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lparser.c
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/*
** $Id: lparser.c $
** Lua Parser
** See Copyright Notice in lua.h
*/
#define lparser_c
#define LUA_CORE
#include "lprefix.h"
#include <limits.h>
#include <string.h>
#include "lua.h"
#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "llex.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
/* maximum number of local variables per function (must be smaller
than 250, due to the bytecode format) */
#define MAXVARS 200
#define hasmultret(k) ((k) == VCALL || (k) == VVARARG)
/* because all strings are unified by the scanner, the parser
can use pointer equality for string equality */
#define eqstr(a,b) ((a) == (b))
/*
** nodes for block list (list of active blocks)
*/
typedef struct BlockCnt {
struct BlockCnt *previous; /* chain */
int firstlabel; /* index of first label in this block */
int firstgoto; /* index of first pending goto in this block */
lu_byte nactvar; /* # active locals outside the block */
lu_byte upval; /* true if some variable in the block is an upvalue */
lu_byte isloop; /* 1 if 'block' is a loop; 2 if it has pending breaks */
lu_byte insidetbc; /* true if inside the scope of a to-be-closed var. */
} BlockCnt;
/*
** prototypes for recursive non-terminal functions
*/
static void statement (LexState *ls);
static void expr (LexState *ls, expdesc *v);
static l_noret error_expected (LexState *ls, int token) {
luaX_syntaxerror(ls,
luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
}
static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
lua_State *L = fs->ls->L;
const char *msg;
int line = fs->f->linedefined;
const char *where = (line == 0)
? "main function"
: luaO_pushfstring(L, "function at line %d", line);
msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
what, limit, where);
luaX_syntaxerror(fs->ls, msg);
}
void luaY_checklimit (FuncState *fs, int v, int l, const char *what) {
if (l_unlikely(v > l)) errorlimit(fs, l, what);
}
/*
** Test whether next token is 'c'; if so, skip it.
*/
static int testnext (LexState *ls, int c) {
if (ls->t.token == c) {
luaX_next(ls);
return 1;
}
else return 0;
}
/*
** Check that next token is 'c'.
*/
static void check (LexState *ls, int c) {
if (ls->t.token != c)
error_expected(ls, c);
}
/*
** Check that next token is 'c' and skip it.
*/
static void checknext (LexState *ls, int c) {
check(ls, c);
luaX_next(ls);
}
#define check_condition(ls,c,msg) { if (!(c)) luaX_syntaxerror(ls, msg); }
/*
** Check that next token is 'what' and skip it. In case of error,
** raise an error that the expected 'what' should match a 'who'
** in line 'where' (if that is not the current line).
*/
static void check_match (LexState *ls, int what, int who, int where) {
if (l_unlikely(!testnext(ls, what))) {
if (where == ls->linenumber) /* all in the same line? */
error_expected(ls, what); /* do not need a complex message */
else {
luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
"%s expected (to close %s at line %d)",
luaX_token2str(ls, what), luaX_token2str(ls, who), where));
}
}
}
static TString *str_checkname (LexState *ls) {
TString *ts;
check(ls, TK_NAME);
ts = ls->t.seminfo.ts;
luaX_next(ls);
return ts;
}
static void init_exp (expdesc *e, expkind k, int i) {
e->f = e->t = NO_JUMP;
e->k = k;
e->u.info = i;
}
static void codestring (expdesc *e, TString *s) {
e->f = e->t = NO_JUMP;
e->k = VKSTR;
e->u.strval = s;
}
static void codename (LexState *ls, expdesc *e) {
codestring(e, str_checkname(ls));
}
/*
** Register a new local variable in the active 'Proto' (for debug
** information).
*/
static short registerlocalvar (LexState *ls, FuncState *fs,
TString *varname) {
Proto *f = fs->f;
int oldsize = f->sizelocvars;
luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars,
LocVar, SHRT_MAX, "local variables");
while (oldsize < f->sizelocvars)
f->locvars[oldsize++].varname = NULL;
f->locvars[fs->ndebugvars].varname = varname;
f->locvars[fs->ndebugvars].startpc = fs->pc;
luaC_objbarrier(ls->L, f, varname);
return fs->ndebugvars++;
