Branch 5.2 - new releases for 5.2 go from here, main trunk goes

for next version

1 files changed, 1019 insertions, 0 deletions

diff --git a/lstrlib.c b/lstrlib.c
new file mode 100644
index 00000000..fcc61c9a
--- /dev/null
+++ b/lstrlib.c
@@ -0,0 +1,1019 @@
+/*
+** $Id: lstrlib.c,v 1.178 2012/08/14 18:12:34 roberto Exp $
+** Standard library for string operations and pattern-matching
+** See Copyright Notice in lua.h
+*/
+
+
+#include <ctype.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define lstrlib_c
+#define LUA_LIB
+
+#include "lua.h"
+
+#include "lauxlib.h"
+#include "lualib.h"
+
+
+/*
+** maximum number of captures that a pattern can do during
+** pattern-matching. This limit is arbitrary.
+*/
+#if !defined(LUA_MAXCAPTURES)
+#define LUA_MAXCAPTURES         32
+#endif
+
+
+/* macro to `unsign' a character */
+#define uchar(c)        ((unsigned char)(c))
+
+
+
+static int str_len (lua_State *L) {
+  size_t l;
+  luaL_checklstring(L, 1, &l);
+  lua_pushinteger(L, (lua_Integer)l);
+  return 1;
+}
+
+
+/* translate a relative string position: negative means back from end */
+static size_t posrelat (ptrdiff_t pos, size_t len) {
+  if (pos >= 0) return (size_t)pos;
+  else if (0u - (size_t)pos > len) return 0;
+  else return len - ((size_t)-pos) + 1;
+}
+
+
+static int str_sub (lua_State *L) {
+  size_t l;
+  const char *s = luaL_checklstring(L, 1, &l);
+  size_t start = posrelat(luaL_checkinteger(L, 2), l);
+  size_t end = posrelat(luaL_optinteger(L, 3, -1), l);
+  if (start < 1) start = 1;
+  if (end > l) end = l;
+  if (start <= end)
+    lua_pushlstring(L, s + start - 1, end - start + 1);
+  else lua_pushliteral(L, "");
+  return 1;
+}
+
+
+static int str_reverse (lua_State *L) {
+  size_t l, i;
+  luaL_Buffer b;
+  const char *s = luaL_checklstring(L, 1, &l);
+  char *p = luaL_buffinitsize(L, &b, l);
+  for (i = 0; i < l; i++)
+    p[i] = s[l - i - 1];
+  luaL_pushresultsize(&b, l);
+  return 1;
+}
+
+
+static int str_lower (lua_State *L) {
+  size_t l;
+  size_t i;
+  luaL_Buffer b;
+  const char *s = luaL_checklstring(L, 1, &l);
+  char *p = luaL_buffinitsize(L, &b, l);
+  for (i=0; i<l; i++)
+    p[i] = tolower(uchar(s[i]));
+  luaL_pushresultsize(&b, l);
+  return 1;
+}
+
+
+static int str_upper (lua_State *L) {
+  size_t l;
+  size_t i;
+  luaL_Buffer b;
+  const char *s = luaL_checklstring(L, 1, &l);
+  char *p = luaL_buffinitsize(L, &b, l);
+  for (i=0; i<l; i++)
+    p[i] = toupper(uchar(s[i]));
+  luaL_pushresultsize(&b, l);
+  return 1;
+}
+
+
+/* reasonable limit to avoid arithmetic overflow */
+#define MAXSIZE         ((~(size_t)0) >> 1)
+
+static int str_rep (lua_State *L) {
+  size_t l, lsep;
+  const char *s = luaL_checklstring(L, 1, &l);
+  int n = luaL_checkint(L, 2);
+  const char *sep = luaL_optlstring(L, 3, "", &lsep);
+  if (n <= 0) lua_pushliteral(L, "");
+  else if (l + lsep < l || l + lsep >= MAXSIZE / n)  /* may overflow? */
+    return luaL_error(L, "resulting string too large");
+  else {
+    size_t totallen = n * l + (n - 1) * lsep;
+    luaL_Buffer b;
+    char *p = luaL_buffinitsize(L, &b, totallen);
+    while (n-- > 1) {  /* first n-1 copies (followed by separator) */
+      memcpy(p, s, l * sizeof(char)); p += l;
+      if (lsep > 0) {  /* avoid empty 'memcpy' (may be expensive) */
+        memcpy(p, sep, lsep * sizeof(char)); p += lsep;
+      }
+    }
+    memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
+    luaL_pushresultsize(&b, totallen);
+  }
+  return 1;
+}
+
+
+static int str_byte (lua_State *L) {
+  size_t l;
+  const char *s = luaL_checklstring(L, 1, &l);
+  size_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
+  size_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
