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Change in the handling of 'L->top' when calling metamethods 

Instead of updating 'L->top' in every place that may call a
metamethod, the metamethod functions themselves (luaT_trybinTM and
luaT_callorderTM) correct the top. (When calling metamethods from
the C API, however, the callers must preserve 'L->top'.)
pull/23/head
Roberto Ierusalimschy 5 years ago
parent
e70f275f32
commit
b80077b8f3
10 changed files with 75 additions and 29 deletions
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  1. 2
      lapi.c
  2. 2
      lobject.c
  3. 2
      lopcodes.c
  4. 12
      ltm.c
  5. 1
      ltm.h
  6. 44
      lvm.c
  7. 17
      testes/api.lua
  8. 2
      testes/coroutine.lua
  9. 15
      testes/events.lua
  10. 7
      testes/strings.lua

2
lapi.c
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@ -329,12 +329,14 @@ LUA_API int lua_compare (lua_State *L, int index1, int index2, int op) {
o1 = index2value(L, index1);
o2 = index2value(L, index2);
if (isvalid(L, o1) && isvalid(L, o2)) {
ptrdiff_t top = savestack(L, L->top);
switch (op) {
case LUA_OPEQ: i = luaV_equalobj(L, o1, o2); break;
case LUA_OPLT: i = luaV_lessthan(L, o1, o2); break;
case LUA_OPLE: i = luaV_lessequal(L, o1, o2); break;
default: api_check(L, 0, "invalid option");
}
L->top = restorestack(L, top);
}
lua_unlock(L);
return i;

2
lobject.c
View File

@ -127,7 +127,9 @@ void luaO_arith (lua_State *L, int op, const TValue *p1, const TValue *p2,
StkId res) {
if (!luaO_rawarith(L, op, p1, p2, s2v(res))) {
/* could not perform raw operation; try metamethod */
ptrdiff_t top = savestack(L, L->top);
luaT_trybinTM(L, p1, p2, res, cast(TMS, (op - LUA_OPADD) + TM_ADD));
L->top = restorestack(L, top);
}
}

2
lopcodes.c
View File

@ -101,7 +101,7 @@ LUAI_DDEF const lu_byte luaP_opmodes[NUM_OPCODES] = {
,opmode(0, 1, 0, 0, iABC) /* OP_SETLIST */
,opmode(0, 0, 0, 1, iABx) /* OP_CLOSURE */
,opmode(1, 0, 0, 1, iABC) /* OP_VARARG */
,opmode(0, 0, 0, 1, iABC) /* OP_VARARGPREP */
,opmode(0, 1, 0, 1, iABC) /* OP_VARARGPREP */
,opmode(0, 0, 0, 0, iAx) /* OP_EXTRAARG */
};

12
ltm.c
View File

@ -147,11 +147,9 @@ static int callbinTM (lua_State *L, const TValue *p1, const TValue *p2,
void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
StkId res, TMS event) {
L->top = L->ci->top;
if (!callbinTM(L, p1, p2, res, event)) {
switch (event) {
case TM_CONCAT:
luaG_concaterror(L, p1, p2);
/* call never returns, but to avoid warnings: *//* FALLTHROUGH */
case TM_BAND: case TM_BOR: case TM_BXOR:
case TM_SHL: case TM_SHR: case TM_BNOT: {
if (ttisnumber(p1) && ttisnumber(p2))
@ -167,6 +165,13 @@ void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
}
void luaT_tryconcatTM (lua_State *L) {
StkId top = L->top;
if (!callbinTM(L, s2v(top - 2), s2v(top - 1), top - 2, TM_CONCAT))
luaG_concaterror(L, s2v(top - 2), s2v(top - 1));
}
void luaT_trybinassocTM (lua_State *L, const TValue *p1, const TValue *p2,
StkId res, int flip, TMS event) {
if (flip)
@ -186,6 +191,7 @@ void luaT_trybiniTM (lua_State *L, const TValue *p1, lua_Integer i2,
int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
TMS event) {
L->top = L->ci->top;
if (callbinTM(L, p1, p2, L->top, event)) /* try original event */
return !l_isfalse(s2v(L->top));
#if defined(LUA_COMPAT_LT_LE)

