569 lines
13 KiB
Plaintext
569 lines
13 KiB
Plaintext
/* Parse C expressions for CCCP.
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Copyright (C) 1987, 2000, 2001 Free Software Foundation.
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Adapted from expread.y of GDB by Paul Rubin, July 1986.
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Adapted to ANSI C, Richard Stallman, Jan 1987
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Dusted off, polished, and adapted for use as traditional
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preprocessor only, Zack Weinberg, Jul 2000
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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This program 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 this program; if not, write to the Free Software
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Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Parse a C expression from text in a string */
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%{
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#include "config.h"
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#include "system.h"
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#include "intl.h"
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#include "tradcpp.h"
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#include <setjmp.h>
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static int yylex PARAMS ((void));
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static void yyerror PARAMS ((const char *msgid)) ATTRIBUTE_NORETURN;
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static int parse_number PARAMS ((int));
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static int parse_escape PARAMS ((const char **));
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static int expression_value;
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static jmp_buf parse_return_error;
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/* During parsing of a C expression, the pointer to the next
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character is in this variable. */
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static const char *lexptr;
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%}
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%union {
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struct constant {long value; int unsignedp;} integer;
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int voidval;
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char *sval;
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}
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%type <integer> exp exp1 start
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%token <integer> INT CHAR
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%token <sval> NAME
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%token <integer> ERROR
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%right '?' ':'
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%left ','
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%left OR
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%left AND
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%left '|'
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%left '^'
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%left '&'
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%left EQUAL NOTEQUAL
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%left '<' '>' LEQ GEQ
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%left LSH RSH
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%left '+' '-'
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%left '*' '/' '%'
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%right UNARY
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/* %expect 40 */
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%%
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start : exp1
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{ expression_value = $1.value; }
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;
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/* Expressions, including the comma operator. */
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exp1 : exp
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| exp1 ',' exp
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{ $$ = $3; }
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;
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/* Expressions, not including the comma operator. */
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exp : '-' exp %prec UNARY
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{ $$.value = - $2.value;
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$$.unsignedp = $2.unsignedp; }
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| '!' exp %prec UNARY
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{ $$.value = ! $2.value;
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$$.unsignedp = 0; }
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| '+' exp %prec UNARY
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{ $$ = $2; }
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| '~' exp %prec UNARY
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{ $$.value = ~ $2.value;
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$$.unsignedp = $2.unsignedp; }
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| '(' exp1 ')'
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{ $$ = $2; }
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;
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/* Binary operators in order of decreasing precedence. */
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exp : exp '*' exp
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{ $$.unsignedp = $1.unsignedp || $3.unsignedp;
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if ($$.unsignedp)
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$$.value = (unsigned) $1.value * $3.value;
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else
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$$.value = $1.value * $3.value; }
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| exp '/' exp
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{ if ($3.value == 0)
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{
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error ("division by zero in #if");
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$3.value = 1;
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}
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$$.unsignedp = $1.unsignedp || $3.unsignedp;
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if ($$.unsignedp)
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$$.value = (unsigned) $1.value / $3.value;
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else
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$$.value = $1.value / $3.value; }
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| exp '%' exp
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{ if ($3.value == 0)
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{
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error ("division by zero in #if");
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$3.value = 1;
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}
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$$.unsignedp = $1.unsignedp || $3.unsignedp;
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if ($$.unsignedp)
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$$.value = (unsigned) $1.value % $3.value;
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else
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$$.value = $1.value % $3.value; }
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| exp '+' exp
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{ $$.value = $1.value + $3.value;
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$$.unsignedp = $1.unsignedp || $3.unsignedp; }
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| exp '-' exp
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{ $$.value = $1.value - $3.value;
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$$.unsignedp = $1.unsignedp || $3.unsignedp; }
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| exp LSH exp
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{ $$.unsignedp = $1.unsignedp;
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if ($$.unsignedp)
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$$.value = (unsigned) $1.value << $3.value;
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else
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$$.value = $1.value << $3.value; }
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| exp RSH exp
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{ $$.unsignedp = $1.unsignedp;
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if ($$.unsignedp)
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$$.value = (unsigned) $1.value >> $3.value;
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else
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$$.value = $1.value >> $3.value; }
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| exp EQUAL exp
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{ $$.value = ($1.value == $3.value);
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$$.unsignedp = 0; }
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| exp NOTEQUAL exp
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{ $$.value = ($1.value != $3.value);
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$$.unsignedp = 0; }
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| exp LEQ exp
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{ $$.unsignedp = 0;
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if ($1.unsignedp || $3.unsignedp)
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$$.value =
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(unsigned) $1.value <= (unsigned) $3.value;
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else
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$$.value = $1.value <= $3.value; }
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| exp GEQ exp
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{ $$.unsignedp = 0;
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if ($1.unsignedp || $3.unsignedp)
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$$.value =
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(unsigned) $1.value >= (unsigned) $3.value;
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else
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$$.value = $1.value >= $3.value; }
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| exp '<' exp
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{ $$.unsignedp = 0;
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if ($1.unsignedp || $3.unsignedp)
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$$.value =
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(unsigned) $1.value < (unsigned) $3.value;
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else
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$$.value = $1.value < $3.value; }
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| exp '>' exp
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{ $$.unsignedp = 0;
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if ($1.unsignedp || $3.unsignedp)
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$$.value =
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(unsigned) $1.value > (unsigned) $3.value;
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else
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$$.value = $1.value > $3.value; }
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| exp '&' exp
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{ $$.value = $1.value & $3.value;
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$$.unsignedp = $1.unsignedp || $3.unsignedp; }
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| exp '^' exp
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{ $$.value = $1.value ^ $3.value;
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$$.unsignedp = $1.unsignedp || $3.unsignedp; }
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| exp '|' exp
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{ $$.value = $1.value | $3.value;
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$$.unsignedp = $1.unsignedp || $3.unsignedp; }
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| exp AND exp
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{ $$.value = ($1.value && $3.value);
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$$.unsignedp = 0; }
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| exp OR exp
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{ $$.value = ($1.value || $3.value);
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$$.unsignedp = 0; }
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| exp '?' exp ':' exp
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{ $$.value = $1.value ? $3.value : $5.value;
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$$.unsignedp = $3.unsignedp || $5.unsignedp; }
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| INT
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{ $$ = yylval.integer; }
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| CHAR
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{ $$ = yylval.integer; }
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| NAME
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{ $$.value = 0;
