4b087712af
* Provide some GNUisms as extensions. * Provide dynamically growable string space. * Make define(defn(foo)) work correctly for builtins. (The current version is supposed to be capable of satisfying autoconf.) All still relevant NetBSD changes have been preserved in this version, and formatting and style fixes have been applied in various places. Thanks to Masao Uebayashi <uebayasi@soum.co.jp> for pointing this out.
605 lines
10 KiB
C
605 lines
10 KiB
C
/* $NetBSD: expr.c,v 1.12 2001/11/14 06:16:08 tv Exp $ */
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/* $OpenBSD: expr.c,v 1.11 2000/01/11 14:00:57 espie Exp $ */
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/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Ozan Yigit at York University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)expr.c 8.2 (Berkeley) 4/29/95";
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#else
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__RCSID("$NetBSD: expr.c,v 1.12 2001/11/14 06:16:08 tv Exp $");
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#endif
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#endif /* not lint */
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#include <sys/cdefs.h>
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#include <ctype.h>
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#include <err.h>
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#include <stddef.h>
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#include <stdio.h>
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#include "mdef.h"
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#include "extern.h"
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/*
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* expression evaluator: performs a standard recursive
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* descent parse to evaluate any expression permissible
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* within the following grammar:
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*
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* expr : query EOS
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* query : lor
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* | lor "?" query ":" query
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* lor : land { "||" land }
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* land : not { "&&" not }
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* not : eqrel
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* | '!' not
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* eqrel : shift { eqrelop shift }
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* shift : primary { shop primary }
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* primary : term { addop term }
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* term : exp { mulop exp }
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* exp : unary { expop unary }
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* unary : factor
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* | unop unary
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* factor : constant
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* | "(" query ")"
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* constant: num
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* | "'" CHAR "'"
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* num : DIGIT
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* | DIGIT num
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* shop : "<<"
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* | ">>"
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* eqrel : "="
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* | "=="
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* | "!="
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* | "<"
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* | ">"
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* | "<="
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* | ">="
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*
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*
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* This expression evaluator is lifted from a public-domain
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* C Pre-Processor included with the DECUS C Compiler distribution.
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* It is hacked somewhat to be suitable for m4.
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*
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* Originally by: Mike Lutz
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* Bob Harper
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*/
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#define EQL 0
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#define NEQ 1
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#define LSS 2
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#define LEQ 3
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#define GTR 4
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#define GEQ 5
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#define OCTAL 8
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#define DECIMAL 10
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#define HEX 16
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static const char *nxtch; /* Parser scan pointer */
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static const char *where;
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static int query __P((void));
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static int lor __P((void));
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static int land __P((void));
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static int not __P((void));
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static int eqrel __P((void));
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static int shift __P((void));
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static int primary __P((void));
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static int term __P((void));
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static int exp __P((void));
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static int unary __P((void));
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static int factor __P((void));
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static int constant __P((void));
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static int num __P((void));
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static int geteqrel __P((void));
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static int skipws __P((void));
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static void experr __P((const char *));
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/*
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* For longjmp
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*/
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#include <setjmp.h>
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static jmp_buf expjump;
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/*
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* macros:
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* ungetch - Put back the last character examined.
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* getch - return the next character from expr string.
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*/
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#define ungetch() nxtch--
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#define getch() *nxtch++
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int
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expr(expbuf)
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const char *expbuf;
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{
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int rval;
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nxtch = expbuf;
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where = expbuf;
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if (setjmp(expjump) != 0)
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return FALSE;
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rval = query();
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if (skipws() == EOS)
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return rval;
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printf("m4: ill-formed expression.\n");
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return FALSE;
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}
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/*
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* query : lor | lor '?' query ':' query
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*/
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static int
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query()
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{
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int bool, true_val, false_val;
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bool = lor();
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if (skipws() != '?') {
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ungetch();
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return bool;
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}
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true_val = query();
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if (skipws() != ':')
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experr("bad query");
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false_val = query();
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return bool ? true_val : false_val;
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}
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/*
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* lor : land { '||' land }
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*/
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static int
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lor()
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{
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int c, vl, vr;
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vl = land();
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while ((c = skipws()) == '|') {
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if (getch() != '|')
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ungetch();
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vr = land();
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vl = vl || vr;
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}
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ungetch();
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return vl;
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}
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/*
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* land : not { '&&' not }
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*/
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static int
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land()
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{
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int c, vl, vr;
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vl = not();
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while ((c = skipws()) == '&') {
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if (getch() != '&')
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ungetch();
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vr = not();
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vl = vl && vr;
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}
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ungetch();
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return vl;
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}
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/*
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* not : eqrel | '!' not
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*/
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static int
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not()
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{
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int val, c;
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if ((c = skipws()) == '!' && getch() != '=') {
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ungetch();
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val = not();
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return !val;
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}
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if (c == '!')