}
/*
** Create a new local variable with the given 'name' and given 'kind'.
** Return its index in the function.
*/
static int new_localvarkind (LexState *ls, TString *name, lu_byte kind) {
lua_State *L = ls->L;
FuncState *fs = ls->fs;
Dyndata *dyd = ls->dyd;
Vardesc *var;
luaY_checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
MAXVARS, "local variables");
luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
dyd->actvar.size, Vardesc, SHRT_MAX, "local variables");
var = &dyd->actvar.arr[dyd->actvar.n++];
var->vd.kind = kind; /* default */
var->vd.name = name;
return dyd->actvar.n - 1 - fs->firstlocal;
}
/*
** Create a new local variable with the given 'name' and regular kind.
*/
static int new_localvar (LexState *ls, TString *name) {
return new_localvarkind(ls, name, VDKREG);
}
#define new_localvarliteral(ls,v) \
new_localvar(ls, \
luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1));
/*
** Return the "variable description" (Vardesc) of a given variable.
** (Unless noted otherwise, all variables are referred to by their
** compiler indices.)
*/
static Vardesc *getlocalvardesc (FuncState *fs, int vidx) {
return &fs->ls->dyd->actvar.arr[fs->firstlocal + vidx];
}
/*
** Convert 'nvar', a compiler index level, to its corresponding
** register. For that, search for the highest variable below that level
** that is in a register and uses its register index ('ridx') plus one.
*/
static lu_byte reglevel (FuncState *fs, int nvar) {
while (nvar-- > 0) {
Vardesc *vd = getlocalvardesc(fs, nvar); /* get previous variable */
if (vd->vd.kind != RDKCTC) /* is in a register? */
return cast_byte(vd->vd.ridx + 1);
}
return 0; /* no variables in registers */
}
/*
** Return the number of variables in the register stack for the given
** function.
*/
lu_byte luaY_nvarstack (FuncState *fs) {
return reglevel(fs, fs->nactvar);
}
/*
** Get the debug-information entry for current variable 'vidx'.
*/
static LocVar *localdebuginfo (FuncState *fs, int vidx) {
Vardesc *vd = getlocalvardesc(fs, vidx);
if (vd->vd.kind == RDKCTC)
return NULL; /* no debug info. for constants */
else {
int idx = vd->vd.pidx;
lua_assert(idx < fs->ndebugvars);
return &fs->f->locvars[idx];
}
}
/*
** Create an expression representing variable 'vidx'
*/
static void init_var (FuncState *fs, expdesc *e, int vidx) {
e->f = e->t = NO_JUMP;
e->k = VLOCAL;
e->u.var.vidx = cast(unsigned short, vidx);
e->u.var.ridx = getlocalvardesc(fs, vidx)->vd.ridx;
}
/*
** Raises an error if variable described by 'e' is read only
*/
static void check_readonly (LexState *ls, expdesc *e) {
FuncState *fs = ls->fs;
TString *varname = NULL; /* to be set if variable is const */
switch (e->k) {
case VCONST: {
varname = ls->dyd->actvar.arr[e->u.info].vd.name;
break;
}
case VLOCAL: {
Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx);
if (vardesc->vd.kind != VDKREG) /* not a regular variable? */
varname = vardesc->vd.name;
break;
}
case VUPVAL: {
Upvaldesc *up = &fs->f->upvalues[e->u.info];
if (up->kind != VDKREG)
varname = up->name;
break;
}
default:
return; /* other cases cannot be read-only */
}
if (varname) {
const char *msg = luaO_pushfstring(ls->L,
"attempt to assign to const variable '%s'", getstr(varname));
luaK_semerror(ls, msg); /* error */
}
}
/*
** Start the scope for the last 'nvars' created variables.
*/
static void adjustlocalvars (LexState *ls, int nvars) {
FuncState *fs = ls->fs;
int reglevel = luaY_nvarstack(fs);
int i;
for (i = 0; i < nvars; i++) {
int vidx = fs->nactvar++;
Vardesc *var = getlocalvardesc(fs, vidx);
var->vd.ridx = cast_byte(reglevel++);
var->vd.pidx = registerlocalvar(ls, fs, var->vd.name);
}
}
/*
** Close the scope for all variables up to level 'tolevel'.
** (debug info.)
*/
static void removevars (FuncState *fs, int tolevel) {
fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
while (fs->nactvar > tolevel) {
LocVar *var = localdebuginfo(fs, --fs->nactvar);
if (var) /* does it have debug information? */
var->endpc = fs->pc;