1
ltm.h
View File

@ -75,6 +75,7 @@ LUAI_FUNC void luaT_callTMres (lua_State *L, const TValue *f,
const TValue *p1, const TValue *p2, StkId p3);
LUAI_FUNC void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
StkId res, TMS event);
LUAI_FUNC void luaT_tryconcatTM (lua_State *L);
LUAI_FUNC void luaT_trybinassocTM (lua_State *L, const TValue *p1,
const TValue *p2, StkId res, int inv, TMS event);
LUAI_FUNC void luaT_trybiniTM (lua_State *L, const TValue *p1, lua_Integer i2,

44
lvm.c
View File

@ -515,8 +515,11 @@ int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
}
if (tm == NULL) /* no TM? */
return 0; /* objects are different */
luaT_callTMres(L, tm, t1, t2, L->top); /* call TM */
return !l_isfalse(s2v(L->top));
else {
L->top = L->ci->top;
luaT_callTMres(L, tm, t1, t2, L->top); /* call TM */
return !l_isfalse(s2v(L->top));
}
}
@ -548,7 +551,7 @@ void luaV_concat (lua_State *L, int total) {
int n = 2; /* number of elements handled in this pass (at least 2) */
if (!(ttisstring(s2v(top - 2)) || cvt2str(s2v(top - 2))) ||
!tostring(L, s2v(top - 1)))
luaT_trybinTM(L, s2v(top - 2), s2v(top - 1), top - 2, TM_CONCAT);
luaT_tryconcatTM(L);
else if (isemptystr(s2v(top - 1))) /* second operand is empty? */
cast_void(tostring(L, s2v(top - 2))); /* result is first operand */
else if (isemptystr(s2v(top - 2))) { /* first operand is empty string? */
@ -747,7 +750,7 @@ void luaV_finishOp (lua_State *L) {
break;
}
case OP_CONCAT: {
StkId top = L->top - 1; /* top when 'luaT_trybinTM' was called */
StkId top = L->top - 1; /* top when 'luaT_tryconcatTM' was called */
int a = GETARG_A(inst); /* first element to concatenate */
int total = cast_int(top - 1 - (base + a)); /* yet to concatenate */
setobjs2s(L, top - 2, top); /* put TM result in proper position */
@ -801,7 +804,7 @@ void luaV_finishOp (lua_State *L) {
setfltvalue(s2v(ra), fop(L, nb, fimm)); \
} \
else \
Protect(luaT_trybiniTM(L, v1, imm, flip, ra, tm)); }
ProtectNT(luaT_trybiniTM(L, v1, imm, flip, ra, tm)); }
/*
@ -836,7 +839,7 @@ void luaV_finishOp (lua_State *L) {
setfltvalue(s2v(ra), fop(L, n1, n2)); \
} \
else \
Protect(luaT_trybinTM(L, v1, v2, ra, tm)); }
ProtectNT(luaT_trybinTM(L, v1, v2, ra, tm)); }
/*
@ -877,7 +880,7 @@ void luaV_finishOp (lua_State *L) {
setfltvalue(s2v(ra), fop(L, n1, n2)); \
} \
else \
Protect(luaT_trybinassocTM(L, v1, v2, ra, flip, tm)); } }
ProtectNT(luaT_trybinassocTM(L, v1, v2, ra, flip, tm)); } }
/*
@ -891,7 +894,7 @@ void luaV_finishOp (lua_State *L) {
setfltvalue(s2v(ra), fop(L, n1, n2)); \
} \
else \
Protect(luaT_trybinTM(L, v1, v2, ra, tm)); }
ProtectNT(luaT_trybinTM(L, v1, v2, ra, tm)); }
/*
@ -906,7 +909,7 @@ void luaV_finishOp (lua_State *L) {
setivalue(s2v(ra), op(L, i1, i2)); \
} \
else \
Protect(luaT_trybiniTM(L, v1, i2, TESTARG_k(i), ra, tm)); }
