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sx/examples/ffi/1214-ffi-06-callback.sx
agra 66bdc70bf1 test: group examples into per-category folders
Move examples/*.sx and their expected/ snapshots into per-category
subfolders (examples/<category>/...). Folder = leading filename token,
with ffi-objc/ffi-jni kept whole; filenames are unchanged. The corpus
runner and LSP sweep now discover each category's expected/ dir, while
issues/ stays flat. Example 1058's repo-root-relative companion import
is made file-relative. Path strings embedded in 164 snapshots were
regenerated (path-only changes). Test-layout docs in CLAUDE.md updated.
2026-06-21 14:41:34 +03:00

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// Phase 0 baseline (PLAN-FFI.md step 0.6): sx function passed to C
// as a function pointer; C invokes it; sx-side observable effect.
// Mirrors the `app->onInputEvent` install pattern in
// library/modules/platform/android.sx.
//
// Two arities covered:
// 1. (i32) -> i32 — single-arg callback
// 2. (*void, i32) -> i32 — pointer + value (onInputEvent shape)
//
// Plus a side-effect via a global so we can confirm the callback
// actually fired (return value + state mutation both observable).
#import "modules/std.sx";
#import c {
#source "1214-ffi-06-callback.c";
};
ffi_apply_callback :: (cb: (i32) -> i32 abi(.c), value: i32) -> i32 extern;
ffi_apply_callback2 :: (cb: (*void, i32) -> i32 abi(.c), ctx: *void, v: i32) -> i32 extern;
g_callback_hits : i32 = 0;
g_callback_sum : i32 = 0;
double_it :: (x: i32) -> i32 abi(.c) {
g_callback_hits += 1;
g_callback_sum += x;
x * 2
}
add_with_ctx :: (ctx: *void, v: i32) -> i32 abi(.c) {
g_callback_hits += 1;
// Pass a sentinel via ctx to prove the pointer arg also survives the
// round-trip — read it back as an i32 through *i32.
p : *i32 = xx ctx;
p.* + v
}
main :: () -> i32 {
// ── Single-arg callback ────────────────────────────────────────
r1 := ffi_apply_callback(double_it, 21);
print("callback returned = {}\n", r1);
print("hits after first call = {}\n", g_callback_hits);
print("sum after first call = {}\n", g_callback_sum);
// Two more calls confirm the same fn pointer keeps working.
ffi_apply_callback(double_it, 7);
ffi_apply_callback(double_it, 11);
print("hits after three calls = {}\n", g_callback_hits);
print("sum after three calls = {}\n", g_callback_sum);
// ── Two-arg callback with opaque ctx pointer ───────────────────
ctx_val : i32 = 100;
r2 := ffi_apply_callback2(add_with_ctx, xx @ctx_val, 42);
print("ctx + value = {}\n", r2);
print("hits after ctx callback = {}\n", g_callback_hits);
0
}