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$$.unsignedp = 0; }
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| '#' { $$.value =
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test_assertion ((unsigned char **) &lexptr); }
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;
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%%
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/* Take care of parsing a number (anything that starts with a digit).
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Set yylval and return the token type; update lexptr.
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LEN is the number of characters in it. */
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/* maybe needs to actually deal with floating point numbers */
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static int
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parse_number (olen)
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int olen;
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{
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const char *p = lexptr;
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long n = 0;
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int c;
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int base = 10;
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int len = olen;
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for (c = 0; c < len; c++)
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if (p[c] == '.') {
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/* It's a float since it contains a point. */
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yyerror ("floating point numbers not allowed in #if expressions");
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return ERROR;
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}
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/* Traditionally, all numbers are signed. However, we make it
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unsigned if requested with a suffix. */
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yylval.integer.unsignedp = 0;
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if (len >= 3 && (!strncmp (p, "0x", 2) || !strncmp (p, "0X", 2))) {
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p += 2;
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base = 16;
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len -= 2;
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}
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else if (*p == '0')
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base = 8;
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while (len > 0) {
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c = *p++;
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len--;
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if (ISUPPER (c))
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c = TOLOWER (c);
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if (ISDIGIT (c)
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|| (base == 16 && ISXDIGIT (c))) {
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n = (n * base) + hex_value (c);
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} else {
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/* `l' means long, and `u' means unsigned. */
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while (1) {
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if (c == 'l' || c == 'L')
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;
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else if (c == 'u' || c == 'U')
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yylval.integer.unsignedp = 1;
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else
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break;
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if (len == 0)
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break;
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c = *p++;
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len--;
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}
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/* Don't look for any more digits after the suffixes. */
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break;
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}
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}
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if (len != 0) {
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yyerror ("invalid number in #if expression");
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return ERROR;
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}
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lexptr = p;
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yylval.integer.value = n;
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return INT;
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}
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struct token {
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const char *const operator;
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const int token;
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};
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#ifndef NULL
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#define NULL 0
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#endif
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static const struct token tokentab2[] = {
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{"&&", AND},
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{"||", OR},
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{"<<", LSH},
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{">>", RSH},
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{"==", EQUAL},
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{"!=", NOTEQUAL},
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{"<=", LEQ},
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{">=", GEQ},
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{NULL, ERROR}
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};
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/* Read one token, getting characters through lexptr. */
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static int
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yylex ()
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{
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int c;
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int namelen;
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const char *tokstart;
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const struct token *toktab;
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retry:
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tokstart = lexptr;
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c = *tokstart;
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/* See if it is a special token of length 2. */
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for (toktab = tokentab2; toktab->operator != NULL; toktab++)
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if (c == *toktab->operator && tokstart[1] == toktab->operator[1]) {
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lexptr += 2;
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return toktab->token;
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}
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switch (c) {
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case 0:
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return 0;
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case ' ':
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case '\t':
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case '\r':
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case '\n':
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lexptr++;
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goto retry;
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case '\'':
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lexptr++;
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c = *lexptr++;
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if (c == '\\')
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c = parse_escape (&lexptr);
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/* Sign-extend the constant if chars are signed on target machine. */
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{
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if (lookup ((const unsigned char *)"__CHAR_UNSIGNED__",
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sizeof ("__CHAR_UNSIGNED__")-1, -1)
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|| ((c >> (CHAR_TYPE_SIZE - 1)) & 1) == 0)
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yylval.integer.value = c & ((1 << CHAR_TYPE_SIZE) - 1);
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else
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yylval.integer.value = c | ~((1 << CHAR_TYPE_SIZE) - 1);
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}
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yylval.integer.unsignedp = 0;
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c = *lexptr++;
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if (c != '\'') {
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yyerror ("invalid character constant in #if");
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return ERROR;
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}
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return CHAR;
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/* some of these chars are invalid in constant expressions;
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maybe do something about them later */
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case '/':
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case '+':
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case '-':
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case '*':
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case '%':
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case '|':
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case '&':
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case '^':
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case '~':
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case '!':
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case '@':
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case '<':
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case '>':
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case '(':
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case ')':
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case '[':
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case ']':
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case '.':
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case '?':
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case ':':
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case '=':
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case '{':
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case '}':
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case ',':
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case '#':
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lexptr++;
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return c;
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case '"':
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yyerror ("double quoted strings not allowed in #if expressions");
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return ERROR;
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}
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if (ISDIGIT (c)) {
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/* It's a number */
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for (namelen = 0;
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c = tokstart[namelen], is_idchar (c) || c == '.';
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namelen++)
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;
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return parse_number (namelen);
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}
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if (!is_idstart (c)) {
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yyerror ("invalid token in expression");
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return ERROR;
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}
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/* It is a name. See how long it is. */
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for (namelen = 0;
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is_idchar (tokstart[namelen]);
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namelen++)
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;
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lexptr += namelen;
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return NAME;
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}
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/* Parse a C escape sequence. STRING_PTR points to a variable
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containing a pointer to the string to parse. That pointer
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is updated past the characters we use. The value of the
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escape sequence is returned.
