--- /dev/null
+;;;; CHAR-CODE -- Conversions between characters and byte
+;;;; representations thereof
+
+(defpackage :charcode
+ (:use :cl #+sbcl :sb-gray #-sbcl :gray)
+ (:export "MAKE-ENCODER" "MAKE-DECODER" "ENCODE-STRING" "DECODE-STRING"
+ "CODING-ERROR"
+ "LATIN-1" "LATIN1" "UTF-8" "UTF8"))
+(in-package :charcode)
+
+;;; General stuff
+
+(define-condition coding-error (error)
+ ((input :initarg :input)
+ (position :initarg :position)
+ (result :initarg :result)))
+
+(define-condition simple-coding-error (coding-error simple-error) ())
+
+(defun coding-error (input position result format &rest format-args)
+ (error 'simple-coding-error
+ :input input :position position :result result
+ :format-control format :format-arguments format-args))
+
+(deftype decoder-fun () `(function ((array (unsigned-byte 8))
+ (array character)
+ &key (start fixnum) (end fixnum))
+ (member t nil)))
+(deftype encoder-fun () `(function ((array character)
+ (array (unsigned-byte 8))
+ &key (start fixnum) (end fixnum))
+ (member t nil)))
+
+(defmacro define-encoder ((name) &body make-encoder)
+ `(setf (get ',name 'make-encoder) #'(lambda () ,@make-encoder)))
+
+(defmacro define-decoder ((name) &body make-decoder)
+ `(setf (get ',name 'make-decoder) #'(lambda () ,@make-decoder)))
+
+(defmacro define-codec-synonyms (name &rest synonyms)
+ `(eval-when (:load-toplevel :execute)
+ ,@(mapcar #'(lambda (sym)
+ `(setf (get ',sym 'make-encoder) (get ',name 'make-encoder)
+ (get ',sym 'make-decoder) (get ',name 'make-decoder)))
+ synonyms)))
+
+(defun make-encoder (name)
+ (the encoder-fun (values (funcall (get name 'make-encoder)))))
+
+(defun make-decoder (name)
+ (the decoder-fun (values (funcall (get name 'make-decoder)))))
+
+(defun encode-string (string coding)
+ (declare (type string string))
+ (let ((encoder (make-encoder coding))
+ (buf (make-array (list (length string)) :element-type '(unsigned-byte 8) :adjustable t :fill-pointer 0)))
+ (unless (funcall encoder string buf)
+ (coding-error string (length string) buf "Encoding of string in ~A ended prematurely." coding))
+ buf))
+
+(defun decode-string (buffer coding)
+ (declare (type (array (unsigned-byte 8)) buffer))
+ (let ((decoder (make-decoder coding))
+ (buf (make-array (list (length buffer)) :element-type 'character :adjustable t :fill-pointer 0)))
+ (unless (funcall decoder buffer buf)
+ (coding-error buffer (length buffer) buf "~A byte sequence ended prematurely." coding))
+ buf))
+
+;;; Gray stream implementation
+
+(defclass codec-character-stream (fundamental-character-input-stream fundamental-character-output-stream)
+ ((decoder :initarg :decoder)
+ (encoder :initarg :encoder)
+ (back :initarg :back)
+ (read-pos :initform 0)
+ (buffer :initform (make-array '(64) :element-type 'character :adjustable t :fill-pointer 0))))
+
+(defmethod close ((stream codec-character-stream) &key abort)
+ (with-slots (back) stream
+ (close back :abort abort))
+ (call-next-method))
+
+(defmethod open-stream-p ((stream codec-character-stream))
+ (with-slots (back) stream
+ (open-stream-p stream)))
+
+(defun ccs-ensure-buffer (stream len)
+ (declare (type codec-character-stream stream)
+ (type integer len))
+ (with-slots (decoder back buffer read-pos) stream
+ (let ((readbuf (make-array (list len) :element-type '(unsigned-byte 8))))
+ (loop (unless (< (- (length buffer) read-pos) len) (return t))
+ (let ((readlen (read-sequence readbuf back)))
+ (when (= readlen 0)
+ (return-from ccs-ensure-buffer nil))
+ (funcall decoder readbuf buffer :end readlen))))))
+
+(defun ccs-clear-buffer (stream)
+ (declare (type codec-character-stream stream))
+ (with-slots (read-pos buffer) stream
+ (replace buffer buffer :start2 read-pos)
+ (setf (fill-pointer buffer) (- (fill-pointer buffer) read-pos)
+ read-pos 0)))
+
