426 lines
10 KiB
C
426 lines
10 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* $XConsortium: ifparser.c,v 1.8 95/06/03 00:01:41 gildea Exp $
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*
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* Copyright 1992 Network Computing Devices, Inc.
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose and without fee is hereby granted, provided
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* that the above copyright notice appear in all copies and that both that
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* copyright notice and this permission notice appear in supporting
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* documentation, and that the name of Network Computing Devices may not be
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* used in advertising or publicity pertaining to distribution of the software
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* without specific, written prior permission. Network Computing Devices makes
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* no representations about the suitability of this software for any purpose.
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* It is provided ``as is'' without express or implied warranty.
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*
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* NETWORK COMPUTING DEVICES DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
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* SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
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* IN NO EVENT SHALL NETWORK COMPUTING DEVICES BE LIABLE FOR ANY SPECIAL,
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* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*
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* Author: Jim Fulton
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* Network Computing Devices, Inc.
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*
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* Simple if statement processor
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*
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* This module can be used to evaluate string representations of C language
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* if constructs. It accepts the following grammar:
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*
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* EXPRESSION := VALUE
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* | VALUE BINOP EXPRESSION
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*
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* VALUE := '(' EXPRESSION ')'
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* | '!' VALUE
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* | '-' VALUE
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* | 'defined' '(' variable ')'
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* | 'defined' variable
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* | # variable '(' variable-list ')'
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* | variable
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* | number
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*
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* BINOP := '*' | '/' | '%'
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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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* The normal C order of precidence is supported.
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*
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*
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* External Entry Points:
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*
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* ParseIfExpression parse a string for #if
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*/
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#include "ifparser.h"
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#include <ctype.h>
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#include <stdlib.h>
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#include <string.h>
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/****************************************************************************
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Internal Macros and Utilities for Parser
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****************************************************************************/
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#define DO(val) if (!(val)) return NULL
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#define CALLFUNC(ggg,fff) (*((ggg)->funcs.fff))
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#define SKIPSPACE(ccc) while (isspace((unsigned char)*ccc)) ccc++
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#define isvarfirstletter(ccc) (isalpha((unsigned char)(ccc)) || (ccc) == '_')
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static const char *
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parse_variable (IfParser *g, const char *cp, const char **varp)
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{
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SKIPSPACE (cp);
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if (!isvarfirstletter (*cp))
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return CALLFUNC(g, handle_error) (g, cp, "variable name");
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*varp = cp;
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/* EMPTY */
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for (cp++; isalnum((unsigned char)*cp) || *cp == '_'; cp++) ;
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return cp;
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}
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static const char *
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parse_number (IfParser *g, const char *cp, int *valp)
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{
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SKIPSPACE (cp);
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if (!isdigit((unsigned char)*cp))
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return CALLFUNC(g, handle_error) (g, cp, "number");
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#ifdef _WIN32
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{
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char *cp2;
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*valp = strtol(cp, &cp2, 0);
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}
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#else
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*valp = atoi (cp);
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/* EMPTY */
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for (cp++; isdigit((unsigned char)*cp); cp++) ;
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#endif
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return cp;
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}
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static const char *
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parse_value (IfParser *g, const char *cp, int *valp)
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{
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const char *var;
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*valp = 0;
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SKIPSPACE (cp);
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if (!*cp)
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return cp;
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switch (*cp) {
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case '(':
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DO (cp = ParseIfExpression (g, cp + 1, valp));
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SKIPSPACE (cp);
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if (*cp != ')')
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return CALLFUNC(g, handle_error) (g, cp, ")");
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return cp + 1; /* skip the right paren */
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case '!':
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DO (cp = parse_value (g, cp + 1, valp));
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*valp = !(*valp);
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return cp;
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case '-':
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DO (cp = parse_value (g, cp + 1, valp));
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*valp = -(*valp);
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return cp;
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case '#':
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DO (cp = parse_variable (g, cp + 1, &var));
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SKIPSPACE (cp);
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if (*cp != '(')
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return CALLFUNC(g, handle_error) (g, cp, "(");
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do {
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DO (cp = parse_variable (g, cp + 1, &var));
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SKIPSPACE (cp);
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} while (*cp && *cp != ')');
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if (*cp != ')')
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return CALLFUNC(g, handle_error) (g, cp, ")");
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*valp = 1; /* XXX */
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return cp + 1;
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case 'd':
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if (strncmp (cp, "defined", 7) == 0 && !isalnum((unsigned char)cp[7])) {
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int paren = 0;
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size_t len;
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cp += 7;
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SKIPSPACE (cp);
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if (*cp == '(') {
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paren = 1;
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cp++;
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}
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DO (cp = parse_variable (g, cp, &var));
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len = (size_t)(cp - var);
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SKIPSPACE (cp);
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if (paren && *cp != ')')
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return CALLFUNC(g, handle_error) (g, cp, ")");
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*valp = (*(g->funcs.eval_defined)) (g, var, len);
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return cp + paren; /* skip the right paren */
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}
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/* fall out */
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}
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if (isdigit((unsigned char)*cp)) {
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DO (cp = parse_number (g, cp, valp));
