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rebDid()/Didnt() don't decay, check void
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The concept behind DID and DIDN'T as the prefix form of the
test used by ELSE and THEN evolved over time.  At one point
these tested against "pure null" vs. null isotopes (which
were "unstable").  But it came to be that null itself was
an isotopic WORD! that was "stable"...and the unstable form
was actually an isotopic BLOCK! that encoded a null, which
decayed to its first value.

This change didn't make it through to the API variations of
rebDid() and rebDidnt().  The values they tested were
pre-decayed, hence they would not react to boxed nulls or
voids correctly.  (Also, void wasn't tested at all, as the
APIs predated the existence of a reified void state.)

Here those issues are addressed (although it doesn't
handle isotopic objects--which are an experimental concept
that may be dropped.)  It names the evaluation routines
explicitly in terms of whether they decay or not.  So long
as they were being renamed, it also encodes the fact that
va_end() is called unconditionally by the routine in the
name...rather than needing to have a comment to that effect
at every callsite.
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@hostilefork
hostilefork committed Sep 11, 2023
1 parent f7adbf1 commit 45080dc
Showing 1 changed file with 40 additions and 44 deletions.
84 changes: 40 additions & 44 deletions src/core/a-lib.c
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Original file line number Diff line number Diff line change
Expand Up @@ -910,6 +910,9 @@ static bool Run_Va_Throws(

bool threw = Trampoline_Throws(out, f);

if (not threw and (flags & FRAME_FLAG_META_RESULT))
assert(QUOTE_BYTE(out) >= QUASI_2);

// (see also Reb_State->saved_sigmask RE: if a longjmp happens)
Eval_Sigmask = saved_sigmask;

Expand All @@ -927,7 +930,7 @@ static bool Run_Va_Throws(
// or use rebElide() and say it doesn't matter. (or just find a way in the
// executed code passed to not have it evaluate to none)
//
inline static void Run_Va_No_Decay_May_Fail(
inline static void Run_Va_Undecayed_May_Fail_Calls_Va_End(
REBVAL *out,
const void *p, // first pointer (may be END, nullptr means NULLED)
va_list *vaptr // va_end() handled by feed for all cases (throws, fails)
Expand All @@ -948,12 +951,12 @@ inline static void Run_Va_No_Decay_May_Fail(
// APIs just as if you'd tried to do a SET-WORD!...so you don't have to worry
// about multi-return packs etc.
//
inline static void Run_Va_May_Fail(
inline static void Run_Va_Decay_May_Fail_Calls_Va_End(
REBVAL *out,
const void *p, // first pointer (may be END, nullptr means NULLED)
va_list *vaptr // va_end() handled by feed for all cases (throws, fails)
){
Run_Va_No_Decay_May_Fail(out, p, vaptr);
Run_Va_Undecayed_May_Fail_Calls_Va_End(out, p, vaptr);

Decay_If_Unstable(out);
}
Expand Down Expand Up @@ -1022,9 +1025,9 @@ REBVAL *RL_rebValue(const void *p, va_list *vaptr)
ENTER_API;

REBVAL *result = Alloc_Value();
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (Is_Nulled(result)) { // tolerate isotopes
if (Is_Nulled(result)) {
rebRelease(result);
return nullptr; // No NULLED cells in API, see NULLIFY_NULLED()
}
Expand Down Expand Up @@ -1118,7 +1121,7 @@ REBVAL *RL_rebMeta(const void *p, va_list *vaptr)
if (Run_Va_Throws(v, interruptible, FRAME_FLAG_META_RESULT, p, vaptr))
fail (Error_No_Catch_For_Throw(TOP_FRAME)); // panic?

assert(not Is_Nulled(v)); // meta operations do not produce NULL
assert(not Is_Nulled(v)); // meta operations cannot produce NULL

return v; // caller must rebRelease()
}
Expand Down Expand Up @@ -1148,11 +1151,7 @@ REBVAL *RL_rebEntrap(const void *p, va_list *vaptr)
Meta_Quotify(v);
}

if (Is_Nulled(v)) { // tolerate isotopes
assert(!"Meta values are not supposed to be NULL");
rebRelease(v);
return nullptr; // No NULLED API cells, see notes on NULLIFY_NULLED()
}
assert(not Is_Nulled(v)); // meta operations cannot produce NULL

return v; // caller must rebRelease()
}
Expand Down Expand Up @@ -1184,11 +1183,7 @@ REBVAL *RL_rebEntrapInterruptible(
Meta_Quotify(v);
}

if (Is_Nulled(v)) { // tolerate isotopes
assert(!"Meta values are not supposed to be NULL");
rebRelease(v);
return nullptr; // No NULLED API cells, see notes on NULLIFY_NULLED()
}
assert(not Is_Nulled(v)); // META operations can't return null

return v; // caller must rebRelease()
}
Expand All @@ -1210,7 +1205,7 @@ REBVAL *RL_rebQuote(const void *p, va_list *vaptr)
ENTER_API;

REBVAL *result = Alloc_Value();
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

return Quotify(result, 1); // nulled cells legal for API if quoted
}
Expand All @@ -1230,7 +1225,7 @@ void RL_rebElide(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (elided);
Run_Va_No_Decay_May_Fail(elided, p, vaptr); // calls va_end()
Run_Va_Undecayed_May_Fail_Calls_Va_End(elided, p, vaptr);
}


Expand Down Expand Up @@ -1260,7 +1255,7 @@ void RL_rebJumps(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (dummy);
Run_Va_May_Fail(dummy, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(dummy, p, vaptr);

