Structs, arrays, owned strings, memory model, modules, debug info

- struct with default values; constructors Point(1, 2) / Point(x: 1); field access, auto-deref through pointers
- []T arrays with bounds checks, literals, for-each, push/pop/insert/remove/clear/resize/find/contains/join/slice/reverse/sort
- str carries its length: .len, s[i], +, comparison, sub/find/split/trim/upper/lower/replace/repeat/bytes, str(x), int(s), float(s)
- Memory: values own their memory and are freed at the end of their block; assignment copies, temporaries move;
  parameters are lent and only copied when the function changes them; defer; new()/free() for manual heap memory
- input(), read_file/write_file/file_exists, exit(), fn main([]str args)
- Finch modules: import name, module.fn(), module.Struct
- C structs from headers (fields, fixed arrays, nested); passed and returned by value with the System V x86-64 ABI;
  addr(fn) gives C a callback
- link "file.c" compiles and links your own C code
- -g emits DWARF debug info (gdb/lldb)
- Small C runtime (runtime/finch_rt.c) embedded in the compiler, cached in ~/.cache/finch
- Tests: 58, all clean under valgrind (MEMCHECK=1 tests/run.sh)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Nexoniarz 2026-10-08 18:57:37 +02:00
commit 1dc976bd8f
59 changed files with 4577 additions and 1047 deletions

426
runtime/finch_rt.c Normal file
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// The Finch runtime: string and array helpers, input, files and runtime errors.
// It is embedded in the compiler, compiled once into a cache folder, and linked
// statically into every Finch program. Everything here is plain C with no state.
//
// Layout shared with the compiler (src/codegen.cpp):
// str = { char *ptr; int64 len; int64 cap } ptr is always NUL-terminated
// cap > 0 : heap memory owned by the value (cap bytes allocated)
// cap == 0 : a string literal, valid forever, never written to
// cap == -1: borrowed from C, must be copied before it is kept
// []T = { T *ptr; int64 len; int64 cap } owns ptr when cap > 0
#include <ctype.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct {
char *ptr;
int64_t len;
int64_t cap;
} FStr;
typedef struct {
void *ptr;
int64_t len;
int64_t cap;
} FArr;
static char empty[1] = "";
// ---------- runtime errors ----------
__attribute__((noreturn, cold)) void finch_panic(const char *file, int64_t line, const char *msg) {
fflush(stdout);
fprintf(stderr, "%s:%lld: runtime error: %s\n", file, (long long)line, msg);
exit(1);
}
__attribute__((noreturn, cold)) void finch_panic_index(const char *file, int64_t line, int64_t i, int64_t len) {
char msg[128];
snprintf(msg, sizeof msg, "index %lld is out of range (the length is %lld)", (long long)i, (long long)len);
finch_panic(file, line, msg);
}
static void *must(void *p) {
if (!p) {
fflush(stdout);
fprintf(stderr, "runtime error: out of memory\n");
exit(1);
}
return p;
}
void *finch_alloc(int64_t n) { return must(malloc(n ? (size_t)n : 1)); }
void *finch_zalloc(int64_t n) { return must(calloc(1, n ? (size_t)n : 1)); }
// ---------- strings ----------
static void str_heap(FStr *out, const char *p, int64_t len) {
char *m = finch_alloc(len + 1);
if (len) memcpy(m, p, (size_t)len);
m[len] = 0;
out->ptr = m;
out->len = len;
out->cap = len + 1;
}
static void str_static(FStr *out, const char *lit) {
out->ptr = (char *)lit;
out->len = (int64_t)strlen(lit);
out->cap = 0;
}
// A copy that can be kept: literals are shared, everything else is duplicated.
void finch_str_copy(FStr *out, const FStr *s) {
if (s->cap == 0) *out = *s;
else str_heap(out, s->ptr, s->len);
}
// Make `s` writable (before s[i] = c).
