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simpler implementation for `for' loops

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This commit is contained in:
Roberto Ierusalimschy
2002-02-05 20:39:12 -02:00
parent addbe8c8b0
commit 38b0e6128d
7 changed files with 57 additions and 95 deletions
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67
lvm.c
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@@ -26,6 +26,9 @@
#include "lvm.h"
/* limit for table tag-method chains (to avoid loops) */
#define MAXTAGLOOP 10000
static void luaV_checkGC (lua_State *L, StkId top) {
if (G(L)->nblocks >= G(L)->GCthreshold) {
@@ -65,6 +68,8 @@ static void traceexec (lua_State *L, lua_Hook linehook) {
int *lineinfo = ci_func(ci)->l.p->lineinfo;
int pc = cast(int, *ci->pc - ci_func(ci)->l.p->code) - 1;
int newline;
if (testOpMode(GET_OPCODE(*(*ci->pc - 1)), OpModeNoTrace))
return;
if (ci->line == -1) return; /* no linehooks for this function */
else if (ci->line == 0) { /* first linehook? */
if (pc == 0) { /* function is starting now? */
@@ -123,6 +128,7 @@ static void callTM (lua_State *L, const TObject *f,
*/
void luaV_gettable (lua_State *L, StkId t, TObject *key, StkId res) {
const TObject *tm;
int loop = 0;
init:
if (ttype(t) == LUA_TTABLE) { /* `t' is a table? */
Table *et = hvalue(t)->metatable;
@@ -145,6 +151,7 @@ void luaV_gettable (lua_State *L, StkId t, TObject *key, StkId res) {
if (ttype(tm) == LUA_TFUNCTION)
callTMres(L, tm, t, key, res);
else {
if (++loop == MAXTAGLOOP) luaD_error(L, "loop in gettable");
t = (StkId)tm; /* ?? */
goto init; /* return luaV_gettable(L, tm, key, res); */
}
@@ -156,6 +163,7 @@ void luaV_gettable (lua_State *L, StkId t, TObject *key, StkId res) {
*/
void luaV_settable (lua_State *L, StkId t, TObject *key, StkId val) {
const TObject *tm;
int loop = 0;
init:
if (ttype(t) == LUA_TTABLE) { /* `t' is a table? */
Table *et = hvalue(t)->metatable;
@@ -173,6 +181,7 @@ void luaV_settable (lua_State *L, StkId t, TObject *key, StkId val) {
if (ttype(tm) == LUA_TFUNCTION)
callTM(L, tm, t, key, val);
else {
if (++loop == MAXTAGLOOP) luaD_error(L, "loop in settable");
t = (StkId)tm; /* ?? */
goto init; /* luaV_settable(L, tm, key, val); */
}
@@ -301,8 +310,8 @@ static void powOp (lua_State *L, StkId ra, StkId rb, StkId rc) {
#define Arith(op, optm) { \
const TObject *b = RB(i); const TObject *c = RKC(i); \
TObject tempb, tempc; \
if ((ttype(b) == LUA_TNUMBER || (b = luaV_tonumber(b, &tempb)) != NULL) && \
(ttype(c) == LUA_TNUMBER || (c = luaV_tonumber(c, &tempc)) != NULL)) { \
if ((b = luaV_tonumber(b, &tempb)) != NULL && \
(c = luaV_tonumber(c, &tempc)) != NULL) { \
setnvalue(ra, nvalue(b) op nvalue(c)); \
} else \
call_arith(L, RB(i), RKC(i), ra, optm); \
@@ -423,7 +432,7 @@ StkId luaV_execute (lua_State *L) {
}
case OP_UNM: {
const TObject *rb = RB(i);
if (ttype(rb) == LUA_TNUMBER || (rb=luaV_tonumber(rb, ra)) != NULL) {
if ((rb=luaV_tonumber(rb, ra)) != NULL) {
setnvalue(ra, -nvalue(rb));
}
else {
@@ -441,7 +450,7 @@ StkId luaV_execute (lua_State *L) {
case OP_CONCAT: {
int b = GETARG_B(i);
int c = GETARG_C(i);
luaV_strconc(L, c-b+1, c); /* this call may change `base' (and `ra') */
luaV_strconc(L, c-b+1, c); /* may change `base' (and `ra') */
setobj(base+GETARG_A(i), base+b);
luaV_checkGC(L, base+c+1);
break;
@@ -532,53 +541,41 @@ StkId luaV_execute (lua_State *L) {
}
break;
}
case OP_FORPREP: {
if (luaV_tonumber(ra, ra) == NULL)
case OP_FORLOOP: {
lua_Number step, index, limit;
int j = GETARG_sBc(i);
pc += j; /* jump back before tests (for error messages) */
if (ttype(ra) != LUA_TNUMBER)
luaD_error(L, "`for' initial value must be a number");
if (luaV_tonumber(ra+1, ra+1) == NULL)
luaD_error(L, "`for' limit must be a number");
if (luaV_tonumber(ra+2, ra+2) == NULL)
luaD_error(L, "`for' step must be a number");
/* decrement index (to be incremented) */
chgnvalue(ra, nvalue(ra) - nvalue(ra+2));
pc += -GETARG_sBc(i); /* `jump' to loop end (delta is negated here) */
/* store in `ra+1' total number of repetitions */
chgnvalue(ra+1, (nvalue(ra+1)-nvalue(ra))/nvalue(ra+2));
/* go through */
}
case OP_FORLOOP: {
runtime_check(L, ttype(ra+1) == LUA_TNUMBER &&
ttype(ra+2) == LUA_TNUMBER);
if (ttype(ra) != LUA_TNUMBER)
luaD_error(L, "`for' index must be a number");
chgnvalue(ra+1, nvalue(ra+1) - 1); /* decrement counter */
if (nvalue(ra+1) >= 0) {
chgnvalue(ra, nvalue(ra) + nvalue(ra+2)); /* increment index */
dojump(pc, i); /* repeat loop */
}
step = nvalue(ra+2);
index = nvalue(ra) + step; /* increment index */
limit = nvalue(ra+1);
if (step > 0 ? index <= limit : index >= limit)
chgnvalue(ra, index); /* update index */
else
pc -= j; /* undo jump */
break;
}
case OP_TFORPREP: {
if (ttype(ra) != LUA_TTABLE)
luaD_error(L, "`for' table must be a table");
setnvalue(ra+1, -1); /* initial index */
setnilvalue(ra+2);
setnilvalue(ra+3);
pc += -GETARG_sBc(i); /* `jump' to loop end (delta is negated here) */
/* go through */
}
case OP_TFORLOOP: {
Table *t;
int n;
runtime_check(L, ttype(ra) == LUA_TTABLE &&
ttype(ra+1) == LUA_TNUMBER);
int j = GETARG_sBc(i);
pc += j; /* jump back before tests (for error messages) */
if (ttype(ra) != LUA_TTABLE)
luaD_error(L, "`for' table must be a table");
runtime_check(L, ttype(ra+1) == LUA_TNUMBER);
t = hvalue(ra);
n = cast(int, nvalue(ra+1));
n = luaH_nexti(t, n, ra+2);
if (n != -1) { /* repeat loop? */
setnvalue(ra+1, n); /* index */
dojump(pc, i); /* repeat loop */
}
else
pc -= j; /* undo jump */
break;
}
case OP_SETLIST: