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Csv::Parser (csv-parser)

Compile-time and runtime CSV parser written in C++17

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Features

Header-only.
Requires only standard C++ (C++17).
Supports reading CSV data from std::string_view during compilation (using constexpr).
Fully supports RFC 4180, including quoted values, escaped quotes, and newlines in field values.
Liberal in terms of accepting not-quite-standard CSV files, but detects errors when needed.
Supports Excel CSV variations.
Supports reading data as different types (string, double, empty field) (runtime only).
Extensively tested using Catch2.

API Reference

Automatically generated API reference describes the public API in detail.

Usage Examples

Runtime Parsing into 2D std::vector

Example:

#include "csv_parser.h"

// ...

using namespace std::string_view_literals;

// Data to parse
std::string_view data = "abc,def\n5,6"sv;

// Let "cell_refs" be a vector of columns.
// After parsing, each element will contain Csv::CellReference object. If the cell data type
// is Csv::CellType::String, Csv::CellReference object will reference a part of the original data.
// Other Cell* types, as well as floating point and integral types can also be used here.
std::vector<std::vector<Csv::CellReference>> cell_refs;

Csv::Parser parser;

try {
    // This throws Csv::ParseError on error.
    parser.parseTo2DVector(data, cell_refs);
}
catch(Csv::ParseError& ex) {
    std::cerr << "CSV parse error: " << ex.what() << std::endl;
    return EXIT_FAILURE;
}

assert(cell_refs.size() == 2);
assert(cell_refs[0].size() == 2);
assert(cell_refs[1].size() == 2);

assert(cell_refs[0][0].getType() == Csv::CellType::String);
assert(cell_refs[1][0].getType() == Csv::CellType::String);
assert(cell_refs[0][1].getType() == Csv::CellType::Double);
assert(cell_refs[1][1].getType() == Csv::CellType::Double);

std::cout << "Column 0, row 0: " << cell_refs[0][0].getCleanString().value() << std::endl;  // abc
std::cout << "Column 1, row 0: " << cell_refs[1][0].getCleanString().value() << std::endl;  // def
std::cout << "Column 0, row 1: " << cell_refs[0][1].getDouble().value() << std::endl;  // 5
std::cout << "Column 1, row 1: " << cell_refs[1][1].getDouble().value() << std::endl;  // 6

Runtime Parsing of Numeric Matrix Into 1D Vector With Row-Major Order

Example:

#include "csv_parser.h"

// ...

using namespace std::string_view_literals;

// Data to parse
std::string_view data = "11,12,13\n21,22,23"sv;

// Let matrix_data be a flat matrix of doubles in row-major order.
// Other floating point and integral types, as well as Cell* types can also be used here.
std::vector<double> matrix_data;

Csv::Parser parser;
Csv::MatrixInformation info;

try {
    // This throws Csv::ParseError on error.
    info = parser.parseToVectorRowMajor(data, matrix_data);
}
catch(Csv::ParseError& ex) {
    std::cerr << "CSV parse error: " << ex.what() << std::endl;
    return EXIT_FAILURE;
}

assert(matrix_data.size() == 3 * 2);
assert(info.getColumns() == 3);
assert(info.getRows() == 2);

std::cout << "Row 0, column 0: " << matrix_data[0] << std::endl;  // 11
std::cout << "Row 0, column 1: " << matrix_data[1] << std::endl;  // 12
std::cout << "Row 0, column 2: " << matrix_data[2] << std::endl;  // 13

// matrixIndex(row, column) can be used to avoid accidental mistakes
std::cout << "Row 1, column 0: " << matrix_data[info.matrixIndex(1, 0)] << std::endl;  // 21
std::cout << "Row 1, column 1: " << matrix_data[info.matrixIndex(1, 1)] << std::endl;  // 22
std::cout << "Row 1, column 2: " << matrix_data[info.matrixIndex(1, 2)] << std::endl;  // 23

return EXIT_SUCCESS;

Compile-Time Parsing

Currently, parsing at compile-time has some restrictions:

Only string_views are supported for output (no doubles).
To collapse consecutive double-quotes in strings, a compile-time-allocated buffer has to be used.

One (possibly useful) consequence of compile-time parsing is that a parse error also causes a compilation error.

Example:

#include "csv_parser.h"

// ...

using namespace std::string_view_literals;

constexpr std::string_view data =
R"(abc, "def"
"with ""quote inside",6)";

constexpr std::size_t columns = 2, rows = 2;

constexpr Csv::Parser parser;

// parse into std::array<std::array<CellStringReference, rows>, columns>
constexpr auto matrix = parser.parseTo2DArray<rows, columns>(data);

// Verify the data at compile time.
// Note that consecutive double-quotes are not collapsed when using
// getOriginalStringView(). To collapse them, use the getCleanStringBuffer()
// approach below.
static_assert(matrix[0][0].getOriginalStringView() == "abc"sv);
static_assert(matrix[1][0].getOriginalStringView() == "def"sv);
static_assert(matrix[1][1].getOriginalStringView() == "6"sv);

// To support consecutive double-quote collapsing at compile-time, allocate a compile-time
// buffer to place the clean string inside. The buffer size has to be at least that
// of an uncollapsed string value.
// If the buffer is too small, the code will simply not compile.
constexpr auto buffer_size = matrix[0][1].getRequiredBufferSize();  // uncollapsed size
constexpr auto buffer = matrix[0][1].getCleanStringBuffer<buffer_size>();
static_assert(buffer.getStringView() == R"(with "quote inside)"sv);

Awesome

Csv::Parser (csv-parser)

Features

API Reference

Usage Examples

Runtime Parsing into 2D std::vector

Example:

Runtime Parsing of Numeric Matrix Into 1D Vector With Row-Major Order

Example:

Compile-Time Parsing

Example:

Copyright