+# -*- Autoconf -*-
+
+cat <<EOF
+
+Simple Calculator.
+
+EOF
+
+## ---------------------------------------------------- ##
+## Compile the grammar described in the documentation. ##
+## ---------------------------------------------------- ##
+
+# We use integers to avoid dependencies upon the precision of doubles.
+AT_SETUP(Compiling a grammar)
+
+AT_DATA([calc.y],
+[[/* Infix notation calculator--calc */
+
+%{
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#define YYSTYPE int
+
+static int power (int base, int exponent);
+static int read_signed_integer (FILE *stream);
+extern void perror (const char *s);
+%}
+
+/* BISON Declarations */
+%token NUM
+%left '-' '+'
+%left '*' '/'
+%left NEG /* negation--unary minus */
+%right '^' /* exponentiation */
+
+/* Grammar follows */
+%%
+input: /* empty string */
+ | input line
+;
+
+line: '\n'
+ | exp '\n' { printf ("%d", $1); }
+;
+
+exp: NUM { $$ = $1; }
+ | exp '+' exp { $$ = $1 + $3; }
+ | exp '-' exp { $$ = $1 - $3; }
+ | exp '*' exp { $$ = $1 * $3; }
+ | exp '/' exp { $$ = $1 / $3; }
+ | '-' exp %prec NEG { $$ = -$2; }
+ | exp '^' exp { $$ = power ($1, $3); }
+ | '(' exp ')' { $$ = $2; }
+;
+%%
+int
+main (int argn, const char **argv)
+{
+ if (argn == 2)
+ stdin = fopen (argv[1], "r");
+ if (!stdin)
+ {
+ perror (argv[1]);
+ exit (1);
+ }
+ yyparse ();
+ return 0;
+}
+
+int
+yyerror (const char *s)
+{
+ fprintf (stderr, "%s\n", s);
+}
+
+static int
+read_signed_integer (FILE *stream)
+{
+ int c = getc (stream);
+ int sign = 1;
+ int n = 0;
+
+ if (c == '-')
+ {
+ c = getc (stream);
+ sign = -1;
+ }
+
+ while (isdigit (c))
+ {
+ n = 10 * n + (c - '0');
+ c = getc (stream);
+ }
+
+ ungetc (c, stream);
+
+ return sign * n;
+}
+
+/*---------------------------------------------------------------.
+| Lexical analyzer returns an integer on the stack and the token |
+| NUM, or the ASCII character read if not a number. Skips all |
+| blanks and tabs, returns 0 for EOF. |
+`---------------------------------------------------------------*/
+
+int
+yylex ()
+{
+ int c;
+
+ /* Skip white space. */
+ while ((c = getchar ()) == ' ' || c == '\t')
+ ;
+ /* process numbers */
+ if (c == '.' || isdigit (c))
+ {
+ ungetc (c, stdin);
+ yylval = read_signed_integer (stdin);
+ return NUM;
+ }
+ /* Return end-of-file. */
+ if (c == EOF)
+ return 0;
+ /* Return single chars. */
+ return c;
+}
+
+static int
+power (int base, int exponent)
+{
+ int res = 1;
+ if (exponent < 0)
+ exit (1);
+ for (/* Niente */; exponent; --exponent)
+ res *= base;
+ return res;
+}
+]])
+
+# Specify the output files to avoid problems on different file systems.
+AT_CHECK([bison calc.y -o calc.c], 0, [], [])
+AT_CHECK([$CC $CFLAGS calc.c -o calc], 0, [], [])
+
+# AT_CHECK_CALC(INPUT, OUTPUT)
+# ----------------------------
+# Run `calc' on INPUT, and expect OUTPUT.
+AT_DEFINE([AT_CHECK_CALC],
+[AT_CHECK([echo "$1" | calc], 0, [$2], [])])
+
+# Test the priorities.
+AT_CHECK_CALC([1 + 2 * 3], [7])
+AT_CHECK_CALC([1 + 2 * -3], [-5])
+
+AT_CHECK_CALC([-1^2], [-1])
+AT_CHECK_CALC([(-1)^2], [1])
+
+AT_CHECK_CALC([---1], [-1])
+
+AT_CHECK_CALC([1 - 2 - 3], [-4])
+AT_CHECK_CALC([1 - (2 - 3)], [2])
+
+AT_CHECK_CALC([2^2^3], [256])
+AT_CHECK_CALC([(2^2)^3], [64])
+
+AT_CLEANUP(calc calc.c)
projects / bison.git / commitdiff
