"

 COPYRIGHT (c) 2004 by eXept Software AG

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

"{ Package: 'stx:libbasic' }"

"{ NameSpace: CharacterEncoderImplementations }"

TwoByteEncoder subclass:#ISO10646_to_UTF8

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Collections-Text-Encodings'

!

!ISO10646_to_UTF8 class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 2004 by eXept Software AG

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

examples

"

  Encoding (unicode to utf8)

     ISO10646_to_UTF8 encodeString:'hello'.

  Decoding (utf8 to unicode):

     |t|

     t := ISO10646_to_UTF8 encodeString:'Helloś'.

     ISO10646_to_UTF8 decodeString:t.

"

! !

!ISO10646_to_UTF8 methodsFor:'encoding & decoding'!

decode:aCode

    self shouldNotImplement "/ no single byte conversion possible

!

decodeString:aStringOrByteCollection

    "given a string in UTF8 encoding,

     return a new string containing the same characters, in 16bit (or more) encoding.

     Returns either a normal String, a TwoByteString or a FourByteString instance.

     Only useful, when reading from external sources.

     This only handles up-to 30bit characters.

     If you work a lot with utf8 encoded textFiles,

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

    |sz anyAbove7BitAscii nBitsRequired

     ascii "{ Class: SmallInteger }"

     byte  "{ Class: SmallInteger }"

     s newString idx next6Bits last6Bits

     errorReporter|

    "/ avoid creation of new strings

    aStringOrByteCollection isString ifTrue:[

        aStringOrByteCollection contains8BitCharacters ifFalse:[^ aStringOrByteCollection].

    ].

    next6Bits := [

                    | byte |

                    byte := s nextByte.

                    byte isNil ifTrue:[^ errorReporter value:'short utf8 string'].

                    ascii := (ascii bitShift:6) bitOr:(byte bitAnd:2r00111111).

                    (byte bitAnd:2r11000000) ~~ 2r10000000 ifTrue:[

                        ^ errorReporter value:'illegal followbyte'.].

                 ].

    last6Bits := [

                    | a byte |

                    byte := s nextByte.

                    byte isNil ifTrue:[^ errorReporter value:'short utf8 string'].

                    a := (ascii bitShift:6) bitOr:(byte bitAnd:2r00111111).

                    (a > 16r3FFFFFFF) ifTrue:[

                        "/ ST/X can only represent 30 bit unicode characters.

                        errorReporter value:'unicode character out of range'.

                        a := 16r3FFFFFFF.

                    ].

                    ascii := a.

                    (byte bitAnd:2r11000000) ~~ 2r10000000 ifTrue:[

                        ^ errorReporter value:'illegal followbyte'.].

                 ].

    nBitsRequired := 8.

    anyAbove7BitAscii := false.

    sz := 0.

    s := aStringOrByteCollection readStream.

    [s atEnd] whileFalse:[

        byte := ascii := s nextByte.

        (byte bitAnd:16r80) ~~ 0 ifTrue:[

            anyAbove7BitAscii := true.

            (byte bitAnd:2r11100000) == 2r11000000 ifTrue:[

                "/ 80 .. 7FF

                ascii := (byte bitAnd:2r00011111).

                next6Bits value.

                ascii > 16rFF ifTrue:[

                    nBitsRequired := nBitsRequired max:16

                ].

                "/ a strict utf8 decoder does not allow overlong sequences

                ascii < 16r80 ifTrue:[

                    errorReporter value:'overlong utf8 sequence'

                ].

            ] ifFalse:[

                (byte bitAnd:2r11110000) == 2r11100000 ifTrue:[

                    "/ 800 .. FFFF

                    ascii := (byte bitAnd:2r00001111).

                    next6Bits value.

                    next6Bits value.

                    ascii > 16rFF ifTrue:[

                        nBitsRequired := nBitsRequired max:16

                    ].

                    ascii < 16r800 ifTrue:[

                        errorReporter value:'overlong utf8 sequence'

                    ].

                ] ifFalse:[

                    (byte bitAnd:2r11111000) == 2r11110000 ifTrue:[

                        "/ 10000 .. 1FFFFF

                        ascii := (byte bitAnd:2r00000111).

                        next6Bits value.

                        next6Bits value.

                        next6Bits value.

                        ascii > 16rFF ifTrue:[

                            ascii > 16rFFFF ifTrue:[

                                nBitsRequired := nBitsRequired max:32

                            ] ifFalse:[

                                nBitsRequired := nBitsRequired max:16

                            ]

                        ].

