migrate from NHunspell to WeCantSpell.Hunspell

Directory.Build.props

@@ -16,7 +16,7 @@
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
     <PackageOutputPath>$(MSBuildThisFileDirectory)/artifacts</PackageOutputPath>
     <SignAssembly>true</SignAssembly>
-    <WarningsAsErrors>NU1605;CS8002</WarningsAsErrors>
+    <WarningsAsErrors>NU1605</WarningsAsErrors>
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)/liblcm.snk</AssemblyOriginatorKeyFile>
     <IncludeSymbols>true</IncludeSymbols>
     <SymbolPackageFormat>snupkg</SymbolPackageFormat>

src/SIL.LCModel.Core/SIL.LCModel.Core.csproj

@@ -22,6 +22,7 @@ SIL.LCModel.Core provides a base library with core functionality.</Description>
     <PackageReference Include="System.Drawing.Common" Version="6.0.0" />
     <PackageReference Include="System.Runtime.InteropServices.RuntimeInformation" Version="4.3.0" />
     <PackageReference Include="vswhere" Version="2.8.4" PrivateAssets="all" />
+    <PackageReference Include="WeCantSpell.Hunspell" Version="5.0.0" />
     <ProjectReference Include="..\CSTools\Tools\Tools.csproj" />
     <ProjectReference Include="..\SIL.LCModel.Build.Tasks\SIL.LCModel.Build.Tasks.csproj" />
     <ProjectReference Include="..\SIL.LCModel.Utils\SIL.LCModel.Utils.csproj" />

src/SIL.LCModel.Core/SpellChecking/SpellEngine.cs

@@ -26,10 +26,12 @@ internal static SpellEngine Create(string affixPath, string dictPath, string exc
 			SpellEngine spellEngine = null;
 			try
 			{
-				if (Platform.IsWindows)
-					spellEngine = CreateSpellEngineWindows(affixPath, dictPath, exceptionPath);
-				else
-					spellEngine = CreateSpellEngineLinux(affixPath, dictPath, exceptionPath);
+				if (SpellingHelper.UseWeCantSpell)
+				{
+					spellEngine = new SpellEngineWeCantSpell(affixPath, dictPath, exceptionPath);
+				} else {
+					spellEngine = Platform.IsWindows ? CreateSpellEngineWindows(affixPath, dictPath, exceptionPath) : CreateSpellEngineLinux(affixPath, dictPath, exceptionPath);
+				}
 
 				spellEngine.Initialize();
 			}
@@ -87,9 +89,20 @@ private void Initialize()
 		/// <inheritdoc />
 		public abstract bool Check(string word);
 
+		private bool _isVernacular;
+		private bool _gotIsVernacular;
+		public bool IsVernacular
+		{
+			get
+			{
+				if (_gotIsVernacular)
+					return _isVernacular;
 
-		/// <inheritdoc />
-		public abstract bool IsVernacular { get; }
+				_isVernacular = Check(SpellingHelper.PrototypeWord);
+				_gotIsVernacular = true;
+				return _isVernacular;
+			}
+		}
 
 		/// <inheritdoc />
 		public abstract ICollection<string> Suggest(string badWord);

src/SIL.LCModel.Core/SpellChecking/SpellEngineLinux.cs

@@ -13,8 +13,6 @@ namespace SIL.LCModel.Core.SpellChecking
 	internal sealed class SpellEngineLinux: SpellEngine
 	{
 		private IntPtr _hunspellHandle;
-		private bool _isVernacular;
-		private bool _gotIsVernacular;
 
 		internal SpellEngineLinux(string affixPath, string dictPath, string exceptionPath)
 			: base(exceptionPath)
@@ -218,20 +216,6 @@ public override ICollection<string> Suggest(string badWord)
 			Hunspell_free_list(_hunspellHandle, ref pointerToAddressStringArray, resultCount);
 			return results;
 		}
-
-		/// <inheritdoc />
-		public override bool IsVernacular
-		{
-			get
-			{
-				if (_gotIsVernacular)
-					return _isVernacular;
-
-				_isVernacular = Check(SpellingHelper.PrototypeWord);
-				_gotIsVernacular = true;
-				return _isVernacular;
-			}
-		}
 	}
 