}
}
/*
** Search the upvalues of the function 'fs' for one
** with the given 'name'.
*/
static int searchupvalue (FuncState *fs, TString *name) {
int i;
Upvaldesc *up = fs->f->upvalues;
for (i = 0; i < fs->nups; i++) {
if (eqstr(up[i].name, name)) return i;
}
return -1; /* not found */
}
static Upvaldesc *allocupvalue (FuncState *fs) {
Proto *f = fs->f;
int oldsize = f->sizeupvalues;
luaY_checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
Upvaldesc, MAXUPVAL, "upvalues");
while (oldsize < f->sizeupvalues)
f->upvalues[oldsize++].name = NULL;
return &f->upvalues[fs->nups++];
}
static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
Upvaldesc *up = allocupvalue(fs);
FuncState *prev = fs->prev;
if (v->k == VLOCAL) {
up->instack = 1;
up->idx = v->u.var.ridx;
up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind;
lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name));
}
else {
up->instack = 0;
up->idx = cast_byte(v->u.info);
up->kind = prev->f->upvalues[v->u.info].kind;
lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name));
}
up->name = name;
luaC_objbarrier(fs->ls->L, fs->f, name);
return fs->nups - 1;
}
/*
** Look for an active local variable with the name 'n' in the
** function 'fs'. If found, initialize 'var' with it and return
** its expression kind; otherwise return -1.
*/
static int searchvar (FuncState *fs, TString *n, expdesc *var) {
int i;
for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
Vardesc *vd = getlocalvardesc(fs, i);
if (eqstr(n, vd->vd.name)) { /* found? */
if (vd->vd.kind == RDKCTC) /* compile-time constant? */
init_exp(var, VCONST, fs->firstlocal + i);
else /* real variable */
init_var(fs, var, i);
return cast_int(var->k);
}
}
return -1; /* not found */
}
/*
** Mark block where variable at given level was defined
** (to emit close instructions later).
*/
static void markupval (FuncState *fs, int level) {
BlockCnt *bl = fs->bl;
while (bl->nactvar > level)
bl = bl->previous;
bl->upval = 1;
fs->needclose = 1;
}
/*
** Mark that current block has a to-be-closed variable.
*/
static void marktobeclosed (FuncState *fs) {
BlockCnt *bl = fs->bl;
bl->upval = 1;
bl->insidetbc = 1;
fs->needclose = 1;
}
/*
** Find a variable with the given name 'n'. If it is an upvalue, add
** this upvalue into all intermediate functions. If it is a global, set
** 'var' as 'void' as a flag.
*/
static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
if (fs == NULL) /* no more levels? */
init_exp(var, VVOID, 0); /* default is global */
else {
int v = searchvar(fs, n, var); /* look up locals at current level */
if (v >= 0) { /* found? */
if (v == VLOCAL && !base)
markupval(fs, var->u.var.vidx); /* local will be used as an upval */
}
else { /* not found as local at current level; try upvalues */
int idx = searchupvalue(fs, n); /* try existing upvalues */
if (idx < 0) { /* not found? */
singlevaraux(fs->prev, n, var, 0); /* try upper levels */
if (var->k == VLOCAL || var->k == VUPVAL) /* local or upvalue? */
idx = newupvalue(fs, n, var); /* will be a new upvalue */
else /* it is a global or a constant */
return; /* don't need to do anything at this level */
}
init_exp(var, VUPVAL, idx); /* new or old upvalue */
}
}
}
/*
** Find a variable with the given name 'n', handling global variables
** too.
*/
static void singlevar (LexState *ls, expdesc *var) {
TString *varname = str_checkname(ls);
FuncState *fs = ls->fs;
singlevaraux(fs, varname, var, 1);
if (var->k == VVOID) { /* global name? */
expdesc key;
