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NHunspell - Hunspell for the .NET platform

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21 Jul 2014LGPL31 min read 269.4K   2.9K   60   107
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:

MC++
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:

MC++
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:

C#
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)


Written By
CEO
Germany Germany
I'm a Senior Software Consultant
Thomas Maierhofer Consulting

Comments and Discussions

 
AnswerRe: NHunspell 0.6.0 released Pin
Thomas Maierhofer (Tom)24-May-09 23:50
Thomas Maierhofer (Tom)24-May-09 23:50 
QuestionRe: NHunspell 0.6.0 released Pin
dushafer28-May-09 3:35
dushafer28-May-09 3:35 
AnswerRe: NHunspell 0.6.0 released Pin
Thomas Maierhofer (Tom)28-May-09 22:16
Thomas Maierhofer (Tom)28-May-09 22:16 
GeneralRe: NHunspell 0.6.0 released Pin
dushafer29-May-09 10:35
dushafer29-May-09 10:35 
QuestionThesaurus function to find synonyms? Pin
WojciechD9-Apr-09 5:48
professionalWojciechD9-Apr-09 5:48 
AnswerRe: Thesaurus function to find synonyms? Pin
Thomas Maierhofer (Tom)27-Apr-09 0:55
Thomas Maierhofer (Tom)27-Apr-09 0:55 
QuestionError with hunspell Pin
sagun shrestha27-Mar-09 0:30
sagun shrestha27-Mar-09 0:30 
AnswerRe: Error with hunspell Pin
Thomas Maierhofer (Tom)27-Mar-09 2:53
Thomas Maierhofer (Tom)27-Mar-09 2:53 
Have you installed the VC++ 2008 SP1 redistributables?

Kind Regards Thomas


modified 4-Dec-14 6:09am.

GeneralRe: Error with hunspell Pin
conbo18-May-09 18:22
conbo18-May-09 18:22 
GeneralRe: Error with hunspell Pin
Thomas Maierhofer (Tom)18-May-09 19:48
Thomas Maierhofer (Tom)18-May-09 19:48 
Generalok wrapper Pin
Donsw21-Mar-09 15:39
Donsw21-Mar-09 15:39 
GeneralGreek language [modified] Pin
zissop20-Mar-09 14:58
zissop20-Mar-09 14:58 
GeneralRe: Greek language Pin
Thomas Maierhofer (Tom)20-Mar-09 22:57
Thomas Maierhofer (Tom)20-Mar-09 22:57 
GeneralRe: Greek language Pin
zissop20-Mar-09 23:48
zissop20-Mar-09 23:48 
GeneralRe: Greek language Pin
Thomas Maierhofer (Tom)21-Mar-09 2:30
Thomas Maierhofer (Tom)21-Mar-09 2:30 
GeneralRefactoring of NHunspell Pin
Thomas Maierhofer (Tom)15-Mar-09 23:05
Thomas Maierhofer (Tom)15-Mar-09 23:05 
GeneralProblem with spanish dictionary Pin
Eugenio Serrano14-Mar-09 5:19
Eugenio Serrano14-Mar-09 5:19 
GeneralRe: Problem with spanish dictionary Pin
Thomas Maierhofer (Tom)14-Mar-09 23:02
Thomas Maierhofer (Tom)14-Mar-09 23:02 
GeneralRe: Problem with spanish dictionary Pin
Eugenio Serrano15-Mar-09 20:15
Eugenio Serrano15-Mar-09 20:15 
GeneralQuestion fpr usage with C# Pin
hsp6012-Mar-09 2:24
hsp6012-Mar-09 2:24 
GeneralRe: Question fpr usage with C# Pin
Thomas Maierhofer (Tom)12-Mar-09 2:43
Thomas Maierhofer (Tom)12-Mar-09 2:43 
GeneralRe: Question fpr usage with C# Pin
hsp6013-Mar-09 5:06
hsp6013-Mar-09 5:06 
GeneralNHunspell 0.5.4. beta is released - download from Sourceforge Pin
Thomas Maierhofer (Tom)3-Mar-09 8:39
Thomas Maierhofer (Tom)3-Mar-09 8:39 
GeneralRe: NHunspell 0.5.4. beta is released - download from Sourceforge Pin
Paul Selormey8-Mar-09 6:00
Paul Selormey8-Mar-09 6:00 
GeneralRe: NHunspell 0.5.4. beta is released - download from Sourceforge Pin
Thomas Maierhofer (Tom)8-Mar-09 22:22
Thomas Maierhofer (Tom)8-Mar-09 22:22 

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