 	/// <summary>

src/SIL.LCModel.Core/SpellChecking/SpellEngineWeCantSpell.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using WeCantSpell.Hunspell;
+
+namespace SIL.LCModel.Core.SpellChecking
+{
+	internal class SpellEngineWeCantSpell: SpellEngine
+	{
+		private readonly WordList _wordList;
+		private readonly WordList.Builder _customWordsBuilder;
+		private WordList _customWordList;
+		private readonly HashSet<string> _badWords = new HashSet<string>();
+
+		public SpellEngineWeCantSpell(string affixPath, string dictPath, string exceptionPath) : base(exceptionPath)
+		{
+			_wordList = WordList.CreateFromFiles(dictPath, affixPath);
+			_customWordsBuilder = new WordList.Builder(_wordList.Affix);
+			_customWordList = _customWordsBuilder.ToImmutable();
+		}
+
+		public override bool Check(string word)
+		{
+			if (_badWords.Contains(word)) return false;
+			if (_customWordList.Check(word)) return true;
+			return _wordList.Check(word);
+		}
+
+		public override ICollection<string> Suggest(string badWord)
+		{
+			var suggestions = _wordList.Suggest(badWord).Union(_customWordList.Suggest(badWord));
+			return suggestions.Where(suggestion => !_badWords.Contains(suggestion)).ToArray();
+		}
+
+		protected override void SetStatusInternal(string word1, bool isCorrect)
+		{
+			// WeCantSpell does not support modifying the word list, so we have to use 2 and merge them.
+			if (isCorrect)
+			{
+				var detail = IsVernacular
+					? new WordEntryDetail(FlagSet.Empty,
+						MorphSet.Create(new []{SpellingHelper.PrototypeWord}),
+						WordEntryOptions.None)
+					: WordEntryDetail.Default;
+				_customWordsBuilder.Add(word1, detail);
+				_customWordList = _customWordsBuilder.ToImmutable();
+			}
+			else
+			{
+				_badWords.Add(word1);
+			}
+		}
+	}
+}

src/SIL.LCModel.Core/SpellChecking/SpellEngineWindows.cs

@@ -22,8 +22,6 @@ internal class NoLinuxRepack : System.Attribute
 	internal sealed class SpellEngineWindows: SpellEngine
 	{
 		private readonly Hunspell _hunspellHandle;
-		private bool _isVernacular;
-		private bool _gotIsVernacular;
 
 		internal SpellEngineWindows(string affixPath, string dictPath, string exceptionPath)
 			: base(exceptionPath)
@@ -87,20 +85,6 @@ public override ICollection<string> Suggest(string badWord)
 			return _hunspellHandle.Suggest(MarshallAsUtf8Bytes(badWord));
 		}
 
-		/// <inheritdoc />
-		public override bool IsVernacular
-		{
-			get
-			{
-				if (_gotIsVernacular)
-					return _isVernacular;
-
-				_isVernacular = Check(MarshallAsUtf8Bytes(SpellingHelper.PrototypeWord));
-				_gotIsVernacular = true;
-				return _isVernacular;
-			}
-		}
-
 		/// <summary>
 		/// We can't declare these arguments (char * in C++) as [MarshalAs(UnmanagedType.LPStr)] string, because that
 		/// unconditionally coverts the string to bytes using the current system code page, which is never what we want.

src/SIL.LCModel.Core/SpellChecking/SpellingHelper.cs

@@ -22,6 +22,17 @@ namespace SIL.LCModel.Core.SpellChecking
 	/// </summary>
 	public static class SpellingHelper
 	{
+		/// <summary>
+		/// FieldWorks uses NHunspell for spell checking, but NHunspell is not available on Linux.
+		/// Use this flag to switch between NHunspell and WeCantSpell as needed. On dotnet framework we use NHunspell by default.
+		/// On dotnet core we use WeCantSpell by default.
+		/// </summary>
+		public static bool UseWeCantSpell { get; set; } =
+			#if NETFRAMEWORK
+			false;
+			#else
+			true;
+			#endif
 		// A helper object used to ensure that the spelling engines are properly disposed of
 		private sealed class SingletonToDispose : IDisposable
 		{