/******************************************************************************
 *
 * Project:  ISO 8211 Access
 * Purpose:  Implements the DDFFieldDefn class.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include "cpl_port.h"
#include "iso8211.h"

#include <cctype>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_string.h"

CPL_CVSID("$Id: ddffielddefn.cpp 36552 2016-11-29 06:01:45Z goatbar $");

#define CPLE_DiscardedFormat   1301

/************************************************************************/
/*                            DDFFieldDefn()                            */
/************************************************************************/

DDFFieldDefn::DDFFieldDefn() :
    poModule(NULL),
    pszTag(NULL),
    _fieldName(NULL),
    _arrayDescr(NULL),
    _formatControls(NULL),
    bRepeatingSubfields(FALSE),
    nFixedWidth(0),
    _data_struct_code(dsc_elementary),
    _data_type_code(dtc_char_string),
    nSubfieldCount(0),
    papoSubfields(NULL)
{}

/************************************************************************/
/*                           ~DDFFieldDefn()                            */
/************************************************************************/

DDFFieldDefn::~DDFFieldDefn()

{
    CPLFree( pszTag );
    CPLFree( _fieldName );
    CPLFree( _arrayDescr );
    CPLFree( _formatControls );

    for( int i = 0; i < nSubfieldCount; i++ )
        delete papoSubfields[i];
    CPLFree( papoSubfields );
}

/************************************************************************/
/*                            AddSubfield()                             */
/************************************************************************/

void DDFFieldDefn::AddSubfield( const char *pszName,
                                const char *pszFormat )

{
    DDFSubfieldDefn *poSFDefn = new DDFSubfieldDefn;

    poSFDefn->SetName( pszName );
    poSFDefn->SetFormat( pszFormat );
    AddSubfield( poSFDefn );
}

/************************************************************************/
/*                            AddSubfield()                             */
/************************************************************************/

void DDFFieldDefn::AddSubfield( DDFSubfieldDefn *poNewSFDefn,
                                int bDontAddToFormat )

{
    nSubfieldCount++;
    papoSubfields = static_cast<DDFSubfieldDefn **>(
        CPLRealloc( papoSubfields, sizeof(void*) * nSubfieldCount ));
    papoSubfields[nSubfieldCount-1] = poNewSFDefn;

    if( bDontAddToFormat )
        return;

/* -------------------------------------------------------------------- */
/*      Add this format to the format list.  We don't bother            */
/*      aggregating formats here.                                       */
/* -------------------------------------------------------------------- */
    if( _formatControls == NULL || strlen(_formatControls) == 0 )
    {
        CPLFree( _formatControls );
        _formatControls = CPLStrdup( "()" );
    }

    const int nOldLen = static_cast<int>(strlen(_formatControls));

    char *pszNewFormatControls = static_cast<char *>(
        CPLMalloc(nOldLen+3+strlen(poNewSFDefn->GetFormat())));

    strcpy( pszNewFormatControls, _formatControls );
    pszNewFormatControls[nOldLen-1] = '\0';
    if( pszNewFormatControls[nOldLen-2] != '(' )
        strcat( pszNewFormatControls, "," );

    strcat( pszNewFormatControls, poNewSFDefn->GetFormat() );
    strcat( pszNewFormatControls, ")" );

    CPLFree( _formatControls );
    _formatControls = pszNewFormatControls;

/* -------------------------------------------------------------------- */
/*      Add the subfield name to the list.                              */
/* -------------------------------------------------------------------- */
    if( _arrayDescr == NULL )
        _arrayDescr = CPLStrdup("");

    _arrayDescr = (char *)
        CPLRealloc(_arrayDescr,
                   strlen(_arrayDescr)+strlen(poNewSFDefn->GetName())+2);
    if( strlen(_arrayDescr) > 0 &&
       (_arrayDescr[0] != '*' || strlen(_arrayDescr) > 1) )
        strcat( _arrayDescr, "!" );
    strcat( _arrayDescr, poNewSFDefn->GetName() );
}

