"{ Package: 'stx:libbasic' }"

"{ NameSpace: CharacterEncoderImplementations }"

TwoByteEncoder subclass:#JIS0208_to_JIS7

	instanceVariableNames:''

	classVariableNames:'Jis7KanjiEscapeSequence Jis7RomanEscapeSequence

		JisISO2022EscapeSequence Jis7KanjiOldEscapeSequence'

	poolDictionaries:''

	category:'Collections-Text-Encodings'

!

!JIS0208_to_JIS7 class methodsFor:'documentation'!

examples

"

  Encoding (jis0208 to jis-7)

     |t|

     t := JIS0208_to_JIS7 decodeString:'hello'.

     JIS0208_to_JIS7 encodeString:t. 

 Decoding (jis-7 to jis0208):

     JIS0208_to_JIS7 decodeString:'hello'  

 ending with a crippled escape:

     |s|

     s := 'hello' copyWith:Character esc.

     JIS0208_to_JIS7 decodeString:s

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$A.

     JIS0208_to_JIS7 decodeString:s

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$$.

     JIS0208_to_JIS7 decodeString:s

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$$.

     s := s copyWith:$A.

     JIS0208_to_JIS7 decodeString:s

 ending with a KANJI-in,  but no more chars:

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$$.

     s := s copyWith:$B.

     JIS0208_to_JIS7 decodeString:s

 ending with a KANJI-in, followed by $3 (KO):

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$$.

     s := s copyWith:$B.

     s := s , '$3'.

     JIS0208_to_JIS7 decodeString:s

 ending with a KANJI-in, followed by $3$l$OF| (KO RE HA NI):

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$$.

     s := s copyWith:$B.

     s := s , '$3$l$OF|'.

     JIS0208_to_JIS7 decodeString:s

 a KO in between:

     |s|

     s := 'hello' copyWith:Character esc.

     s := s copyWith:$$.

     s := s copyWith:$B.

     s := s , '$3'.

     s := s copyWith:Character esc.

     s := s copyWith:$(.

     s := s copyWith:$B.

     s := s , 'hello'.

     JIS0208_to_JIS7 decodeString:s

 I dont know what that means ;-):

     |s t l|

     s := 'kterm ' copyWith:Character esc.

     s := s copyWith:$$.

     s := s copyWith:$B.

     s := s , '$N4A;zC<Kv%(%_%e%l!!<%?'.

     s := s copyWith:Character esc.

     s := s copyWith:$(.

     s := s copyWith:$B.

     s := s , ' kterm'.

     t := JIS0208_to_JIS7 decodeString:s.

     l := Label new.

     l label:t.

     l font:(Font family:'k14' face:nil style:nil size:nil).

     l font:(Font family:'gothic' size:17).

     l font:(Font family:'mincho' size:23).

     l realize

"

! !

!JIS0208_to_JIS7 class methodsFor:'constants'!

jis7KanjiEscapeSequence

    "return the escape sequence used to switch to kanji in jis7 encoded strings.

     This happens to be the same as ISO2022-JP's escape sequence."

    Jis7KanjiEscapeSequence isNil ifTrue:[

	Jis7KanjiEscapeSequence := Character esc asString , '$B'.

    ].

    ^ Jis7KanjiEscapeSequence.

    "Created: 26.2.1996 / 17:38:08 / cg"

    "Modified: 30.6.1997 / 16:03:16 / cg"

!

jis7RomanEscapeSequence

    "return the escape sequence used to switch to roman in jis7 encoded strings"

    Jis7RomanEscapeSequence isNil ifTrue:[

	Jis7RomanEscapeSequence := Character esc asString , '(J'.

    ].

    ^ Jis7RomanEscapeSequence.

    "Created: 26.2.1996 / 17:38:08 / cg"

    "Modified: 30.6.1997 / 16:03:16 / cg"

!

jisISO2022EscapeSequence

    "return the escape sequence used to switch to kanji in iso2022 encoded strings"

    JisISO2022EscapeSequence isNil ifTrue:[

        JisISO2022EscapeSequence := Character esc asString , '&@' , Character esc asString , '$B'.

    ].

    ^ JisISO2022EscapeSequence.

! !

!JIS0208_to_JIS7 class methodsFor:'queries'!

nameOfDecodedCode

    "I encode jis0208 into jis7 and vice versa"

    ^ #'jis0208'

!

nameOfEncoding

    "I encode jis0208 into jis7 and vice versa"

    ^ #'jis7'

!

namesOfEncoding

    "I encode jis0208 into jis7 and vice versa"

    ^ #( 'jis7' 'jis-7' 'x-jis7' 'x-iso2022-jp' 'iso2022-jp')

! !

!JIS0208_to_JIS7 methodsFor:'encoding & decoding'!

decode:aCode

    self shouldNotImplement "/ no single byte conversion possible

!

decodeString:aString

    "given a string in JIS7 encoding,

     return a new string containing the same characters, in JIS0208 encoding.

     The argument is interpreted as a JIS7 or ISO2022-JP encoded singleByte string.

     There are various JIS encodings around (New-JIS, Old-JIS, NEC-JIS and ISO2022);

     this one understands New-JIS, ISO2022 and treats Old-JIS just the same.

