Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

https://github.com/ashaduri/csv-parser

Compile-time and runtime CSV parser written in C++17
https://github.com/ashaduri/csv-parser

cplusplus cplusplus-17 cpp cpp-library cpp17 csv parser

Last synced: about 2 months ago
JSON representation

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

Lists

README 

        
# Csv::Parser (csv-parser)

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



![GitHub](https://img.shields.io/github/license/ashaduri/csv-parser)

![Language](https://img.shields.io/badge/language-ISO%20C++17-blue)



## 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](https://www.ietf.org/rfc/rfc4180.txt), 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](https://github.com/catchorg/Catch2).



## Usage Examples



### Runtime Parsing into 2D std::vector



#### Example:



``` C++

#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> 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:



``` C++

#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 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:

``` C++

#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, columns>

constexpr auto matrix = parser.parseTo2DArray(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();

static_assert(buffer.getStringView() == R"(with "quote inside)"sv);

```



## Copyright



Copyright: Alexander Shaduri    

License: Zlib