+  int n, i;
+  if (posi < 1) posi = 1;
+  if (pose > l) pose = l;
+  if (posi > pose) return 0;  /* empty interval; return no values */
+  n = (int)(pose -  posi + 1);
+  if (posi + n <= pose)  /* (size_t -> int) overflow? */
+    return luaL_error(L, "string slice too long");
+  luaL_checkstack(L, n, "string slice too long");
+  for (i=0; i<n; i++)
+    lua_pushinteger(L, uchar(s[posi+i-1]));
+  return n;
+}
+
+
+static int str_char (lua_State *L) {
+  int n = lua_gettop(L);  /* number of arguments */
+  int i;
+  luaL_Buffer b;
+  char *p = luaL_buffinitsize(L, &b, n);
+  for (i=1; i<=n; i++) {
+    int c = luaL_checkint(L, i);
+    luaL_argcheck(L, uchar(c) == c, i, "value out of range");
+    p[i - 1] = uchar(c);
+  }
+  luaL_pushresultsize(&b, n);
+  return 1;
+}
+
+
+static int writer (lua_State *L, const void* b, size_t size, void* B) {
+  (void)L;
+  luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);
+  return 0;
+}
+
+
+static int str_dump (lua_State *L) {
+  luaL_Buffer b;
+  luaL_checktype(L, 1, LUA_TFUNCTION);
+  lua_settop(L, 1);
+  luaL_buffinit(L,&b);
+  if (lua_dump(L, writer, &b) != 0)
+    return luaL_error(L, "unable to dump given function");
+  luaL_pushresult(&b);
+  return 1;
+}
+
+
+
+/*
+** {======================================================
+** PATTERN MATCHING
+** =======================================================
+*/
+
+
+#define CAP_UNFINISHED  (-1)
+#define CAP_POSITION    (-2)
+
+
+typedef struct MatchState {
+  int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
+  const char *src_init;  /* init of source string */
+  const char *src_end;  /* end ('\0') of source string */
+  const char *p_end;  /* end ('\0') of pattern */
+  lua_State *L;
+  int level;  /* total number of captures (finished or unfinished) */
+  struct {
+    const char *init;
+    ptrdiff_t len;
+  } capture[LUA_MAXCAPTURES];
+} MatchState;
+
+
+/* recursive function */
+static const char *match (MatchState *ms, const char *s, const char *p);
+
+
+/* maximum recursion depth for 'match' */
+#if !defined(MAXCCALLS)
+#define MAXCCALLS       200
+#endif
+
+
+#define L_ESC           '%'
+#define SPECIALS        "^$*+?.([%-"
+
+
+static int check_capture (MatchState *ms, int l) {
+  l -= '1';
+  if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
+    return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
+  return l;
+}
+
+
+static int capture_to_close (MatchState *ms) {
+  int level = ms->level;
+  for (level--; level>=0; level--)
+    if (ms->capture[level].len == CAP_UNFINISHED) return level;
+  return luaL_error(ms->L, "invalid pattern capture");
+}
+
+
+static const char *classend (MatchState *ms, const char *p) {
+  switch (*p++) {
+    case L_ESC: {
+      if (p == ms->p_end)
+        luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
+      return p+1;
+    }
+    case '[': {
+      if (*p == '^') p++;
+      do {  /* look for a `]' */
+        if (p == ms->p_end)
+          luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
+        if (*(p++) == L_ESC && p < ms->p_end)
+          p++;  /* skip escapes (e.g. `%]') */
+      } while (*p != ']');
+      return p+1;
+    }
+    default: {
+      return p;
+    }
+  }
+}
+
+
+static int match_class (int c, int cl) {
+  int res;
+  switch (tolower(cl)) {
+    case 'a' : res = isalpha(c); break;
+    case 'c' : res = iscntrl(c); break;
+    case 'd' : res = isdigit(c); break;
+    case 'g' : res = isgraph(c); break;
+    case 'l' : res = islower(c); break;
+    case 'p' : res = ispunct(c); break;
+    case 's' : res = isspace(c); break;
+    case 'u' : res = isupper(c); break;
+    case 'w' : res = isalnum(c); break;
