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+%% Oh Emacs, this is a -*- Lisp -*- file, despite appearance.
+\documentclass{article}
+\usepackage{axiom}
+
+\title{\$SPAD/src/interp metalex.lisp}
+\author{Timothy Daly}
+
+\begin{document}
+\maketitle
+\begin{abstract}
+\end{abstract}
+\eject
+\tableofcontents
+\eject
+
+\section{License}
+
+<<license>>=
+;; Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
+;; 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.
+;;
+;; - Neither the name of The Numerical ALgorithms Group Ltd. nor the
+;; names of its contributors may be used to endorse or promote products
+;; derived from this software without specific prior written permission.
+;;
+;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+;; IS" AND ANY EXPRESS 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 COPYRIGHT OWNER
+;; OR CONTRIBUTORS 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.
+
+@
+<<*>>=
+<<license>>
+
+; NAME: MetaLex.lisp
+; PURPOSE: Parsing support routines for Meta code
+; CONTENTS:
+;
+; 1. META File Handling
+; 2. META Line Handling
+; 3. META Token Handling
+; 4. META Token Parsing Actions
+; 5. META Error Handling
+
+(in-package "BOOT")
+
+; *** 1. META file handling
+
+(defun in-meta ()
+ (setq XTokenReader 'get-META-token)
+ (setq Line-Handler 'next-META-line)
+ (setq Meta_Error_Handler 'meta-meta-error-handler)
+ (setq $BOOT nil))
+
+(defun newrule ()
+ (in-meta)
+ (setq meta_prefix "PARSE-")
+ (test Rule1)
+ (eval (pop-stack-1))
+ (ioclear)
+ (in-boot))
+
+(defun meta (&optional (*meta-input-file* "/spad/meta.meta")
+ (*meta-output-file* nil))
+ (ioclear)
+ (in-meta)
+ (with-open-stream
+ (in-stream (open *meta-input-file* :direction :input))
+ (with-open-stream
+ (out-stream (if *meta-output-file*
+ (open *meta-output-file* :direction :output)
+ *terminal-io*))
+ (format out-stream
+ "~&;;; -*- Mode:Lisp; Package:Boot -*-~%~%")
+ (parse-program)
+ (IOClear in-stream out-stream)))
+ T)
+
+; *** 2. META Line Handling
+
+(defun next-META-line (&optional (in-stream t))
+
+"Get next line, trimming trailing blanks and trailing comments.
+One trailing blank is added to a non-blank line to ease between-line
+processing for Next Token (i.e., blank takes place of return). Returns T
+if it gets a non-blank line, and NIL at end of stream."
+
+ (prog (string)
+empty (if File-Closed (return nil))
+ (setq string (kill-trailing-blanks (kill-comments
+ (get-a-line in-stream))))
+ (if (= (length string) 0) (go empty))
+ (Line-New-Line (suffix #\Space string) Current-Line)
+ (if Echo-Meta (Print-New-Line (Line-Buffer Current-Line) out-stream))
+ (return t)))
+
+(defparameter Comment-Character #\% "Delimiter of comments in Meta code.")
+
+(defun kill-comments (string)
+ "Deletes from comment character % to end of STRING."
+ (subseq string 0
+ (let ((mi (maxindex string)))
+ (do ((i 0 (1+ i)))
+ ((> i mi) i)
+ (if (and (char= (elt string i) Comment-Character)
+ (or (eq i 0) (char/= (elt string (1- i)) #\\)))
+ (return i))))))
+
+(defun kill-trailing-blanks (string)
+
+ "Remove white space from end of STRING."
+
+ ; Coding note: yes, I know, use string-trim -- but it is broken
+ ; in Symbolics Common Lisp for short strings
+
+ (let* ((sl (length string))
+ (right (if (= sl 0) -1
+ (or
+ (position-if-not
+ #'(lambda (x)
+ (member x '(#\Space #\Tab #\Newline) :test #'char=))
+ string :from-end t)
+ -1))))
+ (if (>= right 0) (subseq string 0 (1+ right)) (make-string 0))))
+
+; *** 3. META Token Handling
+
+; STRING: "'" { Chars - "'" }* "'"
+; BSTRING: "[" ... "]*"
+; ID: letters, _ and then numbers
+; NUMBER: digits, ., digits, e, +-, digits
+
+(defun-parse-token STRING)
+(defun-parse-token BSTRING)
+(defun-parse-token IDENTIFIER)
+(defun-parse-token NUMBER)
+
+; Meta tokens fall into the following categories:
+;
+; Number
+; Identifier
+; Dollar-sign
+; Special character
+;
+; Special characters are represented as characters, numbers as numbers, and
+; identifiers as strings. The reason identifiers are represented as strings is
+; that the full print-name of the intern of a string depends on the package you
+; are currently executing in; this can lead to very confusing results!
+
+(defun get-META-token (token)
+ (prog nil
+ loop (if (not (skip-blanks)) (return nil))
+ (case (token-lookahead-type (current-char))
+ (id (return (get-identifier-token token)))
+ (num (return (get-number-token token)))
+ (string (return (get-string-token token)))
+ (bstring (return (get-bstring-token token)))
+; (dollar (return (get-identifier-token token)))
+ (special-char (return (get-special-token token)))
+ (eof (return nil)))))
+
+(defun skip-blanks ()
+ (loop (let ((cc (current-char)))
+ (if (not cc) (return nil))
+ (if (eq (token-lookahead-type cc) 'white)
+ (if (not (advance-char)) (return nil))
+ (return t)))))
+
+(defparameter Escape-Character #\\ "Superquoting character.")