singlevaraux(fs, ls->envn, var, 1); /* get environment variable */
lua_assert(var->k != VVOID); /* this one must exist */
luaK_exp2anyregup(fs, var); /* but could be a constant */
codestring(&key, varname); /* key is variable name */
luaK_indexed(fs, var, &key); /* env[varname] */
}
}
/*
** Adjust the number of results from an expression list 'e' with 'nexps'
** expressions to 'nvars' values.
*/
static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
FuncState *fs = ls->fs;
int needed = nvars - nexps; /* extra values needed */
if (hasmultret(e->k)) { /* last expression has multiple returns? */
int extra = needed + 1; /* discount last expression itself */
if (extra < 0)
extra = 0;
luaK_setreturns(fs, e, extra); /* last exp. provides the difference */
}
else {
if (e->k != VVOID) /* at least one expression? */
luaK_exp2nextreg(fs, e); /* close last expression */
if (needed > 0) /* missing values? */
luaK_nil(fs, fs->freereg, needed); /* complete with nils */
}
if (needed > 0)
luaK_reserveregs(fs, needed); /* registers for extra values */
else /* adding 'needed' is actually a subtraction */
fs->freereg = cast_byte(fs->freereg + needed); /* remove extra values */
}
#define enterlevel(ls) luaE_incCstack(ls->L)
#define leavelevel(ls) ((ls)->L->nCcalls--)
/*
** Generates an error that a goto jumps into the scope of some
** local variable.
*/
static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) {
TString *tsname = getlocalvardesc(ls->fs, gt->nactvar)->vd.name;
const char *varname = getstr(tsname);
const char *msg = "<goto %s> at line %d jumps into the scope of local '%s'";
msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname);
luaK_semerror(ls, msg); /* raise the error */
}
/*
** Closes the goto at index 'g' to given 'label' and removes it
** from the list of pending gotos.
** If it jumps into the scope of some variable, raises an error.
** The goto needs a CLOSE if it jumps out of a block with upvalues,
** or out of the scope of some variable and the block has upvalues
** (signaled by parameter 'bup').
*/
static void closegoto (LexState *ls, int g, Labeldesc *label, int bup) {
int i;
FuncState *fs = ls->fs;
Labellist *gl = &ls->dyd->gt; /* list of gotos */
Labeldesc *gt = &gl->arr[g]; /* goto to be resolved */
lua_assert(eqstr(gt->name, label->name));
if (l_unlikely(gt->nactvar < label->nactvar)) /* enter some scope? */
jumpscopeerror(ls, gt);
if (gt->close ||
(label->nactvar < gt->nactvar && bup)) { /* needs close? */
lu_byte stklevel = reglevel(fs, label->nactvar);
/* move jump to CLOSE position */
fs->f->code[gt->pc + 1] = fs->f->code[gt->pc];
/* put CLOSE instruction at original position */
fs->f->code[gt->pc] = CREATE_ABCk(OP_CLOSE, stklevel, 0, 0, 0);
gt->pc++; /* must point to jump instruction */
}
luaK_patchlist(ls->fs, gt->pc, label->pc); /* goto jumps to label */
for (i = g; i < gl->n - 1; i++) /* remove goto from pending list */
gl->arr[i] = gl->arr[i + 1];
gl->n--;
}
/*
** Search for an active label with the given name, starting at
** index 'ilb' (so that it can searh for all labels in current block
** or all labels in current function).
*/
static Labeldesc *findlabel (LexState *ls, TString *name, int ilb) {
Dyndata *dyd = ls->dyd;
for (; ilb < dyd->label.n; ilb++) {
Labeldesc *lb = &dyd->label.arr[ilb];
if (eqstr(lb->name, name)) /* correct label? */
return lb;
}
return NULL; /* label not found */
}
/*
** Adds a new label/goto in the corresponding list.
*/
static int newlabelentry (LexState *ls, Labellist *l, TString *name,
int line, int pc) {
int n = l->n;
luaM_growvector(ls->L, l->arr, n, l->size,
Labeldesc, SHRT_MAX, "labels/gotos");
l->arr[n].name = name;
l->arr[n].line = line;
l->arr[n].nactvar = ls->fs->nactvar;
l->arr[n].close = 0;
l->arr[n].pc = pc;
l->n = n + 1;
return n;
