+
+# Cake - Uncomment if you are using it
+# tools/**
+# !tools/packages.config
+
+# Tabs Studio
+*.tss
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+# Telerik's JustMock configuration file
+*.jmconfig
+
+# BizTalk build output
+*.btp.cs
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+# OpenCover UI analysis results
+OpenCover/
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+# Azure Stream Analytics local run output
+ASALocalRun/
+
+# MSBuild Binary and Structured Log
+*.binlog
+
+# NVidia Nsight GPU debugger configuration file
+*.nvuser
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+.mfractor/
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+.localhistory/
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+# BeatPulse healthcheck temp database
+healthchecksdb
+
+# Backup folder for Package Reference Convert tool in Visual Studio 2017
+MigrationBackup/
+
+# Ionide (cross platform F# VS Code tools) working folder
+.ionide/
+
+# Fody - auto-generated XML schema
+FodyWeavers.xsd
+
diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..6908dfa
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,27 @@
+{
+   // Use IntelliSense to find out which attributes exist for C# debugging
+   // Use hover for the description of the existing attributes
+   // For further information visit https://github.com/OmniSharp/omnisharp-vscode/blob/master/debugger-launchjson.md
+   "version": "0.2.0",
+   "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            // If you have changed target frameworks, make sure to update the program path.
+            "program": "${workspaceFolder}/DotnetPgn.Test/bin/Debug/net5.0/DotnetPgn.Test.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}/DotnetPgn.Test",
+            // For more information about the 'console' field, see https://aka.ms/VSCode-CS-LaunchJson-Console
+            "console": "internalConsole",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach",
+            "processId": "${command:pickProcess}"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
new file mode 100644
index 0000000..60924e5
--- /dev/null
+++ b/.vscode/tasks.json
@@ -0,0 +1,42 @@
+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "build",
+                "${workspaceFolder}/DotnetPgn.Test/DotnetPgn.Test.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "publish",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "publish",
+                "${workspaceFolder}/DotnetPgn.Test/DotnetPgn.Test.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "watch",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "watch",
+                "run",
+                "${workspaceFolder}/DotnetPgn.Test/DotnetPgn.Test.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/DotnetPgn.Test/DotnetPgn.Test.csproj b/DotnetPgn.Test/DotnetPgn.Test.csproj
new file mode 100644
index 0000000..0e90980
--- /dev/null
+++ b/DotnetPgn.Test/DotnetPgn.Test.csproj
@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">

+

+  <PropertyGroup>

+    <TargetFramework>net5.0</TargetFramework>

+

+    <IsPackable>false</IsPackable>

+  </PropertyGroup>

+

+  <ItemGroup>

+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />

+    <PackageReference Include="xunit" Version="2.4.1" />

+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">

+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

+      <PrivateAssets>all</PrivateAssets>

+    </PackageReference>

+    <PackageReference Include="coverlet.collector" Version="1.3.0">

+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

+      <PrivateAssets>all</PrivateAssets>

+    </PackageReference>

+  </ItemGroup>

+

+  <ItemGroup>
+    <ProjectReference Include="..\DotnetPgn\DotnetPgn.csproj" />
+  </ItemGroup>

+

+</Project>

diff --git a/DotnetPgn.Test/PieceParserTest.cs b/DotnetPgn.Test/PieceParserTest.cs
new file mode 100644
index 0000000..e8aacf6
--- /dev/null
+++ b/DotnetPgn.Test/PieceParserTest.cs
@@ -0,0 +1,17 @@
+using System.Linq;
+using DotnetPgn.Models;
+using Xunit;
+
+namespace DotnetPgn.Test
+{
+    public class PieceParserTest
+    {
+        [Theory]
+        [InlineData("K", Piece.King)]
+        [InlineData("Q", Piece.Queen)]
+        public void ParsePieceTest(string input, Piece expectedOutput)
+        {
+            Assert.Equal(expectedOutput, PieceParser.ParsePiece(input));
+        }
+    }
+}
diff --git a/DotnetPgn.Test/TokenizerTest.cs b/DotnetPgn.Test/TokenizerTest.cs
new file mode 100644
index 0000000..cb9940b
--- /dev/null
+++ b/DotnetPgn.Test/TokenizerTest.cs
@@ -0,0 +1,82 @@
+using System;

+using System.Collections.Generic;

+using System.IO;

+using System.Linq;

+using DotnetPgn.Models;

+using Xunit;

+

+namespace DotnetPgn.Test

+{

+    public class TokenizerTest

+    {

+        [Fact]

+        public void ParseMovesTest()

+        {

+            var moveText = "1. e4 e5 2. Nf3 Qe7 3. d3 h5\n";

+            IEnumerable<HalfMove> halfmoves;

+

+            #region Expected

+            List<HalfMove> expectedHalfMoves = new()