void finch_str_own(FStr *s) {
if (s->cap > 0) return;
FStr t;
str_heap(&t, s->ptr, s->len);
*s = t;
}
void finch_str_drop(FStr *s) {
if (s->cap > 0) free(s->ptr);
}
void finch_str_from_c(FStr *out, const char *p) {
if (!p) {
str_static(out, empty);
return;
}
out->ptr = (char *)p;
out->len = (int64_t)strlen(p);
out->cap = -1;
}
void finch_str_concat(FStr *out, const FStr *a, const FStr *b) {
int64_t len = a->len + b->len;
char *m = finch_alloc(len + 1);
memcpy(m, a->ptr, (size_t)a->len);
memcpy(m + a->len, b->ptr, (size_t)b->len);
m[len] = 0;
out->ptr = m;
out->len = len;
out->cap = len + 1;
}
int finch_str_eq(const FStr *a, const FStr *b) {
return a->len == b->len && memcmp(a->ptr, b->ptr, (size_t)a->len) == 0;
}
int64_t finch_str_cmp(const FStr *a, const FStr *b) {
int64_t n = a->len < b->len ? a->len : b->len;
int c = memcmp(a->ptr, b->ptr, (size_t)n);
if (c) return c < 0 ? -1 : 1;
return a->len < b->len ? -1 : a->len > b->len;
}
void finch_str_from_int(FStr *out, int64_t v) {
char buf[32];
int n = snprintf(buf, sizeof buf, "%lld", (long long)v);
str_heap(out, buf, n);
}
void finch_str_from_uint(FStr *out, uint64_t v) {
char buf[32];
int n = snprintf(buf, sizeof buf, "%llu", (unsigned long long)v);
str_heap(out, buf, n);
}
void finch_str_from_float(FStr *out, double v) {
char buf[64];
int n = snprintf(buf, sizeof buf, "%g", v);
str_heap(out, buf, n);
}
void finch_str_from_char(FStr *out, char c) { str_heap(out, &c, 1); }
void finch_str_from_bool(FStr *out, int b) { str_static(out, b ? "true" : "false"); }
static void bad_number(const FStr *s, const char *kind, const char *file, int64_t line) {
char msg[200];
snprintf(msg, sizeof msg, "can't turn \"%.*s\" into %s", (int)(s->len > 100 ? 100 : s->len), s->ptr, kind);
finch_panic(file, line, msg);
}
int64_t finch_str_to_int(const FStr *s, const char *file, int64_t line) {
const char *p = s->ptr;
while (isspace((unsigned char)*p)) p++;
char *end;
errno = 0;
long long v = strtoll(p, &end, 10);
while (isspace((unsigned char)*end)) end++;
if (end == p || *end || errno == ERANGE) bad_number(s, "int", file, line);
return v;
}
double finch_str_to_float(const FStr *s, const char *file, int64_t line) {
const char *p = s->ptr;
while (isspace((unsigned char)*p)) p++;
char *end;
double v = strtod(p, &end);
while (isspace((unsigned char)*end)) end++;
if (end == p || *end) bad_number(s, "float", file, line);
return v;
}
void finch_str_sub(FStr *out, const FStr *s, int64_t start, int64_t end, const char *file, int64_t line) {
if (start < 0 || end > s->len || start > end) {
char msg[160];
snprintf(msg, sizeof msg, "sub(%lld, %lld) is out of range (the length is %lld)", (long long)start,
(long long)end, (long long)s->len);
finch_panic(file, line, msg);
}
str_heap(out, s->ptr + start, end - start);
}
int64_t finch_str_find(const FStr *s, const FStr *t) {
if (t->len == 0) return 0;
for (int64_t i = 0; i + t->len <= s->len; i++)
if (s->ptr[i] == t->ptr[0] && memcmp(s->ptr + i, t->ptr, (size_t)t->len) == 0) return i;
return -1;
}
int finch_str_starts(const FStr *s, const FStr *t) {
return t->len <= s->len && memcmp(s->ptr, t->ptr, (size_t)t->len) == 0;
}
int finch_str_ends(const FStr *s, const FStr *t) {
return t->len <= s->len && memcmp(s->ptr + s->len - t->len, t->ptr, (size_t)t->len) == 0;
