;;;; EVAL and friends ;;;; 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") (defparameter *eval-calls* 0) (defun !eval-cold-init () (setf *eval-calls* 0 *evaluator-mode* :compile) #!+sb-eval (setf sb!eval::*eval-level* -1 sb!eval::*eval-verbose* nil)) ;;; general case of EVAL (except in that it can't handle toplevel ;;; EVAL-WHEN magic properly): Delegate to #'COMPILE. (defun %simple-eval (expr lexenv) ;; FIXME: It might be nice to quieten the toplevel by muffling ;; warnings generated by this compilation (since we're about to ;; execute the results irrespective of the warnings). We might want ;; to be careful about not muffling warnings arising from inner ;; evaluations/compilations, though [e.g. the ignored variable in ;; (DEFUN FOO (X) 1)]. -- CSR, 2003-05-13 ;; ;; As of 1.0.21.6 we muffle compiler notes lexically here, which seems ;; always safe. --NS (let* (;; why PROGN? So that attempts to eval free declarations ;; signal errors rather than return NIL. -- CSR, 2007-05-01 (lambda `(lambda () (declare (muffle-conditions compiler-note)) (progn ,expr))) (fun (sb!c:compile-in-lexenv nil lambda lexenv))) (funcall fun))) ;;; Handle PROGN and implicit PROGN. (defun simple-eval-progn-body (progn-body lexenv) (unless (list-with-length-p progn-body) (let ((*print-circle* t)) (error 'simple-program-error :format-control "~@" :format-arguments (list progn-body)))) ;; Note: ;; * We can't just use (MAP NIL #'EVAL PROGN-BODY) here, because we ;; need to take care to return all the values of the final EVAL. ;; * It's left as an exercise to the reader to verify that this ;; gives the right result when PROGN-BODY is NIL, because ;; (FIRST NIL) = (REST NIL) = NIL. (do* ((i progn-body rest-i) (rest-i (rest i) (rest i))) (nil) (if rest-i ; if not last element of list (simple-eval-in-lexenv (first i) lexenv) (return (simple-eval-in-lexenv (first i) lexenv))))) (defun simple-eval-locally (exp lexenv &key vars) (multiple-value-bind (body decls) (parse-body (rest exp) :doc-string-allowed nil) (let ((lexenv ;; KLUDGE: Uh, yeah. I'm not anticipating ;; winning any prizes for this code, which was ;; written on a "let's get it to work" basis. ;; These seem to be the variables that need ;; bindings for PROCESS-DECLS to work ;; (*FREE-FUNS* and *FREE-VARS* so that ;; references to free functions and variables ;; in the declarations can be noted; ;; *UNDEFINED-WARNINGS* so that warnings about ;; undefined things can be accumulated [and ;; then thrown away, as it happens]). -- CSR, ;; 2002-10-24 (let* ((sb!c:*lexenv* lexenv) (sb!c::*free-funs* (make-hash-table :test 'equal)) (sb!c::*free-vars* (make-hash-table :test 'eq)) (sb!c::*undefined-warnings* nil)) ;; FIXME: VALUES declaration (sb!c::process-decls decls vars nil :lexenv lexenv :context :eval)))) (simple-eval-progn-body body lexenv)))) ;;;; EVAL-ERROR ;;;; ;;;; Analogous to COMPILER-ERROR, but simpler. (define-condition eval-error (encapsulated-condition) () (:report (lambda (condition stream) (print-object (encapsulated-condition condition) stream)))) (defun eval-error (condition) (signal 'eval-error :condition condition) (bug "Unhandled EVAL-ERROR")) ;;; Pick off a few easy cases, and the various top level EVAL-WHEN ;;; magical cases, and call %SIMPLE-EVAL for the rest. (defun simple-eval-in-lexenv (original-exp lexenv) (declare (optimize (safety 1))) ;; (aver (lexenv-simple-p lexenv)) (incf *eval-calls*) (handler-bind ((sb!c:compiler-error (lambda (c) (if (boundp 'sb!c::*compiler-error-bailout*) ;; if we're in the compiler, delegate either to a higher ;; authority or, if that's us, back down to the ;; outermost compiler handler... (progn (signal c) nil) ;; ... if we're not in the compiler, better signal the ;; error straight away. (invoke-restart 'sb!c::signal-error))))) (let ((exp (macroexpand original-exp lexenv))) (handler-bind ((eval-error (lambda (condition) (error 'interpreted-program-error :condition (encapsulated-condition condition) :form exp)))) (typecase exp (symbol (ecase (info :variable :kind exp) ((:special :global :constant :unknown) (symbol-value exp)) ;; FIXME: This special case here is a symptom of non-ANSI ;; weirdness in SBCL's ALIEN implementation, which could ;; cause problems for e.g. code walkers. It'd probably be ;; good to ANSIfy it by making alien variable accessors ;; into ordinary forms, e.g. (SB-UNIX:ENV) and (SETF ;; SB-UNIX:ENV), instead of magical symbols, e.g. plain ;; SB-UNIX:ENV. Then if the old magical-symbol syntax is to ;; be retained for compatibility, it can be implemented ;; with DEFINE-SYMBOL-MACRO, keeping the code walkers ;; happy. (:alien (%simple-eval original-exp lexenv)))) (list (let ((name (first exp)) (n-args (1- (length exp)))) (case name ((function) (unless (= n-args 1) (error "wrong number of args to FUNCTION:~% ~S" exp)) (let ((name (second exp))) (if (and (legal-fun-name-p name) (not (consp (let ((sb!c:*lexenv* lexenv)) (sb!c:lexenv-find name funs))))) (%coerce-name-to-fun name) (%simple-eval original-exp lexenv)))) ((quote) (unless (= n-args 1) (error "wrong number of args to QUOTE:~% ~S" exp)) (second exp)) (setq (unless (evenp n-args) (error "odd number of args to SETQ:~% ~S" exp)) (unless (zerop n-args) (do ((name (cdr exp) (cddr name))) ((null name) (do ((args (cdr exp) (cddr args))) ((null (cddr args)) ;; We duplicate the call to SET so that the ;; correct value gets returned. (set (first args) (simple-eval-in-lexenv (second args) lexenv))) (set (first args) (simple-eval-in-lexenv (second args) lexenv)))) (let ((symbol (first name))) (case (info :variable :kind symbol) (:special) (t (return (%simple-eval original-exp lexenv)))) (unless (type= (info :variable :type symbol) *universal-type*) ;; let the compiler deal with type checking (return (%simple-eval original-exp lexenv))))))) ((progn) (simple-eval-progn-body (rest exp) lexenv)) ((eval-when) ;; FIXME: DESTRUCTURING-BIND returns ARG-COUNT-ERROR ;; instead of PROGRAM-ERROR when there's something wrong ;; with the syntax here (e.g. missing SITUATIONS). This ;; could be fixed by hand-crafting clauses to catch and ;; report each possibility, but it would probably be ;; cleaner to write a new macro ;; DESTRUCTURING-BIND-PROGRAM-SYNTAX which does ;; DESTRUCTURING-BIND and promotes any mismatch to ;; PROGRAM-ERROR, then to use it here and in (probably ;; dozens of) other places where the same problem ;; arises. (destructuring-bind (eval-when situations &rest body) exp (declare (ignore eval-when)) (multiple-value-bind (ct lt e) (sb!c:parse-eval-when-situations situations) ;; CLHS 3.8 - Special Operator EVAL-WHEN: The use of ;; the situation :EXECUTE (or EVAL) controls whether ;; evaluation occurs for other EVAL-WHEN forms; that ;; is, those that are not top level forms, or those ;; in code processed by EVAL or COMPILE. If the ;; :EXECUTE situation is specified in such a form, ;; then the body forms are processed as an implicit ;; PROGN; otherwise, the EVAL-WHEN form returns NIL. (declare (ignore ct lt)) (when e (simple-eval-progn-body body lexenv))))) ((locally) (simple-eval-locally exp lexenv)) ((macrolet) (destructuring-bind (definitions &rest body) (rest exp) (let ((lexenv (let ((sb!c:*lexenv* lexenv)) (sb!c::funcall-in-macrolet-lexenv definitions (lambda (&key funs) (declare (ignore funs)) sb!c:*lexenv*) :eval)))) (simple-eval-locally `(locally ,@body) lexenv)))) ((symbol-macrolet) (destructuring-bind (definitions &rest body) (rest exp) (multiple-value-bind (lexenv vars) (let ((sb!c:*lexenv* lexenv)) (sb!c::funcall-in-symbol-macrolet-lexenv definitions (lambda (&key vars) (values sb!c:*lexenv* vars)) :eval)) (simple-eval-locally `(locally ,@body) lexenv :vars vars)))) ((if) (destructuring-bind (test then &optional else) (rest exp) (eval-in-lexenv (if (eval-in-lexenv test lexenv) then else) lexenv))) ((let let*) (destructuring-bind (definitions &rest body) (rest exp) (if (null definitions) (simple-eval-locally `(locally ,@body) lexenv) (%simple-eval exp lexenv)))) (t (if (and (symbolp name) (eq (info :function :kind name) :function)) (collect ((args)) (dolist (arg (rest exp)) (args (eval-in-lexenv arg lexenv))) (apply (symbol-function name) (args))) (%simple-eval exp lexenv)))))) (t exp)))))) (defun eval-in-lexenv (exp lexenv) #!+sb-eval (if (eq *evaluator-mode* :compile) (simple-eval-in-lexenv exp lexenv) (sb!eval:eval-in-native-environment exp lexenv)) #!-sb-eval (simple-eval-in-lexenv exp lexenv)) (defun eval (original-exp) #!+sb-doc "Evaluate the argument in a null lexical environment, returning the result or results." (eval-in-lexenv original-exp (make-null-lexenv))) ;;; miscellaneous full function definitions of things which are ;;; ordinarily handled magically by the compiler (defun apply (function arg &rest arguments) #!+sb-doc "Apply FUNCTION to a list of arguments produced by evaluating ARGUMENTS in the manner of LIST*. That is, a list is made of the values of all but the last argument, appended to the value of the last argument, which must be a list." (cond ((atom arguments) (apply function arg)) ((atom (cdr arguments)) (apply function (cons arg (car arguments)))) (t (do* ((a1 arguments a2) (a2 (cdr arguments) (cdr a2))) ((atom (cdr a2)) (rplacd a1 (car a2)) (apply function (cons arg arguments))))))) (defun funcall (function &rest arguments) #!+sb-doc "Call FUNCTION with the given ARGUMENTS." (apply function arguments)) (defun values (&rest values) #!+sb-doc "Return all arguments, in order, as values." (declare (truly-dynamic-extent values)) (values-list values)) (defun values-list (list) #!+sb-doc "Return all of the elements of LIST, in order, as values." (values-list list))