ogrcsvlayer.cpp

来自「支持各种栅格图像和矢量图像读取的库」· C++ 代码 · 共 455 行 · 第 1/2 页

    if( papszTokens == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Create the OGR feature.                                         */
/* -------------------------------------------------------------------- */
    OGRFeature *poFeature;

    poFeature = new OGRFeature( poFeatureDefn );

/* -------------------------------------------------------------------- */
/*      Set attributes for any indicated attribute records.             */
/* -------------------------------------------------------------------- */
    int         iAttr;
    int         nAttrCount = MIN(CSLCount(papszTokens),
                                 poFeatureDefn->GetFieldCount() );
    
    for( iAttr = 0; iAttr < nAttrCount; iAttr++)
    {
        poFeature->SetField( iAttr, papszTokens[iAttr] );
    }

    CSLDestroy( papszTokens );

/* -------------------------------------------------------------------- */
/*      Translate the record id.                                        */
/* -------------------------------------------------------------------- */
    poFeature->SetFID( nNextFID++ );

    m_nFeaturesRead++;

    return poFeature;
}


/************************************************************************/
/*                           GetNextFeature()                           */
/************************************************************************/

OGRFeature *OGRCSVLayer::GetNextFeature()

{
    OGRFeature  *poFeature = NULL;

    if( bNeedRewind )
        ResetReading();
    
/* -------------------------------------------------------------------- */
/*      Read features till we find one that satisfies our current       */
/*      spatial criteria.                                               */
/* -------------------------------------------------------------------- */
    while( TRUE )
    {
        poFeature = GetNextUnfilteredFeature();
        if( poFeature == NULL )
            break;

        if( m_poAttrQuery == NULL || m_poAttrQuery->Evaluate( poFeature ) )
            break;

        delete poFeature;
    }

    return poFeature;
}

/************************************************************************/
/*                           TestCapability()                           */
/************************************************************************/

int OGRCSVLayer::TestCapability( const char * pszCap )

{
    if( EQUAL(pszCap,OLCSequentialWrite) )
        return bInWriteMode;
    else if( EQUAL(pszCap,OLCCreateField) )
        return bNew && !bHasFieldNames;
    else
        return FALSE;
}

/************************************************************************/
/*                            CreateField()                             */
/************************************************************************/

OGRErr OGRCSVLayer::CreateField( OGRFieldDefn *poNewField, int bApproxOK )

{
/* -------------------------------------------------------------------- */
/*      If we have already written our field names, then we are not     */
/*      allowed to add new fields.                                      */
/* -------------------------------------------------------------------- */
    if( bHasFieldNames || !bNew )
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Unable to create new fields after first feature written.");
        return OGRERR_FAILURE;
    }

/* -------------------------------------------------------------------- */
/*      Does this duplicate an existing field?                          */
/* -------------------------------------------------------------------- */
    if( poFeatureDefn->GetFieldIndex( poNewField->GetNameRef() ) != -1 )
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Attempt to create field %s, but a field with this name already exists.",
                  poNewField->GetNameRef() );

        return OGRERR_FAILURE;
    }

/* -------------------------------------------------------------------- */
/*      Is this a legal field type for CSV?  For now we only allow      */
/*      simple integer, real and string fields.                         */
/* -------------------------------------------------------------------- */
    switch( poNewField->GetType() )
    {
      case OFTInteger:
      case OFTReal:
      case OFTString:
        // these types are OK.
        break;

      default:
        if( bApproxOK )
        {
            CPLError( CE_Warning, CPLE_AppDefined, 
                      "Attempt to create field of type %s, but this is not supported\n"
                      "for .csv files.  Just treating as a plain string.",
                      poNewField->GetFieldTypeName( poNewField->GetType() ) );
        }
        else
        {
            CPLError( CE_Failure, CPLE_AppDefined, 
                      "Attempt to create field of type %s, but this is not supported\n"
                      "for .csv files.",
                      poNewField->GetFieldTypeName( poNewField->GetType() ) );
            return OGRERR_FAILURE;
        }
    }
    
/* -------------------------------------------------------------------- */
/*      Seems ok, add to field list.                                    */
/* -------------------------------------------------------------------- */
    poFeatureDefn->AddFieldDefn( poNewField );

    return OGRERR_NONE;
}

/************************************************************************/
/*                           CreateFeature()                            */
/************************************************************************/

OGRErr OGRCSVLayer::CreateFeature( OGRFeature *poNewFeature )

{
    int iField;

    bNeedRewind = TRUE;

/* -------------------------------------------------------------------- */
/*      Write field names if we haven't written them yet.               */
/* -------------------------------------------------------------------- */
    if( !bHasFieldNames )
    {
        for( iField = 0; iField < poFeatureDefn->GetFieldCount(); iField++ )
        {
            char *pszEscaped;

            if( iField > 0 )
                fprintf( fpCSV, "%s", "," );

            pszEscaped = 
                CPLEscapeString( poFeatureDefn->GetFieldDefn(iField)->GetNameRef(), 
                                 -1, CPLES_CSV );

            VSIFPrintf( fpCSV, "%s", pszEscaped );
            CPLFree( pszEscaped );
        }
        if( bUseCRLF )
            VSIFPutc( 13, fpCSV );
        VSIFPutc( '\n', fpCSV );

        bHasFieldNames = TRUE;
    }

/* -------------------------------------------------------------------- */
/*      Make sure we are at the end of the file.                        */
/* -------------------------------------------------------------------- */
    VSIFSeek( fpCSV, 0, SEEK_END );

/* -------------------------------------------------------------------- */
/*      Write out all the field values.                                 */
/* -------------------------------------------------------------------- */
    
    for( iField = 0; iField < poFeatureDefn->GetFieldCount(); iField++ )
    {
        char *pszEscaped;
        
        if( iField > 0 )
            fprintf( fpCSV, "%s", "," );
        
        pszEscaped = 
            CPLEscapeString( poNewFeature->GetFieldAsString(iField),
                             -1, CPLES_CSV );
        
        VSIFWrite( pszEscaped, 1, strlen(pszEscaped), fpCSV );
        CPLFree( pszEscaped );
    }
    
    if( bUseCRLF )
        VSIFPutc( 13, fpCSV );
    VSIFPutc( '\n', fpCSV );

    return OGRERR_NONE;
}

/************************************************************************/
/*                              SetCRLF()                               */
/************************************************************************/

void OGRCSVLayer::SetCRLF( int bNewValue )

{
    bUseCRLF = bNewValue;
}