11.51 srfi.207 - 文字列表示のバイトベクタ ¶

Module: srfi.207 ¶

このSRFIはバイトベクタの別形式の外部表現を定義し、 バイトベクタをバイト列(bytestring)として扱える多くの手続きを提供します。

Gaucheはバイトベクタの「文字列」表現を組み込みでサポートしています。 リーダーは、数値形式(例: #u(65 66 67 68))、 文字列形式(例: #u8"ABCD")、のどちらでも読むことができます。 ライターはデフォルトで数値形式を使いますが、 <write-controls>のbytestringスロットを真にすると 文字列形式を使うようになります。

gosh> #u8(65 66 67 68)
#u8(65 66 67 68)
gosh> ,pm bytestring #t
Current print mode:
       length :  50           base :  10  exact-decimal :  #f
        level :  10   radix-prefix :  #f          array : compact
       pretty :  #t  string-length : 256        complex : rectangular
        width :  79     bytestring :  #t
gosh> #u8(65 66 67 68)
#u8"ABCD"

Function: bytestring arg … ¶

[SRFI-207]{srfi.207} 各引数はそれぞれ以下のいずれかでなければなりません。 手続きは与えられた引数を全部つなげた新たなバイトベクタを作って返します。

• 0から255までの間の整数
• ASCII文字
• バイトベクタ
• ASCII文字列

上記以外のオブジェクトが引数に与えられた場合はエラーが投げられます。

(bytestring "lor" #\r #\x65 #u8(#x6d))
  ⇒ #u8(108 111 114 114 101 109)  ; #u8"lorrem"

Function: make-bytestring lis ¶

[SRFI-207]{srfi.207} lisの要素をつなげた内容を持つバイトベクタを作って返します。 lisの各要素は、0以上255以下の正確な整数、ASCII文字、 バイトベクタ、あるいはASCII文字列のいずれかでなければなりません。 実質的には(apply bytestring lis)と同じです。

Function: make-bytestring! bv at lis ¶

[SRFI-207]{srfi.207} バイトベクタbvの、インデックスat以降を、 lisの要素で埋めます。 lisの各要素は、0以上255以下の正確な整数、ASCII文字、 バイトベクタ、あるいはASCII文字列のいずれかでなければなりません。

戻り値は未定義です。

(rlet1 bv (make-u8vector 10)
  (make-bytestring! bv 1 '("ab" #\c #u8"de")))
  ⇒ #u8(0 97 98 99 100 101 0 0 0 0)

Function: bytevector->hex-string bv ¶

Function: hex-string->bytevector string ¶

[SRFI-207]{srfi.207} それぞれ、バイトベクタと十六進数文字列とを相互に変換します。

hex-string->bytevectorが、引数中に十六進数と解釈できない 文字に出会った場合は、bytestring-error?を満たすコンディションが投げられます。

(bytevector->hex-string #u8"aloha")
  ⇒ "616c6f6861"
(hex-string->bytevector "616C6F6861")
  ⇒ #u8(97 108 111 104 97)  ; #u8"aloha"

Function: bytevector->base64 bv :optional digits ¶

Function: base64->bytevector string :optional digits ¶

[SRFI-207]{srfi.207} それぞれ、バイトベクタとBase64文字列とを相互に変換します。

hex-string->bytevectorが、引数がBase64と解釈できない 場合は、bytestring-error?を満たすコンディションが投げられます。 但し、空白文字は許されて、それは単に無視されます。

デフォルトでは標準のBase64マッピングが使われます。 マッピングの62と63に使う代わりの文字を、2文字のASCII文字列列として digitsに渡すことで、それらの文字のマッピングを変更できます。 いわゆる「URL安全」なBase64バリエーションを使うには、 "-_"をdigitsに渡します。

Gauche特有のBase64ライブラリには他のAPIも提供されています。 rfc.base64 - Base64エンコーディングを参照してください。

Function: bytestring->list bv :optional start end ¶

[SRFI-207]{srfi.207} Converts each element of a bytevector bv to either a character (if the element is an integer between 32 and 127, inclusive) or an integer, and returns a list of converted elements. If you pass the resulting list to make-bytestring, you can obtain the same bytevector as bv.

If you pass the optional start and end indexes, only the specified range of bv is considered.

Function: make-bytestring-generator arg … ¶

[SRFI-207]{srfi.207} Returns a generator that works as the same as (uvector->generator (bytestring arg …)), but this can skip creating intermediate bytestrings.

Function: bytestring-pad bv len char-or-u8 ¶

Function: bytestring-pad-right bv len char-or-u8 ¶

[SRFI-207]{srfi.207} Returns a newly allocated bytevector of at least len long. If bv is shorter than len, the rest is padded with char-or-u8 (which can be either an ASCII character or an exact integer between 0 and 255). The pad is added to the left with bytestring-pad, and to the right with bytestring-pad-right.

This is a bytestring version of string-pad and string-pad-right (see 文字列の選択).

Function: bytestring-trim bv pred ¶

Function: bytestring-trim-right bv pred ¶

Function: bytestring-trim-both bv pred ¶

[SRFI-207]{srfi.207} Remove octets that satisfies pred at the beginning / at the end / at both ends of a bitvector bv. The procedure pred receives an exact integer between 0 and 255.

They always return a fresh bytevector, even when no octets are trimmed.

This is a bytestring version of string-trim, string-trim-right, and string-trim-both (see 文字列の選択).

