annotate data/fileio/CSVStreamWriter.h @ 1438:09c2ba31a711 streaming-csv-writer

Formatting and naming changes more in line with SV conventions.

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2017 Queen Mary, University of London.
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#ifndef CSV_STREAM_WRITER_H
#define CSV_STREAM_WRITER_H

#include "base/BaseTypes.h"
#include "base/Selection.h"
#include "base/ProgressReporter.h"
#include "base/DataExportOptions.h"
#include "data/model/Model.h"
#include <QString>
#include <algorithm>

namespace CSVStreamWriter
{

template <class OutStream>
bool writeInChunks(OutStream& oss,
                   const Model& model,
                   const Selection& extents,
                   ProgressReporter* reporter = nullptr,
                   QString delimiter = ",",
                   DataExportOptions options = DataExportDefaults,
                   const sv_frame_t blockSize = 16384)
{
    if (blockSize <= 0) return false;
    sv_frame_t readPtr = extents.isEmpty() ?
        model.getStartFrame() : extents.getStartFrame();
    sv_frame_t endFrame = extents.isEmpty() ?
        model.getEndFrame() : extents.getEndFrame();
    int previousPercentagePoint = 0;

    const auto wasCancelled = [&reporter]() { 
        return reporter && reporter->wasCancelled(); 
    };

    while (readPtr < endFrame) {
        if (wasCancelled()) return false;

        const auto start = readPtr;
        const auto end = std::min(start + blockSize, endFrame);

        oss << model.toDelimitedDataStringSubsetWithOptions(
            delimiter,
            options,
            start,
            end
        ) << (end < endFrame ? "\n" : "");

        const auto currentPercentage = 100 * end / endFrame;
        const bool hasIncreased = currentPercentage > previousPercentagePoint;

        if (hasIncreased) {
            if (reporter) reporter->setProgress(currentPercentage);
            previousPercentagePoint = currentPercentage;
        }
        readPtr = end;
    }
    return !wasCancelled(); // setProgress could process event loop
}

template <class OutStream>
bool writeInChunks(OutStream& oss,
                   const Model& model,
                   ProgressReporter* reporter = nullptr,
                   QString delimiter = ",",
                   DataExportOptions options = DataExportDefaults,
                   const sv_frame_t blockSize = 16384)
{
    const Selection empty;
    return CSV::writeInChunks(
        oss,
        model,
        empty,
        reporter,
        delimiter,
        options,
        blockSize
    );
}
} // namespace CSVStreamWriter
#endif