* Fetch value string for this node.
 *
 * @return A non-NULL string is always returned.  The returned pointer is to
 * the internal value of this node, and should not be modified, or freed.
 */

/************************************************************************/
/*                              SetValue()                              */
/************************************************************************/

/**
 * Set the node value.
 *
 * @param pszNewValue the new value to assign to this node.  The passed
 * string is duplicated and remains the responsibility of the caller.
 */

void OGR_SRSNode::SetValue( const char * pszNewValue )

{
    CPLFree( pszValue );
    pszValue = CPLStrdup( pszNewValue );
}

/************************************************************************/
/*                               Clone()                                */
/************************************************************************/

/**
 * Make a duplicate of this node, and it's children.
 *
 * @return a new node tree, which becomes the responsiblity of the caller.
 */

OGR_SRSNode *OGR_SRSNode::Clone() const

{
    OGR_SRSNode *poNew;

    poNew = new OGR_SRSNode( pszValue );

    for( int i = 0; i < nChildren; i++ )
    {
        poNew->AddChild( papoChildNodes[i]->Clone() );
    }

    return poNew;
}

/************************************************************************/
/*                            NeedsQuoting()                            */
/*                                                                      */
/*      Does this node need to be quoted when it is exported to Wkt?    */
/************************************************************************/

int OGR_SRSNode::NeedsQuoting() const

{
    // non-terminals are never quoted.
    if( GetChildCount() != 0 )
        return FALSE;

    // As per bugzilla bug 201, the OGC spec says the authority code
    // needs to be quoted even though it appears well behaved.
    if( poParent != NULL && EQUAL(poParent->GetValue(),"AUTHORITY") )
        return TRUE;
    
    // As per bugzilla bug 294, the OGC spec says the direction
    // values for the AXIS keywords should *not* be quoted.
    if( poParent != NULL && EQUAL(poParent->GetValue(),"AXIS") 
        && this != poParent->GetChild(0) )
        return FALSE;

    // Non-numeric tokens are generally quoted while clean numeric values
    // are generally not. 
    for( int i = 0; pszValue[i] != '\0'; i++ )
    {
        if( (pszValue[i] < '0' || pszValue[i] > '9')
            && pszValue[i] != '.'
            && pszValue[i] != '-' && pszValue[i] != '+'
            && pszValue[i] != 'e' && pszValue[i] != 'E' )
            return TRUE;
    }

    return FALSE;
}

/************************************************************************/
/*                            exportToWkt()                             */
/************************************************************************/

/**
 * Convert this tree of nodes into WKT format.
 *
 * Note that the returned WKT string should be freed with OGRFree() or
 * CPLFree() when no longer needed.  It is the responsibility of the caller.
 *
 * @param ppszResult the resulting string is returned in this pointer.
 *
 * @return currently OGRERR_NONE is always returned, but the future it
 * is possible error conditions will develop. 
 */
 

OGRErr OGR_SRSNode::exportToWkt( char ** ppszResult ) const

{
    char        **papszChildrenWkt = NULL;
    int         nLength = strlen(pszValue)+4;
    int         i;

/* -------------------------------------------------------------------- */
/*      Build a list of the WKT format for the children.                */
/* -------------------------------------------------------------------- */
    papszChildrenWkt = (char **) CPLCalloc(sizeof(char*),(nChildren+1));
    
    for( i = 0; i < nChildren; i++ )
    {
        papoChildNodes[i]->exportToWkt( papszChildrenWkt + i );
        nLength += strlen(papszChildrenWkt[i]) + 1;
    }

/* -------------------------------------------------------------------- */
/*      Allocate the result string.                                     */
/* -------------------------------------------------------------------- */
    *ppszResult = (char *) CPLMalloc(nLength);
    *ppszResult[0] = '\0';
    
/* -------------------------------------------------------------------- */
/*      Capture this nodes value.  We put it in double quotes if        */
/*      this is a leaf node, otherwise we assume it is a well formed    */
/*      node name.                                                      */
/* -------------------------------------------------------------------- */
    if( NeedsQuoting() )
    {
        strcat( *ppszResult, "\"" );
        strcat( *ppszResult, pszValue ); /* should we do quoting? */
        strcat( *ppszResult, "\"" );
    }
    else
        strcat( *ppszResult, pszValue );

/* -------------------------------------------------------------------- */
/*      Add the children strings with appropriate brackets and commas.  */
/* -------------------------------------------------------------------- */
    if( nChildren > 0 )
        strcat( *ppszResult, "[" );
    
    for( i = 0; i < nChildren; i++ )
    {
        strcat( *ppszResult, papszChildrenWkt[i] );
        if( i == nChildren-1 )
            strcat( *ppszResult, "]" );
        else
            strcat( *ppszResult, "," );
    }

    CSLDestroy( papszChildrenWkt );

    return OGRERR_NONE;
}

/************************************************************************/
/*                         exportToPrettyWkt()                          */
/************************************************************************/