}
/*
** Create an entry for the goto and the code for it. As it is not known
** at this point whether the goto may need a CLOSE, the code has a jump
** followed by an CLOSE. (As the CLOSE comes after the jump, it is a
** dead instruction; it works as a placeholder.) When the goto is closed
** against a label, if it needs a CLOSE, the two instructions swap
** positions, so that the CLOSE comes before the jump.
*/
static int newgotoentry (LexState *ls, TString *name, int line) {
FuncState *fs = ls->fs;
int pc = luaK_jump(fs); /* create jump */
luaK_codeABC(fs, OP_CLOSE, 0, 1, 0); /* spaceholder, marked as dead */
return newlabelentry(ls, &ls->dyd->gt, name, line, pc);
}
/*
** Create a new label with the given 'name' at the given 'line'.
** 'last' tells whether label is the last non-op statement in its
** block. Solves all pending gotos to this new label and adds
** a close instruction if necessary.
** Returns true iff it added a close instruction.
*/
static void createlabel (LexState *ls, TString *name, int line, int last) {
FuncState *fs = ls->fs;
Labellist *ll = &ls->dyd->label;
int l = newlabelentry(ls, ll, name, line, luaK_getlabel(fs));
if (last) { /* label is last no-op statement in the block? */
/* assume that locals are already out of scope */
ll->arr[l].nactvar = fs->bl->nactvar;
}
}
/*
** Traverse the pending goto's of the finishing block checking whether
** each match some label of that block. Those that do not match are
** "exported" to the outer block, to be solved there. In particular,
** its 'nactvar' is updated with the level of the inner block,
** as the variables of the inner block are now out of scope.
*/
static void solvegotos (FuncState *fs, BlockCnt *bl) {
LexState *ls = fs->ls;
Labellist *gl = &ls->dyd->gt;
int outlevel = reglevel(fs, bl->nactvar); /* level outside the block */
int igt = bl->firstgoto; /* first goto in the finishing block */
while (igt < gl->n) { /* for each pending goto */
Labeldesc *gt = &gl->arr[igt];
/* search for a matching label in the current block */
Labeldesc *lb = findlabel(ls, gt->name, bl->firstlabel);
if (lb != NULL) /* found a match? */
closegoto(ls, igt, lb, bl->upval); /* close and remove goto */
else { /* adjust 'goto' for outer block */
/* block has variables to be closed and goto escapes the scope of
some variable? */
if (bl->upval && reglevel(fs, gt->nactvar) > outlevel)
gt->close = 1; /* jump may need a close */
gt->nactvar = bl->nactvar; /* correct level for outer block */
igt++; /* go to next goto */
}
}
ls->dyd->label.n = bl->firstlabel; /* remove local labels */
}
static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
bl->isloop = isloop;
bl->nactvar = fs->nactvar;
bl->firstlabel = fs->ls->dyd->label.n;
bl->firstgoto = fs->ls->dyd->gt.n;
bl->upval = 0;
bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc);
bl->previous = fs->bl;
fs->bl = bl;
lua_assert(fs->freereg == luaY_nvarstack(fs));
}
/*
** generates an error for an undefined 'goto'.
*/
static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
const char *msg = "no visible label '%s' for <goto> at line %d";
msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
/* breaks are checked when created, cannot be undefined */
lua_assert(!eqstr(gt->name, luaS_newliteral(ls->L, "break")));
luaK_semerror(ls, msg);
}
static void leaveblock (FuncState *fs) {
BlockCnt *bl = fs->bl;
LexState *ls = fs->ls;
lu_byte stklevel = reglevel(fs, bl->nactvar); /* level outside block */
if (bl->previous && bl->upval) /* need a 'close'? */
luaK_codeABC(fs, OP_CLOSE, stklevel, 0, 0);
fs->freereg = stklevel; /* free registers */
removevars(fs, bl->nactvar); /* remove block locals */
lua_assert(bl->nactvar == fs->nactvar); /* back to level on entry */
if (bl->isloop == 2) /* has to fix pending breaks? */
createlabel(ls, luaS_newliteral(ls->L, "break"), 0, 0);
solvegotos(fs, bl);
if (bl->previous == NULL) { /* was it the last block? */
if (bl->firstgoto < ls->dyd->gt.n) /* still pending gotos? */
undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]); /* error */
}
fs->bl = bl->previous; /* current block now is previous one */
}
/*
** adds a new prototype into list of prototypes
*/
static Proto *addprototype (LexState *ls) {
Proto *clp;
lua_State *L = ls->L;
FuncState *fs = ls->fs;
Proto *f = fs->f; /* prototype of current function */
if (fs->np >= f->sizep) {
int oldsize = f->sizep;
luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
while (oldsize < f->sizep)
f->p[oldsize++] = NULL;
}
f->p[fs->np++] = clp = luaF_newproto(L);
luaC_objbarrier(L, f, clp);
return clp;
