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;;; guile-email --- Guile email parser
;;; Copyright © 2018, 2019, 2020 Arun Isaac <arunisaac@systemreboot.net>
;;;
;;; This file is part of guile-email.
;;;
;;; guile-email is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU Affero General Public License as
;;; published by the Free Software Foundation; either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; guile-email is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; Affero General Public License for more details.
;;;
;;; You should have received a copy of the GNU Affero General Public
;;; License along with guile-email. If not, see
;;; <http://www.gnu.org/licenses/>.
(define-module (email utils)
#:use-module (ice-9 match)
#:use-module (ice-9 peg codegen)
#:use-module (ice-9 binary-ports)
#:use-module (ice-9 textual-ports)
#:use-module (rnrs bytevectors)
#:use-module ((rnrs io ports)
#:select (call-with-port))
#:use-module (rnrs io simple)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:export (get-line-with-delimiter
read-objects
read-while
read-bytes-till
acons*
alist-combine))
(define (read-objects read-proc port)
"Read all objects using READ-PROC from PORT and return them as a
list."
(let ((x (read-proc port)))
(if (eof-object? x)
(list)
(cons x (read-objects read-proc port)))))
(define* (read-while port read-proc pred)
"Read from PORT using READ-PROC while PRED returns #t and the
end-of-file has not been reached. READ-PROC is invoked with the input
port as argument. PRED is invoked with each string returned by
READ-PROC as argument. The string for which PRED returns #f is ungot
back into PORT."
(define (read-while-loop output)
(let ((x (read-proc port)))
(cond
((eof-object? x) x)
((pred x)
(put-string output x)
(read-while-loop output))
(else (unget-string port x)))))
(call-with-port (open-output-string)
(lambda (out)
(let ((read-result (read-while-loop out))
(str (get-output-string out)))
(if (and (eof-object? read-result)
(string-null? str))
read-result
str)))))
(define (read-bytes-till port sequence)
"Read bytes from PORT until byte SEQUENCE is seen or end-of-file is
reached. If SEQUENCE is seen, unget it to PORT and return."
(define (read-bytes-and-write-till in out sequence)
(let ((octet (get-u8 in)))
(cond
((eof-object? octet) octet)
;; If octet read matches first octet of sequence, try matching
;; the full sequence.
((= octet (bytevector-u8-ref sequence 0))
(unget-bytevector in sequence 0 1)
(let ((bv (get-bytevector-n in (bytevector-length sequence))))
(cond
((bytevector=? bv sequence) (unget-bytevector in bv))
(else (unget-bytevector in bv 1)
(put-u8 out octet)
(read-bytes-and-write-till in out sequence)))))
;; Else, output the octet and continue reading.
(else (put-u8 out octet)
(read-bytes-and-write-till in out sequence)))))
(call-with-values open-bytevector-output-port
(lambda (out get-bytevector)
(let ((read-result (read-bytes-and-write-till port out sequence))
(bv (get-bytevector)))
(if (and (eof-object? read-result)
(bytevector=? bv #vu8()))
read-result
bv)))))
(define (get-line-with-delimiter port)
"Read a line from PORT and return it as a string including the
delimiting linefeed character."
(let ((line (get-line port)))
(if (eof-object? line)
line
(string-append line "\n"))))
(define acons*
(match-lambda*
((key value)
(acons key value (list)))
((key value . rest)
(acons key value (apply acons* rest)))
((alist) alist)))
(define (alist-combine alist1 alist2)
"Combine two association lists ALIST1 and ALIST2 into a single
association list. Key-value pairs in ALIST2 are more significant and
override those in ALIST1."
(append alist2
(remove (match-lambda
((key . _)
(assoc key alist2)))
alist1)))
(define (cg-string-ci pat accum)
(syntax-case pat ()
((pat-str-syntax) (string? (syntax->datum #'pat-str-syntax))
(let ((pat-str (syntax->datum #'pat-str-syntax)))
(let ((plen (string-length pat-str)))
#`(lambda (str len pos)
(let ((end (+ pos #,plen)))
(and (<= end len)
(string-ci= str #,pat-str pos end)
#,(case accum
((all) #`(list end (list 'cg-string #,pat-str)))
((name) #`(list end 'cg-string))
((body) #`(list end #,pat-str))
((none) #`(list end '()))
(else (error "bad accum" accum)))))))))))
(add-peg-compiler! 'string-ci cg-string-ci)
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