You can edit this page using wiki syntax for markup.

Article contents:== Outdated egg! This is an egg for CHICKEN 4, the unsupported old release. You're almost certainly looking for [[/eggref/5/async-io|the CHICKEN 5 version of this egg]], if it exists. If it does not exist, there may be equivalent functionality provided by another egg; have a look at the [[https://wiki.call-cc.org/chicken-projects/egg-index-5.html|egg index]]. Otherwise, please consider porting this egg to the current version of CHICKEN. [[toc:]] == async-io Asynchronous I/O Library for Chicken Scheme. === Repository [[https://github.com/yarnoiser/async-io|https://github.com/yarnoiser/async-io]] === Usage <enscript highlight="scheme"> (use async-io) </enscript> ==== Readers Readers are used to read strings from a file descriptor asynchronously and return tokens identified by a separator procedure. ===== make-reader <procedure>(make-reader fd sep-proc)</procedure> Sets the file descriptor ''fd'' to non-blocking mode. Returns a reader which is used to read input from the file descriptor ''fd''. This reader separates tokens using ''sep-proc''. ===== reader? <procedure> (reader? x) </procedure> Returns true if ''x'' is a reader object, otherwise returns false. ===== reader-fd <procedure> (reader-fd x) </procedure> Returns the file descriptor belonging to reader ''x''. ===== reader-ready? <procedure> (reader-ready? x) </procedure> Returns true if there is input waiting to be read by the reader ''x''. ===== thread-wait-for-reader! <procedure> (thread-wait-for-reader! x) </procedure> Suspends the current thread until the file descriptor belonging to reader ''x'' is ready to be read. Equivalent to: <enscript highlight="scheme"> (thread-wait-for-i/o! (reader-fd x)) </enscript> ===== reader-read! <procedure> (reader-read! x) </procedure> Reads input from the file descriptor belonging to reader ''x''. Performs separation on any input read. Throws an exception if there is no input to be read by the reader. ===== reader-has-token? <procedure> (reader-has-token? x) </procedure> Returns true if the reader ''x'' has a complete token from it's input stream. Otherwise returns false. ===== reader-get-token! <procedure> (reader-get-token! x) </procedure> If reader ''x'' found a token using it's separator procedure during the last call to (reader-read! x), then that token will be returned as a string. Otherwise an empty string is returned. ===== Example Echo the first scheme expression from stdin. <enscript highlight="scheme"> (define reader (make-reader fileno/stdin sep-scheme-expr)) (let loop () (cond ((reader-has-token? reader) (print (reader-get-token! reader))) ((reader-ready? reader) (begin (reader-read! reader) (loop))) (else (loop)))) </enscript> ==== Separator Procedures Separator procedures are used by readers to identify tokens to be returned with ''reader-get-token!''. These procedures take a string to separate as an argument and return two values: a token separated from the main string, and the remainder of the string after the token. Token separation is done with every call to reader-read! before input is placed within a reader's buffer. This egg comes with two pre-made separator procedure: sep-scheme-expr and sep-line. ==== Example The following separator procedure separates tokens delimited by commas. <enscript highlight="scheme"> (use srfi-13) (define (sep-comma str) (let ((len (string-length str))) (let loop ((i 0)) (cond ((= i len) (values "" str)) ((eqv? (string-ref str i) #\,) (values (string-take str (add1 i)) (string-drop str (add1 i)))) (else (loop (add1 i))))))) </enscript> ===== sep-scheme-expr <procedure> (sep-scheme-expr str) </procedure> A separator procedure for scheme expressions (without chicken extensions). Returns two values: The first value returned is the first complete scheme expression found in ''str'' or an empty string if no scheme expressions were found. The second value returned is the remainder of the ''str'' after the first complete scheme expression, or an empty string if there is no content after the first expression. ===== sep-line <procedure> (sep-line str) </procedure> A separator procedure for lines. Returns two values: The first value returned is the first line found in ''str'', including the newline character. The second value returned is the remainder of ''str'' after the first line, or an empty string if ''str'' only contained one line. ==== Writers Writers are used to asynchronously write strings to a file descriptor. ===== make-writer <procedure> (make-writer fd) </procedure> Sets the file descriptor ''fd'' into non-blocking mode and returns a writer which is used to read input from ''fd''. ===== writer? <procedure> (writer? x) </procedure> Returns true if ''x'' is a writer. Otherwise returns false. ===== writer-fd <procedure> (writer-fd x) </procedure> Returns the file descriptor belonging to the writer ''x''. ===== writer-ready? <procedure> (writer-ready? x) </procedure> Returns true if the file descriptor belonging to writer ''x'' is ready to be written to. Otherwise returns false. ===== thread-wait-for-writer! <procedure> (thread-wait-for-writer! x) </procedure> Suspends the current thread until the file descriptor belonging to writer ''x'' is ready to be written to. Equivalent to: <enscript highlight="scheme"> (thread-wait-for-i/o! (writer-fd x)) </enscript> ===== writer-enqueue! <procedure> (writer-enqueue! x str) </procedure> Places string ''str'' in writer ''x'''s buffer. Portions of ''str'' will be written to ''x'''s file descriptor on subsequent calls to ''writer-write!''. ===== writer-write! <procedure> (writer-write! x) </procedure> Writes characters from writer ''x'''s buffer to ''x'''s file descriptor. Throws an exception if ''x'''s file descriptor is not ready to be written to. ===== writer-finished? <procedure> (writer-finished? x) </procedure> Returns true if the writer ''x'' has nothing queued to be written to it's file descriptor. Otherwise returns false. ===== Example Write the string "hello, world!\n" to stdout using an async-io writer. <enscript highlight="scheme"> (use async-io posix) (define writer (make-writer fileno/stdout)) (writer-enqueue! writer "hello, world!\n") (let loop () (cond ((writer-finished? writer) (void)) ((writer-ready? writer) (begin (writer-write! writer) (loop))) (else (loop)))) </enscript> === About the Author Robert Smiley, the author of this egg can be reached at yarnoiserdev@gmail.com. Description of your changes:

I would like to authenticate

Spam control

What do you get when you add 3 to 23?