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Fix generator teardown leaks, add RETURN-in-GEN and LOOP conditions on DO EACH

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Review findings and follow-ups from PR #61 review:

- runtime_generator.c: akbasic_runtime_release_generator() now releases the
  forGeneratorEnv of every scope it walks through. Abandoning a generator
  that was itself suspended inside a FOR EACH over another generator
  stranded the inner generator's pool slot; a loop doing so exhausted the
  twelve-slot pool and died far from the cause.
- runtime.c/runtime.h: new akbasic_runtime_unwind_to_environment(), the
  shared teardown for the error unwinds in pump_generator() and
  call_function() -- both previously bare prev_environment() loops with the
  same suspended-generator blindness.
- runtime_commands.c: bare RETURN standing in a GEN's own frame ends the
  generator exactly as END GEN does -- a GEN is a function at heart. RETURN
  with a value there is refused (values leave a GEN only through EMIT). The
  no-frame error message now says "GOSUB, DEF, or GEN".
- runtime_structure.c: LOOP WHILE/UNTIL composes with DO EACH -- checked
  after each trip with the loop variable still holding that trip's value; a
  condition that stops the loop abandons the generator exactly as EXIT
  does. Previously the condition was silently ignored, while the verb
  reference documented it as working.
- parser_commands.c: trailing tokens after the generator call on a FOR
  EACH/DO EACH line are refused at parse. Previously they sat unparsed and
  blew up only after the loop completed, when the parent scope resumed the
  line mid-statement -- an error at the loop's end pointing at its start.
- tests/generators.c: pool-exhaustion tests for the nested-abandonment and
  LOOP-condition paths, RETURN semantics tests, and a direct test of the
  unwind primitive. Three new golden pairs cover RETURN, LOOP conditions
  and the misplaced-condition parse error.
- docs: RETURN and LOOP-condition semantics in 04-control-flow.md and
  11-verb-reference.md; corrected the self-recursion analogy (functions
  are re-entrant here). TODO.md 1.10 records the generator design
  decisions the code comments were already citing, plus the zero-arg
  parameter-list limitation. MAINTENANCE.md gains the abandoned-generators
  invariant those comments also cited.

Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Ishikawa
2026-08-06 11:29:17 -04:00
committed by Andrew Kesterson
parent f7e8d4b82b
commit a29c7f34fe
17 changed files with 426 additions and 13 deletions
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20
src/runtime_structure.c
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@@ -149,11 +149,27 @@ akerr_ErrorContext *akbasic_cmd_loop(akbasic_Runtime *obj, akbasic_ASTLeaf *expr
akbasic_Environment *loopenv = obj->environment;
PASS(errctx, akbasic_environment_stop_waiting(obj->environment, "LOOP"));
if ( loopenv->forGeneratorEnv != NULL ) {
/*
* A condition on the LOOP composes with EACH: it is checked after each
* trip through the body, with the loop variable still holding that
* trip's value, before the generator is pumped for the next one. A
* condition that says stop abandons the generator exactly as EXIT does.
*/
again = true;
arg = (expr != NULL ? expr->right : NULL);
if ( arg != NULL ) {
kind = (int)arg->literal_int;
PASS(errctx, loop_continues(obj, arg->left, kind, &again));
}
if ( !again && loopenv->forGeneratorEnv != NULL ) {
PASS(errctx, akbasic_runtime_release_generator(obj, loopenv->forGeneratorEnv));
loopenv->forGeneratorEnv = NULL;
}
if ( again && loopenv->forGeneratorEnv != NULL ) {
obj->environment = loopenv->forGeneratorEnv;
PASS(errctx, akbasic_runtime_pump_generator(obj, loopenv));
}
again = (loopenv->forGeneratorEnv != NULL);
again = (again && loopenv->forGeneratorEnv != NULL);
} else {
PASS(errctx, akbasic_environment_stop_waiting(obj->environment, "LOOP"));
/*