}
/*
** codes instruction to create new closure in parent function.
** The OP_CLOSURE instruction uses the last available register,
** so that, if it invokes the GC, the GC knows which registers
** are in use at that time.
*/
static void codeclosure (LexState *ls, expdesc *v) {
FuncState *fs = ls->fs->prev;
init_exp(v, VRELOC, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
luaK_exp2nextreg(fs, v); /* fix it at the last register */
}
static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
lua_State *L = ls->L;
Proto *f = fs->f;
fs->prev = ls->fs; /* linked list of funcstates */
fs->ls = ls;
ls->fs = fs;
fs->pc = 0;
fs->previousline = f->linedefined;
fs->iwthabs = 0;
fs->lasttarget = 0;
fs->freereg = 0;
fs->nk = 0;
fs->nabslineinfo = 0;
fs->np = 0;
fs->nups = 0;
fs->ndebugvars = 0;
fs->nactvar = 0;
fs->needclose = 0;
fs->firstlocal = ls->dyd->actvar.n;
fs->firstlabel = ls->dyd->label.n;
fs->bl = NULL;
f->source = ls->source;
luaC_objbarrier(L, f, f->source);
f->maxstacksize = 2; /* registers 0/1 are always valid */
fs->kcache = luaH_new(L); /* create table for function */
sethvalue2s(L, L->top.p, fs->kcache); /* anchor it */
luaD_inctop(L);
enterblock(fs, bl, 0);
}
static void close_func (LexState *ls) {
lua_State *L = ls->L;
FuncState *fs = ls->fs;
Proto *f = fs->f;
luaK_ret(fs, luaY_nvarstack(fs), 0); /* final return */
leaveblock(fs);
lua_assert(fs->bl == NULL);
luaK_finish(fs);
luaM_shrinkvector(L, f->code, f->sizecode, fs->pc, Instruction);
luaM_shrinkvector(L, f->lineinfo, f->sizelineinfo, fs->pc, ls_byte);
luaM_shrinkvector(L, f->abslineinfo, f->sizeabslineinfo,
fs->nabslineinfo, AbsLineInfo);
luaM_shrinkvector(L, f->k, f->sizek, fs->nk, TValue);
luaM_shrinkvector(L, f->p, f->sizep, fs->np, Proto *);
luaM_shrinkvector(L, f->locvars, f->sizelocvars, fs->ndebugvars, LocVar);
luaM_shrinkvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
ls->fs = fs->prev;
L->top.p--; /* pop kcache table */
luaC_checkGC(L);
}
/*
** {======================================================================
** GRAMMAR RULES
** =======================================================================
*/
/*
** check whether current token is in the follow set of a block.
** 'until' closes syntactical blocks, but do not close scope,
** so it is handled in separate.
*/
static int block_follow (LexState *ls, int withuntil) {
switch (ls->t.token) {
case TK_ELSE: case TK_ELSEIF:
case TK_END: case TK_EOS:
return 1;
case TK_UNTIL: return withuntil;
default: return 0;
}
}
static void statlist (LexState *ls) {
/* statlist -> { stat [';'] } */
while (!block_follow(ls, 1)) {
if (ls->t.token == TK_RETURN) {
statement(ls);
return; /* 'return' must be last statement */
}
statement(ls);
}
}
static void fieldsel (LexState *ls, expdesc *v) {
/* fieldsel -> ['.' | ':'] NAME */
FuncState *fs = ls->fs;
expdesc key;
luaK_exp2anyregup(fs, v);
luaX_next(ls); /* skip the dot or colon */
codename(ls, &key);
luaK_indexed(fs, v, &key);
}
static void yindex (LexState *ls, expdesc *v) {
/* index -> '[' expr ']' */
luaX_next(ls); /* skip the '[' */
expr(ls, v);
luaK_exp2val(ls->fs, v);
checknext(ls, ']');
}
/*
** {======================================================================
** Rules for Constructors
** =======================================================================
*/
typedef struct ConsControl {
expdesc v; /* last list item read */
expdesc *t; /* table descriptor */
int nh; /* total number of 'record' elements */
int na; /* number of array elements already stored */
int tostore; /* number of array elements pending to be stored */
