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To-be-closed variable in 'for' loop separated from the state

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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.)
This commit is contained in:
Roberto Ierusalimschy
2018-11-07 14:42:05 -02:00
parent b8fed93215
commit 7f6f70853c
6 changed files with 76 additions and 29 deletions
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25
lparser.c
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@@ -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);
}