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A negative value means the sequence \ newline was seen,
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which is supposed to be equivalent to nothing at all.
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If \ is followed by a null character, we return a negative
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value and leave the string pointer pointing at the null character.
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If \ is followed by 000, we return 0 and leave the string pointer
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after the zeros. A value of 0 does not mean end of string. */
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static int
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parse_escape (string_ptr)
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const char **string_ptr;
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{
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int c = *(*string_ptr)++;
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switch (c)
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{
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case 'a':
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return TARGET_BELL;
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case 'b':
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return TARGET_BS;
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case 'e':
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return 033;
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case 'f':
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return TARGET_FF;
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case 'n':
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return TARGET_NEWLINE;
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case 'r':
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return TARGET_CR;
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case 't':
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return TARGET_TAB;
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case 'v':
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return TARGET_VT;
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case '\n':
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return -2;
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case 0:
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(*string_ptr)--;
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return 0;
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case '^':
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c = *(*string_ptr)++;
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if (c == '\\')
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c = parse_escape (string_ptr);
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if (c == '?')
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return 0177;
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return (c & 0200) | (c & 037);
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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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{
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int i = c - '0';
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int count = 0;
|
||
while (++count < 3)
|
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{
|
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c = *(*string_ptr)++;
|
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if (c >= '0' && c <= '7')
|
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i = (i << 3) + c - '0';
|
||
else
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{
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(*string_ptr)--;
|
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break;
|
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}
|
||
}
|
||
if ((i & ~((1 << CHAR_TYPE_SIZE) - 1)) != 0)
|
||
{
|
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i &= (1 << CHAR_TYPE_SIZE) - 1;
|
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warning ("octal character constant does not fit in a byte");
|
||
}
|
||
return i;
|
||
}
|
||
case 'x':
|
||
{
|
||
int i = 0;
|
||
for (;;)
|
||
{
|
||
c = *(*string_ptr)++;
|
||
if (hex_p (c))
|
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i = (i << 4) + hex_value (c);
|
||
else
|
||
{
|
||
(*string_ptr)--;
|
||
break;
|
||
}
|
||
}
|
||
if ((i & ~((1 << BITS_PER_UNIT) - 1)) != 0)
|
||
{
|
||
i &= (1 << BITS_PER_UNIT) - 1;
|
||
warning ("hex character constant does not fit in a byte");
|
||
}
|
||
return i;
|
||
}
|
||
default:
|
||
return c;
|
||
}
|
||
}
|
||
|
||
static void
|
||
yyerror (msgid)
|
||
const char *msgid;
|
||
{
|
||
error ("%s", _(msgid));
|
||
longjmp (parse_return_error, 1);
|
||
}
|
||
|
||
/* This page contains the entry point to this file. */
|
||
|
||
/* Parse STRING as an expression, and complain if this fails
|
||
to use up all of the contents of STRING. */
|
||
/* We do not support C comments. They should be removed before
|
||
this function is called. */
|
||
|
||
int
|
||
parse_c_expression (string)
|
||
const char *string;
|
||
{
|
||
lexptr = string;
|
||
|
||
if (lexptr == 0 || *lexptr == 0) {
|
||
error ("empty #if expression");
|
||
return 0; /* don't include the #if group */
|
||
}
|
||
|
||
/* if there is some sort of scanning error, just return 0 and assume
|
||
the parsing routine has printed an error message somewhere.
|
||
there is surely a better thing to do than this. */
|
||
if (setjmp (parse_return_error))
|
||
return 0;
|
||
|
||
if (yyparse ())
|
||
return 0; /* actually this is never reached
|
||
the way things stand. */
|
||
if (*lexptr)
|
||
error ("Junk after end of expression.");
|
||
|
||
return expression_value; /* set by yyparse () */
|
||
}
|