/************************************************************************/
/*                               Create()                               */
/*                                                                      */
/*      Initialize a new field defn from application input, instead     */
/*      of from an existing file.                                       */
/************************************************************************/

int DDFFieldDefn::Create( const char *pszTagIn, const char *pszFieldName,
                          const char *pszDescription,
                          DDF_data_struct_code eDataStructCode,
                          DDF_data_type_code   eDataTypeCode,
                          const char *pszFormat )

{
    CPLAssert( pszTag == NULL );
    poModule = NULL;
    pszTag = CPLStrdup( pszTagIn );
    _fieldName = CPLStrdup( pszFieldName );
    _arrayDescr = CPLStrdup( pszDescription );

    _data_struct_code = eDataStructCode;
    _data_type_code = eDataTypeCode;

    if( pszFormat != NULL )
        _formatControls = CPLStrdup( pszFormat );
    else
        _formatControls = CPLStrdup( "" );

    if( pszDescription != NULL && *pszDescription == '*' )
        bRepeatingSubfields = TRUE;

    return TRUE;
}

/************************************************************************/
/*                         SetFormatControls()                          */
/************************************************************************/

void DDFFieldDefn::SetFormatControls( const char* pszVal )
{
    CPLFree(_formatControls);
    _formatControls = CPLStrdup(pszVal ? pszVal : "");
}

/************************************************************************/
/*                          GenerateDDREntry()                          */
/************************************************************************/

int DDFFieldDefn::GenerateDDREntry( DDFModule * poModuleIn, char **ppachData,
                                    int *pnLength )

{
    const int iFDOffset = poModuleIn->GetFieldControlLength();
    CPLAssert(iFDOffset >= 6 && iFDOffset <= 9);
    *pnLength = static_cast<int>(iFDOffset + strlen(_fieldName) + 1
        + strlen(_arrayDescr) + 1
        + strlen(_formatControls) + 1);

    if( strlen(_arrayDescr) == 0 )
        *pnLength -= 1;
    if( strlen(_formatControls) == 0 )
        *pnLength -= 1;

    if( ppachData == NULL )
        return TRUE;

    *ppachData = static_cast<char *>(CPLMalloc(*pnLength + 1));

    if( _data_struct_code == dsc_elementary )
        (*ppachData)[0] = '0';
    else if( _data_struct_code == dsc_vector )
        (*ppachData)[0] = '1';
    else if( _data_struct_code == dsc_array )
        (*ppachData)[0] = '2';
    else if( _data_struct_code == dsc_concatenated )
        (*ppachData)[0] = '3';

    if( _data_type_code == dtc_char_string )
        (*ppachData)[1] = '0';
    else if( _data_type_code == dtc_implicit_point )
        (*ppachData)[1] = '1';
    else if( _data_type_code == dtc_explicit_point )
        (*ppachData)[1] = '2';
    else if( _data_type_code == dtc_explicit_point_scaled )
        (*ppachData)[1] = '3';
    else if( _data_type_code == dtc_char_bit_string )
        (*ppachData)[1] = '4';
    else if( _data_type_code == dtc_bit_string )
        (*ppachData)[1] = '5';
    else if( _data_type_code == dtc_mixed_data_type )
        (*ppachData)[1] = '6';

