+;;;; os-independent stream functions requiring reader machinery
+
+;;;; This software is part of the SBCL system. See the README file for
+;;;; more information.
+;;;;
+;;;; This software is derived from the CMU CL system, which was
+;;;; written at Carnegie Mellon University and released into the
+;;;; public domain. The software is in the public domain and is
+;;;; provided with absolutely no warranty. See the COPYING and CREDITS
+;;;; files for more information.
+
+(in-package "SB!IMPL")
+
+;;; In the interest of ``once and only once'' this macro contains the
+;;; framework necessary to implement a peek-char function, which has
+;;; two special-cases (one for gray streams and one for echo streams)
+;;; in addition to the normal case.
+;;;
+;;; All arguments are forms which will be used for a specific purpose
+;;; PEEK-TYPE - the current peek-type as defined by ANSI CL
+;;; EOF-VALUE - the eof-value argument to peek-char
+;;; CHAR-VAR - the variable which will be used to store the current character
+;;; READ-FORM - the form which will be used to read a character
+;;; UNREAD-FORM - ditto for unread-char
+;;; SKIPPED-CHAR-FORM - the form to execute when skipping a character
+;;; EOF-DETECTED-FORM - the form to execute when EOF has been detected
+;;; (this will default to CHAR-VAR)
+(eval-when (:compile-toplevel :execute)
+ (sb!xc:defmacro generalized-peeking-mechanism
+ (peek-type eof-value char-var read-form unread-form
+ &optional (skipped-char-form nil) (eof-detected-form nil))
+ `(let ((,char-var ,read-form))
+ (cond ((eql ,char-var ,eof-value)
+ ,(if eof-detected-form
+ eof-detected-form
+ char-var))
+ ((characterp ,peek-type)
+ (do ((,char-var ,char-var ,read-form))
+ ((or (eql ,char-var ,eof-value)
+ (char= ,char-var ,peek-type))
+ (cond ((eql ,char-var ,eof-value)
+ ,(if eof-detected-form
+ eof-detected-form
+ char-var))
+ (t ,unread-form
+ ,char-var)))
+ ,skipped-char-form))
+ ((eql ,peek-type t)
+ (do ((,char-var ,char-var ,read-form))
+ ((or (eql ,char-var ,eof-value)
+ (not (whitespacep ,char-var)))
+ (cond ((eql ,char-var ,eof-value)
+ ,(if eof-detected-form
+ eof-detected-form
+ char-var))
+ (t ,unread-form
+ ,char-var)))
+ ,skipped-char-form))
+ ((null ,peek-type)
+ ,unread-form
+ ,char-var)
+ (t
+ (bug "Impossible case reached in PEEK-CHAR"))))))
+
+;;; We proclaim them INLINE here, then proclaim them MAYBE-INLINE at EOF,
+;;; so, except in this file, they are not inline by default, but they can be.
+#!-sb-fluid (declaim (inline read-char unread-char read-byte listen))
+
+(defun peek-char (&optional (peek-type nil)
+ (stream *standard-input*)
+ (eof-error-p t)
+ eof-value
+ recursive-p)
+ (declare (ignore recursive-p))
+ (the (or character boolean) peek-type)
+ (let ((stream (in-synonym-of stream)))
+ (cond ((typep stream 'echo-stream)
+ (echo-misc stream
+ :peek-char
+ peek-type
+ (list eof-error-p eof-value)))
+ ((ansi-stream-p stream)
+ (generalized-peeking-mechanism
+ peek-type eof-value char
+ (read-char stream eof-error-p eof-value)
+ (unread-char char stream)))
+ (t
+ ;; by elimination, must be Gray streams FUNDAMENTAL-STREAM
+ (generalized-peeking-mechanism
+ peek-type :eof char
+ (if (null peek-type)
+ (stream-peek-char stream)
+ (stream-read-char stream))
+ (if (null peek-type)
+ ()
+ (stream-unread-char stream char))
+ ()
+ (eof-or-lose stream eof-error-p eof-value))))))
+
+(defun echo-misc (stream operation &optional arg1 arg2)
+ (let* ((in (two-way-stream-input-stream stream))
+ (out (two-way-stream-output-stream stream)))
+ (case operation
+ (:listen
+ (or (not (null (echo-stream-unread-stuff stream)))
+ (if (ansi-stream-p in)
+ (or (/= (the fixnum (ansi-stream-in-index in))
+ +ansi-stream-in-buffer-length+)
+ (funcall (ansi-stream-misc in) in :listen))
+ (stream-misc-dispatch in :listen))))
+ (:unread (push arg1 (echo-stream-unread-stuff stream)))
+ (:element-type
+ (let ((in-type (stream-element-type in))
+ (out-type (stream-element-type out)))
+ (if (equal in-type out-type)
+ in-type `(and ,in-type ,out-type))))
+ (:close
+ (set-closed-flame stream))
+ (:peek-char
+ ;; For the special case of peeking into an echo-stream
+ ;; arg1 is PEEK-TYPE, arg2 is (EOF-ERROR-P EOF-VALUE)
+ ;; returns peeked-char, eof-value, or errors end-of-file
+ ;;
+ ;; Note: This code could be moved into PEEK-CHAR if desired.
+ ;; I am unsure whether this belongs with echo-streams because it is
+ ;; echo-stream specific, or PEEK-CHAR because it is peeking code.
+ ;; -- mrd 2002-11-18
+ ;;
+ ;; UNREAD-CHAR-P indicates whether the current character was one
+ ;; that was previously unread. In that case, we need to ensure that
+ ;; the semantics for UNREAD-CHAR are held; the character should
+ ;; not be echoed again.
+ (let ((unread-char-p nil))
+ (flet ((outfn (c)
+ (unless unread-char-p
+ (if (ansi-stream-p out)
+ (funcall (ansi-stream-out out) out c)
+ ;; gray-stream
+ (stream-write-char out c))))
+ (infn ()
+ ;; Obtain input from unread buffer or input stream,
+ ;; and set the flag appropriately.
+ (cond ((not (null (echo-stream-unread-stuff stream)))
+ (setf unread-char-p t)
+ (pop (echo-stream-unread-stuff stream)))
+ (t
+ (setf unread-char-p nil)
+ (read-char in (first arg2) (second arg2))))))
+ (generalized-peeking-mechanism
+ arg1 (second arg2) char
+ (infn)
+ (unread-char char in)
+ (outfn char)))))
+ (t
+ (or (if (ansi-stream-p in)
+ (funcall (ansi-stream-misc in) in operation arg1 arg2)
+ (stream-misc-dispatch in operation arg1 arg2))
+ (if (ansi-stream-p out)
+ (funcall (ansi-stream-misc out) out operation arg1 arg2)
+ (stream-misc-dispatch out operation arg1 arg2)))))))
+
+(declaim (maybe-inline read-char unread-char read-byte listen))
\ No newline at end of file
projects / sbcl.git / commitdiff