From 783aa8a9da5f32eb14b39d9332b41fa01ef81d52 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 31 Mar 2016 16:07:42 -0300
Subject: new way to avoid infinite loops in empty matches: "Python rule"
("Empty matches for the pattern are replaced only when not adjacent to a
previous match")
---
lstrlib.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/lstrlib.c b/lstrlib.c
index ec757284..7f9cd00c 100644
--- a/lstrlib.c
+++ b/lstrlib.c
@@ -1,5 +1,5 @@
/*
-** $Id: lstrlib.c,v 1.241 2016/03/23 17:12:17 roberto Exp roberto $
+** $Id: lstrlib.c,v 1.242 2016/03/23 18:08:26 roberto Exp roberto $
** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h
*/
@@ -681,6 +681,7 @@ static int str_match (lua_State *L) {
typedef struct GMatchState {
const char *src; /* current position */
const char *p; /* pattern */
+ const char *lastmatch; /* end of last match */
MatchState ms; /* match state */
} GMatchState;
@@ -692,9 +693,8 @@ static int gmatch_aux (lua_State *L) {
for (src = gm->src; src <= gm->ms.src_end; src++) {
const char *e;
reprepstate(&gm->ms);
- if ((e = match(&gm->ms, src, gm->p)) != NULL) {
- /* in empty matches, advance at least one position */
- gm->src = (e == src) ? src + 1 : e;
+ if ((e = match(&gm->ms, src, gm->p)) != NULL && e != gm->lastmatch) {
+ gm->src = gm->lastmatch = e;
return push_captures(&gm->ms, src, e);
}
}
@@ -710,7 +710,7 @@ static int gmatch (lua_State *L) {
lua_settop(L, 2); /* keep them on closure to avoid being collected */
gm = (GMatchState *)lua_newuserdata(L, sizeof(GMatchState));
prepstate(&gm->ms, L, s, ls, p, lp);
- gm->src = s; gm->p = p;
+ gm->src = s; gm->p = p; gm->lastmatch = NULL;
lua_pushcclosure(L, gmatch_aux, 3);
return 1;
}
@@ -779,6 +779,7 @@ static int str_gsub (lua_State *L) {
size_t srcl, lp;
const char *src = luaL_checklstring(L, 1, &srcl); /* subject */
const char *p = luaL_checklstring(L, 2, &lp); /* pattern */
+ const char *lastmatch = NULL; /* end of last match */
int tr = lua_type(L, 3); /* replacement type */
lua_Integer max_s = luaL_optinteger(L, 4, srcl + 1); /* max replacements */
int anchor = (*p == '^');
@@ -796,12 +797,11 @@ static int str_gsub (lua_State *L) {
while (n < max_s) {
const char *e;
reprepstate(&ms); /* (re)prepare state for new match */
- if ((e = match(&ms, src, p)) != NULL) { /* match? */
+ if ((e = match(&ms, src, p)) != NULL && e != lastmatch) { /* match? */
n++;
add_value(&ms, &b, src, e, tr); /* add replacement to buffer */
+ src = lastmatch = e;
}
- if (e && e>src) /* non empty match? */
- src = e; /* skip it */
else if (src < ms.src_end) /* otherwise, skip one character */
luaL_addchar(&b, *src++);
else break; /* end of subject */
--
cgit v1.2.3-55-g6feb