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encode.lisp
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encode.lisp
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;;; -*- Mode: LISP; Syntax: COMMON-LISP; Package: FLEXI-STREAMS; Base: 10 -*-
;;; $Header: /usr/local/cvsrep/flexi-streams/encode.lisp,v 1.26 2008/05/26 10:55:08 edi Exp $
;;; Copyright (c) 2005-2008, Dr. Edmund Weitz. All rights reserved.
;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:
;;; * Redistributions of source code must retain the above copyright
;;; notice, this list of conditions and the following disclaimer.
;;; * Redistributions in binary form must reproduce the above
;;; copyright notice, this list of conditions and the following
;;; disclaimer in the documentation and/or other materials
;;; provided with the distribution.
;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
;;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
;;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
;;; ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
;;; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
;;; GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
;;; INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
;;; WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
(in-package :flexi-streams)
(defgeneric char-to-octets (format char writer)
(declare #.*standard-optimize-settings*)
(:documentation "Converts the character CHAR to a sequence of octets
using the external format FORMAT. The conversion is performed by
calling the unary function \(which must be a functional object) WRITER
repeatedly each octet. The return value of this function is
unspecified."))
(defgeneric write-sequence* (format stream sequence start end)
(declare #.*standard-optimize-settings*)
(:documentation "A generic function which dispatches on the external
format and does the real work for STREAM-WRITE-SEQUENCE."))
(defgeneric string-to-octets* (format string start end)
(declare #.*standard-optimize-settings*)
(:documentation "A generic function which dispatches on the external
format and does the real work for STRING-TO-OCTETS."))
(defmethod string-to-octets* :around (format (list list) start end)
(declare #.*standard-optimize-settings*)
(string-to-octets* format (coerce list 'string*) start end))
(defmacro define-sequence-writers ((format-class) &body body)
"Non-hygienic utility macro which defines methods for
WRITE-SEQUENCE* and STRING-TO-OCTETS* for the class FORMAT-CLASS. For
BODY see the docstring of DEFINE-CHAR-ENCODERS."
(let ((body `((locally
(declare #.*fixnum-optimize-settings*)
,@body))))
`(progn
(defmethod string-to-octets* ((format ,format-class) string start end)
(declare #.*standard-optimize-settings*)
(declare (fixnum start end) (string string))
(let ((octets (make-array (compute-number-of-octets format string start end)
:element-type 'octet))
(j 0))
(declare (fixnum j))
(loop for i of-type fixnum from start below end do
(macrolet ((octet-writer (form)
`(progn
(setf (aref (the (array octet *) octets) j) ,form)
(incf j))))
(symbol-macrolet ((char-getter (char string i)))
(progn ,@body))))
octets))
(defmethod write-sequence* ((format ,format-class) stream sequence start end)
(declare #.*standard-optimize-settings*)
(declare (fixnum start end))
(with-accessors ((column flexi-stream-column))
stream
(let* ((octet-seen-p nil)
(buffer-pos 0)
;; estimate should be good enough...
(factor (encoding-factor format))
;; we don't want arbitrarily large buffer, do we?
(buffer-size (min +buffer-size+ (ceiling (* factor (- end start)))))
(buffer (make-octet-buffer buffer-size))
(underlying-stream (flexi-stream-stream stream)))
(declare (fixnum buffer-pos buffer-size)
(boolean octet-seen-p)
(type (array octet *) buffer))
(macrolet ((octet-writer (form)
`(write-octet ,form)))
(labels ((flush-buffer ()
"Sends all octets in BUFFER to the underlying stream."
(write-sequence buffer underlying-stream :end buffer-pos)
(setq buffer-pos 0))
(write-octet (octet)
"Adds one octet to the buffer and flushes it if necessary."
(declare (type octet octet))
(when (>= buffer-pos buffer-size)
(flush-buffer))
(setf (aref buffer buffer-pos) octet)
(incf buffer-pos))
(write-object (object)
"Dispatches to WRITE-OCTET or WRITE-CHARACTER
depending on the type of OBJECT."
