+/* vi: set sw=4 ts=4: */
#include "internal.h"
+#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
-static const char math_usage[] = "math expression ...";
+static const char math_usage[] = "math expression ...\n"
+#ifndef BB_FEATURE_TRIVIAL_HELP
+ "\nThis is a Tiny RPN calculator that understands the\n"
+ "following operations: +, -, /, *, and, or, not, eor.\n"
+ "i.e. 'math 2 2 add' -> 4, and 'math 8 8 \\* 2 2 + /' -> 16\n"
+#endif
+ ;
-static double stack[100];
-static unsigned int pointer;
+static double stack[100];
+static unsigned int pointer;
-static void
-push(double a)
+static void push(double a)
{
- if ( pointer >= (sizeof(stack) / sizeof(*stack)) ) {
+ if (pointer >= (sizeof(stack) / sizeof(*stack))) {
fprintf(stderr, "math: stack overflow\n");
exit(-1);
- }
- else
+ } else
stack[pointer++] = a;
}
-static double
-pop()
+static double pop()
{
- if ( pointer == 0 ) {
+ if (pointer == 0) {
fprintf(stderr, "math: stack underflow\n");
exit(-1);
}
return stack[--pointer];
}
-static void
-add()
+static void add()
{
push(pop() + pop());
}
-static void
-sub()
+static void sub()
{
- double subtrahend = pop();
+ double subtrahend = pop();
push(pop() - subtrahend);
}
-static void
-mul()
+static void mul()
{
push(pop() * pop());
}
-static void
-divide()
+static void divide()
{
- double divisor = pop();
+ double divisor = pop();
+
push(pop() / divisor);
}
-static void
-and()
+static void and()
{
- push((unsigned int)pop() & (unsigned int)pop());
+ push((unsigned int) pop() & (unsigned int) pop());
}
-static void
-or()
+static void or()
{
- push((unsigned int)pop() | (unsigned int)pop());
+ push((unsigned int) pop() | (unsigned int) pop());
}
-static void
-eor()
+static void eor()
{
- push((unsigned int)pop() ^ (unsigned int)pop());
+ push((unsigned int) pop() ^ (unsigned int) pop());
}
-static void
-not()
+static void not()
{
- push(~(unsigned int)pop());
+ push(~(unsigned int) pop());
}
-static void
-print()
+static void print()
{
printf("%g\n", pop());
}
struct op {
- const char * name;
- void (*function)();
+ const char *name;
+ void (*function) ();
};
-static const struct op operators[] = {
- { "add", add },
- { "and", and },
- { "div", divide },
- { "eor", eor },
- { "mul", mul },
- { "not", not },
- { "or", or },
- { "sub", sub },
- { 0, 0 }
+static const struct op operators[] = {
+ {"+", add},
+ {"-", sub},
+ {"*", mul},
+ {"/", divide},
+ {"and", and},
+ {"or", or},
+ {"not", not},
+ {"eor", eor},
+ {0, 0}
};
-static void
-stack_machine(const char * argument)
+static void stack_machine(const char *argument)
{
- char * endPointer = 0;
- double d;
- const struct op * o = operators;
+ char *endPointer = 0;
+ double d;
+ const struct op *o = operators;
- if ( argument == 0 ) {
+ if (argument == 0) {
print();
return;
}
d = strtod(argument, &endPointer);
- if ( endPointer != argument ) {
+ if (endPointer != argument) {
push(d);
return;
}
- while ( o->name != 0 ) {
- if ( strcmp(o->name, argument) == 0 ) {
- (*(o->function))();
+ while (o->name != 0) {
+ if (strcmp(o->name, argument) == 0) {
+ (*(o->function)) ();
return;
}
o++;
exit(-1);
}
-int
-math_main(int argc, char * * argv)
+/* return pointer to next token in buffer and set *buffer to one char
+ * past the end of the above mentioned token
+ */
+static char *get_token(char **buffer)
+{
+ char *start = NULL;
+ char *current = *buffer;
+
+ while (isspace(*current)) { current++; }
+ if (*current != 0) {
+ start = current;
+ while (!isspace(*current) && current != 0) { current++; }
+ *buffer = current;
+ }
+ return start;
+}
+
+/* In Perl one might say, scalar m|\s*(\S+)\s*|g */
+static int number_of_tokens(char *buffer)
{
- while ( argc >= 2 ) {
- stack_machine(argv[1]);
- argv++;
- argc--;
+ int i = 0;
+ char *b = buffer;
+ while (get_token(&b)) { i++; }
+ return i;
+}
+
+int math_main(int argc, char **argv)
+{
+ /* take stuff from stdin if no args are given */
+ if (argc <= 1) {
+ int i, len;
+ char *line = NULL;
+ char *cursor = NULL;
+ char *token = NULL;
+ while ((line = cstring_lineFromFile(stdin))) {
+ cursor = line;
+ len = number_of_tokens(line);
+ for (i = 0; i < len; i++) {
+ token = get_token(&cursor);
+ *cursor++ = 0;
+ stack_machine(token);
+ }
+ free(line);
+ }
+ } else {
+ if (*argv[1]=='-')
+ usage(math_usage);
+ while (argc >= 2) {
+ stack_machine(argv[1]);
+ argv++;
+ argc--;
+ }
}
stack_machine(0);
- return 0;
+ return( TRUE);
}