Squashed 'third_party/lisp/quasiquote_2/' content from commit cac90875d1

git-subtree-dir: third_party/lisp/quasiquote_2
git-subtree-split: cac90875d1f66e9385e559bfebafe6b7808b0930

quasiquote-2.0.lisp

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+;;;; quasiquote-2.0.lisp
+
+(in-package #:quasiquote-2.0)
+
+(defparameter *env* nil)
+
+(defmacro nonsense-error (str)
+  `(error ,(concatenate 'string
+			str
+			" appears as a bare, non DIG-enclosed form. "
+			"For now I don't know how to make sense of this.")))
+
+(defmacro define-nonsense-when-bare (name)
+  `(defmacro ,name (n-or-form &optional form)
+     (declare (ignore n-or-form form))
+     (nonsense-error ,(string name))))
+
+(define-nonsense-when-bare inject)
+(define-nonsense-when-bare oinject)
+(define-nonsense-when-bare splice)
+(define-nonsense-when-bare osplice)
+(define-nonsense-when-bare macro-inject)
+
+(defparameter *depth* 0)
+
+
+(defparameter *injectors* nil)
+
+;; (defmacro with-injector-parsed (form)
+;;   `(let ((kwd (intern (string 
+
+(defun reset-injectors ()
+  (setf *injectors* nil))
+
+(defparameter *known-injectors* '(inject splice oinject osplice
+				  macro-inject omacro-inject
+				  macro-splice omacro-splice
+				  macro-inject-all omacro-inject-all
+				  macro-splice-all omacro-splice-all))
+
+(defun injector-form-p (form)
+  (and (consp form)
+       (find (car form) *known-injectors* :test #'eq)))
+
+(defun injector-level (form)
+  (if (equal 2 (length form))
+      1
+      (cadr form)))
+
+(defun injector-subform (form)
+  (if (equal 2 (length form))
+      (values (cdr form) '(cdr))
+      (values (cddr form) '(cddr))))
+
+(defparameter *opaque-injectors* '(odig oinject osplice omacro-inject))
+
+(defun transparent-p (form)
+  (not (find (car form) *opaque-injectors* :test #'eq)))
+
+(defun look-into-injector (form path)
+  (let ((*depth* (- *depth* (injector-level form))))
+    (multiple-value-bind (subform subpath) (injector-subform form)
+      (search-all-active-sites subform (append subpath path) nil))))
+
+(defparameter *known-diggers* '(dig odig))
+
+(defun dig-form-p (form)
+  (and (consp form)
+       (find (car form) *known-diggers* :test #'eq)))
+
+(defun look-into-dig (form path)
+  (let ((*depth* (+ *depth* (injector-level form))))
+    (multiple-value-bind (subform subpath) (injector-subform form)
+      (search-all-active-sites subform (append subpath path) nil))))
+
+(defun handle-macro-1 (form)
+  (if (atom form)
+      (error "Sorry, symbol-macros are not implemented for now")
+      (let ((fun (macro-function (car form) *env*)))
+	(if (not fun)
+	    (error "The subform of MACRO-1 injector is supposed to be macro, perhaps, something went wrong..."))
+	(macroexpand-1 form *env*))))
+
+(defun handle-macro-all (form)
+  (if (atom form)
+      (error "Sorry, symbol-macros are not implemented for now")
+      (macroexpand form *env*)))
+
+
+(defparameter *macro-handlers* `((macro-inject . ,#'handle-macro-1)
+				 (omacro-inject . ,#'handle-macro-1)
+				 (macro-splice . ,#'handle-macro-1)
+				 (omacro-splice . ,#'handle-macro-1)
+				 (macro-inject-all . ,#'handle-macro-all)
+				 (omacro-inject-all . ,#'handle-macro-all)
+				 (macro-splice-all . ,#'handle-macro-all)
+				 (omacro-splice-all . ,#'handle-macro-all)))
+
+(defun get-macro-handler (sym)
+  (or (cdr (assoc sym *macro-handlers*))
+      (error "Don't know how to handle this macro injector: ~a" sym)))
+
+	
+
+(defun macroexpand-macroinjector (place)
+  (if (not (splicing-injector (car place)))
+      (progn (setf (car place) (funcall (get-macro-handler (caar place))
+					(car (injector-subform (car place)))))
+	     nil)
+      (let ((new-forms (funcall (get-macro-handler (caar place))
+				(car (injector-subform (car place))))))
+	(cond ((not new-forms)
+	       (setf *void-filter-needed* t
+		     (car place) *void-elt*))
+	      ((atom new-forms) (error "We need to splice the macroexpansion, but got atom: ~a" new-forms))
+	      (t (setf (car place) (car new-forms))
+		 (let ((tail (cdr place)))
+		   (setf (cdr place) (cdr new-forms)
+			 (cdr (last new-forms)) tail))))
+	t)))
+	    
+
+(defun search-all-active-sites (form path toplevel-p)
+  ;; (format t "SEARCH-ALL-ACTIVE-SITES: got form ~a~%" form)
+  (if (not form)
+      nil
+      (if toplevel-p
+	  (cond ((atom (car form)) :just-quote-it!)
