commit 7f6f70853c8a2730fca2e95d5968ad52cf470bda
parent b8fed93215a23a3f443c5b0126f0de1725771b44
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 7 Nov 2018 14:41:38 -0200
To-be-closed variable in 'for' loop separated from the state
The variable to be closed in a generic 'for' loop now is the
4th value produced in the loop initialization, instead of being
the loop state (the 2nd value produced). That allows a loop to
use a state with a '__toclose' metamethod but do not close it.
(As an example, 'f:lines()' might use the file 'f' as a state
for the loop, but it should not close the file when the loop ends.)
Diffstat:
6 files changed, 76 insertions(+), 29 deletions(-)
diff --git a/liolib.c b/liolib.c
@@ -386,8 +386,10 @@ static int io_lines (lua_State *L) {
}
aux_lines(L, toclose); /* push iteration function */
if (toclose) {
- lua_pushvalue(L, 1); /* file will be second result */
- return 2;
+ lua_pushnil(L); /* state */
+ lua_pushnil(L); /* control */
+ lua_pushvalue(L, 1); /* file is the to-be-closed variable (4th result) */
+ return 4;
}
else
return 1;
diff --git a/lopcodes.h b/lopcodes.h
@@ -279,9 +279,9 @@ OP_FORLOOP,/* A Bx R(A)+=R(A+2);
if R(A) <?= R(A+1) then { pc-=Bx; R(A+3)=R(A) } */
OP_FORPREP,/* A Bx R(A)-=R(A+2); pc+=Bx */
-OP_TFORPREP,/* A Bx create upvalue A; pc+=Bx */
-OP_TFORCALL,/* A C R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2)); */
-OP_TFORLOOP,/* A Bx if R(A+1) ~= nil then { R(A)=R(A+1); pc -= Bx } */
+OP_TFORPREP,/* A Bx create upvalue for R(A + 3); pc+=Bx */
+OP_TFORCALL,/* A C R(A+4), ... ,R(A+3+C) := R(A)(R(A+1), R(A+2)); */
+OP_TFORLOOP,/* A Bx if R(A+2) ~= nil then { R(A)=R(A+2); pc -= Bx } */
OP_SETLIST,/* A B C R(A)[(C-1)*FPF+i] := R(A+i), 1 <= i <= B */
diff --git a/lparser.c b/lparser.c
@@ -165,6 +165,9 @@ static int registerlocalvar (LexState *ls, TString *varname) {
}
+/*
+** Create a new local variable with the given 'name'.
+*/
static void new_localvar (LexState *ls, TString *name) {
FuncState *fs = ls->fs;
Dyndata *dyd = ls->dyd;
@@ -176,13 +179,8 @@ static void new_localvar (LexState *ls, TString *name) {
dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
}
-
-static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
- new_localvar(ls, luaX_newstring(ls, name, sz));
-}
-
#define new_localvarliteral(ls,v) \
- new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
+ new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1));
static LocVar *getlocvar (FuncState *fs, int i) {
@@ -192,6 +190,9 @@ static LocVar *getlocvar (FuncState *fs, int i) {
}
+/*
+** Start the scope for the last 'nvars' created variables.
+*/
static void adjustlocalvars (LexState *ls, int nvars) {
FuncState *fs = ls->fs;
fs->nactvar = cast_byte(fs->nactvar + nvars);
@@ -1357,7 +1358,6 @@ static void forbody (LexState *ls, int base, int line, int nvars, int kind) {
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
- adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_DO);
prep = luaK_codeABx(fs, forprep[kind], base, 0);
enterblock(fs, &bl, 0); /* scope for declared variables */
@@ -1399,6 +1399,7 @@ static void fornum (LexState *ls, TString *varname, int line) {
luaK_int(fs, fs->freereg, 1);
luaK_reserveregs(fs, 1);
}
+ adjustlocalvars(ls, 3); /* control variables */
forbody(ls, base, line, 1, basicfor);
}
@@ -1407,7 +1408,7 @@ static void forlist (LexState *ls, TString *indexname) {
/* forlist -> NAME {,NAME} IN explist forbody */
FuncState *fs = ls->fs;
expdesc e;
- int nvars = 4; /* gen, state, control, plus at least one declared var */
+ int nvars = 5; /* gen, state, control, toclose, 'indexname' */
int line;
int base = fs->freereg;
/* create control variables */
@@ -1415,6 +1416,7 @@ static void forlist (LexState *ls, TString *indexname) {
new_localvarliteral(ls, "(for state)");
markupval(fs, fs->nactvar); /* state may create an upvalue */
new_localvarliteral(ls, "(for control)");
+ new_localvarliteral(ls, "(for toclose)");
/* create declared variables */
new_localvar(ls, indexname);
while (testnext(ls, ',')) {
@@ -1423,9 +1425,10 @@ static void forlist (LexState *ls, TString *indexname) {
}
checknext(ls, TK_IN);
line = ls->linenumber;
- adjust_assign(ls, 3, explist(ls, &e), &e);
+ adjust_assign(ls, 4, explist(ls, &e), &e);