    (*ppachData)[2] = '0';
    (*ppachData)[3] = '0';
    (*ppachData)[4] = ';';
    (*ppachData)[5] = '&';
    if( iFDOffset > 6 )
        (*ppachData)[6] = ' ';
    if( iFDOffset > 7 )
        (*ppachData)[7] = ' ';
    if( iFDOffset > 8 )
        (*ppachData)[8] = ' ';
    snprintf( *ppachData + iFDOffset, *pnLength+1 - iFDOffset, "%s",
             _fieldName );
    if( strlen(_arrayDescr) > 0 )
        snprintf( *ppachData + strlen(*ppachData),
                  *pnLength+1 - strlen(*ppachData), "%c%s",
                 DDF_UNIT_TERMINATOR, _arrayDescr );
    if( strlen(_formatControls) > 0 )
        snprintf( *ppachData + strlen(*ppachData),
                  *pnLength+1 - strlen(*ppachData), "%c%s",
                 DDF_UNIT_TERMINATOR, _formatControls );
    snprintf( *ppachData + strlen(*ppachData),
              *pnLength+1 - strlen(*ppachData), "%c", DDF_FIELD_TERMINATOR );

    return TRUE;
}

/************************************************************************/
/*                             Initialize()                             */
/*                                                                      */
/*      Initialize the field definition from the information in the     */
/*      DDR record.  This is called by DDFModule::Open().               */
/************************************************************************/

int DDFFieldDefn::Initialize( DDFModule * poModuleIn,
                              const char * pszTagIn,
                              int nFieldEntrySize,
                              const char * pachFieldArea )

{
    int iFDOffset = poModuleIn->GetFieldControlLength();

    poModule = poModuleIn;

    pszTag = CPLStrdup( pszTagIn );

/* -------------------------------------------------------------------- */
/*      Set the data struct and type codes.                             */
/* -------------------------------------------------------------------- */
    switch( pachFieldArea[0] )
    {
      case ' ': /* for ADRG, DIGEST USRP, DIGEST ASRP files */
      case '0':
        _data_struct_code = dsc_elementary;
        break;

      case '1':
        _data_struct_code = dsc_vector;
        break;

      case '2':
        _data_struct_code = dsc_array;
        break;

      case '3':
        _data_struct_code = dsc_concatenated;
        break;

      default:
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Unrecognized data_struct_code value %c.\n"
                  "Field %s initialization incorrect.",
                  pachFieldArea[0], pszTag );
        _data_struct_code = dsc_elementary;
    }

    switch( pachFieldArea[1] )
    {
      case ' ': /* for ADRG, DIGEST USRP, DIGEST ASRP files */
      case '0':
        _data_type_code = dtc_char_string;
        break;

      case '1':
        _data_type_code = dtc_implicit_point;
        break;

      case '2':
        _data_type_code = dtc_explicit_point;
        break;

      case '3':
        _data_type_code = dtc_explicit_point_scaled;
        break;

      case '4':
        _data_type_code = dtc_char_bit_string;
        break;

      case '5':
        _data_type_code = dtc_bit_string;
        break;

      case '6':
        _data_type_code = dtc_mixed_data_type;
        break;

      default:
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Unrecognized data_type_code value %c.\n"
                  "Field %s initialization incorrect.",
                  pachFieldArea[1], pszTag );
        _data_type_code = dtc_char_string;
    }

/* -------------------------------------------------------------------- */
/*      Capture the field name, description (sub field names), and      */
/*      format statements.                                              */
/* -------------------------------------------------------------------- */

    int nCharsConsumed = 0;
    _fieldName =
        DDFFetchVariable( pachFieldArea + iFDOffset,
                          nFieldEntrySize - iFDOffset,
                          DDF_UNIT_TERMINATOR, DDF_FIELD_TERMINATOR,
                          &nCharsConsumed );
    iFDOffset += nCharsConsumed;

    _arrayDescr =
        DDFFetchVariable( pachFieldArea + iFDOffset,
                          nFieldEntrySize - iFDOffset,
                          DDF_UNIT_TERMINATOR, DDF_FIELD_TERMINATOR,
                          &nCharsConsumed );
    iFDOffset += nCharsConsumed;

    _formatControls =
        DDFFetchVariable( pachFieldArea + iFDOffset,
                          nFieldEntrySize - iFDOffset,
                          DDF_UNIT_TERMINATOR, DDF_FIELD_TERMINATOR,
                          &nCharsConsumed );

/* -------------------------------------------------------------------- */
/*      Parse the subfield info.                                        */
/* -------------------------------------------------------------------- */
    if( _data_struct_code != dsc_elementary )
    {
        if( !BuildSubfields() )
            return FALSE;

        if( !ApplyFormats() )
            return FALSE;
    }

    return TRUE;
}

/************************************************************************/
/*                                Dump()                                */
/************************************************************************/

/**
 * Write out field definition info to debugging file.
 *
 * A variety of information about this field definition, and all its
 * subfields is written to the give debugging file handle.
 *
 * @param fp The standard IO file handle to write to.  i.e. stderr
 */

void DDFFieldDefn::Dump( FILE * fp )

{
    const char  *pszValue = "";

    fprintf( fp, "  DDFFieldDefn:\n" );
    fprintf( fp, "      Tag = `%s'\n", pszTag );
    fprintf( fp, "      _fieldName = `%s'\n", _fieldName );
    fprintf( fp, "      _arrayDescr = `%s'\n", _arrayDescr );
    fprintf( fp, "      _formatControls = `%s'\n", _formatControls );

    switch( _data_struct_code )
    {
      case dsc_elementary:
        pszValue = "elementary";
        break;

      case dsc_vector:
        pszValue = "vector";
        break;

      case dsc_array:
        pszValue = "array";
        break;

      case dsc_concatenated:
        pszValue = "concatenated";
        break;

      default:
        CPLAssert( false );
        pszValue = "(unknown)";
    }

    fprintf( fp, "      _data_struct_code = %s\n", pszValue );

    switch( _data_type_code )
    {
      case dtc_char_string:
        pszValue = "char_string";
        break;

      case dtc_implicit_point:
        pszValue = "implicit_point";
        break;

      case dtc_explicit_point:
        pszValue = "explicit_point";
        break;

      case dtc_explicit_point_scaled:
        pszValue = "explicit_point_scaled";
        break;

      case dtc_char_bit_string:
        pszValue = "char_bit_string";
        break;

      case dtc_bit_string:
        pszValue = "bit_string";
        break;

      case dtc_mixed_data_type:
        pszValue = "mixed_data_type";
        break;

      default:
        CPLAssert( false );
        pszValue = "(unknown)";
        break;
    }

    fprintf( fp, "      _data_type_code = %s\n", pszValue );

    for( int i = 0; i < nSubfieldCount; i++ )
        papoSubfields[i]->Dump( fp );
}

/************************************************************************/
/*                           BuildSubfields()                           */
/*                                                                      */
/*      Based on the _arrayDescr build a set of subfields.              */
/************************************************************************/

int DDFFieldDefn::BuildSubfields()

{
    const char *pszSublist = _arrayDescr;

/* -------------------------------------------------------------------- */
/*      It is valid to define a field with _arrayDesc                   */
/*      '*STPT!CTPT!ENPT*YCOO!XCOO' and formatControls '(2b24)'.        */
/*      This basically indicates that there are 3 (YCOO,XCOO)           */
/*      structures named STPT, CTPT and ENPT.  But we can't handle      */
/*      such a case gracefully here, so we just ignore the              */
/*      "structure names" and treat such a thing as a repeating         */
/*      YCOO/XCOO array.  This occurs with the AR2D field of some       */
/*      AML S-57 files for instance.                                    */
/*                                                                      */
/*      We accomplish this by ignoring everything before the last       */
/*      '*' in the subfield list.                                       */
/* -------------------------------------------------------------------- */
    if( strrchr(pszSublist, '*') != NULL )
        pszSublist = strrchr(pszSublist, '*');

/* -------------------------------------------------------------------- */
/*      Strip off the repeating marker, when it occurs, but mark our    */
/*      field as repeating.                                             */
/* -------------------------------------------------------------------- */
    if( pszSublist[0] == '*' )
    {
        bRepeatingSubfields = TRUE;
        pszSublist++;
    }

