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cl-csv

This library aims to simplify working with csvs to the bare minimum of tedium

  • reads/writes csvs from/to strings, streams and files
  • support streaming reads (allowing processing very large csvs, through read-csv's row-fn paramter)
  • supports custom data formating
  • settable quote, separator and quote-escapes
  • supports multiline quoted data
  • A test suite
  • Detailed state about the process on error (line number, column number, char index), current collection state

Rationale

I had many scattered, not well tested, not easily runable pieces of csv code. I was unhappy with this situation then decided to refactor all of this into a single location. I wrote tests for it and had a library so I thought I might release it. This project started as extensions and bugfixes on arnesi's CSV.

I then looked around and saw there are other csv libs out there that probably mostly accomplished what I had set out to do. However, I already had code that was tested and had an easier license (BSD) so, I figured why not just release it anyway.

Other Available CSV libs

Escaping and quotes

There are two modes for escaping currently

  • :quote - by default cl-csv treats "" as an escape for a single double-quote
  • :following - read the character after the escape sequence verbatim, commonly the *quote-escape* will be set to #\\ when the escape mode is following.

Signals and Restarts

  • *enable-signals* will cause a csv-data-read or csv-row-read to be signaled for each piece of data and row read. There is a filter restart available which will cause the filter value to be used instead. Enabling signals is ~2xs as slow as not, so by default they are not enabled.
  • in-csv iterate clause and read-csv support continue and filter restarts for errors occuring during read-csv-row

Functional Filters

  • row-fn (lambda (row) ) - does something with a row instead of collecting it
  • map-fn (lambda (row) ) - can modify a row on the way to collecting it
  • data-map-fn (lambda (datum &key csv-reader &allow-other-keys) ) can modify a single datum on the way to collecting it, used to implement empty string to null conversions

Library Integration

  • data-table - functions for building data-tables from csv's, must (asdf:load-system :cl-csv-data-table)
  • clsql must (asdf:load-system :cl-csv-clsql)
    • import-from-csv
    • serial-import-from-csv
  • iterate - provides an in-csv driver clause for iterating over a CSV

Examples

;; read a file into a list of lists
(cl-csv:read-csv #P"file.csv")
=> (("1" "2" "3") ("4" "5" "6"))

;; read a file that's tab delimited
(cl-csv:read-csv #P"file.tab" :separator #\Tab)

;; read a file and return a list of objects created from each row
(cl-csv:read-csv #P"file.csv"
                 :map-fn #'(lambda (row)
                             (make-instance 'object
                                            :foo (nth 0 row)
                                            :baz (nth 2 row))))
;; read csv from a string (streams also supported)
(cl-csv:read-csv "1,2,3
4,5,6")
=> (("1" "2" "3") ("4" "5" "6"))

;; loop over a CSV for effect
(let ((sum 0))
  (cl-csv:do-csv (row #P"file.csv")
    (incf sum (parse-integer (nth 0 row))))
  sum)
  
  
;; loop over a CSV using iterate
(iter (for (foo bar baz) in-csv #P"file.csv")
  (collect (make-instance 'object :foo foo :baz baz)))

Changelog

  • v 1.0.2 - standardized on csv-reader for a name instead of using table in some places and reader in others Updated iterate clauses

  • v 1.0.1 - New parser, same interface, faster and cleaner, and more flexible added data-map-fn, use this to handle null conversion

  • v 1.0 - Long term stable version

Authors

;; Copyright (c) 2011 Russ Tyndall , Acceleration.net http://www.acceleration.net
;; Copyright (c) 2002-2006, Edward Marco Baringer
;; All rights reserved.
;;
;; Redistribution and use in source and binary forms, with or without
;; modification, are permitted provided that the following conditions are
;; met:
;;
;;  - Redistributions of source code must retain the above copyright
;;    notice, this list of conditions and the following disclaimer.
;;
;;  - Redistributions in binary form must reproduce the above copyright
;;    notice, this list of conditions and the following disclaimer in the
;;    documentation and/or other materials provided with the distribution.
;;
;;  - Neither the name of Edward Marco Baringer, nor BESE, nor the names
;;    of its contributors may be used to endorse or promote products
;;    derived from this software without specific prior written permission.
;;
;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
;; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
;; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;; A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
;; OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
;; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
;; LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
;; DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
;; THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
;; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
;; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.