+            {

+                new HalfMove

+                {

+                    MoveNumber = 1,

+                    Player = Player.White,

+                    Piece = Piece.Pawn,

+                    TargetSquare = new Square('e', 4),

+                },

+                new HalfMove

+                {

+                    MoveNumber = 1,

+                    Player = Player.Black,

+                    Piece = Piece.Pawn,

+                    TargetSquare = new Square('e', 5),

+                },

+                new HalfMove

+                {

+                    MoveNumber = 2,

+                    Player = Player.White,

+                    Piece = Piece.Knight,

+                    TargetSquare = new Square('f', 3),

+                },

+                new HalfMove

+                {

+                    MoveNumber = 2,

+                    Player = Player.Black,

+                    Piece = Piece.Queen,

+                    TargetSquare = new Square('e', 7),

+                },

+                new HalfMove

+                {

+                    MoveNumber = 3,

+                    Player = Player.White,

+                    Piece = Piece.Pawn,

+                    TargetSquare = new Square('d', 3),

+                },

+                new HalfMove

+                {

+                    MoveNumber = 3,

+                    Player = Player.Black,

+                    Piece = Piece.Pawn,

+                    TargetSquare = new Square('h', 5),

+                },

+            };

+            #endregion

+

+            halfmoves = Tokenizer.ParseMoves(moveText);

+

+            for (int i = 0; i < expectedHalfMoves.Count(); i++)

+            {

+                HalfMove generated = halfmoves.ElementAtOrDefault(i);

+                HalfMove expected = expectedHalfMoves.ElementAtOrDefault(i);

+

+                Assert.NotNull(generated);

+                Assert.NotNull(expected);

+                Assert.Equal(expected.MoveNumber, generated.MoveNumber);

+                Assert.Equal(expected.Player, generated.Player);

+                Assert.Equal(expected.Piece, generated.Piece);

+                Assert.Equal(expected.TargetSquare, generated.TargetSquare);

+            }

+        }

+    }

+}

diff --git a/DotnetPgn.sln b/DotnetPgn.sln
new file mode 100644
index 0000000..53fe2ce
--- /dev/null
+++ b/DotnetPgn.sln
@@ -0,0 +1,48 @@
+

+Microsoft Visual Studio Solution File, Format Version 12.00

+# Visual Studio 15

+VisualStudioVersion = 15.0.26124.0

+MinimumVisualStudioVersion = 15.0.26124.0

+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DotnetPgn", "DotnetPgn\DotnetPgn.csproj", "{94582A40-22EF-4884-A2CE-6F08E08776E8}"

+EndProject

+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DotnetPgn.Test", "DotnetPgn.Test\DotnetPgn.Test.csproj", "{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}"

+EndProject

+Global

+	GlobalSection(SolutionConfigurationPlatforms) = preSolution

+		Debug|Any CPU = Debug|Any CPU

+		Debug|x64 = Debug|x64

+		Debug|x86 = Debug|x86

+		Release|Any CPU = Release|Any CPU

+		Release|x64 = Release|x64

+		Release|x86 = Release|x86

+	EndGlobalSection

+	GlobalSection(SolutionProperties) = preSolution

+		HideSolutionNode = FALSE

+	EndGlobalSection

+	GlobalSection(ProjectConfigurationPlatforms) = postSolution

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Debug|Any CPU.Build.0 = Debug|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Debug|x64.ActiveCfg = Debug|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Debug|x64.Build.0 = Debug|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Debug|x86.ActiveCfg = Debug|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Debug|x86.Build.0 = Debug|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Release|Any CPU.ActiveCfg = Release|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Release|Any CPU.Build.0 = Release|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Release|x64.ActiveCfg = Release|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Release|x64.Build.0 = Release|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Release|x86.ActiveCfg = Release|Any CPU

+		{94582A40-22EF-4884-A2CE-6F08E08776E8}.Release|x86.Build.0 = Release|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Debug|Any CPU.Build.0 = Debug|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Debug|x64.ActiveCfg = Debug|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Debug|x64.Build.0 = Debug|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Debug|x86.ActiveCfg = Debug|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Debug|x86.Build.0 = Debug|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Release|Any CPU.ActiveCfg = Release|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Release|Any CPU.Build.0 = Release|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Release|x64.ActiveCfg = Release|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Release|x64.Build.0 = Release|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Release|x86.ActiveCfg = Release|Any CPU

+		{F1ED5B4D-EC5B-4720-A877-B2CE895BD3B7}.Release|x86.Build.0 = Release|Any CPU

+	EndGlobalSection

+EndGlobal

diff --git a/DotnetPgn/DotnetPgn.csproj b/DotnetPgn/DotnetPgn.csproj
new file mode 100644
index 0000000..563e6f9
--- /dev/null
+++ b/DotnetPgn/DotnetPgn.csproj
@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">

