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feat: add Fiber.try() method for catching errors across fiber boundaries

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Implement a new `Fiber.try()` method that allows a calling fiber to catch runtime errors from a called fiber. When a fiber is invoked with `try()` instead of `call()`, any runtime error that occurs in the called fiber is returned as a string to the caller rather than terminating the program with a stack trace. The `callerIsTrying` flag on `ObjFiber` tracks this state, and the `runtimeError` function now checks this flag to redirect the error to the caller's stack. Also adds `Fiber.error` getter to retrieve the error string from a failed fiber, changes `Fiber.isDone` to return `true` for errored fibers, and migrates the fiber error field from a raw `char*` to an `ObjString*` for proper memory management. Includes comprehensive test cases for try behavior, re-entry prevention, and error state queries.
This commit is contained in:
Bob Nystrom
2014-10-15 13:36:42 +00:00
parent d4a858da43
commit d60068db56
13 changed files with 162 additions and 37 deletions
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src/wren_core.c
+32 -1
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@@ -269,10 +269,17 @@ DEF_NATIVE(fiber_call1)
return PRIM_RUN_FIBER;
}
DEF_NATIVE(fiber_error)
{
ObjFiber* runFiber = AS_FIBER(args[0]);
if (runFiber->error == NULL) RETURN_NULL;
RETURN_OBJ(runFiber->error);
}
DEF_NATIVE(fiber_isDone)
{
ObjFiber* runFiber = AS_FIBER(args[0]);
RETURN_BOOL(runFiber->numFrames == 0);
RETURN_BOOL(runFiber->numFrames == 0 || runFiber->error != NULL);
}
DEF_NATIVE(fiber_run)
@@ -320,12 +327,33 @@ DEF_NATIVE(fiber_run1)
return PRIM_RUN_FIBER;
}
DEF_NATIVE(fiber_try)
{
ObjFiber* runFiber = AS_FIBER(args[0]);
if (runFiber->numFrames == 0) RETURN_ERROR("Cannot try a finished fiber.");
if (runFiber->caller != NULL) RETURN_ERROR("Fiber has already been called.");
// Remember who ran it.
runFiber->caller = fiber;
runFiber->callerIsTrying = true;
// If the fiber was yielded, make the yield call return null.
if (runFiber->stackSize > 0)
{
runFiber->stack[runFiber->stackSize - 1] = NULL_VAL;
}
return PRIM_RUN_FIBER;
}
DEF_NATIVE(fiber_yield)
{
if (fiber->caller == NULL) RETURN_ERROR("No fiber to yield to.");
ObjFiber* caller = fiber->caller;
fiber->caller = NULL;
fiber->callerIsTrying = false;
// Make the caller's run method return null.
caller->stack[caller->stackSize - 1] = NULL_VAL;
@@ -341,6 +369,7 @@ DEF_NATIVE(fiber_yield1)
ObjFiber* caller = fiber->caller;
fiber->caller = NULL;
fiber->callerIsTrying = false;
// Make the caller's run method return the argument passed to yield.
caller->stack[caller->stackSize - 1] = args[1];
@@ -1027,9 +1056,11 @@ void wrenInitializeCore(WrenVM* vm)
NATIVE(vm->fiberClass->metaclass, "yield ", fiber_yield1);
NATIVE(vm->fiberClass, "call", fiber_call);
NATIVE(vm->fiberClass, "call ", fiber_call1);
NATIVE(vm->fiberClass, "error", fiber_error);
NATIVE(vm->fiberClass, "isDone", fiber_isDone);
NATIVE(vm->fiberClass, "run", fiber_run);
NATIVE(vm->fiberClass, "run ", fiber_run1);
NATIVE(vm->fiberClass, "try", fiber_try);
vm->fnClass = defineClass(vm, "Fn");