open()

bool MayaFlux::IO::DelimitedTextReader::open ( const std::string &  filepath, FileReadOptions  options = FileReadOptions::ALL  )

overridevirtual

Open a CSV or TSV file and establish its Composite layout.

Parameters

filepath	Source path.
options	FileReader options.

Returns

True when the file and header are valid.

Implements MayaFlux::IO::FileReader.

Definition at line 213 of file DelimitedTextReader.cpp.

{
    close();
    m_last_error.clear();
    if (!can_read(filepath)) {
        m_last_error = "Expected a .csv or .tsv file";
        return false;
    }
 
    if (!m_has_header && !m_requested_layout) {
        m_last_error = "Headerless input requires a supplied CompositeLayout";
        return false;
    }
 
    m_filepath = resolve_path(filepath);
    m_active_delimiter = m_delimiter != '\0'
        ? m_delimiter
        : (extension_of(filepath) == ".tsv" ? '\t' : ',');
 
    m_file.open(m_filepath, std::ios::binary);
    if (!m_file) {
        m_last_error = "Cannot open delimited text file";
        return false;
    }
 
    std::vector<ParsedField> names;
    bool at_end = false;
    if (m_has_header) {
        if (!read_record(names, at_end) || at_end) {
            if (at_end)
                m_last_error = "Delimited text file has no header";
            close();
            return false;
        }
 
        if (!names.empty() && names.front().value.starts_with("\xEF\xBB\xBF"))
            names.front().value.erase(0, 3);
    }
 
    if (m_requested_layout) {
        m_layout = *m_requested_layout;
        const auto& fields = m_layout->fields();
        if (fields.empty() || (m_has_header && fields.size() != names.size())) {
            m_last_error = "Header does not match the supplied CompositeLayout";
            close();
            return false;
        }
 
        for (size_t i = 0; i < fields.size(); ++i) {
            if (!supported_field(fields[i])
                || (m_has_header && fields[i].name != names[i].value)) {
                m_last_error = "Unsupported or mismatched Composite field: " + fields[i].name;
                close();
                return false;
            }
        }
    } else {
        Kakshya::CompositeLayout layout;
        for (auto& name : names) {
            if (!layout.add_field<std::string>(std::move(name.value))) {
                m_last_error = "Header field names must be nonempty and unique";
                close();
                return false;
            }
        }
 
        m_layout = std::move(layout);
    }
 
    Kakshya::CompositeArray empty(*m_layout);
    m_layout = empty.layout();
 
    m_data_start = m_file.tellg();
    if (m_data_start == std::streampos(-1)) {
        m_file.clear();
        m_file.seekg(0, std::ios::end);
        m_data_start = m_file.tellg();
    }
 
    m_file.clear();
    m_file.seekg(m_data_start);
 
    m_row_position = 0;
    m_at_end = false;
    return true;
}

References MayaFlux::Kakshya::CompositeLayout::add_field(), can_read(), close(), MayaFlux::Kakshya::CompositeArray::layout(), m_active_delimiter, m_at_end, m_data_start, m_delimiter, m_file, m_filepath, m_has_header, MayaFlux::IO::CompositeReader::m_last_error, m_layout, m_requested_layout, m_row_position, name, read_record(), MayaFlux::IO::FileReader::resolve_path(), and value.

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