Function: bytrestring-replace bv1 bv2 start1 end1 :optional start2 end2 ¶

[SRFI-207]{srfi.207} Returns a new bytevector whose content is a copy of a bytevector bv1, except the part beginning from the index start1 (inclusive) and ending at the index end1 (exclusive) is replaced by a byvetvector bv2. When optional start2 and end2 arguments are given, bv2 is trimmed first accordingly. The size of the gap, (- end1 start1), doesn’t need to be the same as the size of the inserted bytevector. Effectively, this is the same as the following code.

(bytevector-append (subseq bv1 0 start1)
                   (subseq bv2 start2 end2)
                   (subseq bv1 end1 (bytevector-length bv1)))

This is a bytestring version of string-replace (see 他の文字列操作).

Function: bytestring<? bv1 bv2 ¶

Function: bytestring<=? bv1 bv2 ¶

Function: bytestring>? bv1 bv2 ¶

Function: bytestring>=? bv1 bv2 ¶

[SRFI-207]{srfi.207} Compare two bytevectors lexicographically. These are bytestring version of string<? (see 文字列の色々な比較).

There’s no bytestring=?, for you can check equality of bytevectors by bytevector=? in scheme.bytevector and gauche.uvector (see バイトベクタ互換性).

Note that bytevector-comparator compares bytevectors differently. The comparator first compares the lengths, and only uses elements when both vectors are of the same length (see 用意されている比較器).

(bytestring<? #u8"abc" #u8"ac") ⇒ #t
(<? bytevector-comparator #u8"abc" #u8"ac") ⇒ #f

This contrasts SRFI-207’s view of bytevectors as a string of bytes, with the view of them as an array of bytes.

Function: bytestring-index bv pred :optional start end ¶

Function: bytestring-index-right bv pred :optional start end ¶

[SRFI-207]{srfi.207} Returns the first or last index of the octet that satisfies pred in a bytevector bv. The optional start and end arguments limit the range to search.

These are bytestring version of string-index and string-index-right (see 文字列の探索).

Function: bytestring-break bv pred ¶

Function: bytestring-span bv pred ¶

[SRFI-207]{srfi.207} Returns two bytevectors, the first one is a maximum prefix of bv whose element does not / does satisfy pred, and the second one is the rest of bv.

(bytestring-break #u8"abracadabra" (cut = <> 100))
 ⇒ #u8(97 98 114 97 99 97) and #u8(100 97 98 114 97)
(bytestring-span #u8(1 2 3 4 5 4 3 2 1) (cut < <> 5))
 ⇒ #u8(1 2 3 4) and #u8(5 4 3 2 1)

Function: bytestring-join bv-list delim :optional grammar ¶

[SRFI-207]{srfi.207} Given list of bytevectors bv-list, concatenates the bytevectors with a delimiter delim, which can be an exact integer between 0 and 255 inclusive, an ASCII character, a bytevector or a string of ASCII characters.

The grammar argument must be one of the symbols infix, strict-infix, suffix, and prefix, as in string-join (see 文字列を扱うその他の手続き). The difference between infix and strict-infix is that the former allows to join zero byvectors (returns #u8()), while the latter raises an error when bv-list is empty. When omitted, infix is assumed.

(bytestring-join '(#u8"a" #u8"b" #u8"c") 0) ⇒ #u8(97 0 98 0 99)
(bytestring-join '(#u8"a" #u8"b" #u8"c") 0 'prefix) ⇒ #u8(0 97 0 98 0 99)
(bytestring-join '(#u8"a" #u8"b" #u8"c") 0 'suffix) ⇒ #u8(97 0 98 0 99 0)

Function: bytestring-split bv delim :optional grammar ¶

[SRFI-207]{srfi.207} Split a bytevector bv with delim, which must be either an exact integer between 0 and 255 inclusive or an ASCII character, and returns a list of bytevectors. Delimiters themselves are not included in the result.

The grammar argument is, if given, either one of the symbols infix, strict-infix, prefix, or suffix, similar to bytestring-join. If it is prefix/suffix, the preceding/succeeding delim is ignored, if any. There are no difference between infix and strict-infix. The default is infix.

(bytestring-split #u8"abracadabra" #\a)
 ⇒ (#u8() #u8(98 114) #u8(99) #u8(100) #u8(98 114) #u8())
(bytestring-split #u8"abracadabra" #\a 'prefix)
 ⇒ (#u8(98 114) #u8(99) #u8(100) #u8(98 114) #u8())
(bytestring-split #u8"abracadabra" #\a 'suffix)
 ⇒ (#u8() #u8(98 114) #u8(99) #u8(100) #u8(98 114))

Function: read-textual-bytestring prefix :optional port ¶

[SRFI-207]{srfi.207} This parses a textual representation of a bytestring read from port (defaults to the current input port) and returns a bytevector. If prefix is false, it assumes the preceding "#u8" has already been read. If the input can’t be parsed as a valid textual representation of a bytestring, an error satisfying bytestring-error? is raised.

(with-input-from-string "#u8\"abc\\x80;\"" (cut read-textual-bytestring #t))
  ⇒ #u8(97 98 99 128)

Function: write-textual-bytestring bv :optional port ¶

[SRFI-207]{srfi.207} Writes a bytevector bv in the textual representation to port (defaults to the current output port).

(write-textual-bytestring #u8(65 66 128 255 0))
 ⇒ prints #u8"AB\x80;\xff;\x00;"

Function: write-binary-bitestring port arg … ¶

[SRFI-207]{srfi.207}

Works like (write-textual-bytestring (bytestring arg ...) port),
but without creating the intermediate bytevector.
If any arguments are invalid to construct a bytevector, an error
satisfying bytestring-error? signaled.

Function: bytestring-error? obj ¶

[SRFI-207]{srfi.207} Returns #t if obj is a condition thrown from bytestring operations.