/* -------------------------------------------------------------------- */
/*      split list of fields .                                          */
/* -------------------------------------------------------------------- */
    char **papszSubfieldNames =
        CSLTokenizeStringComplex( pszSublist, "!", FALSE, FALSE );

/* -------------------------------------------------------------------- */
/*      minimally initialize the subfields.  More will be done later.   */
/* -------------------------------------------------------------------- */
    const int nSFCount = CSLCount( papszSubfieldNames );
    for( int iSF = 0; iSF < nSFCount; iSF++ )
    {
        DDFSubfieldDefn *poSFDefn = new DDFSubfieldDefn;

        poSFDefn->SetName( papszSubfieldNames[iSF] );
        AddSubfield( poSFDefn, TRUE );
    }

    CSLDestroy( papszSubfieldNames );

    return TRUE;
}

/************************************************************************/
/*                          ExtractSubstring()                          */
/*                                                                      */
/*      Extract a substring terminated by a comma (or end of            */
/*      string).  Commas in brackets are ignored as terminated with     */
/*      bracket nesting understood gracefully.  If the returned         */
/*      string would being and end with a bracket then strip off the    */
/*      brackets.                                                       */
/*                                                                      */
/*      Given a string like "(A,3(B,C),D),X,Y)" return "A,3(B,C),D".    */
/*      Give a string like "3A,2C" return "3A".                         */
/************************************************************************/

char *DDFFieldDefn::ExtractSubstring( const char * pszSrc )

{
    int nBracket = 0;
    int i = 0;  // Used after for.
    for( ;
         pszSrc[i] != '\0' && (nBracket > 0 || pszSrc[i] != ',');
         i++ )
    {
        if( pszSrc[i] == '(' )
            nBracket++;
        else if( pszSrc[i] == ')' )
            nBracket--;
    }

    char *pszReturn = NULL;
    if( pszSrc[0] == '(' )
    {
        pszReturn = CPLStrdup( pszSrc + 1 );
        pszReturn[i-2] = '\0';
    }
    else
    {
        pszReturn = CPLStrdup( pszSrc  );
        pszReturn[i] = '\0';
    }

    return pszReturn;
}

/************************************************************************/
/*                            ExpandFormat()                            */
/************************************************************************/

char *DDFFieldDefn::ExpandFormat( const char * pszSrc )

{
    size_t nDestMax = 32;
    char *pszDest = static_cast<char *>(CPLMalloc(nDestMax + 1));
    int nRepeat = 0;

    size_t iSrc = 0;
    size_t iDst = 0;
    pszDest[0] = '\0';

    while( pszSrc[iSrc] != '\0' )
    {
        // This is presumably an extra level of brackets around some
        // binary stuff related to rescanning which we don't care to do
        // (see 6.4.3.3 of the standard.  We just strip off the extra
        // layer of brackets.
        if( (iSrc == 0 || pszSrc[iSrc-1] == ',') && pszSrc[iSrc] == '(' )
        {
            char *pszContents = ExtractSubstring( pszSrc+iSrc );
            char *pszExpandedContents = ExpandFormat( pszContents );

            if( strlen(pszExpandedContents) + strlen(pszDest) + 1 > nDestMax )
            {
                nDestMax = 2 * (strlen(pszExpandedContents) + strlen(pszDest));
                pszDest = static_cast<char *>(CPLRealloc(pszDest,nDestMax + 1));
            }

            strcat( pszDest, pszExpandedContents );
            iDst = strlen(pszDest);

            iSrc = iSrc + strlen(pszContents) + 2;

            CPLFree( pszContents );
            CPLFree( pszExpandedContents );
        }

        // This is a repeated subclause.
        else if( (iSrc == 0 || pszSrc[iSrc-1] == ',')
                 && isdigit(pszSrc[iSrc]) )
        {
            nRepeat = atoi(pszSrc+iSrc);

