21.4. Bulk Input and Output

21.4.1. Bulk Input
21.4.2. Bulk Output
21.4.3. Rationale

21.4.1. Bulk Input

In addition to READ-SEQUENCE, the following two functions are provided:

EXT:READ-BYTE-SEQUENCE performs multiple READ-BYTE operations:

(EXT:READ-BYTE-SEQUENCE sequence stream &KEY :START :END :NO-HANG :INTERACTIVE) fills the subsequence of sequence specified by :START and :END with INTEGERs consecutively read from stream. It returns the index of the first element of sequence that was not updated (= end or < end if the stream reached its end). When no-hang is non-NIL, it does not block: it treats input unavailability as end-of-stream. When no-hang is NIL and interactive is non-NIL, it can block for reading the first byte but does not block for any further bytes.

This function is especially efficient if sequence is a (VECTOR (UNSIGNED-BYTE 8)) and stream is a file/pipe/socket STREAM with STREAM-ELEMENT-TYPE (UNSIGNED-BYTE 8).

EXT:READ-CHAR-SEQUENCE performs multiple READ-CHAR operations:

(EXT:READ-CHAR-SEQUENCE sequence stream &KEY :START :END) fills the subsequence of sequence specified by :START and :END with characters consecutively read from stream. It returns the index of the first element of sequence that was not updated (= end or < end if the stream reached its end).

This function is especially efficient if sequence is a STRING and stream is a file/pipe/socket STREAM with STREAM-ELEMENT-TYPE CHARACTER or an input STRING-STREAM.

21.4.2. Bulk Output

In addition to WRITE-SEQUENCE, the following two functions are provided:

EXT:WRITE-BYTE-SEQUENCE performs multiple WRITE-BYTE operations:

(EXT:WRITE-BYTE-SEQUENCE sequence stream &KEY :START :END :NO-HANG :INTERACTIVE) outputs the INTEGERs of the subsequence of sequence specified by :START and :END to stream. When no-hang is non-NIL, does not block. When no-hang is NIL and interactive is non-NIL, it can block for writing the first byte but does not block for any further bytes. Returns two values: sequence and the index of the first byte that was not output.

This function is especially efficient if sequence is a (VECTOR (UNSIGNED-BYTE 8)) and stream is a file/pipe/socket STREAM with STREAM-ELEMENT-TYPE (UNSIGNED-BYTE 8).

EXT:WRITE-CHAR-SEQUENCE performs multiple WRITE-CHAR operations:

(EXT:WRITE-CHAR-SEQUENCE sequence stream &KEY :START :END) outputs the characters of the subsequence of sequence specified by :START and :END to stream. Returns the sequence argument.

This function is especially efficient if sequence is a STRING and stream is a file/pipe/socket STREAM with STREAM-ELEMENT-TYPE CHARACTER.

21.4.3. Rationale

The rationale for EXT:READ-CHAR-SEQUENCE, EXT:READ-BYTE-SEQUENCE, EXT:WRITE-CHAR-SEQUENCE and EXT:WRITE-BYTE-SEQUENCE is that some STREAMs support both character and binary i/o, and when you read into a SEQUENCE that can hold both (e.g., LIST or SIMPLE-VECTOR) you cannot determine which kind of input to use. In such situation READ-SEQUENCE and WRITE-SEQUENCE SIGNAL an ERROR, while EXT:READ-CHAR-SEQUENCE, EXT:READ-BYTE-SEQUENCE, EXT:WRITE-CHAR-SEQUENCE and EXT:WRITE-BYTE-SEQUENCE work just fine.


These notes document CLISP version 2.49+Last modified: 2016-09-05