                        ascii < 16r10000 ifTrue:[

                            errorReporter value:'overlong utf8 sequence'

                        ].

                    ] ifFalse:[

                        (byte bitAnd:2r11111100) == 2r11111000 ifTrue:[

                            "/ 200000 .. 3FFFFFF

                            ascii := (byte bitAnd:2r00000011).

                            next6Bits value.

                            next6Bits value.

                            next6Bits value.

                            next6Bits value.

                            ascii > 16rFF ifTrue:[

                                ascii > 16rFFFF ifTrue:[

                                    nBitsRequired := nBitsRequired max:32

                                ] ifFalse:[

                                    nBitsRequired := nBitsRequired max:16

                                ]

                            ].

                            ascii < 200000 ifTrue:[

                                errorReporter value:'overlong utf8 sequence'

                            ].

                        ] ifFalse:[

                            (byte bitAnd:2r11111110) == 2r11111100 ifTrue:[

                                "/ 4000000 .. 7FFFFFFF

                                ascii := (byte bitAnd:2r00000001).

                                next6Bits value.

                                next6Bits value.

                                next6Bits value.

                                next6Bits value.

                                last6Bits value.

                                ascii > 16rFF ifTrue:[

                                    ascii > 16rFFFF ifTrue:[

                                        nBitsRequired := nBitsRequired max:32

                                    ] ifFalse:[

                                        nBitsRequired := nBitsRequired max:16

                                    ]

                                ].

                                ascii < 16r4000000 ifTrue:[

                                    errorReporter value:'overlong utf8 sequence'

                                ].

                            ] ifFalse:[

                                errorReporter value:'invalid utf8 encoding'

                            ]

                        ]

                    ]

                ]

            ].

        ].

        sz := sz + 1.

    ].

    nBitsRequired == 8 ifTrue:[

        anyAbove7BitAscii ifFalse:[

            "/ can return the original string

            aStringOrByteCollection isString ifTrue:[^ aStringOrByteCollection].

        ].

        newString := String uninitializedNew:sz

    ] ifFalse:[

        nBitsRequired <= 16 ifTrue:[

            newString := Unicode16String new:sz

        ] ifFalse:[

            newString := Unicode32String new:sz

        ]

    ].

    next6Bits := [

                    |byte|

                    byte := s nextByte.

                    ascii := (ascii bitShift:6) bitOr:(byte bitAnd:2r00111111).

                 ].

    s := aStringOrByteCollection readStream.

    idx := 1.

    [s atEnd] whileFalse:[

        byte := ascii := s nextByte.

        (byte bitAnd:2r10000000) ~~ 0 ifTrue:[

            (byte bitAnd:2r11100000) == 2r11000000 ifTrue:[

                ascii := (byte bitAnd:2r00011111).

                next6Bits value.

            ] ifFalse:[

                (byte bitAnd:2r11110000) == 2r11100000 ifTrue:[

                    ascii := (byte bitAnd:2r00001111).

                    next6Bits value.

                    next6Bits value.

                ] ifFalse:[

                    (byte bitAnd:2r11111000) == 2r11110000 ifTrue:[

                        ascii := (byte bitAnd:2r00000111).

                        next6Bits value.

                        next6Bits value.

                        next6Bits value.

                    ] ifFalse:[

                        (byte bitAnd:2r11111100) == 2r11111000 ifTrue:[

                            ascii := (byte bitAnd:2r00000011).

                            next6Bits value.

                            next6Bits value.

                            next6Bits value.

                            next6Bits value.

                        ] ifFalse:[

                            (byte bitAnd:2r11111110) == 2r11111100 ifTrue:[

                                ascii := (byte bitAnd:2r00000001).

                                next6Bits value.

                                next6Bits value.

                                next6Bits value.

                                next6Bits value.

                                last6Bits value.

                            ]

                        ]

                    ]

                ]

            ].

        ].

        newString at:idx put:(Character value:ascii).

        idx := idx + 1.

    ].