}
void finch_str_trim(FStr *out, const FStr *s) {
int64_t a = 0, b = s->len;
while (a < b && isspace((unsigned char)s->ptr[a])) a++;
while (b > a && isspace((unsigned char)s->ptr[b - 1])) b--;
str_heap(out, s->ptr + a, b - a);
}
void finch_str_upper(FStr *out, const FStr *s) {
str_heap(out, s->ptr, s->len);
for (int64_t i = 0; i < out->len; i++) out->ptr[i] = (char)toupper((unsigned char)out->ptr[i]);
}
void finch_str_lower(FStr *out, const FStr *s) {
str_heap(out, s->ptr, s->len);
for (int64_t i = 0; i < out->len; i++) out->ptr[i] = (char)tolower((unsigned char)out->ptr[i]);
}
void finch_str_replace(FStr *out, const FStr *s, const FStr *from, const FStr *to) {
if (from->len == 0) {
str_heap(out, s->ptr, s->len);
return;
}
int64_t count = 0;
for (int64_t i = 0; i + from->len <= s->len;) {
if (memcmp(s->ptr + i, from->ptr, (size_t)from->len) == 0) {
count++;
i += from->len;
} else {
i++;
}
}
int64_t len = s->len + count * (to->len - from->len);
char *m = finch_alloc(len + 1), *w = m;
for (int64_t i = 0; i < s->len;) {
if (i + from->len <= s->len && memcmp(s->ptr + i, from->ptr, (size_t)from->len) == 0) {
memcpy(w, to->ptr, (size_t)to->len);
w += to->len;
i += from->len;
} else {
*w++ = s->ptr[i++];
}
}
*w = 0;
out->ptr = m;
out->len = len;
out->cap = len + 1;
}
static void arr_push_str(FArr *a, const char *p, int64_t len);
// "a,b,,c".split(",") -> ["a", "b", "", "c"]; split("") gives single characters.
void finch_str_split(FArr *out, const FStr *s, const FStr *sep) {
out->ptr = NULL;
out->len = out->cap = 0;
if (sep->len == 0) {
for (int64_t i = 0; i < s->len; i++) arr_push_str(out, s->ptr + i, 1);
return;
}
int64_t start = 0;
for (int64_t i = 0; i + sep->len <= s->len;) {
if (memcmp(s->ptr + i, sep->ptr, (size_t)sep->len) == 0) {
arr_push_str(out, s->ptr + start, i - start);
i += sep->len;
start = i;
} else {
i++;
}
}
arr_push_str(out, s->ptr + start, s->len - start);
}
void finch_str_join(FStr *out, const FArr *parts, const FStr *sep) {
const FStr *p = parts->ptr;
int64_t len = 0;
for (int64_t i = 0; i < parts->len; i++) len += p[i].len + (i ? sep->len : 0);
char *m = finch_alloc(len + 1), *w = m;
for (int64_t i = 0; i < parts->len; i++) {
if (i) {
memcpy(w, sep->ptr, (size_t)sep->len);
w += sep->len;
}
memcpy(w, p[i].ptr, (size_t)p[i].len);
w += p[i].len;
}
*w = 0;
out->ptr = m;
out->len = len;
out->cap = len + 1;
}
void finch_str_repeat(FStr *out, const FStr *s, int64_t n) {
if (n < 0) n = 0;
int64_t len = s->len * n;
char *m = finch_alloc(len + 1);
for (int64_t i = 0; i < n; i++) memcpy(m + i * s->len, s->ptr, (size_t)s->len);
m[len] = 0;
out->ptr = m;
out->len = len;
out->cap = len + 1;
}
void finch_str_from_bytes(FStr *out, const FArr *bytes) { str_heap(out, bytes->ptr, bytes->len); }
// ---------- arrays ----------
void finch_arr_reserve(FArr *a, int64_t need, int64_t es) {
if (need <= a->cap) return;
int64_t cap = a->cap * 2;
if (cap < 4) cap = 4;
if (cap < need) cap = need;
a->ptr = must(realloc(a->cap > 0 ? a->ptr : NULL, (size_t)(cap * es)));
a->cap = cap;
}
void finch_arr_make(FArr *out, int64_t len, int64_t es) {
if (len < 0) len = 0;
out->ptr = len ? finch_zalloc(len * es) : NULL;
out->len = len;
out->cap = len;
}