+    case 'x' : res = isxdigit(c); break;
+    case 'z' : res = (c == 0); break;  /* deprecated option */
+    default: return (cl == c);
+  }
+  return (islower(cl) ? res : !res);
+}
+
+
+static int matchbracketclass (int c, const char *p, const char *ec) {
+  int sig = 1;
+  if (*(p+1) == '^') {
+    sig = 0;
+    p++;  /* skip the `^' */
+  }
+  while (++p < ec) {
+    if (*p == L_ESC) {
+      p++;
+      if (match_class(c, uchar(*p)))
+        return sig;
+    }
+    else if ((*(p+1) == '-') && (p+2 < ec)) {
+      p+=2;
+      if (uchar(*(p-2)) <= c && c <= uchar(*p))
+        return sig;
+    }
+    else if (uchar(*p) == c) return sig;
+  }
+  return !sig;
+}
+
+
+static int singlematch (MatchState *ms, const char *s, const char *p,
+                        const char *ep) {
+  if (s >= ms->src_end)
+    return 0;
+  else {
+    int c = uchar(*s);
+    switch (*p) {
+      case '.': return 1;  /* matches any char */
+      case L_ESC: return match_class(c, uchar(*(p+1)));
+      case '[': return matchbracketclass(c, p, ep-1);
+      default:  return (uchar(*p) == c);
+    }
+  }
+}
+
+
+static const char *matchbalance (MatchState *ms, const char *s,
+                                   const char *p) {
+  if (p >= ms->p_end - 1)
+    luaL_error(ms->L, "malformed pattern "
+                      "(missing arguments to " LUA_QL("%%b") ")");
+  if (*s != *p) return NULL;
+  else {
+    int b = *p;
+    int e = *(p+1);
+    int cont = 1;
+    while (++s < ms->src_end) {
+      if (*s == e) {
+        if (--cont == 0) return s+1;
+      }
+      else if (*s == b) cont++;
+    }
+  }
+  return NULL;  /* string ends out of balance */
+}
+
+
+static const char *max_expand (MatchState *ms, const char *s,
+                                 const char *p, const char *ep) {
+  ptrdiff_t i = 0;  /* counts maximum expand for item */
+  while (singlematch(ms, s + i, p, ep))
+    i++;
+  /* keeps trying to match with the maximum repetitions */
+  while (i>=0) {
+    const char *res = match(ms, (s+i), ep+1);
+    if (res) return res;
+    i--;  /* else didn't match; reduce 1 repetition to try again */
+  }
+  return NULL;
+}
+
+
+static const char *min_expand (MatchState *ms, const char *s,
+                                 const char *p, const char *ep) {
+  for (;;) {
+    const char *res = match(ms, s, ep+1);
+    if (res != NULL)
+      return res;
+    else if (singlematch(ms, s, p, ep))
+      s++;  /* try with one more repetition */
+    else return NULL;
+  }
+}
+
+
+static const char *start_capture (MatchState *ms, const char *s,
+                                    const char *p, int what) {
+  const char *res;
+  int level = ms->level;
+  if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
+  ms->capture[level].init = s;
+  ms->capture[level].len = what;
+  ms->level = level+1;
+  if ((res=match(ms, s, p)) == NULL)  /* match failed? */
+    ms->level--;  /* undo capture */
+  return res;
+}
+
+
+static const char *end_capture (MatchState *ms, const char *s,
+                                  const char *p) {
+  int l = capture_to_close(ms);
+  const char *res;
+  ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
+  if ((res = match(ms, s, p)) == NULL)  /* match failed? */
+    ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
+  return res;
+}
+
+
+static const char *match_capture (MatchState *ms, const char *s, int l) {
+  size_t len;
+  l = check_capture(ms, l);
+  len = ms->capture[l].len;
+  if ((size_t)(ms->src_end-s) >= len &&
+      memcmp(ms->capture[l].init, s, len) == 0)
+    return s+len;
+  else return NULL;
+}
+
+
+static const char *match (MatchState *ms, const char *s, const char *p) {
+  if (ms->matchdepth-- == 0)
