new vocab io.encodings.detect: borrow binary file/text encoding detection heuristics from a certain text editor written in java

db4
Joe Groff 2010-06-09 00:11:01 -07:00
parent da198f6314
commit 4997489980
4 changed files with 91 additions and 0 deletions

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Joe Groff

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! (c)2010 Joe Groff bsd license
USING: byte-arrays.hex io.encodings.8-bit.koi8-r io.encodings.detect tools.test ;
IN: io.encodings.detect.tests
! UTF encodings with BOMs
[ utf16be ] [ HEX{ FEFF 0031 0032 0033 } detect-byte-array ] unit-test
[ utf16le ] [ HEX{ FFFE 3100 3200 3300 } detect-byte-array ] unit-test
[ utf32be ] [ HEX{ 0000FEFF 00000031 00000032 00000033 } detect-byte-array ] unit-test
[ utf32le ] [ HEX{ FFFE0000 31000000 32000000 33000000 } detect-byte-array ] unit-test
[ utf8 ] [ HEX{ EF BB BF 31 32 33 } detect-byte-array ] unit-test
! XML prolog
[ utf8 ]
[ """<?xml version="1.0"?>""" >byte-array detect-byte-array ]
unit-test
[ utf8 ]
[ """<?xml version="1.0" encoding="UTF-8"?>""" >byte-array detect-byte-array ]
unit-test
[ latin1 ]
[ """<?xml version='1.0' encoding='ISO-8859-1'?>""" >byte-array detect-byte-array ]
unit-test
[ latin1 ]
[ """<?xml version='1.0' encoding="ISO-8859-1" """ >byte-array detect-byte-array ]
unit-test
! Default to utf8 if decoding succeeds and there are no nulls
[ utf8 ] [ HEX{ 31 32 33 } detect-byte-array ] unit-test
[ utf8 ] [ HEX{ 31 32 C2 A0 33 } detect-byte-array ] unit-test
[ latin1 ] [ HEX{ 31 32 A0 33 } detect-byte-array ] unit-test
[ koi8-r ] [
koi8-r default-8bit-encoding [
HEX{ 31 32 A0 33 } detect-byte-array
] with-variable
] unit-test
[ binary ] [ HEX{ 31 32 33 C2 A0 00 } detect-byte-array ] unit-test
[ binary ] [ HEX{ 31 32 33 C2 A0 00 30 } detect-byte-array ] unit-test

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! (c)2010 Joe Groff bsd license
USING: accessors byte-arrays byte-arrays.hex combinators
continuations fry io io.encodings io.encodings.8-bit.latin1
io.encodings.ascii io.encodings.binary io.encodings.iana
io.encodings.string io.encodings.utf16 io.encodings.utf32
io.encodings.utf8 io.files io.streams.string kernel literals
math namespaces sequences strings ;
IN: io.encodings.detect
SYMBOL: default-8bit-encoding
default-8bit-encoding [ latin1 ] initialize
<PRIVATE
: prolog-tag ( bytes -- string )
CHAR: > over index [ 1 + ] [ dup length ] if* head-slice >string ;
: prolog-encoding ( string -- iana-encoding )
'[
_ "encoding=" over start
10 + swap [ [ 1 - ] dip nth ] [ index-from ] [ swapd subseq ] 2tri
] [ drop "UTF-8" ] recover ;
: detect-xml-prolog ( bytes -- encoding )
prolog-tag prolog-encoding name>encoding [ ascii ] unless* ;
: valid-utf8? ( bytes -- ? )
utf8 decode 1 head-slice* replacement-char swap member? not ;
PRIVATE>
: detect-byte-array ( bytes -- encoding )
{
{ [ dup HEX{ 0000FEFF } head? ] [ drop utf32be ] }
{ [ dup HEX{ FFFE0000 } head? ] [ drop utf32le ] }
{ [ dup HEX{ FEFF } head? ] [ drop utf16be ] }
{ [ dup HEX{ FFFE } head? ] [ drop utf16le ] }
{ [ dup HEX{ EF BB BF } head? ] [ drop utf8 ] }
{ [ dup $[ "<?xml" >byte-array ] head? ] [ detect-xml-prolog ] }
{ [ 0 over member? ] [ drop binary ] }
{ [ dup valid-utf8? ] [ drop utf8 ] }
[ drop default-8bit-encoding get ]
} cond ;
: detect-stream ( stream -- sample encoding )
256 swap stream-read dup detect-byte-array ;
: detect-file ( file -- encoding )
binary [ input-stream get detect-stream nip ] with-file-reader ;

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Heuristic auto-detection of text encodings and binary files