     This conversion is only needed to convert strings as read from some external file.

     If you work a lot with jis7 encoded textFiles, 

     this is a first-class candidate for a primitive."

    |newString 

     sz         "{ Class: SmallInteger }"

     dstIdx     "{ Class: SmallInteger }"

     start      "{ Class: SmallInteger }"

     stop       "{ Class: SmallInteger }"

     n1 n2 n3  

     b1         "{ Class: SmallInteger }"

     b2         "{ Class: SmallInteger }"

     val        "{ Class: SmallInteger }"

     singleBytes katakana c|

    sz := aString size.

    newString := JISEncodedString new:sz.

    sz ~~ 0 ifTrue:[

        dstIdx := 1.

        start := 1.

        singleBytes := true.

        katakana := false.

        [true] whileTrue:[

            "/

            "/ scan for next escape"

            "/

            stop := aString indexOf:(Character esc) startingAt:start.

            stop == 0 ifTrue:[

                stop := sz + 1.

            ] ifFalse:[

                (stop + 2) > sz ifTrue:[

                    stop := sz + 1.

                ]

            ].

            singleBytes ifTrue:[

                start to:(stop - 1) do:[:i |

                    c := aString at:i.

                    newString at:dstIdx put:c.

                    dstIdx := dstIdx + 1.

                ].

            ] ifFalse:[

                start to:(stop - 2) by:2 do:[:i |

                    val := (b1 bitShift:8) bitOr:b2.

                    newString at:dstIdx put:(Character value:val).

                    dstIdx := dstIdx + 1.

                ]

            ].

            stop > sz ifTrue:[

                ^ newString copyFrom:1 to:dstIdx - 1.

            ].

            start := stop.

            "/

            "/ found an escape (at start) 

            "/ - check for KI (<ESC> '$' 'B') or OLD-JIS-KI (<ESC> '$' '@')

            "/ and KO(ASCII) (<ESC> '(' 'B') or KO(ROMAN) (<ESC> '(' 'J')

            "/

            n1 := aString at:start.

            n2 := aString at:(start + 1).

            n3 := aString at:(start + 2).

            katakana := false.

            (n2 == $$ and:[n3 == $B ]) ifTrue:[

                singleBytes := false.

            ] ifFalse:[

                (n2 == $$ and:[n3 == $@ ]) ifTrue:[

                    singleBytes := false.

                ] ifFalse:[

                    (n2 == $( and:[n3 == $B ]) ifTrue:[

                        singleBytes := true.

                    ] ifFalse:[

                        (n2 == $( and:[n3 == $J ]) ifTrue:[

                            singleBytes := true.

                        ] ifFalse:[

                            (n2 == $( and:[n3 == $I ]) ifTrue:[

                                singleBytes := true.

                                katakana := true.

                            ] ifFalse:[

                                singleBytes ifTrue:[

                                    newString at:dstIdx put:n1.

                                    newString at:(dstIdx + 1) put:n2.

                                    newString at:(dstIdx + 2) put:n3.

                                    dstIdx := dstIdx + 3.

                                ] ifFalse:[

                                    DecodingError 

                                            raiseWith:aString

                                            errorString:'JIS7 decoding failed (not JIS7 encoded ?)'.

                                    newString at:dstIdx put:n1.

                                    newString at:(dstIdx + 1) put:n2.

                                    newString at:(dstIdx + 2) put:n3.

                                    dstIdx := dstIdx + 3.

                                ]

                            ]

                        ]

                    ]

                ]

            ].

            start := start + 3.

            start > sz ifTrue:[

                ^ newString copyFrom:1 to:dstIdx-1.

            ]

        ]

    ].

    ^ newString

!

encode:aCode

    self shouldNotImplement "/ no single byte conversion possible

!

encodeString:aJISString

    "return a new string with aJISStrings characters as JIS7 encoded 7bit string,

     The receiver must be a JIS encoded character string.

     The resulting string is only useful to be stored on some external file,

     not for being used inside ST/X.

     If you work a lot with jis7 encoded textFiles, 

     this is a first-class candidate for a primitive."

    |sz "{ Class:SmallInteger }"

     b1 "{ Class:SmallInteger }"

     val romans out inSingleByteMode c kanji roman val2|

    inSingleByteMode := true.

    kanji := self class jis7KanjiEscapeSequence.

    roman := self class jis7RomanEscapeSequence.

    romans := CharacterEncoder::JIS0208 romanTable.

    sz := aJISString size.

    sz == 0 ifTrue:[^ ''].

    out := WriteStream on:(String new:(sz * 2)).

    1 to:sz do:[:srcIndex |

"/                    b1 >= 160 ifTrue:[

"/                        ('no rep for ' , b1 printString) printNL.

"/                    ].

"/                    EncodingFailedError

"/                        raiseWith:aJISString

"/                        errorString:'JIS7 encoding failed (contains 8-bit characters ?)'.

    ].

    inSingleByteMode ifFalse:[

    ].

    ^ out contents

    "simple:

     JIS0208_to_JIS7 encodeString:(JISEncodedString encodeRomans:'hello')

    "

! !

!JIS0208_to_JIS7 class methodsFor:'documentation'!

version

! !