csv.cpp

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/*
 * csv.cpp
 *
 * Copyright (C) 2007  Thomas A. Vaughan
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THOMAS A. VAUGHAN ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THOMAS A. VAUGHAN BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Implementation of the CSV class (see csv.h)
 */

// includes --------------------------------------------------------------------
#include "csv.h"                        // always include our own header first!

#include "common/wave_ex.h"



////////////////////////////////////////////////////////////////////////////////
//
//      static helper methods
//
////////////////////////////////////////////////////////////////////////////////

static bool
getNextValue
(
IN std::istream& in,
IN std::string& val,
IN bool& eol
)
{
        ASSERT(in.good(), "bad?");
        val = "";
        eol = false;

        // keep reading until comma or end-of-line
        while (!in.eof()) {
                char a;
                in.read(&a, 1);
                if ('\n' == a) {
                        eol = true;
                        return true;
                } else if (',' == a) {
                        return true;
                }

                val += a;
        }

        // can only get here if file ends!
        return false;
}



////////////////////////////////////////////////////////////////////////////////
//
//      public API
//
////////////////////////////////////////////////////////////////////////////////

void
parseCsvStream
(
IN std::istream& in,
IN const VecString& columns,
IN csv_callback_fn callback,
IN void * context
)
{
        ASSERT(in.good(), "bad?");
        ASSERT(columns.size(), "no columns requested?");
        ASSERT(callback, "null callback provided?");
        // ASSERT(context) -- we don't care if this is null

        // the mapOut array is the key to the whole algorithm: if the value of
        //  the ith element is a non-negative integer j, we need to map from
        //  the input column i to the output (col_data_t) at index j 
        static const int s_maxColumns           = 32;
        ASSERT((int) columns.size() <= s_maxColumns,
            "caller is looking for a lot of columns! (more than %d)",
            s_maxColumns);
        int mapOut[s_maxColumns];
        int N = columns.size();

        // set up output
        vec_col_t data;
        data.resize(N);
        for (int i = 0; i < N; ++i) {
                col_data_t& cd = data[i];
                cd.col_name = NULL;
                cd.value = NULL;
        }

        // run through header and construct mapOut
        bool eol = false;       // not yet at end-of-line
        int idx = 0;
        for (; !eol; ++idx) {

                // initialize
                mapOut[idx] = -1;

                // read column header
                std::string val;
                if (!getNextValue(in, val, eol)) {
                        WAVE_EX(wex);
                        wex << "Premature end of stream while parsing header";
                }
                // DPRINTF("Read column header: '%s'", val.c_str());

                // does this match an input?
                for (int i = 0; i < N; ++i) {
                        const char * col = columns[i].c_str();
                        if (!strcmp(col, val.c_str())) {
                                // match!
                                // DPRINTF("Input column '%s' at index %d found",
                                //     col, i);
                                mapOut[idx] = i;
                                col_data_t& cd = data[i];
                                cd.col_name = col;
                                break;
                        }
                }
        }
        int nCols = idx;
        // DPRINTF("Read %d columns total", nCols);
        ASSERT(nCols > 0, "no columns?");
        ASSERT(nCols >= N, "read fewer columns (%d) than requested (%d)?",
            nCols, N);

        // verify all requested columns were found
        for (int i = 0; i < N; ++i) {
                col_data_t& cd = data[i];
                if (!cd.col_name) {
                        WAVE_EX(wex);
                        wex << "Unable to find index " << i << ": '";
                        wex << columns[i] << "'";
                }
        }

        // okay, have our output mapping.  Now parse all the rows
        VecString vals;
        vals.resize(N);
        std::string val;
        while (!in.eof()) {
                // read entire row
                for (int idx = 0; idx < nCols; ++idx) {
                        if (!getNextValue(in, val, eol)) {
                                if (0 == idx) {
                                        // assume end of file!
                                        break;
                                }
                                else if (idx < nCols - 1) {
                                        WAVE_EX(wex);
                                        wex << "Premature end of stream while ";
                                        wex << "parsing data columns";
                                }
                        }
                        if (eol && idx < nCols - 1) {
                                WAVE_EX(wex);
                                wex << "Row had only " << (idx + 1);
                                wex << " columns?   Need " << nCols;
                        }

                        int j = mapOut[idx];
                        if (j < 0)
                                continue;

                        vals[j] = val;
                        col_data_t& cd = data[j];
                        cd.value = vals[j].c_str();
                }

                // tell client about this row
                callback(context, data);
        }
}