mirror of https://github.com/n-hys/bash.git
132 lines
3.4 KiB
Modula-2
132 lines
3.4 KiB
Modula-2
This file is let.def, from which is created let.c.
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It implements the builtin "let" in Bash.
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Copyright (C) 1987-2009 Free Software Foundation, Inc.
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This file is part of GNU Bash, the Bourne Again SHell.
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Bash is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
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$BUILTIN let
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$FUNCTION let_builtin
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$PRODUCES let.c
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$SHORT_DOC let arg [arg ...]
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Evaluate arithmetic expressions.
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Evaluate each ARG as an arithmetic expression. Evaluation is done in
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fixed-width integers with no check for overflow, though division by 0
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is trapped and flagged as an error. The following list of operators is
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grouped into levels of equal-precedence operators. The levels are listed
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in order of decreasing precedence.
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id++, id-- variable post-increment, post-decrement
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++id, --id variable pre-increment, pre-decrement
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-, + unary minus, plus
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!, ~ logical and bitwise negation
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** exponentiation
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*, /, % multiplication, division, remainder
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+, - addition, subtraction
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<<, >> left and right bitwise shifts
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<=, >=, <, > comparison
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==, != equality, inequality
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& bitwise AND
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^ bitwise XOR
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| bitwise OR
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&& logical AND
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|| logical OR
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expr ? expr : expr
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conditional operator
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=, *=, /=, %=,
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+=, -=, <<=, >>=,
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&=, ^=, |= assignment
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Shell variables are allowed as operands. The name of the variable
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is replaced by its value (coerced to a fixed-width integer) within
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an expression. The variable need not have its integer attribute
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turned on to be used in an expression.
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Operators are evaluated in order of precedence. Sub-expressions in
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parentheses are evaluated first and may override the precedence
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rules above.
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Exit Status:
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If the last ARG evaluates to 0, let returns 1; let returns 0 otherwise.
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$END
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#include <config.h>
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#if defined (HAVE_UNISTD_H)
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# ifdef _MINIX
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# include <sys/types.h>
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# endif
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# include <unistd.h>
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#endif
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#include "../bashintl.h"
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#include "../shell.h"
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#include "common.h"
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/* Arithmetic LET function. */
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int
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let_builtin (list)
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WORD_LIST *list;
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{
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intmax_t ret;
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int expok;
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CHECK_HELPOPT (list);
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/* Skip over leading `--' argument. */
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if (list && list->word && ISOPTION (list->word->word, '-'))
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list = list->next;
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if (list == 0)
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{
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builtin_error (_("expression expected"));
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return (EXECUTION_FAILURE);
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}
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for (; list; list = list->next)
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{
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ret = evalexp (list->word->word, EXP_EXPANDED, &expok);
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if (expok == 0)
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return (EXECUTION_FAILURE);
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}
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return ((ret == 0) ? EXECUTION_FAILURE : EXECUTION_SUCCESS);
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}
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#ifdef INCLUDE_UNUSED
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int
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exp_builtin (list)
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WORD_LIST *list;
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{
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char *exp;
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intmax_t ret;
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int expok;
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if (list == 0)
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{
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builtin_error (_("expression expected"));
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return (EXECUTION_FAILURE);
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}
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exp = string_list (list);
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ret = evalexp (exp, EXP_EXPANDED, &expok);
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(void)free (exp);
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return (((ret == 0) || (expok == 0)) ? EXECUTION_FAILURE : EXECUTION_SUCCESS);
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}
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#endif
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