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NHunspell - Hunspell for the .NET platform

, 21 Jul 2014 LGPL3
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The spell checking and hyphenation features of OpenOffice for the .NET platform.

Introduction

I was looking for a good spell checker and hyphenation library for .NET, and I found the free (LGPL licensed) Hunspell spell checker and Hyphen libraries used in OpenOffice. Hunspell wasn't available for the .NET platform. So, I decided to write a wrapper/port. It is quite nice that a lot of the OpenOffice dictionaries are LGPL licensed too and can be used in proprietary applications.

Interop code to the native Hunspell functions

I used Managed C++ to write the wrapper/port, because I could use the original source code of Hunspell and Hyphen. It was quite nice to write the interop code between managed classes and the unmanaged Hunspell and Hyphen libraries. The original source code is almost unchanged, so that new versions of Hunspell or Hyphen can be easily adopted. Hunspell and Hyphen use unmanaged memory functions, so I had to implement the IDisposable interface and used this pattern to free unmanaged memory early.

Because Hunspell uses UTF8 coding, I had to provide conversion functions from/to UTF8:

char * NHunspell::MarshalHelper::AllocUTF8FromString(String ^value)
{
    array<Byte> ^ byteArray = Encoding::UTF8->GetBytes(value);
    int size = Marshal::SizeOf(byteArray[0]) * (byteArray->Length + 1);
    IntPtr buffer = Marshal::AllocHGlobal(size);
    Marshal::Copy(byteArray, 0, buffer, byteArray->Length);
    Marshal::WriteByte(buffer, size - 1, 0);
    return (char *) buffer.ToPointer();
}

String ^ NHunspell::MarshalHelper::AllocStringFromUTF8( char * value )
{
    int size = strlen(value);
    array<Byte> ^ byteArray = gcnew array<Byte>(size);
    Marshal::Copy(IntPtr(value), byteArray, 0, size);
    return Encoding::UTF8->GetString(byteArray);
}

Another big thing is to handle the unmanaged memory. I implement destructors and finalizers to deal with this:

NHunspell::Hunspell::~Hunspell()
{
    this->!Hunspell();
}

NHunspell::Hunspell::!Hunspell()
{
    if( handle != 0 )
    {
        delete handle;
        handle = 0;
    }
}

bool NHunspell::Hunspell::IsDisposed::get()
{
    return handle == 0;
}

NHunspell spell checking and hyphenation sample

This is a short demo of how to use NHunspell for spell checking, suggestions, and hyphenation:

Console.WriteLine("NHunspell functions and classes demo");

Console.WriteLine("");
Console.WriteLine("Spell Check with with Hunspell");

// Important: Due to the fact Hunspell will use unmanaged memory
// you have to serve the IDisposable pattern
// In this block of code this is be done
// by a using block. But you can also call hunspell.Dispose()
using (Hunspell hunspell = new Hunspell("en_us.aff", "en_us.dic"))
{
    Console.WriteLine("Check if the word 'Recommendation' is spelled correct"); 
    bool correct = hunspell.Spell("Recommendation");
    Console.WriteLine("Recommendation is spelled " + 
              (correct ? "correct" : "not correct"));

    Console.WriteLine("");
    Console.WriteLine("Make suggestions for the word 'Recommendatio'");
    List<string> suggestions = hunspell.Suggest("Recommendatio");
    Console.WriteLine("There are " + suggestions.Count.ToString() + 
                      " suggestions" );
    foreach (string suggestion in suggestions)
    {
        Console.WriteLine("Suggestion is: " + suggestion );
    }
}

Console.WriteLine("");
Console.WriteLine("Hyphenation with Hyph");

// Important: Due to the fact Hyphen will use unmanaged
// memory you have to serve the IDisposable pattern
// In this block of code this is be done by a using block.
// But you can also call hyphen.Dispose()
using (Hyphen hyphen = new Hyphen("hyph_en_us.dic"))
{
    Console.WriteLine("Get the hyphenation of the word 'Recommendation'"); 
    HyphenResult hyphenated = hyphen.Hyphenate("Recommendation");
    Console.WriteLine("'Recommendation' is hyphenated as: " + 
                      hyphenated.HyphenatedWord ); 
}

Console.WriteLine("");
Console.WriteLine("Press any key to continue...");
Console.ReadKey();

Because Hunspell is native C++ code, you must include the correct assembly for your platform. On x86 platforms (32 bit), use the NHunspell.dll from the X86 folder. On X64 platforms, use the NHunspell.dll from the X64 folder.

License

This article, along with any associated source code and files, is licensed under The GNU Lesser General Public License (LGPLv3)

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About the Author

I'm working on a new project called Crawler-Lib. It is a generalized back-end processing and hosting framework for Microsoft .NET and Mono. Please take a look at it:
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Comments and Discussions

 
GeneralNHunspell Version 0.9.5 released [modified] PinmemberThomas Maierhofer19-Jul-10 0:05 
GeneralProblem loading the native DLL PinmemberRune Jacobsen1-Jul-10 2:08 
GeneralRe: Problem loading the native DLL [modified] PinmemberThomas Maierhofer18-Jul-10 23:50 
GeneralRe: Problem loading the native DLL PinmemberRune Jacobsen11-Aug-10 0:41 
This was a bit hard to debug because it is an ASP.NET MVC application, where all binaries are apparently in the \bin\ folder.. But after a good debugging session and updating to 0.9.6 (since that came out in the meantime), it works!
 
Thank you very much for the help and the library. You are a hero! Smile | :)
QuestionSom question that i have PinmemberViki Vic1-Jun-10 23:34 
AnswerRe: Som question that i have [modified] PinmemberThomas Maierhofer18-Jul-10 23:59 
GeneralProblem exporting solution Pinmemberyunou13-May-10 13:59 
GeneralRe: Problem exporting solution PinmemberThomas Maierhofer19-Jul-10 0:01 
GeneralNot Working in Windows Form Pinmembermouthpiec7-Mar-10 7:29 
GeneralRe: Not Working in Windows Form Pinmembermouthpiec7-Mar-10 7:47 

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