beho / zig-csv

Low-level CSV parser library for Zig language.

zig-csv

Low-level CSV parser library for Zig language. Each non-empty line in input is parsed as one or more tokens of type field, followed by row_end.

This library was conceived as Zig learning project and it was not used by me in production software.

Features

• Reads UTF-8 files.
• Provides iterator interface to stream of tokens.
• Handles quoted fields in which column/row separator can be used. Quote itself can be used in field by doubling it (e.g. "This is quote: "".")
• Configurable column separator (default ,), row separator (\n) and quote (").
  • Currently only single byte characters.
• Parser does not allocate – caller provides a buffer that parser operates in. Buffer must be longer than a longest field in input.

Example

Following code reads CSV tokens from a file while very naively printing them as table to standard output.

const std = @import("std");
const csv = @import("csv");

pub fn main() anyerror!void {
    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    defer arena.deinit();

    const allocator = &arena.allocator;
    var buffer = try allocator.alloc(u8, 4096);

    const args = try std.process.argsAlloc(allocator);
    defer std.process.argsFree(allocator, args);

    if (args.len != 2) {
        std.log.warn("Single arg is expected", .{});
        std.process.exit(1);
    }

    const file = try std.fs.cwd().openFile(args[1], .{});
    defer file.close();

    var csv_tokenizer = try csv.CsvTokenizer(std.fs.File.Reader).init(file.reader(), buffer, .{});
    const stdout = std.io.getStdOut().writer();

    while (try csv_tokenizer.next()) |token| {
        switch (token) {
            .field => |val| {
                try stdout.writeAll(val);
                try stdout.writeAll("\t");
            },
            .row_end => {
                try stdout.writeAll("\n");
            },
        }
    }
}