ProtectNT(luaT_trybiniTM(L, v1, i2, TESTARG_k(i), ra, tm)); }
/*
@ -920,7 +923,7 @@ void luaV_finishOp (lua_State *L) {
setivalue(s2v(ra), op(L, i1, i2)); \
} \
else \
Protect(luaT_trybinTM(L, v1, v2, ra, tm)); }
ProtectNT(luaT_trybinTM(L, v1, v2, ra, tm)); }
/*
@ -937,7 +940,7 @@ void luaV_finishOp (lua_State *L) {
else if (ttisnumber(s2v(ra)) && ttisnumber(rb)) \
cond = opf(s2v(ra), rb); \
else \
Protect(cond = other(L, s2v(ra), rb)); \
ProtectNT(cond = other(L, s2v(ra), rb)); \
docondjump(); }
@ -956,7 +959,7 @@ void luaV_finishOp (lua_State *L) {
} \
else { \
int isf = GETARG_C(i); \
Protect(cond = luaT_callorderiTM(L, s2v(ra), im, inv, isf, tm)); \
ProtectNT(cond = luaT_callorderiTM(L, s2v(ra), im, inv, isf, tm)); \
} \
docondjump(); }
@ -1094,7 +1097,8 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmfetch();
lua_assert(base == ci->func + 1);
lua_assert(base <= L->top && L->top < L->stack + L->stacksize);
lua_assert(ci->top < L->stack + L->stacksize);
/* invalidate top for instructions not expecting it */
lua_assert(isIT(i) || (L->top = base));
vmdispatch (GET_OPCODE(i)) {
vmcase(OP_MOVE) {
setobjs2s(L, ra, RB(i));
@ -1359,7 +1363,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
if (TESTARG_k(i)) {
ic = -ic; ev = TM_SHL;
}
Protect(luaT_trybiniTM(L, rb, ic, 0, ra, ev));
ProtectNT(luaT_trybiniTM(L, rb, ic, 0, ra, ev));
}
vmbreak;
}
@ -1371,7 +1375,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
setivalue(s2v(ra), luaV_shiftl(ic, ib));
}
else
Protect(luaT_trybiniTM(L, rb, ic, 1, ra, TM_SHL));
ProtectNT(luaT_trybiniTM(L, rb, ic, 1, ra, TM_SHL));
vmbreak;
}
vmcase(OP_ADD) {
@ -1422,7 +1426,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
setivalue(s2v(ra), luaV_shiftl(ib, -ic));
}
else
Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHR));
ProtectNT(luaT_trybinTM(L, rb, rc, ra, TM_SHR));
vmbreak;
}
vmcase(OP_SHL) {
@ -1433,7 +1437,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
setivalue(s2v(ra), luaV_shiftl(ib, ic));
}
else
Protect(luaT_trybinTM(L, rb, rc, ra, TM_SHL));
ProtectNT(luaT_trybinTM(L, rb, rc, ra, TM_SHL));
vmbreak;
}
vmcase(OP_UNM) {
@ -1447,7 +1451,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
setfltvalue(s2v(ra), luai_numunm(L, nb));
}
else
Protect(luaT_trybinTM(L, rb, rb, ra, TM_UNM));
ProtectNT(luaT_trybinTM(L, rb, rb, ra, TM_UNM));
vmbreak;
}
vmcase(OP_BNOT) {
@ -1457,7 +1461,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
setivalue(s2v(ra), intop(^, ~l_castS2U(0), ib));
}
else
Protect(luaT_trybinTM(L, rb, rb, ra, TM_BNOT));
ProtectNT(luaT_trybinTM(L, rb, rb, ra, TM_BNOT));
vmbreak;
}
vmcase(OP_NOT) {
@ -1493,7 +1497,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmcase(OP_EQ) {
int cond;
TValue *rb = vRB(i);
Protect(cond = luaV_equalobj(L, s2v(ra), rb));
ProtectNT(cond = luaV_equalobj(L, s2v(ra), rb));
docondjump();
vmbreak;
}