+    luaL_error(ms->L, "pattern too complex");
+  init: /* using goto's to optimize tail recursion */
+  if (p != ms->p_end) {  /* end of pattern? */
+    switch (*p) {
+      case '(': {  /* start capture */
+        if (*(p + 1) == ')')  /* position capture? */
+          s = start_capture(ms, s, p + 2, CAP_POSITION);
+        else
+          s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
+        break;
+      }
+      case ')': {  /* end capture */
+        s = end_capture(ms, s, p + 1);
+        break;
+      }
+      case '$': {
+        if ((p + 1) != ms->p_end)  /* is the `$' the last char in pattern? */
+          goto dflt;  /* no; go to default */
+        s = (s == ms->src_end) ? s : NULL;  /* check end of string */
+        break;
+      }
+      case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
+        switch (*(p + 1)) {
+          case 'b': {  /* balanced string? */
+            s = matchbalance(ms, s, p + 2);
+            if (s != NULL) {
+              p += 4; goto init;  /* return match(ms, s, p + 4); */
+            }  /* else fail (s == NULL) */
+            break;
+          }
+          case 'f': {  /* frontier? */
+            const char *ep; char previous;
+            p += 2;
+            if (*p != '[')
+              luaL_error(ms->L, "missing " LUA_QL("[") " after "
+                                 LUA_QL("%%f") " in pattern");
+            ep = classend(ms, p);  /* points to what is next */
+            previous = (s == ms->src_init) ? '\0' : *(s - 1);
+            if (!matchbracketclass(uchar(previous), p, ep - 1) &&
+               matchbracketclass(uchar(*s), p, ep - 1)) {
+              p = ep; goto init;  /* return match(ms, s, ep); */
+            }
+            s = NULL;  /* match failed */
+            break;
+          }
+          case '0': case '1': case '2': case '3':
+          case '4': case '5': case '6': case '7':
+          case '8': case '9': {  /* capture results (%0-%9)? */
+            s = match_capture(ms, s, uchar(*(p + 1)));
+            if (s != NULL) {
+              p += 2; goto init;  /* return match(ms, s, p + 2) */
+            }
+            break;
+          }
+          default: goto dflt;
+        }
+        break;
+      }
+      default: dflt: {  /* pattern class plus optional suffix */
+        const char *ep = classend(ms, p);  /* points to optional suffix */
+        /* does not match at least once? */
+        if (!singlematch(ms, s, p, ep)) {
+          if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
+            p = ep + 1; goto init;  /* return match(ms, s, ep + 1); */
+          }
+          else  /* '+' or no suffix */
+            s = NULL;  /* fail */
+        }
+        else {  /* matched once */
+          switch (*ep) {  /* handle optional suffix */
+            case '?': {  /* optional */
+              const char *res;
+              if ((res = match(ms, s + 1, ep + 1)) != NULL)
+                s = res;
+              else {
+                p = ep + 1; goto init;  /* else return match(ms, s, ep + 1); */
+              }
+              break;
+            }
+            case '+':  /* 1 or more repetitions */
+              s++;  /* 1 match already done */
+              /* go through */
+            case '*':  /* 0 or more repetitions */
+              s = max_expand(ms, s, p, ep);
+              break;
+            case '-':  /* 0 or more repetitions (minimum) */
+              s = min_expand(ms, s, p, ep);
+              break;
+            default:  /* no suffix */
+              s++; p = ep; goto init;  /* return match(ms, s + 1, ep); */
+          }
+        }
+        break;
+      }
+    }
+  }
