Rebol Programming/exists-thru?
USAGE:
editEXISTS-THRU? url /check info
DESCRIPTION:
editChecks if a file is in the disk cache. Returns: none, false (out of date), or file
EXISTS-THRU? is a function value.
ARGUMENTS
edit- url -- (Type: url file)
REFINEMENTS
edit- /check -- Checks version, checksum/secure, date, and/or size of cached file.
- info -- (Type: block tuple binary logic date none)
SOURCE CODE
editexists-thru?: func [ {Checks if a file is in the disk cache. Returns: none, false (out of date), or file} url [url! file!] /check {Checks version, checksum/secure, date, and/or size of cached file.} info [block! tuple! binary! logic! date! none!] /local file data date ][ if not file: path-thru url [return none] if not exists? file [return false] if not check [return file] if none? info [return file] if tuple? info [ if not data: attempt [load/header script? file] [return none] if all [ object? data: data/1 tuple? data/version data/version >= info ] [return file] return false ] if binary? info [ if not data: attempt [read/binary file] [return none] if info = checksum/secure data [return file] return false ] if not block? info [info: reduce [info]] foreach item info [ if date? item [ date: get-modes file 'modification-date if (date + 0:00:03) < item [return false] ] if integer? item [ if item <> size? file [return false] ] ] file ]