factor/basis/io/encodings/utf7/utf7.factor

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Factor

! Copyright (C) 2013-2014 Björn Lindqvist
! See http://factorcode.org/license.txt for BSD license
USING: accessors ascii base64 fry grouping.extras io
io.encodings io.encodings.string io.encodings.utf16 kernel math
math.functions sequences splitting strings ;
IN: io.encodings.utf7
TUPLE: utf7codec dialect buffer ;
! These words encodes the difference between standard utf7 and the
! dialect used by IMAP which wants slashes replaced with commas when
! encoding and uses '&' instead of '+' as the escaping character.
: utf7 ( -- utf7codec )
{
{ { } { } }
{ { CHAR: + } { CHAR: - } }
} V{ } utf7codec boa ;
: utf7imap4 ( -- utf7codec )
{
{ { CHAR: / } { CHAR: , } }
{ { CHAR: & } { CHAR: - } }
} V{ } utf7codec boa ;
: >raw-base64 ( bytes -- bytes' )
>string utf16be encode >base64 [ CHAR: = = ] trim-tail ;
: raw-base64> ( str -- str' )
dup length 4 / ceiling 4 * CHAR: = pad-tail base64> utf16be decode ;
: encode-chunk ( repl-pair surround-pair chunk ascii? -- bytes )
[ swap [ first ] [ concat ] bi replace nip ]
[ >raw-base64 -rot [ first2 replace ] [ first2 surround ] bi* ] if ;
: encode-utf7-string ( str codec -- bytes )
[ [ printable? ] group-by ] dip
dialect>> first2 '[ _ _ rot first2 swap encode-chunk ] map
B{ } concat-as ;
M: utf7codec encode-string ( str stream codec -- )
swapd encode-utf7-string swap stream-write ;
DEFER: emit-char
: decode-chunk ( dialect -- ch buffer )
dup first2 swap [ second read-until drop ] [ first2 swap replace ] bi*
[ second first first { } ] [ raw-base64> emit-char ] if-empty ;
: fill-buffer ( dialect -- ch buffer )
dup second first first read1 dup swapd = [
drop decode-chunk
] [ nip { } ] if ;
: emit-char ( dialect buffer -- ch buffer' )
[ fill-buffer ] [ nip unclip swap ] if-empty ;
: replace-all! ( src dst -- )
[ delete-all ] keep push-all ;
M: utf7codec decode-char ( stream codec -- char/f )
swap [
[ dialect>> ] [ buffer>> ] bi [ emit-char ] keep replace-all!
] with-input-stream ;