            // Skip over repeat count.
            const char *pszNext = pszSrc + iSrc;  // Used after for.
            for( ; isdigit(*pszNext); pszNext++ )
                iSrc++;

            char *pszContents = ExtractSubstring( pszNext );
            char *pszExpandedContents = ExpandFormat( pszContents );

            for( int i = 0; i < nRepeat; i++ )
            {
                if( strlen(pszExpandedContents) + strlen(pszDest) + 1 + 1 >
                    nDestMax )
                {
                    nDestMax =
                        2 * (strlen(pszExpandedContents) + strlen(pszDest) + 1);
                    pszDest =
                        static_cast<char *>(CPLRealloc(pszDest,nDestMax + 1));
                }

                strcat( pszDest, pszExpandedContents );
                if( i < nRepeat-1 )
                    strcat( pszDest, "," );
            }

            iDst = strlen(pszDest);

            if( pszNext[0] == '(' )
                iSrc = iSrc + strlen(pszContents) + 2;
            else
                iSrc = iSrc + strlen(pszContents);

            CPLFree( pszContents );
            CPLFree( pszExpandedContents );
        }
        else
        {
            if( iDst+1 >= nDestMax )
            {
                nDestMax = 2 * iDst;
                pszDest = static_cast<char *>(CPLRealloc(pszDest, nDestMax));
            }

            pszDest[iDst++] = pszSrc[iSrc++];
            pszDest[iDst] = '\0';
        }
    }

    return pszDest;
}

/************************************************************************/
/*                            ApplyFormats()                            */
/*                                                                      */
/*      This method parses the format string partially, and then        */
/*      applies a subfield format string to each subfield object.       */
/*      It in turn does final parsing of the subfield formats.          */
/************************************************************************/

int DDFFieldDefn::ApplyFormats()

{
/* -------------------------------------------------------------------- */
/*      Verify that the format string is contained within brackets.     */
/* -------------------------------------------------------------------- */
    if( strlen(_formatControls) < 2
        || _formatControls[0] != '('
        || _formatControls[strlen(_formatControls)-1] != ')' )
    {
        CPLError( CE_Warning, static_cast<CPLErrorNum>(CPLE_DiscardedFormat),
                  "Format controls for `%s' field missing brackets:%s",
                  pszTag, _formatControls );

        return FALSE;
    }

/* -------------------------------------------------------------------- */
/*      Duplicate the string, and strip off the brackets.               */
/* -------------------------------------------------------------------- */

    char *pszFormatList = ExpandFormat( _formatControls );

/* -------------------------------------------------------------------- */
/*      Tokenize based on commas.                                       */
/* -------------------------------------------------------------------- */
    char **papszFormatItems =
        CSLTokenizeStringComplex(pszFormatList, ",", FALSE, FALSE );

    CPLFree( pszFormatList );

/* -------------------------------------------------------------------- */
/*      Apply the format items to subfields.                            */
/* -------------------------------------------------------------------- */
    int iFormatItem = 0;  // Used after for.

    for( ;
         papszFormatItems[iFormatItem] != NULL;
         iFormatItem++ )
    {
        const char *pszPastPrefix = papszFormatItems[iFormatItem];
        while( *pszPastPrefix >= '0' && *pszPastPrefix <= '9' )
            pszPastPrefix++;

        ///////////////////////////////////////////////////////////////
        // Did we get too many formats for the subfields created
        // by names?  This may be legal by the 8211 specification, but
        // isn't encountered in any formats we care about so we just
        // blow.

        if( iFormatItem >= nSubfieldCount )
        {
          CPLError( CE_Warning, static_cast<CPLErrorNum>(CPLE_DiscardedFormat),
                      "Got more formats than subfields for field `%s'.",
                      pszTag );
            break;
        }

        if( !papoSubfields[iFormatItem]->SetFormat(pszPastPrefix) )
        {
            CSLDestroy( papszFormatItems );
            return FALSE;
        }
    }