+(defmethod stream-read-char ((stream codec-character-stream))
+ (unless (ccs-ensure-buffer stream 1)
+ (return-from stream-read-char :eof))
+ (with-slots (read-pos buffer) stream
+ (prog1 (aref buffer read-pos)
+ (when (>= (incf read-pos) 16)
+ (ccs-clear-buffer stream)))))
+
+(defmethod stream-unread-char ((stream codec-character-stream) char)
+ (with-slots (read-pos buffer) stream
+ (when (= read-pos 0)
+ (let ((len (length buffer)))
+ (when (< (array-dimension buffer 0) (+ len 16))
+ (adjust-array buffer (list (setf (fill-pointer buffer)
+ (+ len 16)))))
+ (replace buffer buffer :start1 16 :end2 len)))
+ (setf (aref buffer read-pos) char)
+ (decf read-pos)
+ nil))
+
+(defun ccs-wont-hang-p (stream)
+ (declare (type codec-character-stream stream))
+ (with-slots (read-pos back buffer) stream
+ (or (and (< read-pos (length buffer)) (aref buffer read-pos))
+ (listen back))))
+
+(defmethod stream-read-char-no-hang ((stream codec-character-stream))
+ (if (ccs-wont-hang-p stream)
+ (stream-read-char stream)
+ nil))
+
+(defmethod stream-peek-char ((stream codec-character-stream))
+ (unless (ccs-ensure-buffer stream 1)
+ (return-from stream-peek-char :eof))
+ (with-slots (read-pos buffer) stream
+ (aref buffer read-pos)))
+
+(defmethod stream-listen ((stream codec-character-stream))
+ (if (ccs-wont-hang-p stream)
+ (let ((peek (stream-peek-char stream)))
+ (if (eq peek :eof)
+ nil
+ peek))
+ nil))
+
+(defmethod stream-write-char ((stream codec-character-stream) char)
+ (with-slots (encoder back) stream
+ (let ((seq (make-array '(1) :element-type 'character :initial-element char))
+ (outbuf (make-array '(16) :element-type '(unsigned-byte 8) :adjustable t :fill-pointer 0)))
+ (funcall encoder seq outbuf)
+ (write-sequence outbuf back))))
+
+(defmethod stream-finish-output ((stream codec-character-stream))
+ (finish-output (slot-value stream 'back)))
+
+(defmethod stream-force-output ((stream codec-character-stream))
+ (force-output (slot-value stream 'back)))
+
+(defmethod stream-read-sequence ((stream codec-character-stream) seq &optional (start 0) (end (length seq)))
+ (ccs-ensure-buffer stream (- end start))
+ (with-slots (read-pos buffer) stream
+ (replace seq buffer :start1 start :end1 end :start2 read-pos :end2 (length buffer))
+ (let ((len (min (- end start) (- (length buffer) read-pos))))
+ (when (>= (incf read-pos len) 128)
+ (ccs-clear-buffer stream)))))
+
+(defmethod stream-write-sequence ((stream codec-character-stream) seq &optional (start 0) (end (length seq)))
+ (with-slots (encoder back) stream
+ (let ((outbuf (make-array (list (- end start)) :element-type '(unsigned-byte 8) :adjustable t :fill-pointer 0)))
+ (funcall encoder seq outbuf)
+ (write-sequence outbuf back))))
+
+;;; Implementation-specific functions
+
+#+(or (and clisp unicode) sbcl)
+(defun unicode->char (unicode)
+ (declare (type (unsigned-byte 24) unicode))
+ (code-char unicode))
+
+#+(or (and clisp unicode) sbcl)
+(defun char->unicode (char)
+ (declare (type character char))
+ (char-code char))
+
+;;; Latin-1
+
+(defun decode-latin-1 (byteseq charseq &key (start 0) (end (length byteseq)))
+ (declare (type (array (unsigned-byte 8)) byteseq)
+ (type (array character) charseq)
+ (type fixnum start end))
+ (do ((i start (1+ i)))
+ ((>= i end))
+ (vector-push-extend (unicode->char (aref byteseq i)) charseq))
+ t)
+
+(defun encode-latin-1 (charseq byteseq &key (start 0) (end (length charseq)))
+ (declare (type (array (unsigned-byte 8)) byteseq)
+ (type (array character) charseq)
+ (type fixnum start end))
+ (loop
+ (restart-case
+ (loop
+ (unless (< start end) (return-from encode-latin-1 t))
+ (vector-push-extend (let ((cp (char->unicode (aref charseq (prog1 start (incf start))))))
+ (unless (< cp 256)
+ (coding-error charseq start byteseq "ISO-8859-1 cannot encode code-points higher than 256."))