    ^ newString

    "

     CharacterArray fromUTF8Bytes:#[ 16r41 16r42 ]

     CharacterArray fromUTF8Bytes:#[ 16rC1 16r02 ]

     CharacterArray fromUTF8Bytes:#[ 16rE0 16r81 16r02 ]

     CharacterArray fromUTF8Bytes:#[ 16rEF 16rBF 16rBF ]

   rfc2279 examples:

     CharacterArray fromUTF8Bytes:#[ 16r41 16rE2 16r89 16rA2 16rCE 16r91 16r2E ]

     CharacterArray fromUTF8Bytes:#[ 16rED 16r95 16r9C 16rEA 16rB5 16rAD 16rEC 16r96 16rB4 ]

     CharacterArray fromUTF8Bytes:#[ 16rE6 16r97 16rA5 16rE6 16r9C 16rAC 16rE8 16rAA 16r9E ]

   invalid:

     CharacterArray fromUTF8Bytes:#[ 16rC0 16r80 ]

     CharacterArray fromUTF8Bytes:#[ 16rE0 16r80 16r80 ]

    "

!

encode:aCode

    self shouldNotImplement "/ no single byte conversion possible

!

encodeString:aUnicodeString

    "return the UTF-8 representation of a aUnicodeString.

     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 utf8 encoded textFiles,

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

    |s|

    "/ avoid creation of new strings

    aUnicodeString contains8BitCharacters ifFalse:[^ aUnicodeString].

    s := WriteStream on:(String uninitializedNew:aUnicodeString size).

    aUnicodeString do:[:eachCharacter |

        |codePoint b1 b2 b3 b4 b5 v "{Class: SmallInteger }"|

        codePoint := eachCharacter codePoint.

        codePoint <= 16r7F ifTrue:[

            s nextPut:eachCharacter.

        ] ifFalse:[

            b1 := Character value:((codePoint bitAnd:16r3F) bitOr:2r10000000).

            v := codePoint bitShift:-6.

            v <= 16r1F ifTrue:[

                s nextPut:(Character value:(v bitOr:2r11000000)).

                s nextPut:b1.

            ] ifFalse:[

                b2 := Character value:((v bitAnd:16r3F) bitOr:2r10000000).

                v := v bitShift:-6.

                v <= 16r0F ifTrue:[

                    s nextPut:(Character value:(v bitOr:2r11100000)).

                    s nextPut:b2; nextPut:b1.

                ] ifFalse:[

                    b3 := Character value:((v bitAnd:16r3F) bitOr:2r10000000).

                    v := v bitShift:-6.

                    v <= 16r07 ifTrue:[

                        s nextPut:(Character value:(v bitOr:2r11110000)).

                        s nextPut:b3; nextPut:b2; nextPut:b1.

                    ] ifFalse:[

                        b4 := Character value:((v bitAnd:16r3F) bitOr:2r10000000).

                        v := v bitShift:-6.

                        v <= 16r03 ifTrue:[

                            s nextPut:(Character value:(v bitOr:2r11111000)).

                            s nextPut:b4; nextPut:b3; nextPut:b2; nextPut:b1.

                        ] ifFalse:[

                            b5 := Character value:((v bitAnd:16r3F) bitOr:2r10000000).

                            v := v bitShift:-6.

                            v <= 16r01 ifTrue:[

                                s nextPut:(Character value:(v bitOr:2r11111100)).

                                s nextPut:b5; nextPut:b4; nextPut:b3; nextPut:b2; nextPut:b1.

                            ] ifFalse:[

                                "/ cannot happen - we only support up to 30 bit characters

                                self error:'ascii value > 31bit in utf8Encode'.

                            ]

                        ].

                    ].

                ].

            ].

        ].

    ].

    ^ s contents

    "

     (self encodeString:'hello') asByteArray                             #[104 101 108 108 111]

     (self encodeString:(Character value:16r40) asString) asByteArray    #[64]

     (self encodeString:(Character value:16r7F) asString) asByteArray    #[127]

     (self encodeString:(Character value:16r80) asString) asByteArray    #[194 128]

     (self encodeString:(Character value:16rFF) asString) asByteArray    #[195 191]

     (self encodeString:(Character value:16r100) asString) asByteArray   #[196 128]

     (self encodeString:(Character value:16r200) asString) asByteArray   #[200 128]

     (self encodeString:(Character value:16r400) asString) asByteArray   #[208 128]

     (self encodeString:(Character value:16r800) asString) asByteArray   #[224 160 128]

     (self encodeString:(Character value:16r1000) asString) asByteArray  #[225 128 128]

     (self encodeString:(Character value:16r2000) asString) asByteArray  #[226 128 128]

     (self encodeString:(Character value:16r4000) asString) asByteArray  #[228 128 128]

     (self encodeString:(Character value:16r8000) asString) asByteArray  #[232 128 128]

     (self encodeString:(Character value:16rFFFF) asString) asByteArray  #[239 191 191]

    "

! !

!ISO10646_to_UTF8 methodsFor:'queries'!

nameOfEncoding

    ^ #'utf8'

! !

!ISO10646_to_UTF8 class methodsFor:'documentation'!

version

! !