+		((injector-form-p (car form)) (if (equal *depth* (injector-level (car form)))
+						  :just-form-it!
+						  (if (transparent-p (car form))
+						      (look-into-injector (car form) (cons 'car path)))))
+		((dig-form-p (car form))
+		 ;; (format t "Got dig form ~a~%" form)
+		 (if (transparent-p (car form))
+		     (look-into-dig (car form) (cons 'car path))))
+		(t (search-all-active-sites (car form) (cons 'car path) nil)
+		   (search-all-active-sites (cdr form) (cons 'cdr path) nil)))
+	  (when (consp form)
+	    (cond ((dig-form-p (car form))
+		   ;; (format t "Got dig form ~a~%" form)
+		   (if (transparent-p (car form))
+		       (look-into-dig (car form) (cons 'car path))))
+		  ((injector-form-p (car form))
+		   ;; (format t "Got injector form ~a ~a ~a~%" form *depth* (injector-level (car form)))
+		   (if (equal *depth* (injector-level (car form)))
+		       (if (macro-injector-p (car form))
+			   (progn (macroexpand-macroinjector form)
+				  (return-from search-all-active-sites
+				    (search-all-active-sites form path nil)))
+			   (progn (push (cons form (cons 'car path)) *injectors*)
+				  nil))
+		       (if (transparent-p (car form))
+			   (look-into-injector (car form) (cons 'car path)))))
+		  (t (search-all-active-sites (car form) (cons 'car path) nil)))
+	    (search-all-active-sites (cdr form) (cons 'cdr path) nil)))))
+
+	  
+	      
+(defun codewalk-dig-form (form)
+  (reset-injectors)
+  (let ((it (search-all-active-sites form nil t)))
+    (values (nreverse *injectors*) it)))
+
+(defun %codewalk-dig-form (form)
+  (if (not (dig-form-p form))
+      (error "Supposed to be called on dig form")
+      (let ((*depth* (+ (injector-level form) *depth*)))
+	(codewalk-dig-form (injector-subform form)))))
+
+(defun path->setfable (path var)
+  (let ((res var))
+    ;; First element is artifact of extra CAR-ing
+    (dolist (spec (cdr (reverse path)))
+      (setf res (list spec res)))
+    res))
+
+(defun tree->cons-code (tree)
+  (if (atom tree)
+      `(quote ,tree)
+      `(cons ,(tree->cons-code (car tree))
+	     ,(tree->cons-code (cdr tree)))))
+
+(defparameter *known-splicers* '(splice osplice
+				 macro-splice omacro-splice
+				 macro-splice-all omacro-splice-all))
+
+(defun splicing-injector (form)
+  (and (consp form)
+       (find (car form) *known-splicers* :test #'eq)))
+
+(defparameter *known-macro-injectors* '(macro-inject omacro-inject
+					macro-splice omacro-splice
+					macro-inject-all omacro-inject-all
+					macro-splice-all omacro-splice-all
+					))
+
+(defun macro-injector-p (form)
+  (and (consp form)
+       (find (car form) *known-macro-injectors* :test #'eq)))
+
+(defparameter *void-elt* nil)
+(defparameter *void-filter-needed* nil)
+
+(defun filter-out-voids (lst void-sym)
+  (let (caars cadrs cdars cddrs)
+    ;; search for all occurences of VOID
+    (labels ((rec (x)
+	       (if (consp x)
+		   (progn (cond ((consp (car x))
+				 (cond ((eq void-sym (caar x)) (push x caars))
+				       ((eq void-sym (cdar x)) (push x cdars))))
+				((consp (cdr x))
+				 (cond ((eq void-sym (cadr x)) (push x cadrs))
+				       ((eq void-sym (cddr x)) (push x cddrs)))))
+			  (rec (car x))
+			  (rec (cdr x))))))
+      (rec lst))
+    (if (or cdars cddrs)
+	(error "Void sym found on CDR position, which should not have happened"))
+    ;; destructively transform LST
+    (dolist (elt caars)
+      (setf (car elt) (cdar elt)))
+    (dolist (elt cadrs)
+      (setf (cdr elt) (cddr elt)))
+    ;; check that we indeed filtered-out all VOIDs
+    (labels ((rec (x)
+	       (if (not (atom x))
+		   (progn (rec (car x))
+			  (rec (cdr x)))
+		   (if (eq void-sym x)
+		       (error "Not all VOIDs were filtered")))))
+      (rec lst))
+    lst))
+
+(defun transform-dig-form (form)
+  (let ((the-form (copy-tree form)))
+    (let ((*void-filter-needed* nil)
+	  (*void-elt* (gensym "VOID")))
+      (multiple-value-bind (site-paths cmd) (%codewalk-dig-form the-form)
+	(cond ((eq cmd :just-quote-it!)