(etypecase object
(octet (setq octet-seen-p t)
(write-octet object))
(character (symbol-macrolet ((char-getter object))
,@body)))))
(macrolet ((iterate (&body output-forms)
"An unhygienic macro to implement the actual
iteration through SEQUENCE. OUTPUT-FORM is the form to retrieve one
sequence element and put its octet representation into the buffer."
`(loop for index of-type fixnum from start below end
do (progn ,@output-forms)
finally (when (plusp buffer-pos)
(flush-buffer)))))
(etypecase sequence
(string (iterate
(symbol-macrolet ((char-getter (char sequence index)))
,@body)))
(array (iterate
(symbol-macrolet ((char-getter (aref sequence index)))
,@body)))
(list (iterate (write-object (nth index sequence))))))
;; update the column slot, setting it to NIL if we sent
;; octets
(setq column
(cond (octet-seen-p nil)
(t (let ((last-newline-pos (position #\Newline sequence
:test #'char=
:start start
:end end
:from-end t)))
(cond (last-newline-pos (- end last-newline-pos 1))
(column (+ column (- end start))))))))))))))))
(defmacro define-char-encoders ((lf-format-class cr-format-class crlf-format-class) &body body)
"Non-hygienic utility macro which defines several encoding-related
methods for the classes LF-FORMAT-CLASS, CR-FORMAT-CLASS, and
CRLF-FORMAT-CLASS where it is assumed that CR-FORMAT-CLASS is the same
encoding as LF-FORMAT-CLASS but with CR instead of LF line endings and
similar for CRLF-FORMAT-CLASS, i.e. LF-FORMAT-CLASS is the base class.
BODY is a code template for the code to convert one character to
octets. BODY must contain a symbol CHAR-GETTER representing the form
which is used to obtain the character and a forms like \(OCTET-WRITE
<thing>) to write the octet <thing>. The CHAR-GETTER form might be
called more than once."
`(progn
(defmethod char-to-octets ((format ,lf-format-class) char writer)
(declare #.*fixnum-optimize-settings*)
(declare (character char) (function writer))
(symbol-macrolet ((char-getter char))
(macrolet ((octet-writer (form)
`(funcall writer ,form)))
,@body)))
(define-sequence-writers (,lf-format-class) ,@body)
(define-sequence-writers (,cr-format-class)
;; modify the body so that the getter replaces a #\Newline
;; with a #\Return
,@(sublis `((char-getter . ,(with-unique-names (char)
`(let ((,char char-getter))
(declare (character ,char))
(if (char= ,char #\Newline)
#\Return
,char)))))
body))
(define-sequence-writers (,crlf-format-class)
;; modify the body so that we potentially write octets for
;; two characters (#\Return and #\Linefeed) - the original
;; body is wrapped with the WRITE-CHAR local function
,(with-unique-names (char write-char)
`(flet ((,write-char (,char)
,@(sublis `((char-getter . ,char)) body)))
(let ((,char char-getter))
(declare (character ,char))
(cond ((char= ,char #\Newline)
(,write-char #\Return)
(,write-char #\Linefeed))
(t (,write-char ,char)))))))))
(define-char-encoders (flexi-latin-1-format flexi-cr-latin-1-format flexi-crlf-latin-1-format)
(let ((octet (char-code char-getter)))
(when (> octet 255)
(signal-encoding-error format "~S (code ~A) is not a LATIN-1 character." char-getter octet))
(octet-writer octet)))
(define-char-encoders (flexi-ascii-format flexi-cr-ascii-format flexi-crlf-ascii-format)
(let ((octet (char-code char-getter)))
(when (> octet 127)
(signal-encoding-error format "~S (code ~A) is not an ASCII character." char-getter octet))
(octet-writer octet)))
(define-char-encoders (flexi-8-bit-format flexi-cr-8-bit-format flexi-crlf-8-bit-format)
(with-accessors ((encoding-hash external-format-encoding-hash))
format
(let ((octet (gethash (char-code char-getter) encoding-hash)))
(unless octet
(signal-encoding-error format "~S (code ~A) is not in this encoding." char-getter octet))
