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198 lines
7.2 KiB
EmacsLisp
198 lines
7.2 KiB
EmacsLisp
;;; macroexp.el --- Additional macro-expansion support
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;;
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;; Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
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;;
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;; Author: Miles Bader <miles@gnu.org>
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;; Keywords: lisp, compiler, macros
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;;
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;; This file contains macro-expansions functions that are not defined in
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;; the Lisp core, namely `macroexpand-all', which expands all macros in
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;; a form, not just a top-level one.
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;;
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;;; Code:
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;; Bound by the top-level `macroexpand-all', and modified to include any
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;; macros defined by `defmacro'.
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(defvar macroexpand-all-environment nil)
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(defun maybe-cons (car cdr original-cons)
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"Return (CAR . CDR), using ORIGINAL-CONS if possible."
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(if (and (eq car (car original-cons)) (eq cdr (cdr original-cons)))
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original-cons
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(cons car cdr)))
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;; We use this special macro to iteratively process forms and share list
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;; structure of the result with the input. Doing so recursively using
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;; `maybe-cons' results in excessively deep recursion for very long
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;; input forms.
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(defmacro macroexp-accumulate (var+list &rest body)
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"Return a list of the results of evaluating BODY for each element of LIST.
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Evaluate BODY with VAR bound to each `car' from LIST, in turn.
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Return a list of the values of the final form in BODY.
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The list structure of the result will share as much with LIST as
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possible (for instance, when BODY just returns VAR unchanged, the
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result will be eq to LIST).
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\(fn (VAR LIST) BODY...)"
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(let ((var (car var+list))
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(list (cadr var+list))
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(shared (make-symbol "shared"))
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(unshared (make-symbol "unshared"))
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(tail (make-symbol "tail"))
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(new-el (make-symbol "new-el")))
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`(let* ((,shared ,list)
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(,unshared nil)
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(,tail ,shared)
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,var ,new-el)
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(while ,tail
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(setq ,var (car ,tail)
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,new-el (progn ,@body))
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(unless (eq ,var ,new-el)
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(while (not (eq ,shared ,tail))
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(push (pop ,shared) ,unshared))
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(setq ,shared (cdr ,shared))
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(push ,new-el ,unshared))
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(setq ,tail (cdr ,tail)))
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(nconc (nreverse ,unshared) ,shared))))
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(put 'macroexp-accumulate 'lisp-indent-function 1)
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(defun macroexpand-all-forms (forms &optional skip)
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"Return FORMS with macros expanded. FORMS is a list of forms.
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If SKIP is non-nil, then don't expand that many elements at the start of
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FORMS."
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(macroexp-accumulate (form forms)
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(if (or (null skip) (zerop skip))
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(macroexpand-all-1 form)
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(setq skip (1- skip))
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form)))
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(defun macroexpand-all-clauses (clauses &optional skip)
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"Return CLAUSES with macros expanded.
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CLAUSES is a list of lists of forms; any clause that's not a list is ignored.
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If SKIP is non-nil, then don't expand that many elements at the start of
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each clause."
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(macroexp-accumulate (clause clauses)
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(if (listp clause)
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(macroexpand-all-forms clause skip)
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clause)))
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(defun macroexpand-all-1 (form)
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"Expand all macros in FORM.
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This is an internal version of `macroexpand-all'.
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Assumes the caller has bound `macroexpand-all-environment'."
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(if (and (listp form) (eq (car form) 'backquote-list*))
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;; Special-case `backquote-list*', as it is normally a macro that
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;; generates exceedingly deep expansions from relatively shallow input
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;; forms. We just process it `in reverse' -- first we expand all the
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;; arguments, _then_ we expand the top-level definition.
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(macroexpand (macroexpand-all-forms form 1)
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macroexpand-all-environment)
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;; Normal form; get its expansion, and then expand arguments.
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(setq form (macroexpand form macroexpand-all-environment))
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(if (consp form)
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(let ((fun (car form)))
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(cond
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((eq fun 'cond)
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(maybe-cons fun (macroexpand-all-clauses (cdr form)) form))
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((eq fun 'condition-case)
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(maybe-cons
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fun
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(maybe-cons (cadr form)
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(maybe-cons (macroexpand-all-1 (nth 2 form))
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(macroexpand-all-clauses (nthcdr 3 form) 1)
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(cddr form))
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(cdr form))
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form))
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((eq fun 'defmacro)
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(push (cons (cadr form) (cons 'lambda (cddr form)))
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macroexpand-all-environment)
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(macroexpand-all-forms form 3))
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((eq fun 'defun)
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(macroexpand-all-forms form 3))
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((memq fun '(defvar defconst))
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(macroexpand-all-forms form 2))
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((eq fun 'function)
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(if (and (consp (cadr form)) (eq (car (cadr form)) 'lambda))
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(maybe-cons fun
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(maybe-cons (macroexpand-all-forms (cadr form) 2)
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nil
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(cadr form))
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form)
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form))
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((memq fun '(let let*))
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(maybe-cons fun
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(maybe-cons (macroexpand-all-clauses (cadr form) 1)
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(macroexpand-all-forms (cddr form))
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(cdr form))
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form))
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((eq fun 'quote)
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form)
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((and (consp fun) (eq (car fun) 'lambda))
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;; embedded lambda
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(maybe-cons (macroexpand-all-forms fun 2)
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(macroexpand-all-forms (cdr form))
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form))
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;; The following few cases are for normal function calls that
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;; are known to funcall one of their arguments. The byte
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;; compiler has traditionally handled these functions specially
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;; by treating a lambda expression quoted by `quote' as if it
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;; were quoted by `function'. We make the same transformation
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;; here, so that any code that cares about the difference will
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;; see the same transformation.
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;; First arg is a function:
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((and (memq fun '(apply mapcar mapatoms mapconcat mapc))
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(consp (cadr form))
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(eq (car (cadr form)) 'quote))
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;; We don't use `maybe-cons' since there's clearly a change.
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(cons fun
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(cons (macroexpand-all-1 (cons 'function (cdr (cadr form))))
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(macroexpand-all-forms (cddr form)))))
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;; Second arg is a function:
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((and (eq fun 'sort)
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(consp (nth 2 form))
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(eq (car (nth 2 form)) 'quote))
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;; We don't use `maybe-cons' since there's clearly a change.
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(cons fun
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(cons (macroexpand-all-1 (cadr form))
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(cons (macroexpand-all-1
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(cons 'function (cdr (nth 2 form))))
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(macroexpand-all-forms (nthcdr 3 form))))))
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(t
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;; For everything else, we just expand each argument (for
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;; setq/setq-default this works alright because the variable names
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;; are symbols).
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(macroexpand-all-forms form 1))))
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form)))
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;;;###autoload
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(defun macroexpand-all (form &optional environment)
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"Return result of expanding macros at all levels in FORM.
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If no macros are expanded, FORM is returned unchanged.
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The second optional arg ENVIRONMENT specifies an environment of macro
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definitions to shadow the loaded ones for use in file byte-compilation."
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(let ((macroexpand-all-environment environment))
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(macroexpand-all-1 form)))
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(provide 'macroexp)
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;; arch-tag: af9b8c24-c196-43bc-91e1-a3570790fa5a
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;;; macroexp.el ends here
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