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ungetch();
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ungetch();
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return eqrel();
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}
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/*
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* eqrel : shift { eqrelop shift }
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*/
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static int
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eqrel()
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{
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int vl, vr, eqrelvar;
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vl = shift();
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while ((eqrelvar = geteqrel()) != -1) {
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vr = shift();
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switch (eqrelvar) {
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case EQL:
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vl = (vl == vr);
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break;
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case NEQ:
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vl = (vl != vr);
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break;
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case LEQ:
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vl = (vl <= vr);
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break;
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case LSS:
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vl = (vl < vr);
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break;
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case GTR:
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vl = (vl > vr);
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break;
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case GEQ:
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vl = (vl >= vr);
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break;
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}
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}
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return vl;
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}
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/*
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* shift : primary { shop primary }
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*/
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static int
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shift()
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{
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int vl, vr, c;
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vl = primary();
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while (((c = skipws()) == '<' || c == '>') && getch() == c) {
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vr = primary();
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if (c == '<')
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vl <<= vr;
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else
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vl >>= vr;
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}
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if (c == '<' || c == '>')
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ungetch();
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ungetch();
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return vl;
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}
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/*
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* primary : term { addop term }
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*/
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static int
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primary()
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{
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int c, vl, vr;
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vl = term();
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while ((c = skipws()) == '+' || c == '-') {
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vr = term();
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if (c == '+')
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vl += vr;
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else
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vl -= vr;
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}
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ungetch();
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return vl;
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}
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/*
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* <term> := <exp> { <mulop> <exp> }
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*/
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static int
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term()
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{
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int c, vl, vr;
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vl = exp();
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while ((c = skipws()) == '*' || c == '/' || c == '%') {
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vr = exp();
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switch (c) {
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case '*':
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vl *= vr;
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break;
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case '/':
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if (vr == 0)
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errx(1, "division by zero in eval.");
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else
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vl /= vr;
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break;
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case '%':
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if (vr == 0)
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errx(1, "modulo zero in eval.");
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else
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vl %= vr;
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break;
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}
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}
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ungetch();
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return vl;
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}
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/*
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* <term> := <unary> { <expop> <unary> }
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*/
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static int
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exp()
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{
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int c, vl, vr, n;
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vl = unary();
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switch (c = skipws()) {
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case '*':
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if (getch() != '*') {
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ungetch();
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break;
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}
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case '^':
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vr = exp();
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n = 1;
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while (vr-- > 0)
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n *= vl;
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return n;
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}
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ungetch();
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return vl;
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}
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/*
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* unary : factor | unop unary
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*/
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static int
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unary()
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{
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int val, c;
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if ((c = skipws()) == '+' || c == '-' || c == '~') {
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val = unary();
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switch (c) {
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case '+':
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return val;
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case '-':
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return -val;
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case '~':
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return ~val;
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}
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}
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ungetch();
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return factor();
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}
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/*
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* factor : constant | '(' query ')'
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*/
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static int
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factor()
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{
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int val;
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if (skipws() == '(') {
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val = query();
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if (skipws() != ')')
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experr("bad factor");
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return val;
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}
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ungetch();
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return constant();
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}
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/*
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* constant: num | 'char'
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* Note: constant() handles multi-byte constants
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*/
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static int
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constant()
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{
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int i;
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int value;
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char c;
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int v[sizeof(int)];
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if (skipws() != '\'') {
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ungetch();
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return num();
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}
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for (i = 0; i < sizeof(int); i++) {
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if ((c = getch()) == '\'') {
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ungetch();
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break;
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}
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if (c == '\\') {
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switch (c = getch()) {
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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ungetch();
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c = num();
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break;
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case 'n':
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c = 012;
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break;
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case 'r':
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c = 015;
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break;
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case 't':
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c = 011;
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break;
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case 'b':
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c = 010;
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break;
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case 'f':
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c = 014;
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break;
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}
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}
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v[i] = c;
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}
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if (i == 0 || getch() != '\'')
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experr("illegal character constant");
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for (value = 0; --i >= 0;) {
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value <<= 8;
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value += v[i];
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}
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return value;
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}
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/*
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* num : digit | num digit
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*/
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static int
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num()
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{
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int rval, c, base;
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int ndig;
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base = ((c = skipws()) == '0') ? OCTAL : DECIMAL;
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rval = 0;
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ndig = 0;
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if (base == OCTAL) {
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c = skipws();
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if (c == 'x' || c == 'X') {
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base = HEX;
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c = skipws();
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} else
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ndig++;
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}
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while ((base == HEX && isxdigit(c)) ||
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(c >= '0' && c <= (base == OCTAL ? '7' : '9'))) {
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rval *= base;
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if (isalpha(c))
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rval += (tolower(c) - 'a' + 10);
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else
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rval += (c - '0');
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c = getch();
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ndig++;
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}
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ungetch();
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if (ndig == 0)
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experr("bad constant");
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return rval;
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}
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/*
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* eqrel : '=' | '==' | '!=' | '<' | '>' | '<=' | '>='
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*/
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static int
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geteqrel()
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{
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int c1, c2;
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c1 = skipws();
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c2 = getch();
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switch (c1) {
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case '=':
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if (c2 != '=')
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ungetch();
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return EQL;
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case '!':
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if (c2 == '=')
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return NEQ;
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ungetch();
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ungetch();
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return -1;
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case '<':
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if (c2 == '=')
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return LEQ;
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ungetch();
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return LSS;
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case '>':
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if (c2 == '=')
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return GEQ;
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ungetch();
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return GTR;
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default:
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ungetch();
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ungetch();
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return -1;
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}
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}
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/*
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* Skip over any white space and return terminating char.
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*/
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static int
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skipws()
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{
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char c;
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while ((c = getch()) <= ' ' && c > EOS)
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;
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return c;
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}
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/*
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* resets environment to eval(), prints an error
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* and forces eval to return FALSE.
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*/
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static void
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experr(msg)
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const char *msg;
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{
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printf("m4: %s in expr %s.\n", msg, where);
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longjmp(expjump, -1);
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}
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