131 lines
3.3 KiB
Modula-2
131 lines
3.3 KiB
Modula-2
This file is let.def, from which is created let.c.
|
|
It implements the builtin "let" in Bash.
|
|
|
|
Copyright (C) 1987-2009 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Bash, the Bourne Again SHell.
|
|
|
|
Bash is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
Bash is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with Bash. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
$BUILTIN let
|
|
$FUNCTION let_builtin
|
|
$PRODUCES let.c
|
|
$SHORT_DOC let arg [arg ...]
|
|
Evaluate arithmetic expressions.
|
|
|
|
Evaluate each ARG as an arithmetic expression. Evaluation is done in
|
|
fixed-width integers with no check for overflow, though division by 0
|
|
is trapped and flagged as an error. The following list of operators is
|
|
grouped into levels of equal-precedence operators. The levels are listed
|
|
in order of decreasing precedence.
|
|
|
|
id++, id-- variable post-increment, post-decrement
|
|
++id, --id variable pre-increment, pre-decrement
|
|
-, + unary minus, plus
|
|
!, ~ logical and bitwise negation
|
|
** exponentiation
|
|
*, /, % multiplication, division, remainder
|
|
+, - addition, subtraction
|
|
<<, >> left and right bitwise shifts
|
|
<=, >=, <, > comparison
|
|
==, != equality, inequality
|
|
& bitwise AND
|
|
^ bitwise XOR
|
|
| bitwise OR
|
|
&& logical AND
|
|
|| logical OR
|
|
expr ? expr : expr
|
|
conditional operator
|
|
=, *=, /=, %=,
|
|
+=, -=, <<=, >>=,
|
|
&=, ^=, |= assignment
|
|
|
|
Shell variables are allowed as operands. The name of the variable
|
|
is replaced by its value (coerced to a fixed-width integer) within
|
|
an expression. The variable need not have its integer attribute
|
|
turned on to be used in an expression.
|
|
|
|
Operators are evaluated in order of precedence. Sub-expressions in
|
|
parentheses are evaluated first and may override the precedence
|
|
rules above.
|
|
|
|
Exit Status:
|
|
If the last ARG evaluates to 0, let returns 1; let returns 0 otherwise.
|
|
$END
|
|
|
|
#include <config.h>
|
|
|
|
#if defined (HAVE_UNISTD_H)
|
|
# ifdef _MINIX
|
|
# include <sys/types.h>
|
|
# endif
|
|
# include <unistd.h>
|
|
#endif
|
|
|
|
#include "../bashintl.h"
|
|
|
|
#include "../shell.h"
|
|
#include "common.h"
|
|
|
|
/* Arithmetic LET function. */
|
|
int
|
|
let_builtin (list)
|
|
WORD_LIST *list;
|
|
{
|
|
intmax_t ret;
|
|
int expok;
|
|
|
|
CHECK_HELPOPT (list);
|
|
|
|
/* Skip over leading `--' argument. */
|
|
if (list && list->word && ISOPTION (list->word->word, '-'))
|
|
list = list->next;
|
|
|
|
if (list == 0)
|
|
{
|
|
builtin_error (_("expression expected"));
|
|
return (EXECUTION_FAILURE);
|
|
}
|
|
|
|
for (; list; list = list->next)
|
|
{
|
|
ret = evalexp (list->word->word, &expok);
|
|
if (expok == 0)
|
|
return (EXECUTION_FAILURE);
|
|
}
|
|
|
|
return ((ret == 0) ? EXECUTION_FAILURE : EXECUTION_SUCCESS);
|
|
}
|
|
|
|
#ifdef INCLUDE_UNUSED
|
|
int
|
|
exp_builtin (list)
|
|
WORD_LIST *list;
|
|
{
|
|
char *exp;
|
|
intmax_t ret;
|
|
int expok;
|
|
|
|
if (list == 0)
|
|
{
|
|
builtin_error (_("expression expected"));
|
|
return (EXECUTION_FAILURE);
|
|
}
|
|
|
|
exp = string_list (list);
|
|
ret = evalexp (exp, &expok);
|
|
(void)free (exp);
|
|
return (((ret == 0) || (expok == 0)) ? EXECUTION_FAILURE : EXECUTION_SUCCESS);
|
|
}
|
|
#endif
|