+
+(defun token-lookahead-type (char)
+ "Predicts the kind of token to follow, based on the given initial character."
+ (cond ((not char) 'eof)
+ ((or (char= char Escape-Character) (alpha-char-p char)) 'id)
+ ((digitp char) 'num)
+ ((char= char #\') 'string)
+ ((char= char #\[) 'bstring)
+; ((char= char #\$) (advance-char) 'dollar)
+ ((member char '(#\Space #\Tab #\Return) :test #'char=) 'white)
+ (t 'special-char)))
+
+(defun make-adjustable-string (n)
+ (make-array (list n) :element-type 'character :adjustable t))
+
+(defun get-identifier-token (token)
+ "Take an identifier off the input stream."
+ (prog ((buf (make-adjustable-string 0)))
+ id (let ((cur-char (current-char)))
+ (cond ((equal cur-char Escape-Character)
+ (if (not (advance-char)) (go bye))
+ (suffix (current-char) buf)
+ (if (not (advance-char)) (go bye))
+ (go id))
+ ((or (alpha-char-p cur-char)
+ (char= cur-char #\-)
+ (digitp cur-char)
+ (char= cur-char #\_))
+ (suffix (current-char) buf)
+ (if (not (advance-char)) (go bye))
+ (go id))))
+ bye (return (token-install (intern buf) 'identifier token))))
+
+(defun get-string-token (token)
+ "With 'ABC' on IN-STREAM, extracts and stacks String 'ABC'."
+ (let ((buf (make-adjustable-string 0)))
+ (if (char= (current-char) #\')
+ (progn (advance-char)
+ (loop (case (current-char)
+ (#\' (advance-char)
+ (return (token-install buf 'string token)))
+ (#\\ (advance-char)
+ (suffix (current-char) buf)
+ (advance-char))
+ (#\Return
+ (moan "String should fit on one line!")
+ (advance-char)
+ (meta-syntax-error)
+ (return nil))
+ (t (suffix (current-char) buf)
+ (advance-char))))))))
+
+(defun get-bstring-token (token)
+ "With ABC]* on in-stream, extracts and stacks string ABC."
+ (let ((buf (make-adjustable-string 0)))
+ (if (char= (current-char) #\[)
+ (progn (advance-char)
+ (loop (case (current-char)
+ (#\] (if (char= (next-char) #\*)
+ (progn (advance-char)
+ (advance-char)
+ (return (token-install buf 'bstring token)))
+ (progn (suffix (current-char) buf)
+ (advance-char))))
+ (#\\ (advance-char)
+ (suffix (current-char) buf)
+ (advance-char))
+ (#\Return
+ (moan "String should fit on one line!")
+ (advance-char)
+ (meta-syntax-error)
+ (return nil))
+ (t (suffix (current-char) buf)
+ (advance-char))))))))
+
+(defun get-special-token (token)
+ "Take a special character off the input stream. We let the type name of each
+special character be the atom whose print name is the character itself."
+ (let ((symbol (current-char)))
+ (advance-char)
+ (token-install symbol 'special-char token)))
+
+(defun get-number-token (token)
+ "Take a number off the input stream."
+ (prog ((buf (make-adjustable-string 0)))
+ nu1 (suffix (current-char) buf) ; Integer part
+ (let ((next-chr (next-char)))
+ (cond ((digitp next-chr)
+ (advance-char)
+ (go nu1))))
+ (advance-char)
+ formint(return (token-install
+ (read-from-string buf)
+ 'number token
+ (size buf) ;used to keep track of digit count
+ ))))
+
+; *** 4. META Auxiliary Parsing Actions
+
+(defun make-defun (nametok vars body)
+ (let ((name (INTERN (STRCONC |META_PREFIX| nametok))))
+ (if vars
+ `(DEFUN ,name ,vars (declare (special . ,vars)) ,body)
+ `(DEFUN ,name ,vars ,body))))
+
+(defun print-fluids (fluids)
+ (terpri out-stream)
+ (mapcar #'(lambda (x) (format out-stream "~&(DEFPARAMETER ~S NIL)~%" x)) fluids)
+ (terpri out-stream))
+
+(defun print-package (package)
+ (format out-stream "~&~%(IN-PACKAGE ~S )~%~%" package))
+
+(defparameter Meta_Prefix nil)
+
+(defun set-prefix (prefix) (setq META_PREFIX prefix))
+
+(defun print-rule (x) (print x out-stream) (format out-stream "~%~%"))
+
+; *** 5. META Error Handling
+
+(defun meta-meta-error-handler (&optional (wanted nil) (parsing nil))
+ "Print syntax error indication, underline character, scrub line."
+ (format out-stream "~&% MetaLanguage syntax error: ")
+ (if (Line-Past-End-P Current-Line)
+ (cond ((and wanted parsing)
+ (format out-stream "wanted ~A while parsing ~A.~%"
+ wanted parsing))
+ (wanted (format out-stream "wanted ~A.~%" wanted))
+ (parsing (format out-stream "while parsing ~A.~%" parsing)))
+ (progn (format out-stream "~:[here~;wanted ~A here~]" wanted wanted)
+ (format out-stream "~:[~; while parsing ~A~]:~%" parsing parsing)
+ (current-line-print)
+ (current-line-clear)
+ (current-token)
+ (incf $num_of_meta_errors)
+ (setq Meta_Errors_Occurred t)))
+ nil)
+@
+\eject
+\begin{thebibliography}{99}
+\bibitem{1} nothing
+\end{thebibliography}
+\end{document}
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