+	       `(quote ,(car (injector-subform the-form))))
+	      ((eq cmd :just-form-it!)
+	       (car (injector-subform (car (injector-subform the-form)))))
+	      (t (let ((cons-code (if (not site-paths)
+				      (tree->cons-code (car (injector-subform the-form)))
+				      (really-transform-dig-form the-form site-paths))))
+		   (if (not *void-filter-needed*)
+		       cons-code
+		       `(filter-out-voids ,cons-code ',*void-elt*)))))))))
+
+(defmacro make-list-form (o!-n form)
+  (let ((g!-n (gensym "N"))
+	(g!-i (gensym "I"))
+	(g!-res (gensym "RES")))
+    `(let ((,g!-n ,o!-n)
+	   (,g!-res nil))
+       (dotimes (,g!-i ,g!-n)
+	 (push ,form ,g!-res))
+       (nreverse ,g!-res))))
+
+(defun mk-splicing-injector-let (x)
+  `(let ((it ,(car (injector-subform x))))
+     (assert (listp it))
+     (copy-list it)))
+
+
+
+(defun mk-splicing-injector-setf (path g!-list g!-splicee)
+  (assert (eq 'car (car path)))
+  (let ((g!-rest (gensym "REST")))
+    `(let ((,g!-rest ,(path->setfable (cons 'cdr (cdr path)) g!-list)))
+       (assert (or (not ,g!-rest) (consp ,g!-rest)))
+       (if (not ,g!-splicee)
+	   (setf ,(path->setfable (cdr path) g!-list)
+		 ,g!-rest)
+	   (progn (setf ,(path->setfable (cdr path) g!-list) ,g!-splicee)
+		  (setf (cdr (last ,g!-splicee)) ,g!-rest))))))
+
+
+(defun really-transform-dig-form (the-form site-paths)
+  (let ((gensyms (make-list-form (length site-paths) (gensym "INJECTEE"))))
+    (let ((g!-list (gensym "LIST")))
+      (let ((lets nil)
+	    (splicing-setfs nil)
+	    (setfs nil))
+	(do ((site-path site-paths (cdr site-path))
+	     (gensym gensyms (cdr gensym)))
+	    ((not site-path))
+	  (destructuring-bind (site . path) (car site-path)
+	    (push `(,(car gensym) ,(if (not (splicing-injector (car site)))
+				       (car (injector-subform (car site)))
+				       (mk-splicing-injector-let (car site))))
+		  lets)
+	    (if (not (splicing-injector (car site)))
+		(push `(setf ,(path->setfable path g!-list) ,(car gensym)) setfs)
+		(push (mk-splicing-injector-setf path g!-list (car gensym)) splicing-setfs))
+	    (setf (car site) nil)))
+	`(let ,(nreverse lets)
+	   (let ((,g!-list ,(tree->cons-code (car (injector-subform the-form)))))
+	     ,@(nreverse setfs)
+	     ;; we apply splicing setf in reverse order for them not to bork the paths of each other
+	     ,@splicing-setfs
+	     ,g!-list))))))
+
+
+;; There are few types of recursive injection that may happen:
+;;   * compile-time injection:
+;;     (dig (inject (dig (inject a)))) -- this type will be handled automatically by subsequent macroexpansions
+;;   * run-time injection:
+;;     (dig (dig (inject 2 a)))
+;;     and A is '(dig (inject 3 'foo)) -- this one we guard against ? (probably, first we just ignore it
+;;     -- do not warn about it, and then it wont really happen.
+;;   * macroexpanded compile-time injection:
+;;     (dig (inject (my-macro a b c))),
+;;     where MY-MACRO expands into, say (splice (list 'a 'b 'c))
+;;     This is *not* handled automatically, and therefore we must do it by hand.
+
+      
+;; OK, now how to implement splicing ?
+;;   (dig (a (splice (list b c)) d))
+;; should transform into code that yields
+;;   (a b c d)
+;; what this code is?
+;;   (let ((#:a (copy-list (list b c))))
+;;     (let ((#:res (cons 'a nil 'd)))
+;;       ;; all non-splicing injects go here, as they do not spoil the path-structure
+;;       (setf (cdr #:res) #:a)
+;;       (setf (cdr (last #:a)) (cdr (cdr #:res)))
+;;       #:res)))
+
+
+;; How this macroexpansion should work in general?
+;;   * We go over the cons-tree, keeping track of the depth level, which is
+;;   controlled by DIG's
+;;   * Once we find the INJECT with matching level, we remember the place, where
+;;     this happens
+;;   * We have two special cases:
+;;     * cons-tree is an atom
+;;     * cons-tree is just a single INJECT