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implementation of BREAK

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This commit is contained in:
Roberto Ierusalimschy
2000-04-05 14:51:58 -03:00
parent 9f734094f9
commit 22329e4cdf
6 changed files with 168 additions and 117 deletions
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169
lparser.c
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@@ -1,5 +1,5 @@
/*
** $Id: lparser.c,v 1.74 2000/03/29 20:19:20 roberto Exp roberto $
** $Id: lparser.c,v 1.75 2000/04/03 13:44:55 roberto Exp roberto $
** LL(1) Parser and code generator for Lua
** See Copyright Notice in lua.h
*/
@@ -28,10 +28,17 @@
** it is a list constructor (k = 0) or a record constructor (k = 1)
** or empty (k = ';' or '}')
*/
typedef struct constdesc {
typedef struct Constdesc {
int n;
int k;
} constdesc;
} Constdesc;
typedef struct Breaklabel {
struct Breaklabel *previous; /* chain */
int breaklist;
int stacklevel;
} Breaklabel;
@@ -311,6 +318,21 @@ static int getvarname (LexState *ls, expdesc *var) {
}
static void enterbreak (FuncState *fs, Breaklabel *bl) {
bl->stacklevel = fs->stacklevel;
bl->breaklist = NO_JUMP;
bl->previous = fs->bl;
fs->bl = bl;
}
static void leavebreak (FuncState *fs, Breaklabel *bl) {
fs->bl = bl->previous;
LUA_ASSERT(fs->L, bl->stacklevel == fs->stacklevel, "wrong levels");
luaK_patchlist(fs, bl->breaklist, luaK_getlabel(fs));
}
static void func_onstack (LexState *ls, FuncState *func) {
FuncState *fs = ls->fs;
Proto *f = fs->f;
@@ -332,10 +354,11 @@ static void init_state (LexState *ls, FuncState *fs, TString *source) {
fs->ls = ls;
fs->L = ls->L;
ls->fs = fs;
fs->stacksize = 0;
fs->stacklevel = 0;
fs->nlocalvar = 0;
fs->nupvalues = 0;
fs->lastsetline = 0;
fs->bl = NULL;
fs->f = f;
f->source = source;
fs->pc = 0;
@@ -362,6 +385,7 @@ static void close_func (LexState *ls) {
luaM_reallocvector(L, f->locvars, fs->nvars, LocVar);
}
ls->fs = fs->prev;
LUA_ASSERT(L, fs->bl == NULL, "wrong list end");
}
@@ -375,6 +399,7 @@ Proto *luaY_parser (lua_State *L, ZIO *z) {
if (lexstate.token != TK_EOS)
luaK_error(&lexstate, "<eof> expected");
close_func(&lexstate);
LUA_ASSERT(L, funcstate.prev == NULL, "wrong list end");
return funcstate.f;
}
@@ -416,7 +441,7 @@ static int explist (LexState *ls) {
static void funcargs (LexState *ls, int slf) {
FuncState *fs = ls->fs;
int slevel = fs->stacksize - slf - 1; /* where is func in the stack */
int slevel = fs->stacklevel - slf - 1; /* where is func in the stack */
switch (ls->token) {
case '(': { /* funcargs -> '(' explist ')' */
int line = ls->linenumber;
@@ -444,7 +469,7 @@ static void funcargs (LexState *ls, int slf) {
luaK_error(ls, "function arguments expected");
break;
}
fs->stacksize = slevel; /* call will remove function and arguments */
fs->stacklevel = slevel; /* call will remove function and arguments */
luaK_AB(fs, OP_CALL, slevel, MULT_RET, 0);
}
@@ -581,7 +606,7 @@ static int listfields (LexState *ls) {
static void constructor_part (LexState *ls, constdesc *cd) {
static void constructor_part (LexState *ls, Constdesc *cd) {
switch (ls->token) {
case ';': case '}': /* constructor_part -> empty */
cd->n = 0;
@@ -627,12 +652,12 @@ static void constructor (LexState *ls) {
int line = ls->linenumber;
int pc = luaK_U(fs, OP_CREATETABLE, 0, 1);
int nelems;
constdesc cd;
Constdesc cd;
check(ls, '{');
constructor_part(ls, &cd);
nelems = cd.n;
if (ls->token == ';') {
constdesc other_cd;
Constdesc other_cd;
next(ls);
constructor_part(ls, &other_cd);
if (cd.k == other_cd.k) /* repeated parts? */
@@ -825,14 +850,17 @@ static void whilestat (LexState *ls, int line) {
FuncState *fs = ls->fs;
int while_init = luaK_getlabel(fs);
expdesc v;
Breaklabel bl;
enterbreak(fs, &bl);
setline_and_next(ls); /* trace WHILE when looping */
expr(ls, &v); /* read condition */
luaK_goiftrue(fs, &v, 0);
check(ls, TK_DO);
block(ls);
luaK_fixjump(fs, luaK_S(fs, OP_JMP, 0, 0), while_init);
luaK_patchlist(fs, luaK_jump(fs), while_init);
luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
check_END(ls, TK_WHILE, line);
leavebreak(fs, &bl);
}
@@ -841,12 +869,55 @@ static void repeatstat (LexState *ls, int line) {
FuncState *fs = ls->fs;