int maxtostore; /* maximum number of pending elements */
} ConsControl;
static void recfield (LexState *ls, ConsControl *cc) {
/* recfield -> (NAME | '['exp']') = exp */
FuncState *fs = ls->fs;
lu_byte reg = ls->fs->freereg;
expdesc tab, key, val;
if (ls->t.token == TK_NAME) {
luaY_checklimit(fs, cc->nh, INT_MAX / 2, "items in a constructor");
codename(ls, &key);
}
else /* ls->t.token == '[' */
yindex(ls, &key);
cc->nh++;
checknext(ls, '=');
tab = *cc->t;
luaK_indexed(fs, &tab, &key);
expr(ls, &val);
luaK_storevar(fs, &tab, &val);
fs->freereg = reg; /* free registers */
}
static void closelistfield (FuncState *fs, ConsControl *cc) {
if (cc->v.k == VVOID) return; /* there is no list item */
luaK_exp2nextreg(fs, &cc->v);
cc->v.k = VVOID;
if (cc->tostore >= cc->maxtostore) {
luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore); /* flush */
cc->na += cc->tostore;
cc->tostore = 0; /* no more items pending */
}
}
static void lastlistfield (FuncState *fs, ConsControl *cc) {
if (cc->tostore == 0) return;
if (hasmultret(cc->v.k)) {
luaK_setmultret(fs, &cc->v);
luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
cc->na--; /* do not count last expression (unknown number of elements) */
}
else {
if (cc->v.k != VVOID)
luaK_exp2nextreg(fs, &cc->v);
luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
}
cc->na += cc->tostore;
}
static void listfield (LexState *ls, ConsControl *cc) {
/* listfield -> exp */
expr(ls, &cc->v);
cc->tostore++;
}
static void field (LexState *ls, ConsControl *cc) {
/* field -> listfield | recfield */
switch(ls->t.token) {
case TK_NAME: { /* may be 'listfield' or 'recfield' */
if (luaX_lookahead(ls) != '=') /* expression? */
listfield(ls, cc);
else
recfield(ls, cc);
break;
}
case '[': {
recfield(ls, cc);
break;
}
default: {
listfield(ls, cc);
break;
}
}
}
/*
** Compute a limit for how many registers a constructor can use before
** emitting a 'SETLIST' instruction, based on how many registers are
** available.
*/
static int maxtostore (FuncState *fs) {
int numfreeregs = MAX_FSTACK - fs->freereg;
if (numfreeregs >= 160) /* "lots" of registers? */
return numfreeregs / 5; /* use up to 1/5 of them */
else if (numfreeregs >= 80) /* still "enough" registers? */
return 10; /* one 'SETLIST' instruction for each 10 values */
else /* save registers for potential more nesting */
return 1;
}
static void constructor (LexState *ls, expdesc *t) {
/* constructor -> '{' [ field { sep field } [sep] ] '}'
sep -> ',' | ';' */
FuncState *fs = ls->fs;
int line = ls->linenumber;
int pc = luaK_codevABCk(fs, OP_NEWTABLE, 0, 0, 0, 0);
ConsControl cc;
luaK_code(fs, 0); /* space for extra arg. */
cc.na = cc.nh = cc.tostore = 0;
cc.t = t;
init_exp(t, VNONRELOC, fs->freereg); /* table will be at stack top */
luaK_reserveregs(fs, 1);
init_exp(&cc.v, VVOID, 0); /* no value (yet) */
checknext(ls, '{' /*}*/);
cc.maxtostore = maxtostore(fs);
do {
lua_assert(cc.v.k == VVOID || cc.tostore > 0);
if (ls->t.token == /*{*/ '}') break;
closelistfield(fs, &cc);
field(ls, &cc);
} while (testnext(ls, ',') || testnext(ls, ';'));
check_match(ls, /*{*/ '}', '{' /*}*/, line);
lastlistfield(fs, &cc);
luaK_settablesize(fs, pc, t->u.info, cc.na, cc.nh);
}
/* }====================================================================== */
static void setvararg (FuncState *fs, int nparams) {
fs->f->flag |= PF_ISVARARG;
luaK_codeABC(fs, OP_VARARGPREP, nparams, 0, 0);
}
static void parlist (LexState *ls) {
/* parlist -> [ {NAME ','} (NAME | '...') ] */
FuncState *fs = ls->fs;
Proto *f = fs->f;
int nparams = 0;
int isvararg = 0;