(octet-writer octet))))
(define-char-encoders (flexi-utf-8-format flexi-cr-utf-8-format flexi-crlf-utf-8-format)
;; the old version using LDB was more elegant, but some Lisps had
;; trouble optimizing it
(let ((char-code (char-code char-getter)))
(tagbody
(cond ((< char-code #x80)
(octet-writer char-code)
(go zero))
((< char-code #x800)
(octet-writer (logior* #b11000000 (ash* char-code -6)))
(go one))
((< char-code #x10000)
(octet-writer (logior* #b11100000 (ash* char-code -12)))
(go two))
(t
(octet-writer (logior* #b11110000 (ash* char-code -18)))))
(octet-writer (logior* #b10000000 (logand* #b00111111 (ash* char-code -12))))
two
(octet-writer (logior* #b10000000 (logand* #b00111111 (ash* char-code -6))))
one
(octet-writer (logior* #b10000000 (logand* #b00111111 char-code)))
zero)))
(define-char-encoders (flexi-utf-16-le-format flexi-cr-utf-16-le-format flexi-crlf-utf-16-le-format)
(flet ((write-word (word)
(octet-writer (logand* #x00ff word))
(octet-writer (ash* (logand* #xff00 word) -8))))
(declare (inline write-word))
(let ((char-code (char-code char-getter)))
(declare (type char-code-integer char-code))
(cond ((< char-code #x10000)
(write-word char-code))
(t (decf char-code #x10000)
(write-word (logior* #xd800 (ash* char-code -10)))
(write-word (logior* #xdc00 (logand* #x03ff char-code))))))))
(define-char-encoders (flexi-utf-16-be-format flexi-cr-utf-16-be-format flexi-crlf-utf-16-be-format)
(flet ((write-word (word)
(octet-writer (ash* (logand* #xff00 word) -8))
(octet-writer (logand* #x00ff word))))
(declare (inline write-word))
(let ((char-code (char-code char-getter)))
(declare (type char-code-integer char-code))
(cond ((< char-code #x10000)
(write-word char-code))
(t (decf char-code #x10000)
(write-word (logior* #xd800 (ash* char-code -10)))
(write-word (logior* #xdc00 (logand* #x03ff char-code))))))))
(define-char-encoders (flexi-gbk-format flexi-cr-gbk-format flexi-crlf-gbk-format)
(let ((octet (char-code char-getter)))
(if (<= octet #x7f)
(octet-writer octet)
(flet ((write-word (word)
(octet-writer (ash* (logand* #xff00 word) -8))
(octet-writer (logand* #x00ff word))))
(declare (inline write-word))
(declare (type char-code-integer octet))
(cond ((= octet #x20ac)
(octet-writer #x80))
((= octet #xf8f5)
(octet-writer #xff))
(t
(let ((code (get-multibyte-mapper (if (< octet #x100)
*ucs-to-gbk-special-table*
*ucs-to-gbk-table*)
octet)))
(if code
(write-word code)
(signal-encoding-error format "~S (code ~A) is not in this encoding."
char-getter octet)))))))))
(define-char-encoders (flexi-utf-32-le-format flexi-cr-utf-32-le-format flexi-crlf-utf-32-le-format)
(let ((char-code (char-code char-getter)))
(octet-writer (logand* #x00ff char-code))
(octet-writer (logand* #x00ff (ash* char-code -8)))
(octet-writer (logand* #x00ff (ash* char-code -16)))
(octet-writer (logand* #x00ff (ash* char-code -24)))))
(define-char-encoders (flexi-utf-32-be-format flexi-cr-utf-32-be-format flexi-crlf-utf-32-be-format)
(let ((char-code (char-code char-getter)))
(octet-writer (logand* #x00ff (ash* char-code -24)))
(octet-writer (logand* #x00ff (ash* char-code -16)))
(octet-writer (logand* #x00ff (ash* char-code -8)))
(octet-writer (logand* #x00ff char-code))))
(defmethod char-to-octets ((format flexi-cr-mixin) char writer)
(declare #.*fixnum-optimize-settings*)
(declare (character char))
(if (char= char #\Newline)
(call-next-method format #\Return writer)
(call-next-method)))
(defmethod char-to-octets ((format flexi-crlf-mixin) char writer)
(declare #.*fixnum-optimize-settings*)
(declare (character char))
(cond ((char= char #\Newline)
(call-next-method format #\Return writer)
(call-next-method format #\Linefeed writer))
(t (call-next-method))))