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IDebugGenericParamField::GetConstraints

  • Article

Retrieves the constraints that are associated with this generic parameter.

Syntax

int GetConstraints(
    uint              cConstraints,
    out IDebugField[] ppConstraints,
    ref uint          pcConstraints
);

Parameters

cConstraints
[in] Number of constraints.

ppConstraints
[out] Returns an array that contains the constraints associated with this field.

pcConstraints
[in, out] Number of constraints in the ppConstraints array.

Return Value

If successful, returns S_OK; otherwise, returns an error code.

Example

The following example shows how to implement this method for a CDebugGenericParamFieldType object that exposes the IDebugGenericParamField interface.

HRESULT CDebugGenericParamFieldType::GetConstraints(
    ULONG32 cConstraints,
    IDebugField** ppConstraints,
    ULONG32* pcConstraints)
{
    HRESULT hr = S_OK;
    CComPtr<IMetaDataImport> pMetadata;
    CComPtr<IMetaDataImport2> pMetadata2;
    mdGenericParamConstraint* rgParamConsts = NULL;
    HCORENUM hEnum = 0;
    ULONG cConst = 0;
    ULONG iConst;
    ULONG iConstOut = 0;

    METHOD_ENTRY( CDebugGenericParamFieldType::GetConstraints );

    IfFalseGo(ppConstraints && pcConstraints, E_INVALIDARG );
    *pcConstraints = 0;

    IfNullGo( rgParamConsts = new mdGenericParamConstraint[cConstraints], E_OUTOFMEMORY);

    IfFailGo( m_spSH->GetMetadata( m_idModule, &pMetadata ) );
    IfFailGo( pMetadata->QueryInterface(IID_IMetaDataImport2, (void**)&pMetadata2) );
    IfFailGo( pMetadata2->EnumGenericParamConstraints( &hEnum,
              m_tokParam,
              rgParamConsts,
              cConstraints,
              &cConst) );
    pMetadata->CloseEnum(hEnum);
    hEnum = NULL;

    for (iConst = 0; iConst < cConst; iConst++)
    {
        mdToken tokConst;

        IfFailGo( pMetadata2->GetGenericParamConstraintProps( rgParamConsts[iConst],
                  NULL,
                  &tokConst ) );
        switch (TypeFromToken(tokConst))
        {
            case mdtTypeRef:
                {
                    Module_ID mid;
                    mdTypeDef tokClass;

                    IfFailGo( CDebugClassFieldType::GetClassToken(m_spSH, m_idModule, tokConst, &mid, &tokClass) );
                    IfFailGo( m_spSH->CreateClassType( mid, tokClass, ppConstraints + iConstOut ) );
                    iConstOut++;
                    break;
                }
            case mdtTypeDef:
                {
                    IfFailGo( m_spSH->CreateClassType( m_idModule, tokConst, ppConstraints + iConstOut ) );
                    iConstOut++;
                    break;
                }
            case mdtTypeSpec:
                {
                    PCCOR_SIGNATURE pvSig;
                    ULONG cbSig;
                    DWORD cb = 0;
                    DWORD dwElementType;

                    IfFailGo( pMetadata2->GetTypeSpecFromToken( tokConst, &pvSig, &cbSig) );

                    cb += CorSigUncompressData(&(pvSig[cb]), &dwElementType);

                    IfFailGo( m_spSH->CreateType( pvSig, cbSig, m_idModule, mdMethodDefNil, m_pGenScope, ppConstraints + iConstOut ) );

                    iConstOut++;

                    break;
                }
            default:
                {
                    ASSERT(!"Bad constraint token");
                }
        }
    }

    *pcConstraints = iConstOut;

Error:

    METHOD_EXIT( CDebugGenericParamFieldType::GetConstraints, hr );

    DELETERG(rgParamConsts);

    return hr;
}

See also