HDFSPArrayMissField.cc

/////////////////////////////////////////////////////////////////////////////
// This file is part of the hdf4 data handler for the OPeNDAP data server.
// It retrieves the missing fields for some special NASA HDF4 data products.
// The products include TRMML2_V6,TRMML3B_V6,CER_AVG,CER_ES4,CER_CDAY,CER_CGEO,CER_SRB,CER_SYN,CER_ZAVG,OBPGL2,OBPGL3
// To know more information about these products,check HDFSP.h.
// Some third-dimension coordinate variable values are not provided.
// What we do here is to provide natural number series(1,2,3, ...) for
// these missing values. It doesn't make sense to visualize or analyze
// with vertical cross-section. One can check the data level by level.

//  Authors:   MuQun Yang <myang6@hdfgroup.org>
// Copyright (c) 2010-2012 The HDF Group
/////////////////////////////////////////////////////////////////////////////

#include "HDFSPArrayMissField.h"
#include <iostream>
#include <sstream>
#include <cassert>
#include <libdap/debug.h>
#include "mfhdf.h"
#include "hdf.h"
#include <libdap/InternalErr.h>
#include <BESDebug.h>


using namespace std;
using namespace libdap;

bool
HDFSPArrayMissGeoField::read ()
{

    BESDEBUG("h4","Coming to HDFSPArrayMissGeoField read "<<endl);

    if(length() == 0)                                                                               
        return true; 
    // Declaration of offset,count and step
    vector<int>offset;
    offset.resize(rank);
    vector<int>count;
    count.resize(rank);
    vector<int>step;
    step.resize(rank);

    // Obtain offset,step and count from the client expression constraint
    int nelms = format_constraint(&offset[0],&step[0],&count[0]); 

    vector<int>val;
    val.resize(nelms);

    // Since we always assign the the missing Z dimension as 32-bit
    // integer, so no need to check the type. The missing Z-dim is always
    // 1-D with natural number 1,2,3,....
    if (nelms == tnumelm) {
        for (int i = 0; i < nelms; i++)
            val[i] = i;
        set_value ((dods_int32 *) &val[0], nelms);
    }
    else {
        if (rank != 1) {
            throw InternalErr (__FILE__, __LINE__,
                "Currently the rank of the missing field should be 1");
        }
        for (int i = 0; i < count[0]; i++)
            val[i] = offset[0] + step[0] * i;
        set_value ((dods_int32 *) &val[0], nelms);
    }

    return true;
}

// Standard way of DAP handlers to pass the coordinates of the subsetted region to the handlers
// Return the number of elements to read. 
int
HDFSPArrayMissGeoField::format_constraint (int *offset, int *step, int *count)
{

    long nels = 1;
    int id = 0;

    Dim_iter p = dim_begin ();
    while (p != dim_end ()) {

        int start = dimension_start (p, true);
        int stride = dimension_stride (p, true);
        int stop = dimension_stop (p, true);

        // Check for illegal  constraint
        if (start > stop) {
            ostringstream oss;
            oss << "Array/Grid hyperslab start point "<< start <<
                   " is greater than stop point " <<  stop <<".";
            throw Error(malformed_expr, oss.str());
        }

        offset[id] = start;
        step[id] = stride;
        count[id] = ((stop - start) / stride) + 1;      // count of elements
        nels *= count[id];              // total number of values for variable

        BESDEBUG ("h4",
                         "=format_constraint():"
                         << "id=" << id << " offset=" << offset[id]
                         << " step=" << step[id]
                         << " count=" << count[id]
                         << endl);

        id++;
        p++;
    }// while (p != dim_end ())

    return nels;
}