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