1;;; macroexp.el --- Additional macro-expansion support 2;; 3;; Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc. 4;; 5;; Author: Miles Bader <miles@gnu.org> 6;; Keywords: lisp, compiler, macros 7 8;; This file is part of GNU Emacs. 9 10;; GNU Emacs is free software; you can redistribute it and/or modify 11;; it under the terms of the GNU General Public License as published by 12;; the Free Software Foundation; either version 2, or (at your option) 13;; any later version. 14 15;; GNU Emacs is distributed in the hope that it will be useful, 16;; but WITHOUT ANY WARRANTY; without even the implied warranty of 17;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18;; GNU General Public License for more details. 19 20;; You should have received a copy of the GNU General Public License 21;; along with GNU Emacs; see the file COPYING. If not, write to the 22;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 23;; Boston, MA 02110-1301, USA. 24 25;;; Commentary: 26;; 27;; This file contains macro-expansions functions that are not defined in 28;; the Lisp core, namely `macroexpand-all', which expands all macros in 29;; a form, not just a top-level one. 30;; 31 32;;; Code: 33 34;; Bound by the top-level `macroexpand-all', and modified to include any 35;; macros defined by `defmacro'. 36(defvar macroexpand-all-environment nil) 37 38(defun maybe-cons (car cdr original-cons) 39 "Return (CAR . CDR), using ORIGINAL-CONS if possible." 40 (if (and (eq car (car original-cons)) (eq cdr (cdr original-cons))) 41 original-cons 42 (cons car cdr))) 43 44;; We use this special macro to iteratively process forms and share list 45;; structure of the result with the input. Doing so recursively using 46;; `maybe-cons' results in excessively deep recursion for very long 47;; input forms. 48(defmacro macroexp-accumulate (var+list &rest body) 49 "Return a list of the results of evaluating BODY for each element of LIST. 50Evaluate BODY with VAR bound to each `car' from LIST, in turn. 51Return a list of the values of the final form in BODY. 52The list structure of the result will share as much with LIST as 53possible (for instance, when BODY just returns VAR unchanged, the 54result will be eq to LIST). 55 56\(fn (VAR LIST) BODY...)" 57 (let ((var (car var+list)) 58 (list (cadr var+list)) 59 (shared (make-symbol "shared")) 60 (unshared (make-symbol "unshared")) 61 (tail (make-symbol "tail")) 62 (new-el (make-symbol "new-el"))) 63 `(let* ((,shared ,list) 64 (,unshared nil) 65 (,tail ,shared) 66 ,var ,new-el) 67 (while ,tail 68 (setq ,var (car ,tail) 69 ,new-el (progn ,@body)) 70 (unless (eq ,var ,new-el) 71 (while (not (eq ,shared ,tail)) 72 (push (pop ,shared) ,unshared)) 73 (setq ,shared (cdr ,shared)) 74 (push ,new-el ,unshared)) 75 (setq ,tail (cdr ,tail))) 76 (nconc (nreverse ,unshared) ,shared)))) 77(put 'macroexp-accumulate 'lisp-indent-function 1) 78 79(defun macroexpand-all-forms (forms &optional skip) 80 "Return FORMS with macros expanded. FORMS is a list of forms. 81If SKIP is non-nil, then don't expand that many elements at the start of 82FORMS." 83 (macroexp-accumulate (form forms) 84 (if (or (null skip) (zerop skip)) 85 (macroexpand-all-1 form) 86 (setq skip (1- skip)) 87 form))) 88 89(defun macroexpand-all-clauses (clauses &optional skip) 90 "Return CLAUSES with macros expanded. 91CLAUSES is a list of lists of forms; any clause that's not a list is ignored. 92If SKIP is non-nil, then don't expand that many elements at the start of 93each clause." 94 (macroexp-accumulate (clause clauses) 95 (if (listp clause) 96 (macroexpand-all-forms clause skip) 97 clause))) 98 99(defun macroexpand-all-1 (form) 100 "Expand all macros in FORM. 101This is an internal version of `macroexpand-all'. 