+  ms->matchdepth++;
+  return s;
+}
+
+
+
+static const char *lmemfind (const char *s1, size_t l1,
+                               const char *s2, size_t l2) {
+  if (l2 == 0) return s1;  /* empty strings are everywhere */
+  else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
+  else {
+    const char *init;  /* to search for a `*s2' inside `s1' */
+    l2--;  /* 1st char will be checked by `memchr' */
+    l1 = l1-l2;  /* `s2' cannot be found after that */
+    while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
+      init++;   /* 1st char is already checked */
+      if (memcmp(init, s2+1, l2) == 0)
+        return init-1;
+      else {  /* correct `l1' and `s1' to try again */
+        l1 -= init-s1;
+        s1 = init;
+      }
+    }
+    return NULL;  /* not found */
+  }
+}
+
+
+static void push_onecapture (MatchState *ms, int i, const char *s,
+                                                    const char *e) {
+  if (i >= ms->level) {
+    if (i == 0)  /* ms->level == 0, too */
+      lua_pushlstring(ms->L, s, e - s);  /* add whole match */
+    else
+      luaL_error(ms->L, "invalid capture index");
+  }
+  else {
+    ptrdiff_t l = ms->capture[i].len;
+    if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
+    if (l == CAP_POSITION)
+      lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
+    else
+      lua_pushlstring(ms->L, ms->capture[i].init, l);
+  }
+}
+
+
+static int push_captures (MatchState *ms, const char *s, const char *e) {
+  int i;
+  int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
+  luaL_checkstack(ms->L, nlevels, "too many captures");
+  for (i = 0; i < nlevels; i++)
+    push_onecapture(ms, i, s, e);
+  return nlevels;  /* number of strings pushed */
+}
+
+
+/* check whether pattern has no special characters */
+static int nospecials (const char *p, size_t l) {
+  size_t upto = 0;
+  do {
+    if (strpbrk(p + upto, SPECIALS))
+      return 0;  /* pattern has a special character */
+    upto += strlen(p + upto) + 1;  /* may have more after \0 */
+  } while (upto <= l);
+  return 1;  /* no special chars found */
+}
+
+
+static int str_find_aux (lua_State *L, int find) {
+  size_t ls, lp;
+  const char *s = luaL_checklstring(L, 1, &ls);
+  const char *p = luaL_checklstring(L, 2, &lp);
+  size_t init = posrelat(luaL_optinteger(L, 3, 1), ls);
+  if (init < 1) init = 1;
+  else if (init > ls + 1) {  /* start after string's end? */
+    lua_pushnil(L);  /* cannot find anything */
+    return 1;
+  }
+  /* explicit request or no special characters? */
+  if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
+    /* do a plain search */
+    const char *s2 = lmemfind(s + init - 1, ls - init + 1, p, lp);
+    if (s2) {
+      lua_pushinteger(L, s2 - s + 1);
+      lua_pushinteger(L, s2 - s + lp);
+      return 2;
+    }
+  }
+  else {
+    MatchState ms;
+    const char *s1 = s + init - 1;
+    int anchor = (*p == '^');
+    if (anchor) {
+      p++; lp--;  /* skip anchor character */
+    }
+    ms.L = L;
+    ms.matchdepth = MAXCCALLS;
+    ms.src_init = s;
+    ms.src_end = s + ls;
+    ms.p_end = p + lp;
+    do {
+      const char *res;
+      ms.level = 0;
+      lua_assert(ms.matchdepth == MAXCCALLS);
+      if ((res=match(&ms, s1, p)) != NULL) {
+        if (find) {
+          lua_pushinteger(L, s1 - s + 1);  /* start */
+          lua_pushinteger(L, res - s);   /* end */
+          return push_captures(&ms, NULL, 0) + 2;
+        }
+        else
+          return push_captures(&ms, s1, res);
+      }
+    } while (s1++ < ms.src_end && !anchor);
+  }
+  lua_pushnil(L);  /* not found */
+  return 1;
+}
+
+
+static int str_find (lua_State *L) {
+  return str_find_aux(L, 1);
