Module csv::index

This sub-module provides experimental CSV record indexing.

It is simplistic, but once a CSV index is created, you can use it to jump to any record in the data instantly. In essence, it gives you random access for a modest upfront cost in time and memory.

Simple example

This example shows how to create an in-memory index and use it to jump to any record in the data. (The indexing interface works with seekable readers and writers, so you can use std::fs::File for this too.)

use std::io::{self, Write};
use csv::index::{Indexed, create_index};

let data = "
h1,h2,h3
a,b,c
d,e,f
g,h,i
";

let new_csv_rdr = || csv::Reader::from_string(data);

let mut index_data = io::Cursor::new(Vec::new());
create_index(new_csv_rdr(), index_data.by_ref()).unwrap();
let mut index = Indexed::open(new_csv_rdr(), index_data).unwrap();

// Seek to the second record and read its data. This is done *without*
// reading the first record.
index.seek(1).unwrap();

// Read the first row at this position (which is the second record).
// Since `Indexed` derefs to a `csv::Reader`, we can call CSV reader methods
// on it directly.
let row = index.records().next().unwrap().unwrap();

assert_eq!(row, vec!["d", "e", "f"]);

Structs

Indexed

A type for representing CSV data with a basic record index.

Functions

create_index

Creates a new index for the given CSV reader.