102Assumes the caller has bound `macroexpand-all-environment'." 103 (if (and (listp form) (eq (car form) 'backquote-list*)) 104 ;; Special-case `backquote-list*', as it is normally a macro that 105 ;; generates exceedingly deep expansions from relatively shallow input 106 ;; forms. We just process it `in reverse' -- first we expand all the 107 ;; arguments, _then_ we expand the top-level definition. 108 (macroexpand (macroexpand-all-forms form 1) 109 macroexpand-all-environment) 110 ;; Normal form; get its expansion, and then expand arguments. 111 (setq form (macroexpand form macroexpand-all-environment)) 112 (if (consp form) 113 (let ((fun (car form))) 114 (cond 115 ((eq fun 'cond) 116 (maybe-cons fun (macroexpand-all-clauses (cdr form)) form)) 117 ((eq fun 'condition-case) 118 (maybe-cons 119 fun 120 (maybe-cons (cadr form) 121 (maybe-cons (macroexpand-all-1 (nth 2 form)) 122 (macroexpand-all-clauses (nthcdr 3 form) 1) 123 (cddr form)) 124 (cdr form)) 125 form)) 126 ((eq fun 'defmacro) 127 (push (cons (cadr form) (cons 'lambda (cddr form))) 128 macroexpand-all-environment) 129 (macroexpand-all-forms form 3)) 130 ((eq fun 'defun) 131 (macroexpand-all-forms form 3)) 132 ((memq fun '(defvar defconst)) 133 (macroexpand-all-forms form 2)) 134 ((eq fun 'function) 135 (if (and (consp (cadr form)) (eq (car (cadr form)) 'lambda)) 136 (maybe-cons fun 137 (maybe-cons (macroexpand-all-forms (cadr form) 2) 138 nil 139 (cadr form)) 140 form) 141 form)) 142 ((memq fun '(let let*)) 143 (maybe-cons fun 144 (maybe-cons (macroexpand-all-clauses (cadr form) 1) 145 (macroexpand-all-forms (cddr form)) 146 (cdr form)) 147 form)) 148 ((eq fun 'quote) 149 form) 150 ((and (consp fun) (eq (car fun) 'lambda)) 151 ;; embedded lambda 152 (maybe-cons (macroexpand-all-forms fun 2) 153 (macroexpand-all-forms (cdr form)) 154 form)) 155 ;; The following few cases are for normal function calls that 156 ;; are known to funcall one of their arguments. The byte 157 ;; compiler has traditionally handled these functions specially 158 ;; by treating a lambda expression quoted by `quote' as if it 159 ;; were quoted by `function'. We make the same transformation 160 ;; here, so that any code that cares about the difference will 161 ;; see the same transformation. 162 ;; First arg is a function: 163 ((and (memq fun '(apply mapcar mapatoms mapconcat mapc)) 164 (consp (cadr form)) 165 (eq (car (cadr form)) 'quote)) 166 ;; We don't use `maybe-cons' since there's clearly a change. 167 (cons fun 168 (cons (macroexpand-all-1 (cons 'function (cdr (cadr form)))) 169 (macroexpand-all-forms (cddr form))))) 170 ;; Second arg is a function: 171 ((and (eq fun 'sort) 172 (consp (nth 2 form)) 173 (eq (car (nth 2 form)) 'quote)) 174 ;; We don't use `maybe-cons' since there's clearly a change. 175 (cons fun 176 (cons (macroexpand-all-1 (cadr form)) 177 (cons (macroexpand-all-1 178 (cons 'function (cdr (nth 2 form)))) 179 (macroexpand-all-forms (nthcdr 3 form)))))) 180 (t 181 ;; For everything else, we just expand each argument (for 182 ;; setq/setq-default this works alright because the variable names 183 ;; are symbols). 184 (macroexpand-all-forms form 1)))) 185 form))) 186 187;;;###autoload 188(defun macroexpand-all (form &optional environment) 189 "Return result of expanding macros at all levels in FORM. 190If no macros are expanded, FORM is returned unchanged. 191The second optional arg ENVIRONMENT specifies an environment of macro 192definitions to shadow the loaded ones for use in file byte-compilation." 193 (let ((macroexpand-all-environment environment)) 194 (macroexpand-all-1 form))) 195 196(provide 'macroexp) 197 198;;; arch-tag: af9b8c24-c196-43bc-91e1-a3570790fa5a 199;;; macroexp.el ends here 200