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} else if (!isvarfirstletter(*cp))
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return CALLFUNC(g, handle_error) (g, cp, "variable or number");
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else {
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DO (cp = parse_variable (g, cp, &var));
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*valp = (*(g->funcs.eval_variable)) (g, var, (size_t)(cp - var));
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}
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return cp;
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}
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static const char *
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parse_product (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_value (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '*':
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DO (cp = parse_product (g, cp + 1, &rightval));
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*valp = (*valp * rightval);
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break;
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case '/':
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DO (cp = parse_product (g, cp + 1, &rightval));
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/* Do nothing in the divide-by-zero case. */
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if (rightval) {
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*valp = (*valp / rightval);
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}
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break;
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case '%':
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DO (cp = parse_product (g, cp + 1, &rightval));
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*valp = (*valp % rightval);
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break;
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}
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return cp;
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}
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static const char *
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parse_sum (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_product (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '+':
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DO (cp = parse_sum (g, cp + 1, &rightval));
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*valp = (*valp + rightval);
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break;
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case '-':
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DO (cp = parse_sum (g, cp + 1, &rightval));
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*valp = (*valp - rightval);
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break;
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}
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return cp;
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}
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static const char *
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parse_shift (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_sum (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '<':
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if (cp[1] == '<') {
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DO (cp = parse_shift (g, cp + 2, &rightval));
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*valp = (*valp << rightval);
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}
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break;
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case '>':
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if (cp[1] == '>') {
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DO (cp = parse_shift (g, cp + 2, &rightval));
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*valp = (*valp >> rightval);
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}
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break;
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}
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return cp;
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}
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static const char *
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parse_inequality (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_shift (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '<':
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if (cp[1] == '=') {
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DO (cp = parse_inequality (g, cp + 2, &rightval));
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*valp = (*valp <= rightval);
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} else {
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DO (cp = parse_inequality (g, cp + 1, &rightval));
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*valp = (*valp < rightval);
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}
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break;
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case '>':
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if (cp[1] == '=') {
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DO (cp = parse_inequality (g, cp + 2, &rightval));
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*valp = (*valp >= rightval);
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} else {
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DO (cp = parse_inequality (g, cp + 1, &rightval));
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*valp = (*valp > rightval);
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}
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break;
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}
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return cp;
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}
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static const char *
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parse_equality (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_inequality (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '=':
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if (cp[1] == '=')
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cp++;
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DO (cp = parse_equality (g, cp + 1, &rightval));
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*valp = (*valp == rightval);
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break;
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case '!':
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if (cp[1] != '=')
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break;
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DO (cp = parse_equality (g, cp + 2, &rightval));
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*valp = (*valp != rightval);
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break;
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}
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return cp;
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}
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static const char *
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parse_band (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_equality (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '&':
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if (cp[1] != '&') {
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DO (cp = parse_band (g, cp + 1, &rightval));
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*valp = (*valp & rightval);
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}
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break;
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}
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return cp;
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}
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static const char *
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parse_bor (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_band (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '|':
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if (cp[1] != '|') {
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DO (cp = parse_bor (g, cp + 1, &rightval));
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*valp = (*valp | rightval);
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}
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break;
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}
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return cp;
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}
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static const char *
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parse_land (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_bor (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '&':
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if (cp[1] != '&')
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return CALLFUNC(g, handle_error) (g, cp, "&&");
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DO (cp = parse_land (g, cp + 2, &rightval));
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*valp = (*valp && rightval);
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break;
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}
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return cp;
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}
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static const char *
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parse_lor (IfParser *g, const char *cp, int *valp)
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{
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int rightval;
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DO (cp = parse_land (g, cp, valp));
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SKIPSPACE (cp);
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switch (*cp) {
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case '|':
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if (cp[1] != '|')
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return CALLFUNC(g, handle_error) (g, cp, "||");
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DO (cp = parse_lor (g, cp + 2, &rightval));
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*valp = (*valp || rightval);
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break;
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}
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return cp;
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}
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/****************************************************************************
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External Entry Points
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****************************************************************************/
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const char *
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ParseIfExpression (IfParser *g, const char *cp, int *valp)
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{
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return parse_lor (g, cp, valp);
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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