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new experimental syntax using reserved word 'undef'

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Roberto Ierusalimschy
2018-03-07 12:55:38 -03:00
parent 464658b16a
commit 4a1612ff9b
11 changed files with 113 additions and 43 deletions
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63
lcode.c
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@@ -1,5 +1,5 @@
/*
** $Id: lcode.c,v 2.157 2018/02/21 15:49:32 roberto Exp roberto $
** $Id: lcode.c,v 2.158 2018/02/26 14:16:05 roberto Exp roberto $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
@@ -40,6 +40,14 @@
static int codesJ (FuncState *fs, OpCode o, int sj, int k);
/* semantic error */
l_noret luaK_semerror (LexState *ls, const char *msg) {
ls->t.token = 0; /* remove "near <token>" from final message */
luaX_syntaxerror(ls, msg);
}
/*
** If expression is a numeric constant, fills 'v' with its value
** and returns 1. Otherwise, returns 0.
@@ -670,6 +678,10 @@ void luaK_dischargevars (FuncState *fs, expdesc *e) {
e->k = VNONRELOC; /* becomes a non-relocatable value */
break;
}
case VUNDEF: { /* not a real expression */
luaK_semerror(fs->ls, "'undef' is not a value!!");
break;
}
case VUPVAL: { /* move value to some (pending) register */
e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
e->k = VRELOC;
@@ -1398,6 +1410,48 @@ static void codeeq (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) {
}
static void normalizeindexed (FuncState *fs, expdesc *v) {
if (v->k != VINDEXED) { /* not in proper form? */
int key = fs->freereg; /* register with key value */
luaK_reserveregs(fs, 1);
switch (v->k) {
case VINDEXI:
luaK_int(fs, key, v->u.ind.idx);
break;
case VINDEXSTR:
luaK_codek(fs, key, v->u.ind.idx);
break;
case VINDEXUP:
luaK_codek(fs, key, v->u.ind.idx);
luaK_codeABC(fs, OP_GETUPVAL, fs->freereg, v->u.ind.t, 0);
v->u.ind.t = fs->freereg;
luaK_reserveregs(fs, 1); /* one more register for the upvalue */
break;
default:
luaK_semerror(fs->ls, "'undef' is not a value!!");
break;
}
v->u.ind.idx = key;
v->k = VINDEXED;
}
freeregs(fs, v->u.ind.t, v->u.ind.idx);
}
static void codeisdef (FuncState *fs, int eq, expdesc *v) {
normalizeindexed(fs, v);
v->u.info = luaK_codeABCk(fs, OP_ISDEF, 0, v->u.ind.t, v->u.ind.idx, eq);
v->k = VRELOC;
}
void luaK_codeundef (FuncState *fs, expdesc *v) {
normalizeindexed(fs, v);
v->u.info = luaK_codeABC(fs, OP_UNDEF, v->u.ind.t, v->u.ind.idx, 0);
v->k = VRELOC;
}
/*
** Apply prefix operation 'op' to expression 'e'.
*/
@@ -1446,7 +1500,7 @@ void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
break;
}
case OPR_EQ: case OPR_NE: {
if (!tonumeral(v, NULL))
if (!tonumeral(v, NULL) && fs->ls->t.token != TK_UNDEF)
luaK_exp2RK(fs, v);
/* else keep numeral, which may be an immediate operand */
break;
@@ -1543,7 +1597,10 @@ void luaK_posfix (FuncState *fs, BinOpr opr,
break;
}
case OPR_EQ: case OPR_NE: {
codeeq(fs, opr, e1, e2);
if (e2->k == VUNDEF)
codeisdef(fs, opr == OPR_NE, e1);
else
codeeq(fs, opr, e1, e2);
break;
}
case OPR_LT: case OPR_LE: {