// grow or shrink to `len`; new elements are zero
void finch_arr_resize(FArr *a, int64_t len, int64_t es) {
if (len < 0) len = 0;
finch_arr_reserve(a, len, es);
if (len > a->len) memset((char *)a->ptr + a->len * es, 0, (size_t)((len - a->len) * es));
a->len = len;
}
// a byte-for-byte copy of the elements (the compiler deep-copies owning elements afterwards)
void finch_arr_clone_raw(FArr *out, const FArr *a, int64_t es) {
out->len = a->len;
out->cap = a->len;
out->ptr = a->len ? finch_alloc(a->len * es) : NULL;
if (a->len) memcpy(out->ptr, a->ptr, (size_t)(a->len * es));
}
void finch_arr_free(FArr *a) {
if (a->cap > 0) free(a->ptr);
}
// open a hole at i (0 <= i <= len), len grows by one
void finch_arr_insert_gap(FArr *a, int64_t i, int64_t es, const char *file, int64_t line) {
if (i < 0 || i > a->len) finch_panic_index(file, line, i, a->len);
finch_arr_reserve(a, a->len + 1, es);
char *p = a->ptr;
memmove(p + (i + 1) * es, p + i * es, (size_t)((a->len - i) * es));
a->len++;
}
// close the hole at i (the element was already moved out), len shrinks by one
void finch_arr_remove_gap(FArr *a, int64_t i, int64_t es) {
char *p = a->ptr;
memmove(p + i * es, p + (i + 1) * es, (size_t)((a->len - i - 1) * es));
a->len--;
}
static void arr_push_str(FArr *a, const char *p, int64_t len) {
finch_arr_reserve(a, a->len + 1, (int64_t)sizeof(FStr));
str_heap((FStr *)a->ptr + a->len, p, len);
a->len++;
}
void finch_bytes_from_str(FArr *out, const FStr *s) {
out->len = out->cap = s->len;
out->ptr = s->len ? finch_alloc(s->len) : NULL;
if (s->len) memcpy(out->ptr, s->ptr, (size_t)s->len);
}
// ---------- program arguments, input and files ----------
void finch_args(FArr *out, int argc, char **argv) {
out->len = out->cap = argc;
out->ptr = finch_alloc((int64_t)sizeof(FStr) * (argc ? argc : 1));
for (int i = 0; i < argc; i++) str_heap((FStr *)out->ptr + i, argv[i], (int64_t)strlen(argv[i]));
}
// input("Name? ") prints the prompt and reads one line, without the newline.
void finch_input(FStr *out, const FStr *prompt) {
if (prompt->len) fwrite(prompt->ptr, 1, (size_t)prompt->len, stdout);
fflush(stdout);
char *line = NULL;
size_t size = 0;
ssize_t n = getline(&line, &size, stdin);
if (n < 0) {
free(line);
str_static(out, empty);
return;
}
while (n > 0 && (line[n - 1] == '\n' || line[n - 1] == '\r')) line[--n] = 0;
out->ptr = line;
out->len = n;
out->cap = (int64_t)size;
}
int finch_file_exists(const FStr *path) {
FILE *f = fopen(path->ptr, "rb");
if (f) fclose(f);
return f != NULL;
}
void finch_read_file(FStr *out, const FStr *path, const char *file, int64_t line) {
FILE *f = fopen(path->ptr, "rb");
if (!f) {
char msg[300];
snprintf(msg, sizeof msg, "can't read the file \"%.*s\": %s", (int)(path->len > 200 ? 200 : path->len),
path->ptr, strerror(errno));
finch_panic(file, line, msg);
}
fseek(f, 0, SEEK_END);
long size = ftell(f);
fseek(f, 0, SEEK_SET);
char *m = finch_alloc(size + 1);
size_t got = fread(m, 1, (size_t)size, f);
fclose(f);
m[got] = 0;
out->ptr = m;
out->len = (int64_t)got;
out->cap = size + 1;
}
int finch_write_file(const FStr *path, const FStr *text) {
FILE *f = fopen(path->ptr, "wb");
if (!f) return 0;
size_t put = fwrite(text->ptr, 1, (size_t)text->len, f);
return fclose(f) == 0 && put == (size_t)text->len;
}