OGRErr OGR_SRSNode::exportToPrettyWkt( char ** ppszResult, int nDepth ) const

{
    char        **papszChildrenWkt = NULL;
    int         nLength = strlen(pszValue)+4;
    int         i;

/* -------------------------------------------------------------------- */
/*      Build a list of the WKT format for the children.                */
/* -------------------------------------------------------------------- */
    papszChildrenWkt = (char **) CPLCalloc(sizeof(char*),(nChildren+1));
    
    for( i = 0; i < nChildren; i++ )
    {
        papoChildNodes[i]->exportToPrettyWkt( papszChildrenWkt + i,
                                              nDepth + 1);
        nLength += strlen(papszChildrenWkt[i]) + 2 + nDepth*4;
    }

/* -------------------------------------------------------------------- */
/*      Allocate the result string.                                     */
/* -------------------------------------------------------------------- */
    *ppszResult = (char *) CPLMalloc(nLength);
    *ppszResult[0] = '\0';
    
/* -------------------------------------------------------------------- */
/*      Capture this nodes value.  We put it in double quotes if        */
/*      this is a leaf node, otherwise we assume it is a well formed    */
/*      node name.                                                      */
/* -------------------------------------------------------------------- */
    if( NeedsQuoting() )
    {
        strcat( *ppszResult, "\"" );
        strcat( *ppszResult, pszValue ); /* should we do quoting? */
        strcat( *ppszResult, "\"" );
    }
    else
        strcat( *ppszResult, pszValue );

/* -------------------------------------------------------------------- */
/*      Add the children strings with appropriate brackets and commas.  */
/* -------------------------------------------------------------------- */
    if( nChildren > 0 )
        strcat( *ppszResult, "[" );
    
    for( i = 0; i < nChildren; i++ )
    {
        if( papoChildNodes[i]->GetChildCount() > 0 )
        {
            int  j;

            strcat( *ppszResult, "\n" );
            for( j = 0; j < 4*nDepth; j++ )
                strcat( *ppszResult, " " );
        }
        strcat( *ppszResult, papszChildrenWkt[i] );
        if( i < nChildren-1 )
            strcat( *ppszResult, "," );
    }

    if( nChildren > 0 )
    {
        if( (*ppszResult)[strlen(*ppszResult)-1] == ',' )
            (*ppszResult)[strlen(*ppszResult)-1] = '\0';
        
        strcat( *ppszResult, "]" );
    }

    CSLDestroy( papszChildrenWkt );

    return OGRERR_NONE;
}

/************************************************************************/
/*                           importFromWkt()                            */
/************************************************************************/

/**
 * Import from WKT string.
 *
 * This method will wipe the existing children and value of this node, and
 * reassign them based on the contents of the passed WKT string.  Only as
 * much of the input string as needed to construct this node, and it's
 * children is consumed from the input string, and the input string pointer
 * is then updated to point to the remaining (unused) input.
 *
 * @param ppszInput Pointer to pointer to input.  The pointer is updated to
 * point to remaining unused input text.
 *
 * @return OGRERR_NONE if import succeeds, or OGRERR_CORRUPT_DATA if it
 * fails for any reason.
 */

OGRErr OGR_SRSNode::importFromWkt( char ** ppszInput )

{
    const char  *pszInput = *ppszInput;
    int         bInQuotedString = FALSE;
    
/* -------------------------------------------------------------------- */
/*      Clear any existing children of this node.                       */
/* -------------------------------------------------------------------- */
    ClearChildren();
    
/* -------------------------------------------------------------------- */
/*      Read the ``value'' for this node.                               */
/* -------------------------------------------------------------------- */
    char        szToken[512];
    int         nTokenLen = 0;
    
    while( *pszInput != '\0' && nTokenLen < (int) sizeof(szToken)-1 )
    {
        if( *pszInput == '"' )
        {
            bInQuotedString = !bInQuotedString;
        }
        else if( !bInQuotedString
              && (*pszInput == '[' || *pszInput == ']' || *pszInput == ','
                  || *pszInput == '(' || *pszInput == ')' ) )
        {
            break;
        }
        else if( !bInQuotedString 
                 && (*pszInput == ' ' || *pszInput == '\t' 
                     || *pszInput == 10 || *pszInput == 13) )
        {
            /* just skip over whitespace */
        } 
        else
        {
            szToken[nTokenLen++] = *pszInput;
        }

        pszInput++;
    }

    if( *pszInput == '\0' || nTokenLen == sizeof(szToken) - 1 )
        return OGRERR_CORRUPT_DATA;

    szToken[nTokenLen++] = '\0';
    SetValue( szToken );

/* -------------------------------------------------------------------- */
/*      Read children, if we have a sublist.                            */
/* -------------------------------------------------------------------- */
    if( *pszInput == '[' || *pszInput == '(' )