lstrlib.c

Lua 语言解释器源码

          goto dflt;  /* case default */
        }
      }
    }
    case '\0': {  /* end of pattern */
      return s;  /* match succeeded */
    }
    case '$': {
      if (*(p+1) == '\0')  /* is the `$' the last char in pattern? */
        return (s == ms->src_end) ? s : NULL;  /* check end of string */
      else goto dflt;
    }
    default: dflt: {  /* it is a pattern item */
      const char *ep = luaI_classend(ms, p);  /* points to what is next */
      int m = s<ms->src_end && luaI_singlematch(uchar(*s), p, ep);
      switch (*ep) {
        case '?': {  /* optional */
          const char *res;
          if (m && ((res=match(ms, s+1, ep+1)) != NULL))
            return res;
          p=ep+1; goto init;  /* else return match(ms, s, ep+1); */
        }
        case '*': {  /* 0 or more repetitions */
          return max_expand(ms, s, p, ep);
        }
        case '+': {  /* 1 or more repetitions */
          return (m ? max_expand(ms, s+1, p, ep) : NULL);
        }
        case '-': {  /* 0 or more repetitions (minimum) */
          return min_expand(ms, s, p, ep);
        }
        default: {
          if (!m) return NULL;
          s++; p=ep; goto init;  /* else return match(ms, s+1, ep); */
        }
      }
    }
  }
}



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) {
  int l = ms->capture[i].len;
  if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
  if (l == CAP_POSITION)
    lua_pushnumber(ms->L, (lua_Number)(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;
  luaL_checkstack(ms->L, ms->level, "too many captures");
  if (ms->level == 0 && s) {  /* no explicit captures? */
    lua_pushlstring(ms->L, s, e-s);  /* return whole match */
    return 1;
  }
  else {  /* return all captures */
    for (i=0; i<ms->level; i++)
      push_onecapture(ms, i);
    return ms->level;  /* number of strings pushed */
  }
}


static int str_find (lua_State *L) {
  size_t l1, l2;
  const char *s = luaL_checklstring(L, 1, &l1);
  const char *p = luaL_checklstring(L, 2, &l2);
  sint32 init = posrelat(luaL_optlong(L, 3, 1), l1) - 1;
  if (init < 0) init = 0;
  else if ((size_t)(init) > l1) init = (sint32)l1;
  if (lua_toboolean(L, 4) ||  /* explicit request? */
      strpbrk(p, SPECIALS) == NULL) {  /* or no special characters? */
    /* do a plain search */
    const char *s2 = lmemfind(s+init, l1-init, p, l2);
    if (s2) {
      lua_pushnumber(L, (lua_Number)(s2-s+1));
      lua_pushnumber(L, (lua_Number)(s2-s+l2));
      return 2;
    }
  }
  else {
    MatchState ms;
    int anchor = (*p == '^') ? (p++, 1) : 0;
    const char *s1=s+init;
    ms.L = L;
    ms.src_init = s;
    ms.src_end = s+l1;
    do {
      const char *res;
      ms.level = 0;
      if ((res=match(&ms, s1, p)) != NULL) {
        lua_pushnumber(L, (lua_Number)(s1-s+1));  /* start */
        lua_pushnumber(L, (lua_Number)(res-s));   /* end */
        return push_captures(&ms, NULL, 0) + 2;
      }
    } while (s1++<ms.src_end && !anchor);
  }
  lua_pushnil(L);  /* not found */
  return 1;
}


static int gfind_aux (lua_State *L) {
  MatchState ms;
  const char *s = lua_tostring(L, lua_upvalueindex(1));
  size_t ls = lua_strlen(L, lua_upvalueindex(1));
  const char *p = lua_tostring(L, lua_upvalueindex(2));
  const char *src;
  ms.L = L;
  ms.src_init = s;
  ms.src_end = s+ls;
  for (src = s + (size_t)lua_tonumber(L, lua_upvalueindex(3));
       src <= ms.src_end;
       src++) {
    const char *e;
    ms.level = 0;
    if ((e = match(&ms, src, p)) != NULL) {
      int newstart = e-s;
      if (e == src) newstart++;  /* empty match? go at least one position */
      lua_pushnumber(L, (lua_Number)newstart);
      lua_replace(L, lua_upvalueindex(3));
      return push_captures(&ms, src, e);
    }
  }
  return 0;  /* not found */
}


static int gfind (lua_State *L) {
  luaL_checkstring(L, 1);
  luaL_checkstring(L, 2);
  lua_settop(L, 2);
  lua_pushnumber(L, 0);
  lua_pushcclosure(L, gfind_aux, 3);
  return 1;
}


static void add_s (MatchState *ms, luaL_Buffer *b,
                   const char *s, const char *e) {
  lua_State *L = ms->L;
  if (lua_isstring(L, 3)) {
    const char *news = lua_tostring(L, 3);
    size_t l = lua_strlen(L, 3);
    size_t i;
    for (i=0; i<l; i++) {
      if (news[i] != ESC)
        luaL_putchar(b, news[i]);
      else {
        i++;  /* skip ESC */
        if (!isdigit(uchar(news[i])))
          luaL_putchar(b, news[i]);
        else {
          int level = check_capture(ms, news[i]);
          push_onecapture(ms, level);
          luaL_addvalue(b);  /* add capture to accumulated result */
        }
      }
    }
  }
  else {  /* is a function */
    int n;
    lua_pushvalue(L, 3);
    n = push_captures(ms, s, e);
    lua_call(L, n, 1);
    if (lua_isstring(L, -1))
      luaL_addvalue(b);  /* add return to accumulated result */
    else
      lua_pop(L, 1);  /* function result is not a string: pop it */
  }
}