// Note: If we just `fail()` here, then while MSVC compiles %a-lib.c at
// higher optimization levels it can conclude that RL_rebJumps() never
Expand All @@ -1287,21 +1282,18 @@ void RL_rebJumps(const void *p, va_list *vaptr)
// e.g. "Would the supplied expression run a THEN"
// See DECLARE_NATIVE(did_1) for explanation.
//
// !!! This does not handle isotopic objects, an experimental concept where
// if the object supports a THEN method it would pass the DID test. Review
// this in light of whether isotopic objects are going to be kept.
//
bool RL_rebDid(const void *p, va_list *vaptr)
{
ENTER_API;

DECLARE_LOCAL (condition);
Run_Va_May_Fail(condition, p, vaptr); // calls va_end()

if (IS_BLANK(condition) or IS_LOGIC(condition))
fail (
"SEMANTIC CHANGE: DID tests against NULL only, temporarily not"
" working with blank or logic...use THEN or TO-LOGIC in meantime"
" https://forum.rebol.info/t/498/2"
);
Run_Va_Undecayed_May_Fail_Calls_Va_End(condition, p, vaptr);

return not Is_Nulled(condition); // isotopes okay for this test
return not Is_Nulled(condition) and not Is_Void(condition);
}


Expand All @@ -1311,14 +1303,18 @@ bool RL_rebDid(const void *p, va_list *vaptr)
// Analogue of DIDN'T, which is an isotope-tolerant version of NULL?.
// e.g. "Would the supplied expression run an ELSE"
//
// !!! This does not handle isotopic objects, an experimental concept where
// if the object supports a ELSE method it would pass the DIDN'T test. Review
// this in light of whether isotopic objects are going to be kept.
//
bool RL_rebDidnt(const void *p, va_list *vaptr)
{
ENTER_API;

DECLARE_LOCAL (condition);
Run_Va_May_Fail(condition, p, vaptr); // calls va_end()
Run_Va_Undecayed_May_Fail_Calls_Va_End(condition, p, vaptr);

return Is_Nulled(condition); // isotopes are okay with this test
return Is_Nulled(condition) or Is_Void(condition);
}

//
Expand All @@ -1335,7 +1331,7 @@ bool RL_rebTruthy(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (condition);
Run_Va_May_Fail(condition, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(condition, p, vaptr);

return Is_Truthy(condition); // will fail() on (most) isotopes
}
Expand All @@ -1352,7 +1348,7 @@ bool RL_rebNot(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (condition);
Run_Va_May_Fail(condition, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(condition, p, vaptr);

return Is_Falsey(condition); // will fail() on isotopes
}
Expand All @@ -1374,7 +1370,7 @@ intptr_t RL_rebUnbox(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (result);
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (IS_LOGIC(result)) {
return VAL_LOGIC(result) ? 1 : 0;
Expand Down Expand Up @@ -1402,7 +1398,7 @@ bool RL_rebUnboxLogic(
ENTER_API;

DECLARE_LOCAL (result);
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (not IS_LOGIC(result))
fail ("rebUnboxLogic() called on non-LOGIC!");
Expand All @@ -1421,7 +1417,7 @@ intptr_t RL_rebUnboxInteger(
ENTER_API;

DECLARE_LOCAL (result);
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (not IS_INTEGER(result))
fail ("rebUnboxInteger() called on non-INTEGER!");
Expand All @@ -1439,7 +1435,7 @@ double RL_rebUnboxDecimal(
ENTER_API;

DECLARE_LOCAL (result);
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (IS_DECIMAL(result))
return VAL_DECIMAL(result);
Expand All @@ -1460,7 +1456,7 @@ uint32_t RL_rebUnboxChar(
ENTER_API;

DECLARE_LOCAL (result);
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (not IS_CHAR(result))
fail ("rebUnboxChar() called on non-CHAR");
Expand All @@ -1479,7 +1475,7 @@ void *RL_rebUnboxHandle(
ENTER_API;

DECLARE_LOCAL (result);
Run_Va_May_Fail(result, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(result, p, vaptr);

if (VAL_TYPE(result) != REB_HANDLE)
fail ("rebUnboxHandle() called on non-HANDLE!");
Expand Down Expand Up @@ -1531,7 +1527,7 @@ size_t RL_rebSpellInto(
ENTER_API;

DECLARE_LOCAL (v);
Run_Va_May_Fail(v, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(v, p, vaptr);

return Spell_Into(buf, buf_size, v);
}
Expand All @@ -1551,7 +1547,7 @@ char *RL_rebTrySpell(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (v);
Run_Va_May_Fail(v, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(v, p, vaptr);

if (Is_Nulled(v))
return nullptr;
Expand Down Expand Up @@ -1650,7 +1646,7 @@ unsigned int RL_rebSpellIntoWide(
ENTER_API;

DECLARE_LOCAL (v);
Run_Va_May_Fail(v, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(v, p, vaptr);

return Spell_Into_Wide(buf, buf_chars, v);
}
Expand All @@ -1667,7 +1663,7 @@ REBWCHAR *RL_rebTrySpellWide(const void *p, va_list *vaptr)
ENTER_API;

DECLARE_LOCAL (v);
Run_Va_May_Fail(v, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(v, p, vaptr);

if (Is_Nulled(v))
return nullptr;
Expand Down Expand Up @@ -1770,7 +1766,7 @@ size_t RL_rebBytesInto(
ENTER_API;

DECLARE_LOCAL (v);
Run_Va_May_Fail(v, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(v, p, vaptr);

return Bytes_Into(buf, buf_size, v);
}
Expand All @@ -1790,7 +1786,7 @@ unsigned char *RL_rebTryBytes(
ENTER_API;

DECLARE_LOCAL (v);
Run_Va_May_Fail(v, p, vaptr); // calls va_end()
Run_Va_Decay_May_Fail_Calls_Va_End(v, p, vaptr);

if (Is_Nulled(v)) {
*size_out = 0;
Expand Down

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