ImfAttribute.cpp

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
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//-----------------------------------------------------------------------------
//
//	class Attribute
//
//-----------------------------------------------------------------------------

#include <ImfAttribute.h>
#include "IlmThreadMutex.h"
#include "Iex.h"
#include <string.h>
#include <map>


namespace Imf {

using IlmThread::Mutex;
using IlmThread::Lock;


Attribute::Attribute () {}


Attribute::~Attribute () {}


namespace {

struct NameCompare: std::binary_function <const char *, const char *, bool>
{
    bool
    operator () (const char *x, const char *y) const
    {
    return strcmp (x, y) < 0;
    }
};


typedef Attribute* (*Constructor)();
typedef std::map <const char *, Constructor, NameCompare> TypeMap;


class LockedTypeMap: public TypeMap
{
  public:

    Mutex mutex;
};


LockedTypeMap &
typeMap ()
{
    static Mutex criticalSection;
    Lock lock (criticalSection);

    static LockedTypeMap* typeMap = 0;

    if (typeMap == 0)
    typeMap = new LockedTypeMap ();

    return *typeMap;
}


} // namespace


bool
Attribute::knownType (const char typeName[])
{
    LockedTypeMap& tMap = typeMap();
    Lock lock (tMap.mutex);

    return tMap.find (typeName) != tMap.end();
}


void
Attribute::registerAttributeType (const char typeName[],
                      Attribute *(*newAttribute)())
{
    LockedTypeMap& tMap = typeMap();
    Lock lock (tMap.mutex);

    if (tMap.find (typeName) != tMap.end())
    THROW (Iex::ArgExc, "Cannot register image file attribute "
                "type \"" << typeName << "\". "
                "The type has already been registered.");

    tMap.insert (TypeMap::value_type (typeName, newAttribute));
}


void
Attribute::unRegisterAttributeType (const char typeName[])
{
    LockedTypeMap& tMap = typeMap();
    Lock lock (tMap.mutex);

    tMap.erase (typeName);
}


Attribute *
Attribute::newAttribute (const char typeName[])
{
    LockedTypeMap& tMap = typeMap();
    Lock lock (tMap.mutex);

    TypeMap::const_iterator i = tMap.find (typeName);

    if (i == tMap.end())
    THROW (Iex::ArgExc, "Cannot create image file attribute of "
                "unknown type \"" << typeName << "\".");

    return (i->second)();
}


} // namespace Imf