/* -------------------------------------------------------------------- */
/*      Verify that we got enough formats, cleanup and return.          */
/* -------------------------------------------------------------------- */
    CSLDestroy( papszFormatItems );

    if( iFormatItem < nSubfieldCount )
    {
        CPLError( CE_Warning, static_cast<CPLErrorNum>(CPLE_DiscardedFormat),
                  "Got less formats than subfields for field `%s'.",
                  pszTag );
        return FALSE;
    }

/* -------------------------------------------------------------------- */
/*      If all the fields are fixed width, then we are fixed width      */
/*      too.  This is important for repeating fields.                   */
/* -------------------------------------------------------------------- */
    nFixedWidth = 0;
    for( int i = 0; i < nSubfieldCount; i++ )
    {
        if( papoSubfields[i]->GetWidth() == 0 )
        {
            nFixedWidth = 0;
            break;
        }
        else
        {
            nFixedWidth += papoSubfields[i]->GetWidth();
        }
    }

    return TRUE;
}

/************************************************************************/
/*                          FindSubfieldDefn()                          */
/************************************************************************/

/**
 * Find a subfield definition by its mnemonic tag.
 *
 * @param pszMnemonic The name of the field.
 *
 * @return The subfield pointer, or NULL if there isn't any such subfield.
 */

DDFSubfieldDefn *DDFFieldDefn::FindSubfieldDefn( const char * pszMnemonic )

{
    for( int i = 0; i < nSubfieldCount; i++ )
    {
        if( EQUAL(papoSubfields[i]->GetName(),pszMnemonic) )
            return papoSubfields[i];
    }

    return NULL;
}

/************************************************************************/
/*                            GetSubfield()                             */
/*                                                                      */
/*      Fetch a subfield by its index.                                 */
/************************************************************************/

/**
 * Fetch a subfield by index.
 *
 * @param i The index subfield index. (Between 0 and GetSubfieldCount()-1)
 *
 * @return The subfield pointer, or NULL if the index is out of range.
 */

DDFSubfieldDefn *DDFFieldDefn::GetSubfield( int i )

{
    if( i < 0 || i >= nSubfieldCount )
    {
        CPLAssert( false );
        return NULL;
    }

    return papoSubfields[i];
}

/************************************************************************/
/*                          GetDefaultValue()                           */
/************************************************************************/

/**
 * Return default data for field instance.
 */

char *DDFFieldDefn::GetDefaultValue( int *pnSize )

{
/* -------------------------------------------------------------------- */
/*      Loop once collecting the sum of the subfield lengths.           */
/* -------------------------------------------------------------------- */
    int nTotalSize = 0;

    for( int iSubfield = 0; iSubfield < nSubfieldCount; iSubfield++ )
    {
        int nSubfieldSize = 0;

        if( !papoSubfields[iSubfield]->GetDefaultValue( NULL, 0,
                                                        &nSubfieldSize ) )
            return NULL;
        nTotalSize += nSubfieldSize;
    }

/* -------------------------------------------------------------------- */
/*      Allocate buffer.                                                */
/* -------------------------------------------------------------------- */
    char *pachData = static_cast<char *>(CPLMalloc( nTotalSize ));

    if( pnSize != NULL )
        *pnSize = nTotalSize;

/* -------------------------------------------------------------------- */
/*      Loop again, collecting actual default values.                   */
/* -------------------------------------------------------------------- */
    int nOffset = 0;
    for( int iSubfield = 0; iSubfield < nSubfieldCount; iSubfield++ )
    {
        int nSubfieldSize;

        if( !papoSubfields[iSubfield]->GetDefaultValue(
                pachData + nOffset, nTotalSize - nOffset, &nSubfieldSize ) )
        {
            CPLAssert( false );
            return NULL;
        }

        nOffset += nSubfieldSize;
    }

    CPLAssert( nOffset == nTotalSize );

    return pachData;
}