static int str_gsub (lua_State *L) {
  size_t srcl;
  const char *src = luaL_checklstring(L, 1, &srcl);
  const char *p = luaL_checkstring(L, 2);
  int max_s = luaL_optint(L, 4, srcl+1);
  int anchor = (*p == '^') ? (p++, 1) : 0;
  int n = 0;
  MatchState ms;
  luaL_Buffer b;
  luaL_argcheck(L,
    lua_gettop(L) >= 3 && (lua_isstring(L, 3) || lua_isfunction(L, 3)),
    3, "string or function expected");
  luaL_buffinit(L, &b);
  ms.L = L;
  ms.src_init = src;
  ms.src_end = src+srcl;
  while (n < max_s) {
    const char *e;
    ms.level = 0;
    e = match(&ms, src, p);
    if (e) {
      n++;
      add_s(&ms, &b, src, e);
    }
    if (e && e>src) /* non empty match? */
      src = e;  /* skip it */
    else if (src < ms.src_end)
      luaL_putchar(&b, *src++);
    else break;
    if (anchor) break;
  }
  luaL_addlstring(&b, src, ms.src_end-src);
  luaL_pushresult(&b);
  lua_pushnumber(L, (lua_Number)n);  /* number of substitutions */
  return 2;
}

/* }====================================================== */


/* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
#define MAX_ITEM	512
/* maximum size of each format specification (such as '%-099.99d') */
#define MAX_FORMAT	20


static void luaI_addquoted (lua_State *L, luaL_Buffer *b, int arg) {
  size_t l;
  const char *s = luaL_checklstring(L, arg, &l);
  luaL_putchar(b, '"');
  while (l--) {
    switch (*s) {
      case '"': case '\\': case '\n': {
        luaL_putchar(b, '\\');
        luaL_putchar(b, *s);
        break;
      }
      case '\0': {
        luaL_addlstring(b, "\\000", 4);
        break;
      }
      default: {
        luaL_putchar(b, *s);
        break;
      }
    }
    s++;
  }
  luaL_putchar(b, '"');
}


static const char *scanformat (lua_State *L, const char *strfrmt,
                                 char *form, int *hasprecision) {
  const char *p = strfrmt;
  while (strchr("-+ #0", *p)) p++;  /* skip flags */
  if (isdigit(uchar(*p))) p++;  /* skip width */
  if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
  if (*p == '.') {
    p++;
    *hasprecision = 1;
    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)");
  if (p-strfrmt+2 > MAX_FORMAT)  /* +2 to include `%' and the specifier */
    luaL_error(L, "invalid format (too long)");
  form[0] = '%';
  strncpy(form+1, strfrmt, p-strfrmt+1);
  form[p-strfrmt+2] = 0;
  return p;
}


static int str_format (lua_State *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 != '%')
      luaL_putchar(&b, *strfrmt++);
    else if (*++strfrmt == '%')
      luaL_putchar(&b, *strfrmt++);  /* %% */
    else { /* format item */
      char form[MAX_FORMAT];  /* to store the format (`%...') */
      char buff[MAX_ITEM];  /* to store the formatted item */
      int hasprecision = 0;
      if (isdigit(uchar(*strfrmt)) && *(strfrmt+1) == '$')
        return luaL_error(L, "obsolete option (d$) to `format'");
      arg++;
      strfrmt = scanformat(L, strfrmt, form, &hasprecision);
      switch (*strfrmt++) {
        case 'c':  case 'd':  case 'i': {
          sprintf(buff, form, luaL_checkint(L, arg));
          break;
        }
        case 'o':  case 'u':  case 'x':  case 'X': {
          sprintf(buff, form, (unsigned int)(luaL_checknumber(L, arg)));
          break;
        }
        case 'e':  case 'E': case 'f':
        case 'g': case 'G': {
          sprintf(buff, form, luaL_checknumber(L, arg));
          break;
        }
        case 'q': {
          luaI_addquoted(L, &b, arg);
          continue;  /* skip the `addsize' at the end */
        }
        case 's': {
          size_t l;
          const char *s = luaL_checklstring(L, arg, &l);
          if (!hasprecision && l >= 100) {
            /* no precision and string is too long to be formatted;
               keep original string */
            lua_pushvalue(L, arg);
            luaL_addvalue(&b);
            continue;  /* skip the `addsize' at the end */
          }
          else {
            sprintf(buff, form, s);
            break;
          }
        }
        default: {  /* also treat cases `pnLlh' */
          return luaL_error(L, "invalid option to `format'");
        }
      }
      luaL_addlstring(&b, buff, strlen(buff));
    }
  }
  luaL_pushresult(&b);
  return 1;
}


static const luaL_reg strlib[] = {
  {"len", str_len},
  {"sub", str_sub},
  {"lower", str_lower},
  {"upper", str_upper},
  {"char", str_char},
  {"rep", str_rep},
  {"byte", str_byte},
  {"format", str_format},
  {"dump", str_dump},
  {"find", str_find},
  {"gfind", gfind},
  {"gsub", str_gsub},
  {NULL, NULL}
};


/*
** Open string library
*/
LUALIB_API int luaopen_string (lua_State *L) {
  luaL_openlib(L, LUA_STRLIBNAME, strlib, 0);
  return 1;
}