Function: cl--loop-build-ands

cl--loop-build-ands is a byte-compiled function defined in cl-macs.el.gz.

Signature

(cl--loop-build-ands CLAUSES)

Documentation

Return various representations of (and . CLAUSES).

CLAUSES is a list of Elisp expressions, where clauses of the form
(progn E1 E2 E3 .. t) are the focus of particular optimizations.
The return value has shape (COND BODY COMBO) such that COMBO is equivalent to (and . CLAUSES).

Source Code

;; Defined in /usr/src/emacs/lisp/emacs-lisp/cl-macs.el.gz
(defun cl--loop-build-ands (clauses)
  "Return various representations of (and . CLAUSES).
CLAUSES is a list of Elisp expressions, where clauses of the form
\(progn E1 E2 E3 .. t) are the focus of particular optimizations.
The return value has shape (COND BODY COMBO)
such that COMBO is equivalent to (and . CLAUSES)."
  (let ((ands nil)
	(body nil))
    ;; Look through `clauses', trying to optimize (progn ,@A t) (progn ,@B) ,@C
    ;; into (progn ,@A ,@B) ,@C.
    (while clauses
      (if (and (eq (car-safe (car clauses)) 'progn)
	       (eq (car (last (car clauses))) t))
	  (if (cdr clauses)
	      (setq clauses (cons (nconc (butlast (car clauses))
					 (if (eq (car-safe (cadr clauses))
						 'progn)
					     (cl-cdadr clauses)
					   (list (cadr clauses))))
				  (cddr clauses)))
            ;; A final (progn ,@A t) is moved outside of the `and'.
	    (setq body (cdr (butlast (pop clauses)))))
	(push (pop clauses) ands)))
    (setq ands (or (nreverse ands) (list t)))
    (list (if (cdr ands) (cons 'and ands) (car ands))
	  body
	  (let ((full (if body
			  (append ands (list (cons 'progn (append body '(t)))))
			ands)))
	    (if (cdr full) (cons 'and full) (car full))))))