int repeat_init = luaK_getlabel(fs);
expdesc v;
Breaklabel bl;
enterbreak(fs, &bl);
setline_and_next(ls); /* trace REPEAT when looping */
block(ls);
check_match(ls, TK_UNTIL, TK_REPEAT, line);
expr(ls, &v);
luaK_goiftrue(fs, &v, 0);
luaK_patchlist(fs, v.u.l.f, repeat_init);
if (ls->token == TK_END) {
luaK_patchlist(fs, luaK_jump(fs), repeat_init);
next(ls);
}
else {
check_match(ls, TK_UNTIL, TK_REPEAT, line);
expr(ls, &v);
luaK_goiftrue(fs, &v, 0);
luaK_patchlist(fs, v.u.l.f, repeat_init);
}
leavebreak(fs, &bl);
}
static void test_and_bock (LexState *ls, expdesc *v) {
setline_and_next(ls); /* skip IF or ELSEIF */
expr(ls, v); /* cond */
luaK_goiftrue(ls->fs, v, 0);
setline(ls); /* to trace the THEN */
check(ls, TK_THEN);
block(ls); /* `then' part */
}
static void ifstat (LexState *ls, int line) {
/* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
FuncState *fs = ls->fs;
expdesc v;
int escapelist = NO_JUMP;
test_and_bock(ls, &v); /* IF cond THEN block */
while (ls->token == TK_ELSEIF) {
luaK_concat(fs, &escapelist, luaK_jump(fs));
luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
test_and_bock(ls, &v); /* ELSEIF cond THEN block */
}
if (ls->token == TK_ELSE) {
luaK_concat(fs, &escapelist, luaK_jump(fs));
luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
setline_and_next(ls); /* skip ELSE */
block(ls); /* `else' part */
}
else
luaK_concat(fs, &escapelist, v.u.l.f);
luaK_patchlist(fs, escapelist, luaK_getlabel(fs));
check_END(ls, TK_IF, line);
}
@@ -932,42 +1003,11 @@ static void namestat (LexState *ls) {
}
static void ifpart (LexState *ls) {
/* ifpart -> cond THEN block (ELSEIF ifpart | [ELSE block] END) */
FuncState *fs = ls->fs;
expdesc v;
int elseinit;
setline_and_next(ls); /* skip IF or ELSEIF */
expr(ls, &v); /* cond */
luaK_goiftrue(fs, &v, 0);
setline(ls); /* to trace the THEN */
check(ls, TK_THEN);
block(ls); /* `then' part */
luaK_S(fs, OP_JMP, 0, 0); /* 2nd jump: over `else' part */
elseinit = luaK_getlabel(fs); /* address of 2nd jump == elseinit-1 */
if (ls->token == TK_ELSEIF)
ifpart(ls);
else if (ls->token == TK_ELSE) {
setline_and_next(ls); /* skip ELSE */
block(ls); /* `else' part */
}
if (fs->pc > elseinit) { /* is there an `else' part? */
luaK_fixjump(fs, elseinit-1, luaK_getlabel(fs)); /* fix 2nd jump */
}
else { /* no else part */
fs->pc--; /* remove 2nd jump */
elseinit = luaK_getlabel(fs); /* `elseinit' points to end */
}
luaK_patchlist(fs, v.u.l.f, elseinit); /* fix 1st jump to `else' part */
}
static int stat (LexState *ls) {
int line = ls->linenumber; /* may be needed for error messages */
switch (ls->token) {
case TK_IF: /* stat -> IF ifpart END */
ifpart(ls);
check_END(ls, TK_IF, line);
case TK_IF: /* stat -> ifstat */
ifstat(ls, line);
break;
case TK_WHILE: /* stat -> whilestat */
@@ -1058,15 +1098,30 @@ static void body (LexState *ls, int needself, int line) {
static void ret (LexState *ls) {
/* ret -> [RETURN explist sc] */
if (ls->token == TK_RETURN) {
FuncState *fs = ls->fs;
int nexps; /* number of expressions returned */
setline_and_next(ls); /* skip RETURN */
nexps = explist(ls);
luaK_retcode(fs, ls->fs->nlocalvar, nexps);
fs->stacksize = fs->nlocalvar; /* removes all temp values */
optional(ls, ';');
/* ret -> [RETURN explist sc | BREAK sc] */
FuncState *fs = ls->fs;
switch (ls->token) {
case TK_RETURN: {
int nexps; /* number of expressions returned */
setline_and_next(ls); /* skip RETURN */
nexps = explist(ls);
luaK_retcode(fs, ls->fs->nlocalvar, nexps);
fs->stacklevel = fs->nlocalvar; /* removes all temp values */
optional(ls, ';');
break;
}
case TK_BREAK: {
Breaklabel *bl = fs->bl;
int currentlevel = fs->stacklevel;
if (bl == NULL)
luaK_error(ls, "no breakable structure to break");
setline_and_next(ls); /* skip BREAK */
luaK_adjuststack(fs, currentlevel - bl->stacklevel);
luaK_concat(fs, &bl->breaklist, luaK_jump(fs));
optional(ls, ';');
fs->stacklevel = currentlevel;
break;
}
}
}
@@ -1076,7 +1131,7 @@ static void ret (LexState *ls) {
static void chunk (LexState *ls) {
/* chunk -> { stat [;] } ret */
while (stat(ls)) {
LUA_ASSERT(ls->L, ls->fs->stacksize == ls->fs->nlocalvar,
LUA_ASSERT(ls->L, ls->fs->stacklevel == ls->fs->nlocalvar,
"stack size != # local vars");
optional(ls, ';');
}