+ adjustlocalvars(ls, 4); /* control variables */
luaK_checkstack(fs, 3); /* extra space to call generator */
- forbody(ls, base, line, nvars - 3, 2);
+ forbody(ls, base, line, nvars - 4, 2);
}
@@ -1575,9 +1578,9 @@ static void tocloselocalstat (LexState *ls) {
new_localvar(ls, str_checkname(ls));
checknext(ls, '=');
exp1(ls, 0);
- luaK_codeABC(fs, OP_TBC, fs->nactvar, 0, 0);
markupval(fs, fs->nactvar);
adjustlocalvars(ls, 1);
+ luaK_codeABC(fs, OP_TBC, fs->nactvar - 1, 0, 0);
}
diff --git a/lvm.c b/lvm.c
@@ -1654,11 +1654,11 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmbreak;
}
vmcase(OP_TFORPREP) {
- /* is 'state' a function or has a '__close' metamethod? */
- if (ttisfunction(s2v(ra + 1)) ||
- !ttisnil(luaT_gettmbyobj(L, s2v(ra + 1), TM_CLOSE))) {
+ /* is 'toclose' a function or has a '__close' metamethod? */
+ if (ttisfunction(s2v(ra + 3)) ||
+ !ttisnil(luaT_gettmbyobj(L, s2v(ra + 3), TM_CLOSE))) {
/* create to-be-closed upvalue for it */
- halfProtect(luaF_newtbcupval(L, ra + 1));
+ halfProtect(luaF_newtbcupval(L, ra + 3));
}
pc += GETARG_Bx(i);
i = *(pc++); /* go to next instruction */
@@ -1668,13 +1668,14 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmcase(OP_TFORCALL) {
l_tforcall:
/* 'ra' has the iterator function, 'ra + 1' has the state,
- and 'ra + 2' has the control variable. The call will use
- the stack after these values (starting at 'ra + 3')
+ 'ra + 2' has the control variable, and 'ra + 3' has the
+ to-be-closed variable. The call will use the stack after
+ these values (starting at 'ra + 4')
*/
/* push function, state, and control variable */
- memcpy(ra + 3, ra, 3 * sizeof(*ra));
- L->top = ra + 6;
- Protect(luaD_call(L, ra + 3, GETARG_C(i))); /* do the call */
+ memcpy(ra + 4, ra, 3 * sizeof(*ra));
+ L->top = ra + 4 + 3;
+ Protect(luaD_call(L, ra + 4, GETARG_C(i))); /* do the call */
if (trap) { /* stack may have changed? */
updatebase(ci); /* keep 'base' correct */
ra = RA(i); /* keep 'ra' correct for next instruction */
@@ -1686,8 +1687,8 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
}
vmcase(OP_TFORLOOP) {
l_tforloop:
- if (!ttisnil(s2v(ra + 1))) { /* continue loop? */
- setobjs2s(L, ra, ra + 1); /* save control variable */
+ if (!ttisnil(s2v(ra + 2))) { /* continue loop? */
+ setobjs2s(L, ra, ra + 2); /* save control variable */
pc -= GETARG_Bx(i); /* jump back */
}
vmbreak;
diff --git a/testes/files.lua b/testes/files.lua
@@ -200,7 +200,7 @@ return x + y * z
assert(f:close())
f = coroutine.wrap(dofile)
assert(f(file) == 10)
-print(f(100, 101) == 20)
+assert(f(100, 101) == 20)
assert(f(200) == 100 + 200 * 101)
assert(os.remove(file))
@@ -422,6 +422,41 @@ assert(load(io.lines(file, "L"), nil, nil, t))()
assert(t.a == -((10 + 34) * 2))
+do -- testing closing file in line iteration
+
+ -- get the to-be-closed variable from a loop
+ local function gettoclose (lv)
+ lv = lv + 1
+ for i = 1, math.maxinteger do
+ local n, v = debug.getlocal(lv, i)
+ if n == "(for toclose)" then
+ return v
+ end
+ end
+ end
+
+ local f
+ for l in io.lines(file) do
+ f = gettoclose(1)
+ assert(io.type(f) == "file")
+ break
+ end
+ assert(io.type(f) == "closed file")
+
+ f = nil
+ local function foo (name)
+ for l in io.lines(name) do
+ f = gettoclose(1)
+ assert(io.type(f) == "file")
+ error(f) -- exit loop with an error
+ end
+ end
+ local st, msg = pcall(foo, file)
+ assert(st == false and io.type(msg) == "closed file")
+
+end
+
+
-- test for multipe arguments in 'lines'
io.output(file); io.write"0123456789\n":close()
for a,b in io.lines(file, 1, 1) do
diff --git a/testes/locals.lua b/testes/locals.lua
@@ -371,6 +371,8 @@ do
x = x - 1
if x > 0 then return x end
end,
+ nil, -- state
+ nil, -- control variable
function () -- closing function
numopen = numopen - 1
end
@@ -392,12 +394,16 @@ do
-- repeat test with '__open' metamethod instead of a function
local function open (x)
numopen = numopen + 1
+ local state = setmetatable({x},
+ {__close = function () numopen = numopen - 1 end})
return
function (t) -- iteraction function
t[1] = t[1] - 1
if t[1] > 0 then return t[1] end
end,
- setmetatable({x}, {__close = function () numopen = numopen - 1 end})
+ state,
+ nil,
+ state -- to-be-closed
end
local s = 0