+}
+
+
+static int str_match (lua_State *L) {
+  return str_find_aux(L, 0);
+}
+
+
+static int gmatch_aux (lua_State *L) {
+  MatchState ms;
+  size_t ls, lp;
+  const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
+  const char *p = lua_tolstring(L, lua_upvalueindex(2), &lp);
+  const char *src;
+  ms.L = L;
+  ms.matchdepth = MAXCCALLS;
+  ms.src_init = s;
+  ms.src_end = s+ls;
+  ms.p_end = p + lp;
+  for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
+       src <= ms.src_end;
+       src++) {
+    const char *e;
+    ms.level = 0;
+    lua_assert(ms.matchdepth == MAXCCALLS);
+    if ((e = match(&ms, src, p)) != NULL) {
+      lua_Integer newstart = e-s;
+      if (e == src) newstart++;  /* empty match? go at least one position */
+      lua_pushinteger(L, newstart);
+      lua_replace(L, lua_upvalueindex(3));
+      return push_captures(&ms, src, e);
+    }
+  }
+  return 0;  /* not found */
+}
+
+
+static int gmatch (lua_State *L) {
+  luaL_checkstring(L, 1);
+  luaL_checkstring(L, 2);
+  lua_settop(L, 2);
+  lua_pushinteger(L, 0);
+  lua_pushcclosure(L, gmatch_aux, 3);
+  return 1;
+}
+
+
+static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
+                                                   const char *e) {
+  size_t l, i;
+  const char *news = lua_tolstring(ms->L, 3, &l);
+  for (i = 0; i < l; i++) {
+    if (news[i] != L_ESC)
+      luaL_addchar(b, news[i]);
+    else {
+      i++;  /* skip ESC */
+      if (!isdigit(uchar(news[i]))) {
+        if (news[i] != L_ESC)
+          luaL_error(ms->L, "invalid use of " LUA_QL("%c")
+                           " in replacement string", L_ESC);
+        luaL_addchar(b, news[i]);
+      }
+      else if (news[i] == '0')
+          luaL_addlstring(b, s, e - s);
+      else {
+        push_onecapture(ms, news[i] - '1', s, e);
+        luaL_addvalue(b);  /* add capture to accumulated result */
+      }
+    }
+  }
+}
+
+
+static void add_value (MatchState *ms, luaL_Buffer *b, const char *s,
+                                       const char *e, int tr) {
+  lua_State *L = ms->L;
+  switch (tr) {
+    case LUA_TFUNCTION: {
+      int n;
+      lua_pushvalue(L, 3);
+      n = push_captures(ms, s, e);
+      lua_call(L, n, 1);
+      break;
+    }
+    case LUA_TTABLE: {
+      push_onecapture(ms, 0, s, e);
+      lua_gettable(L, 3);
+      break;
+    }
+    default: {  /* LUA_TNUMBER or LUA_TSTRING */
+      add_s(ms, b, s, e);
+      return;
+    }
+  }
+  if (!lua_toboolean(L, -1)) {  /* nil or false? */
+    lua_pop(L, 1);
+    lua_pushlstring(L, s, e - s);  /* keep original text */
+  }
+  else if (!lua_isstring(L, -1))
+    luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
+  luaL_addvalue(b);  /* add result to accumulator */
+}
+
+
+static int str_gsub (lua_State *L) {
+  size_t srcl, lp;
+  const char *src = luaL_checklstring(L, 1, &srcl);
+  const char *p = luaL_checklstring(L, 2, &lp);
+  int tr = lua_type(L, 3);
+  size_t max_s = luaL_optinteger(L, 4, srcl+1);
+  int anchor = (*p == '^');
+  size_t n = 0;
+  MatchState ms;
+  luaL_Buffer b;
+  luaL_argcheck(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
+                   tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
+                      "string/function/table expected");
+  luaL_buffinit(L, &b);
+  if (anchor) {
+    p++; lp--;  /* skip anchor character */
+  }
+  ms.L = L;
+  ms.matchdepth = MAXCCALLS;
+  ms.src_init = src;
+  ms.src_end = src+srcl;
+  ms.p_end = p + lp;
+  while (n < max_s) {
+    const char *e;
+    ms.level = 0;
+    lua_assert(ms.matchdepth == MAXCCALLS);
+    e = match(&ms, src, p);
+    if (e) {
+      n++;
+      add_value(&ms, &b, src, e, tr);
