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+;;;; "trace.scm" Utility macros for tracing in Scheme.
+;;; Copyright (C) 1991, 1992, 1993, 1994, 1995 Aubrey Jaffer.
+;
+;Permission to copy this software, to redistribute it, and to use it
+;for any purpose is granted, subject to the following restrictions and
+;understandings.
+;
+;1. Any copy made of this software must include this copyright notice
+;in full.
+;
+;2. I have made no warrantee or representation that the operation of
+;this software will be error-free, and I am under no obligation to
+;provide any services, by way of maintenance, update, or otherwise.
+;
+;3. In conjunction with products arising from the use of this
+;material, there shall be no use of my name in any advertising,
+;promotional, or sales literature without prior written consent in
+;each case.
+
+(require 'qp) ;for the qp printer.
+(define debug:indent 0)
+
+(define debug:tracef
+ (let ((null? null?) ;These bindings are so that
+ (not not) ;tracef will not trace parts
+ (car car) (cdr cdr) ;of itself.
+ (eq? eq?) (+ +) (zero? zero?) (modulo modulo)
+ (apply apply) (display display) (qpn qpn))
+ (lambda (function . optname)
+ (set! debug:indent 0)
+ (let ((name (if (null? optname) function (car optname))))
+ (lambda args
+ (cond ((and (not (null? args))
+ (eq? (car args) 'debug:untrace-object)
+ (null? (cdr args)))
+ function)
+ (else
+ (do ((i debug:indent (+ -1 i))) ((zero? i)) (display #\ ))
+ (apply qpn "CALLED" name args)
+ (set! debug:indent (modulo (+ 1 debug:indent) 8))
+ (let ((ans (apply function args)))
+ (set! debug:indent (modulo (+ -1 debug:indent) 8))
+ (do ((i debug:indent (+ -1 i))) ((zero? i)) (display #\ ))
+ (qpn "RETURNED" name ans)
+ ans))))))))
+
+;;; the reason I use a symbol for debug:untrace-object is so
+;;; that functions can still be untraced if this file is read in twice.
+
+(define (debug:untracef function)
+ (set! debug:indent 0)
+ (function 'debug:untrace-object))
+
+;;;;The trace: functions wrap around the debug: functions to provide
+;;; niceties like keeping track of traced functions and dealing with
+;;; redefinition.
+
+(require 'alist)
+(define trace:adder (alist-associator eq?))
+(define trace:deler (alist-remover eq?))
+
+(define *traced-procedures* '())
+(define (trace:tracef fun sym)
+ (cond ((not (procedure? fun))
+ (display "WARNING: not a procedure " (current-error-port))
+ (display sym (current-error-port))
+ (newline (current-error-port))
+ (set! *traced-procedures* (trace:deler *traced-procedures* sym))
+ fun)
+ (else
+ (let ((p (assq sym *traced-procedures*)))
+ (cond ((and p (eq? (cdr p) fun))
+ fun)
+ (else
+ (let ((tfun (debug:tracef fun sym)))
+ (set! *traced-procedures*
+ (trace:adder *traced-procedures* sym tfun))
+ tfun)))))))
+
+(define (trace:untracef fun sym)
+ (let ((p (assq sym *traced-procedures*)))
+ (set! *traced-procedures* (trace:deler *traced-procedures* sym))
+ (cond ((not (procedure? fun)) fun)
+ ((not p) fun)
+ ((eq? (cdr p) fun)
+ (debug:untracef fun))
+ (else fun))))
+
+(define tracef debug:tracef)
+(define untracef debug:untracef)
+
+;;;; Finally, the macros trace and untrace
+
+(defmacro trace xs
+ (if (null? xs)
+ `(begin ,@(map (lambda (x) `(set! ,x (trace:tracef ,x ',x)))
+ (map car *traced-procedures*))
+ (map car *traced-procedures*))
+ `(begin ,@(map (lambda (x) `(set! ,x (trace:tracef ,x ',x))) xs))))
+(defmacro untrace xs
+ (if (null? xs)
+ (slib:eval
+ `(begin ,@(map (lambda (x) `(set! ,x (trace:untracef ,x ',x)))
+ (map car *traced-procedures*))
+ '',(map car *traced-procedures*)))
+ `(begin ,@(map (lambda (x) `(set! ,x (trace:untracef ,x ',x))) xs))))