date and time created 92/06/23 18:44:56 by marc

SCCS-vsn: bin/sh/arith.y 5.1

diff --git a/usr/src/bin/sh/arith.y b/usr/src/bin/sh/arith.y
new file mode 100644 (file)
index 0000000..9a35090
--- /dev/null
+++ b/usr/src/bin/sh/arith.y
@@ -0,0 +1,130 @@
+%token ARITH_OR ARITH_AND ARITH_ADD ARITH_SUBT ARITH_MULT ARITH_DIV ARITH_REM ARITH_EQ ARITH_GT ARITH_GEQ ARITH_LT ARITH_LEQ ARITH_NEQ
+%token ARITH_NUM ARITH_LPAREN ARITH_RPAREN ARITH_NOT ARITH_UNARYMINUS
+
+%left ARITH_OR
+%left ARITH_AND
+%left ARITH_EQ ARITH_NEQ
+%left ARITH_LT ARITH_GT ARITH_GEQ ARITH_LEQ
+%left ARITH_ADD ARITH_SUBT
+%left ARITH_MULT ARITH_DIV ARITH_REM
+%left ARITH_UNARYMINUS ARITH_NOT
+%%
+
+exp:   expr = {
+                       return ($1);
+               }
+       ;
+
+
+expr:  ARITH_LPAREN expr ARITH_RPAREN = { $$ = $2; }
+       | expr ARITH_OR expr   = { $$ = $1 ? $1 : $3 ? $3 : 0; }
+       | expr ARITH_AND expr   = { $$ = $1 ? ( $3 ? $3 : 0 ) : 0; }
+       | expr ARITH_EQ expr   = { $$ = $1 == $3; }
+       | expr ARITH_GT expr   = { $$ = $1 > $3; }
+       | expr ARITH_GEQ expr   = { $$ = $1 >= $3; }
+       | expr ARITH_LT expr   = { $$ = $1 < $3; }
+       | expr ARITH_LEQ expr   = { $$ = $1 <= $3; }
+       | expr ARITH_NEQ expr   = { $$ = $1 != $3; }
+       | expr ARITH_ADD expr   = { $$ = $1 + $3; }
+       | expr ARITH_SUBT expr   = { $$ = $1 - $3; }
+       | expr ARITH_MULT expr   = { $$ = $1 * $3; }
+       | expr ARITH_DIV expr   = {
+                       if ($3 == 0)
+                               yyerror("division by zero");
+                       $$ = $1 / $3; 
+                       }
+       | expr ARITH_REM expr   = { $$ = $1 % $3; }
+       | ARITH_NOT expr        = { $$ = !($2); }
+       | ARITH_UNARYMINUS expr = { $$ = -($2); }
+       | ARITH_NUM
+       ;
+%%
+
+#include "shell.h"
+#include "error.h"
+#include "output.h"
+#include "memalloc.h"
+
+char *arith_buf, *arith_startbuf;
+
+arith(s)
+       char *s; 
+{
+       extern arith_wasoper;
+       long result;
+
+       arith_wasoper = 1;
+       arith_buf = arith_startbuf = s;
+
+       INTOFF;
+       result = yyparse();
+       arith_lex_reset();      /* reprime lex */
+       INTON;
+
+       return (result);
+}
+
+yyerror(s)
+       char *s;
+{
+       extern yytext, yylval;
+
+       yyerrok;
+       yyclearin;
+       arith_lex_reset();      /* reprime lex */
+       error("arithmetic expression: %s: \"%s\"", s, arith_startbuf);
+}
+
+/*
+ *  The exp(1) builtin.
+ */
+expcmd(argc, argv)
+       char **argv;
+{
+       char *p;
+       char *concat;
+       char **ap;
+       long i;
+
+       if (argc > 1) {
+               p = argv[1];
+               if (argc > 2) {
+                       /*
+                        * concatenate arguments
+                        */
+                       STARTSTACKSTR(concat);
+                       ap = argv + 2;
+                       for (;;) {
+                               while (*p)
+                                       STPUTC(*p++, concat);
+                               if ((p = *ap++) == NULL)
+                                       break;
+                               STPUTC(' ', concat);
+                       }
+                       STPUTC('\0', concat);
+                       p = grabstackstr(concat);
+               }
+       } else
+               p = "";
+
+       i = arith(p);
+
+       out1fmt("%d\n", i);
+       return (! i);
+}
+
+/*************************/
+#ifdef TEST_ARITH
+#include <stdio.h>
+main(argc, argv)
+       char *argv[];
+{
+       printf("%d\n", exp(argv[1]));
+}
+error(s)
+       char *s;
+{
+       fprintf(stderr, "exp: %s\n", s);
+       exit(1);
+}
+#endif