+    }
+    if (e && e>src) /* non empty match? */
+      src = e;  /* skip it */
+    else if (src < ms.src_end)
+      luaL_addchar(&b, *src++);
+    else break;
+    if (anchor) break;
+  }
+  luaL_addlstring(&b, src, ms.src_end-src);
+  luaL_pushresult(&b);
+  lua_pushinteger(L, n);  /* number of substitutions */
+  return 2;
+}
+
+/* }====================================================== */
+
+
+
+/*
+** {======================================================
+** STRING FORMAT
+** =======================================================
+*/
+
+/*
+** LUA_INTFRMLEN is the length modifier for integer conversions in
+** 'string.format'; LUA_INTFRM_T is the integer type corresponding to
+** the previous length
+*/
+#if !defined(LUA_INTFRMLEN)     /* { */
+#if defined(LUA_USE_LONGLONG)
+
+#define LUA_INTFRMLEN           "ll"
+#define LUA_INTFRM_T            long long
+
+#else
+
+#define LUA_INTFRMLEN           "l"
+#define LUA_INTFRM_T            long
+
+#endif
+#endif                          /* } */
+
+
+/*
+** LUA_FLTFRMLEN is the length modifier for float conversions in
+** 'string.format'; LUA_FLTFRM_T is the float type corresponding to
+** the previous length
+*/
+#if !defined(LUA_FLTFRMLEN)
+
+#define LUA_FLTFRMLEN           ""
+#define LUA_FLTFRM_T            double
+
+#endif
+
+
+/* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
+#define MAX_ITEM        512
+/* valid flags in a format specification */
+#define FLAGS   "-+ #0"
+/*
+** maximum size of each format specification (such as '%-099.99d')
+** (+10 accounts for %99.99x plus margin of error)
+*/
+#define MAX_FORMAT      (sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)
+
+
+static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
+  size_t l;
+  const char *s = luaL_checklstring(L, arg, &l);
+  luaL_addchar(b, '"');
+  while (l--) {
+    if (*s == '"' || *s == '\\' || *s == '\n') {
+      luaL_addchar(b, '\\');
+      luaL_addchar(b, *s);
+    }
+    else if (*s == '\0' || iscntrl(uchar(*s))) {
+      char buff[10];
+      if (!isdigit(uchar(*(s+1))))
+        sprintf(buff, "\\%d", (int)uchar(*s));
+      else
+        sprintf(buff, "\\%03d", (int)uchar(*s));
+      luaL_addstring(b, buff);
+    }
+    else
+      luaL_addchar(b, *s);
+    s++;
+  }
+  luaL_addchar(b, '"');
+}
+
+static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
+  const char *p = strfrmt;
+  while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++;  /* skip flags */
+  if ((size_t)(p - strfrmt) >= sizeof(FLAGS)/sizeof(char))
+    luaL_error(L, "invalid format (repeated flags)");
+  if (isdigit(uchar(*p))) p++;  /* skip width */
+  if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
+  if (*p == '.') {
+    p++;
+    if (isdigit(uchar(*p))) p++;  /* skip precision */
+    if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
+  }
+  if (isdigit(uchar(*p)))
+    luaL_error(L, "invalid format (width or precision too long)");
+  *(form++) = '%';
+  memcpy(form, strfrmt, (p - strfrmt + 1) * sizeof(char));
+  form += p - strfrmt + 1;
+  *form = '\0';
+  return p;
+}
+
+
+/*
+** add length modifier into formats
+*/
+static void addlenmod (char *form, const char *lenmod) {
+  size_t l = strlen(form);
+  size_t lm = strlen(lenmod);
+  char spec = form[l - 1];
+  strcpy(form + l - 1, lenmod);
+  form[l + lm - 1] = spec;
+  form[l + lm] = '\0';
+}
+
+
+static int str_format (lua_State *L) {
+  int top = lua_gettop(L);
+  int arg = 1;
+  size_t sfl;
+  const char *strfrmt = luaL_checklstring(L, arg, &sfl);
+  const char *strfrmt_end = strfrmt+sfl;
+  luaL_Buffer b;
+  luaL_buffinit(L, &b);
+  while (strfrmt < strfrmt_end) {
+    if (*strfrmt != L_ESC)
+      luaL_addchar(&b, *strfrmt++);
