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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <assert.h>
#include <errno.h>
#define exit_fatal(...) \
do { \
fprintf (stderr, "fatal: " __VA_ARGS__); \
exit (EXIT_FAILURE); \
} while (0)
// --- Safe memory management --------------------------------------------------
static void *
xmalloc (size_t n)
{
void *p = malloc (n);
if (!p)
exit_fatal ("malloc: %s\n", strerror (errno));
return p;
}
static void *
xrealloc (void *o, size_t n)
{
void *p = realloc (o, n);
if (!p && n)
exit_fatal ("realloc: %s\n", strerror (errno));
return p;
}
// --- Dynamically allocated strings -------------------------------------------
struct str
{
char *str; ///< String data, null terminated
size_t alloc; ///< How many bytes are allocated
size_t len; ///< How long the string actually is
};
static void
str_init (struct str *self)
{
self->alloc = 16;
self->len = 0;
self->str = strcpy (xmalloc (self->alloc), "");
}
static void
str_ensure_space (struct str *self, size_t n)
{
// We allocate at least one more byte for the terminating null character
size_t new_alloc = self->alloc;
while (new_alloc <= self->len + n)
new_alloc <<= 1;
if (new_alloc != self->alloc)
self->str = xrealloc (self->str, (self->alloc = new_alloc));
}
static void
str_append_data (struct str *self, const void *data, size_t n)
{
str_ensure_space (self, n);
memcpy (self->str + self->len, data, n);
self->str[self->len += n] = '\0';
}
static void
str_append_c (struct str *self, char c)
{
str_append_data (self, &c, 1);
}
// --- Main --------------------------------------------------------------------
int
main (int argc, char *argv[])
{
struct str program; str_init (&program);
struct str data; str_init (&data);
int c;
while ((c = fgetc (stdin)) != EOF)
str_append_c (&program, c);
if (ferror (stdin))
exit_fatal ("can't read program\n");
FILE *input = fopen ("/dev/tty", "rb");
if (!input)
exit_fatal ("can't open terminal for reading\n");
size_t *pairs = xmalloc (sizeof *pairs * program.len);
size_t *stack = xmalloc (sizeof *stack * program.len);
size_t nesting = 0;
for (size_t i = 0; i < program.len; i++)
{
switch (program.str[i])
{
case '[':
stack[nesting++] = i;
break;
case ']':
assert (nesting > 0);
--nesting;
pairs[stack[nesting]] = i;
pairs[i] = stack[nesting];
}
}
assert (nesting == 0);
size_t dataptr = 0;
str_append_c (&data, 0);
for (size_t i = 0; i < program.len; i++)
{
switch (program.str[i])
{
case '>':
assert (dataptr != SIZE_MAX);
if (++dataptr == data.len)
str_append_c (&data, 0);
break;
case '<':
assert (dataptr != 0);
dataptr--;
break;
case '+': data.str[dataptr]++; break;
case '-': data.str[dataptr]--; break;
case '.':
fputc (data.str[dataptr], stdout);
break;
case ',':
data.str[dataptr] = c = fgetc (input);
assert (c != EOF);
break;
case '[': if (!data.str[dataptr]) i = pairs[i]; break;
case ']': if ( data.str[dataptr]) i = pairs[i]; break;
default:
break;
}
}
return 0;
}
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