commit 58fbdc76d558c8039a966852ca07802f0a413b11
parent a3013046121b186bf4b5e54b247d3209fd76de5a
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 25 May 2000 15:59:37 -0300
better implementation for looh-ahead
Diffstat:
3 files changed, 15 insertions(+), 20 deletions(-)
diff --git a/llex.c b/llex.c
@@ -1,5 +1,5 @@
/*
-** $Id: llex.c,v 1.59 2000/05/24 13:54:49 roberto Exp roberto $
+** $Id: llex.c,v 1.60 2000/05/24 18:04:17 roberto Exp roberto $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/
@@ -108,7 +108,7 @@ static void firstline (LexState *LS)
void luaX_setinput (lua_State *L, LexState *LS, ZIO *z) {
LS->L = L;
LS->current = '\n';
- LS->next.token = TK_EOS; /* no next token */
+ LS->lookahead.token = TK_EOS; /* no look-ahead token */
LS->linenumber = 0;
LS->iflevel = 0;
LS->ifstate[0].skip = 0;
diff --git a/llex.h b/llex.h
@@ -1,5 +1,5 @@
/*
-** $Id: llex.h,v 1.25 2000/05/24 13:54:49 roberto Exp roberto $
+** $Id: llex.h,v 1.26 2000/05/24 18:04:17 roberto Exp roberto $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/
@@ -53,9 +53,9 @@ typedef struct Token {
} Token;
typedef struct LexState {
- int current; /* look ahead character */
- Token t; /* look ahead token */
- Token next; /* to `unget' a token */
+ int current; /* current character */
+ Token t; /* current token */
+ Token lookahead; /* look ahead token */
struct FuncState *fs; /* `FuncState' is private to the parser */
struct lua_State *L;
struct zio *z; /* input stream */
diff --git a/lparser.c b/lparser.c
@@ -1,5 +1,5 @@
/*
-** $Id: lparser.c,v 1.90 2000/05/24 18:04:17 roberto Exp roberto $
+** $Id: lparser.c,v 1.91 2000/05/25 18:26:42 roberto Exp roberto $
** LL(1) Parser and code generator for Lua
** See Copyright Notice in lua.h
*/
@@ -56,18 +56,18 @@ static void exp1 (LexState *ls);
static void next (LexState *ls) {
- if (ls->next.token != TK_EOS) { /* is there an `unget' token? */
- ls->t = ls->next; /* use this one */
- ls->next.token = TK_EOS; /* and discharge it */
+ if (ls->lookahead.token != TK_EOS) { /* is there a look-ahead token? */
+ ls->t = ls->lookahead; /* use this one */
+ ls->lookahead.token = TK_EOS; /* and discharge it */
}
else
ls->t.token = luaX_lex(ls); /* read next token */
}
-static void ungettoken (LexState *ls, Token *t) {
- ls->next = ls->t;
- ls->t = *t;
+static void lookahead (LexState *ls) {
+ LUA_ASSERT(ls->L, ls->lookahead.token == TK_EOS, "two look-aheads");
+ ls->lookahead.token = luaX_lex(ls);
}
@@ -633,13 +633,8 @@ static void constructor_part (LexState *ls, Constdesc *cd) {
break;
}
case TK_NAME: { /* may be listfields or recfields */
- Token current;
- int nexttoken; /* to get the look ahead */
- current = ls->t; /* save for `unget' */
- next(ls);
- nexttoken = ls->t.token;
- ungettoken(ls, ¤t);
- if (nexttoken != '=') /* expression? */
+ lookahead(ls);
+ if (ls->lookahead.token != '=') /* expression? */
goto case_default;
/* else go through to recfields */
}