+    else if (*++strfrmt == L_ESC)
+      luaL_addchar(&b, *strfrmt++);  /* %% */
+    else { /* format item */
+      char form[MAX_FORMAT];  /* to store the format (`%...') */
+      char *buff = luaL_prepbuffsize(&b, MAX_ITEM);  /* to put formatted item */
+      int nb = 0;  /* number of bytes in added item */
+      if (++arg > top)
+        luaL_argerror(L, arg, "no value");
+      strfrmt = scanformat(L, strfrmt, form);
+      switch (*strfrmt++) {
+        case 'c': {
+          nb = sprintf(buff, form, luaL_checkint(L, arg));
+          break;
+        }
+        case 'd': case 'i': {
+          lua_Number n = luaL_checknumber(L, arg);
+          LUA_INTFRM_T ni = (LUA_INTFRM_T)n;
+          lua_Number diff = n - (lua_Number)ni;
+          luaL_argcheck(L, -1 < diff && diff < 1, arg,
+                        "not a number in proper range");
+          addlenmod(form, LUA_INTFRMLEN);
+          nb = sprintf(buff, form, ni);
+          break;
+        }
+        case 'o': case 'u': case 'x': case 'X': {
+          lua_Number n = luaL_checknumber(L, arg);
+          unsigned LUA_INTFRM_T ni = (unsigned LUA_INTFRM_T)n;
+          lua_Number diff = n - (lua_Number)ni;
+          luaL_argcheck(L, -1 < diff && diff < 1, arg,
+                        "not a non-negative number in proper range");
+          addlenmod(form, LUA_INTFRMLEN);
+          nb = sprintf(buff, form, ni);
+          break;
+        }
+        case 'e': case 'E': case 'f':
+#if defined(LUA_USE_AFORMAT)
+        case 'a': case 'A':
+#endif
+        case 'g': case 'G': {
+          addlenmod(form, LUA_FLTFRMLEN);
+          nb = sprintf(buff, form, (LUA_FLTFRM_T)luaL_checknumber(L, arg));
+          break;
+        }
+        case 'q': {
+          addquoted(L, &b, arg);
+          break;
+        }
+        case 's': {
+          size_t l;
+          const char *s = luaL_tolstring(L, arg, &l);
+          if (!strchr(form, '.') && l >= 100) {
+            /* no precision and string is too long to be formatted;
+               keep original string */
+            luaL_addvalue(&b);
+            break;
+          }
+          else {
+            nb = sprintf(buff, form, s);
+            lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
+            break;
+          }
+        }
+        default: {  /* also treat cases `pnLlh' */
+          return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
+                               LUA_QL("format"), *(strfrmt - 1));
+        }
+      }
+      luaL_addsize(&b, nb);
+    }
+  }
+  luaL_pushresult(&b);
+  return 1;
+}
+
+/* }====================================================== */
+
+
+static const luaL_Reg strlib[] = {
+  {"byte", str_byte},
+  {"char", str_char},
+  {"dump", str_dump},
+  {"find", str_find},
+  {"format", str_format},
+  {"gmatch", gmatch},
+  {"gsub", str_gsub},
+  {"len", str_len},
+  {"lower", str_lower},
+  {"match", str_match},
+  {"rep", str_rep},
+  {"reverse", str_reverse},
+  {"sub", str_sub},
+  {"upper", str_upper},
+  {NULL, NULL}
+};
+
+
+static void createmetatable (lua_State *L) {
+  lua_createtable(L, 0, 1);  /* table to be metatable for strings */
+  lua_pushliteral(L, "");  /* dummy string */
+  lua_pushvalue(L, -2);  /* copy table */
+  lua_setmetatable(L, -2);  /* set table as metatable for strings */
+  lua_pop(L, 1);  /* pop dummy string */
+  lua_pushvalue(L, -2);  /* get string library */
+  lua_setfield(L, -2, "__index");  /* metatable.__index = string */
+  lua_pop(L, 1);  /* pop metatable */
+}
+
+
+/*
+** Open string library
+*/
+LUAMOD_API int luaopen_string (lua_State *L) {
+  luaL_newlib(L, strlib);
+  createmetatable(L);
+  return 1;
+}
+