17
testes/api.lua
View File

@ -241,6 +241,23 @@ assert(a == 20 and b == false)
a,b = T.testC("compare LE 5 -6, return 2", a1, 2, 2, a1, 2, 20)
assert(a == 20 and b == true)
do -- testing lessthan and lessequal with metamethods
local mt = {__lt = function (a,b) return a[1] < b[1] end,
__le = function (a,b) return a[1] <= b[1] end,
__eq = function (a,b) return a[1] == b[1] end}
local function O (x)
return setmetatable({x}, mt)
end
local a, b = T.testC("compare LT 2 3; pushint 10; return 2", O(1), O(2))
assert(a == true and b == 10)
local a, b = T.testC("compare LE 2 3; pushint 10; return 2", O(3), O(2))
assert(a == false and b == 10)
local a, b = T.testC("compare EQ 2 3; pushint 10; return 2", O(3), O(3))
assert(a == true and b == 10)
end
-- testing length
local t = setmetatable({x = 20}, {__len = function (t) return t.x end})
a,b,c = T.testC([[

2
testes/coroutine.lua
View File

@ -809,7 +809,7 @@ assert(run(function ()
-- tests for coroutine API
if T==nil then
(Message or print)('\n >>> testC not active: skipping coroutine API tests <<<\n')
return
print "OK"; return
end
print('testing coroutine API')

15
testes/events.lua
View File

@ -217,9 +217,16 @@ t.__le = function (a,b,c)
return a<=b, "dummy"
end
t.__eq = function (a,b,c)
assert(c == nil)
if type(a) == 'table' then a = a.x end
if type(b) == 'table' then b = b.x end
return a == b, "dummy"
end
function Op(x) return setmetatable({x=x}, t) end
local function test ()
local function test (a, b, c)
assert(not(Op(1)<Op(1)) and (Op(1)<Op(2)) and not(Op(2)<Op(1)))
assert(not(1 < Op(1)) and (Op(1) < 2) and not(2 < Op(1)))
assert(not(Op('a')<Op('a')) and (Op('a')<Op('b')) and not(Op('b')<Op('a')))
@ -232,9 +239,13 @@ local function test ()
assert((1 >= Op(1)) and not(1 >= Op(2)) and (Op(2) >= 1))
assert((Op('a')>=Op('a')) and not(Op('a')>=Op('b')) and (Op('b')>=Op('a')))
assert(('a' >= Op('a')) and not(Op('a') >= 'b') and (Op('b') >= Op('a')))
assert(Op(1) == Op(1) and Op(1) ~= Op(2))
assert(Op('a') == Op('a') and Op('a') ~= Op('b'))
assert(a == a and a ~= b)
assert(Op(3) == c)
end
test()
test(Op(1), Op(2), Op(3))
-- test `partial order'

7
testes/strings.lua
View File

@ -167,8 +167,11 @@ do -- tests for '%p' format
local t1 = {}; local t2 = {}
assert(string.format("%p", t1) ~= string.format("%p", t2))
end
assert(string.format("%p", string.rep("a", 10)) ==
string.format("%p", string.rep("a", 10))) -- short strings
do -- short strings
local s1 = string.rep("a", 10)
local s2 = string.rep("a", 10)
assert(string.format("%p", s1) == string.format("%p", s2))
end
do -- long strings
local s1 = string.rep("a", 300); local s2 = string.rep("a", 300)
assert(string.format("%p", s1) ~= string.format("%p", s2))

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