+

+  <PropertyGroup>

+    <TargetFramework>net5.0</TargetFramework>

+  </PropertyGroup>

+

+</Project>

diff --git a/DotnetPgn/Models/Enums.cs b/DotnetPgn/Models/Enums.cs
new file mode 100644
index 0000000..893f2fa
--- /dev/null
+++ b/DotnetPgn/Models/Enums.cs
@@ -0,0 +1,18 @@
+namespace DotnetPgn.Models
+{
+    public enum Piece
+    {
+        Pawn,
+        Knight,
+        Bishop,
+        Rook,
+        Queen,
+        King,
+    }
+
+    public enum Player
+    {
+        White,
+        Black,
+    }
+}
\ No newline at end of file
diff --git a/DotnetPgn/Models/HalfMove.cs b/DotnetPgn/Models/HalfMove.cs
new file mode 100644
index 0000000..b94d77d
--- /dev/null
+++ b/DotnetPgn/Models/HalfMove.cs
@@ -0,0 +1,11 @@
+namespace DotnetPgn.Models
+{
+    public record HalfMove
+    {
+        public int MoveNumber {get; init;}
+        public Player Player { get; init; }
+        public Piece Piece { get; init; }
+        public Square SourceSquare { get; init; }
+        public Square TargetSquare { get; init; }
+    }
+}
\ No newline at end of file
diff --git a/DotnetPgn/Models/Square.cs b/DotnetPgn/Models/Square.cs
new file mode 100644
index 0000000..a3910d3
--- /dev/null
+++ b/DotnetPgn/Models/Square.cs
@@ -0,0 +1,22 @@
+using System;
+
+namespace DotnetPgn.Models
+{
+    public record Square
+    {
+        public char Rank { get; }
+        public int File { get; }
+
+        public Square(char rank, int file)
+        {
+            if (rank < 'a' || rank > 'h')
+                throw new ArgumentException($"Invalid rank '{rank}'.");
+
+            if (file < 1 || file > 8)
+                throw new ArgumentException($"Invalid file '{file}'.");
+
+            Rank = rank;
+            File = file;
+        }
+    }
+}
\ No newline at end of file
diff --git a/DotnetPgn/PieceParser.cs b/DotnetPgn/PieceParser.cs
new file mode 100644
index 0000000..5ea9402
--- /dev/null
+++ b/DotnetPgn/PieceParser.cs
@@ -0,0 +1,22 @@
+using System;

+using DotnetPgn.Models;

+

+namespace DotnetPgn

+{

+    public static class PieceParser

+    {

+        public static Piece ParsePiece(string sanPiece)

+        {

+            return sanPiece switch

+            {

+                "P" or "p" or "" => Piece.Pawn,

+                "N" or "n" => Piece.Knight,

+                "B" or "b" => Piece.Bishop,

+                "R" or "r" => Piece.Rook,

+                "Q" or "q" => Piece.Queen,

+                "K" or "k" => Piece.King,

+                _ => throw new ArgumentException($"'{sanPiece} is not a valid piece.'"),

+            };

+        }

+    }

+}

diff --git a/DotnetPgn/Tokenizer.cs b/DotnetPgn/Tokenizer.cs
new file mode 100644
index 0000000..9f779cb
--- /dev/null
+++ b/DotnetPgn/Tokenizer.cs
@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using System.Text.RegularExpressions;
+using DotnetPgn.Models;
+
+namespace DotnetPgn
+{
+    public static class Tokenizer
+    {
+        private static readonly Regex s_halfMoveRegex =
+            new(@"([KQRBNP]?)([a-h]?[1-8]?)(x?)([a-h][1-8])([+#]?)");
+
+        public static IEnumerable<HalfMove> ParseMoves(string moveText)
+        {
+            StringBuilder currToken = new();
+            char[] moveTextChars = moveText.ToCharArray();
+            int moveNumber = 1;
+            Player currPlayer = Player.White;
+
+            for (int i = 0; i < moveTextChars.Length; i++)
+            {
+                char nextChar = moveTextChars[i];
+
+                if (nextChar is ' ' or '\t' or '\n' or '\r')
+                {
+                    // We should have either a move number or a complete halfmove.
+                    string token = currToken.ToString();
+                    currToken.Clear();
+                    Match match = s_halfMoveRegex.Match(token);
+
+                    if (!match.Success)
+                    {
+                        Console.WriteLine($"Unrecognized token: `{token}`");
+                        Console.WriteLine();
+                        continue;
+                    }
+
+                    Console.WriteLine($"Recognized token: {token}");
+                    Console.WriteLine($"Matching groups: ({match.Groups[1].Value})" +
+                        $"({match.Groups[2].Value})({match.Groups[3].Value})({match.Groups[4].Value})" +
+                        $"({match.Groups[5].Value})");
+
+                    var move = new HalfMove
+                    {
+                        MoveNumber = moveNumber,
+                        Player = currPlayer,
+                        Piece = PieceParser.ParsePiece(match.Groups[1].Value),
+                        TargetSquare = new Square(match.Groups[4].Value[0], Convert.ToInt32(Char.GetNumericValue(match.Groups[4].Value[1]))),
+                    };
+
+                    Console.WriteLine($"Halfmove: {move.MoveNumber}. {move.Player} {move.Piece} from {move.SourceSquare} to {move.TargetSquare}");
+                    Console.WriteLine();
+
+                    if (currPlayer == Player.White)
+                    {
+                        currPlayer = Player.Black;
+                    }
+                    else
+                    {
+                        currPlayer = Player.White;
+                        moveNumber++;
+                    }
+
+                    yield return move;
+                }
+                else
+                {
+                    currToken.Append(nextChar);
+                }
+            }
+        }
+    }
+}
\ No newline at end of file