+ cp)
+ byteseq))
+ (:replace-char (&optional (replacement #\?))
+ :report "Replace this character with another."
+ (vector-push-extend (char->unicode replacement) byteseq))
+ (:skip-char ()
+ :report "Ignore this character."
+ nil))))
+
+(define-decoder (latin-1)
+ #'decode-latin-1)
+
+(define-encoder (latin-1)
+ #'encode-latin-1)
+
+(define-codec-synonyms latin-1 latin1 iso-8859-1)
+
+;;; UTF-8
+
+(defun encode-utf-8 (charseq byteseq &key (start 0) (end (length charseq)))
+ (declare (type (array (unsigned-byte 8)) byteseq)
+ (type (array character) charseq)
+ (type fixnum start end))
+ (do ((i start (1+ i)))
+ ((>= i end))
+ (let ((cp (char->unicode (aref charseq i))))
+ (if (< cp 128)
+ (vector-push-extend cp byteseq)
+ (let ((nbytes 0)
+ (bytes '()))
+ (loop
+ (push (logior (ldb (byte 6 0) cp) #x80) bytes)
+ (setf cp (truncate cp 64))
+ (incf nbytes)
+ (when (< cp (expt 2 (- 6 nbytes)))
+ (push (logior (logand #xff (lognot (1- (expt 2 (- 7 nbytes)))))
+ cp)
+ bytes)
+ (return)))
+ (dolist (byte bytes)
+ (vector-push-extend byte byteseq))))))
+ t)
+
+(define-encoder (utf-8)
+ #'encode-utf-8)
+
+(define-decoder (utf-8)
+ (let ((mbuf 0)
+ (mlen 0))
+ (flet ((decode (byteseq charseq &key (start 0) (end (length byteseq)))
+ (declare (type (array (unsigned-byte 8)) byteseq)
+ (type (array character) charseq)
+ (type fixnum start end))
+ (let ((i start))
+ (flet ((failure (format &rest args)
+ (error 'simple-coding-error
+ :input byteseq :position i :result charseq
+ :format-control format :format-arguments args)))
+ (loop
+ (restart-case
+ (progn
+ (loop
+ (unless (< i end) (return))
+ (let ((byte (aref byteseq (prog1 i (incf i)))))
+ (if (= mlen 0)
+ (if (< byte 128)
+ (vector-push-extend (unicode->char byte) charseq)
+ (setf mlen (block zero
+ (dotimes (i 7)
+ (when (= (ldb (byte 1 (- 7 i)) byte) 0)
+ (when (< i 2)
+ (failure "UTF-8 sequence started with continuation byte: ~D" byte))
+ (return-from zero (1- i))))
+ (failure "Invalid UTF-8 sequence start byte: ~D" byte))
+ mbuf (ldb (byte (- 6 mlen) 0) byte)))
+ (progn (when (not (= (ldb (byte 2 6) byte) 2))
+ (failure "Invalid UTF-8 continuation byte: ~D" byte))
+ (setf mbuf (+ (* mbuf 64) (ldb (byte 6 0) byte)))
+ (when (= (decf mlen) 0)
+ (when (< mbuf 128)
+ (with-simple-restart (:accept "Accept anyway.")
+ (failure "UTF-8 multibyte sequence denoted an ASCII character ~S (either an encoding error or an attempt at breaking security)." (unicode->char mbuf))))
+ (vector-push-extend (unicode->char mbuf) charseq))))))
+ (return-from decode (= mlen 0)))
+ (:replace-char (&optional (replacement (unicode->char #xfffd)))
+ :report "Replace the invalid bytes with a character."
+ (vector-push-extend replacement charseq)
+ (loop (unless (and (< i end) (= (ldb (byte 2 6) (aref byteseq i)) 2))
+ (return))
+ (incf i))
+ (setf mlen 0))
+ (:skip-char ()
+ :report "Ignore the invalid byte sequence."
+ (loop (unless (and (< i end) (= (ldb (byte 2 6) (aref byteseq i)) 2))
+ (return))
+ (incf i))
+ (setf mlen 0))))))))
+ #'decode)))
+
+(define-codec-synonyms utf-8 utf8)
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