/*
** $Id: lstrlib.c,v 1.69 2001/07/17 18:46:49 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 LUA_PRIVATE
#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


typedef long sint32;	/* a signed version for size_t */


static int str_len (lua_State *L) {
  size_t l;
  luaL_check_lstr(L, 1, &l);
  lua_pushnumber(L, l);
  return 1;
}


static sint32 posrelat (sint32 pos, size_t len) {
  /* relative string position: negative means back from end */
  return (pos>=0) ? pos : (sint32)len+pos+1;
}


static int str_sub (lua_State *L) {
  size_t l;
  const l_char *s = luaL_check_lstr(L, 1, &l);
  sint32 start = posrelat(luaL_check_long(L, 2), l);
  sint32 end = posrelat(luaL_opt_long(L, 3, -1), l);
  if (start < 1) start = 1;
  if (end > (sint32)l) end = l;
  if (start <= end)
    lua_pushlstring(L, s+start-1, end-start+1);
  else lua_pushliteral(L, l_s(""));
  return 1;
}


static int str_lower (lua_State *L) {
  size_t l;
  size_t i;
  luaL_Buffer b;
  const l_char *s = luaL_check_lstr(L, 1, &l);
  luaL_buffinit(L, &b);
  for (i=0; i<l; i++)
    luaL_putchar(&b, tolower(uchar(s[i])));
  luaL_pushresult(&b);
  return 1;
}


static int str_upper (lua_State *L) {
  size_t l;
  size_t i;
  luaL_Buffer b;
  const l_char *s = luaL_check_lstr(L, 1, &l);
  luaL_buffinit(L, &b);
  for (i=0; i<l; i++)
    luaL_putchar(&b, toupper(uchar(s[i])));
  luaL_pushresult(&b);
  return 1;
}

static int str_rep (lua_State *L) {
  size_t l;
  luaL_Buffer b;
  const l_char *s = luaL_check_lstr(L, 1, &l);
  int n = luaL_check_int(L, 2);
  luaL_buffinit(L, &b);
  while (n-- > 0)
    luaL_addlstring(&b, s, l);
  luaL_pushresult(&b);
  return 1;
}


static int str_byte (lua_State *L) {
  size_t l;
  const l_char *s = luaL_check_lstr(L, 1, &l);
  sint32 pos = posrelat(luaL_opt_long(L, 2, 1), l);
  luaL_arg_check(L, 0<pos && (size_t)pos<=l, 2,  l_s("out of range"));
  lua_pushnumber(L, uchar(s[pos-1]));
  return 1;
}


static int str_char (lua_State *L) {
  int n = lua_gettop(L);  /* number of arguments */
  int i;
  luaL_Buffer b;
  luaL_buffinit(L, &b);
  for (i=1; i<=n; i++) {
    int c = luaL_check_int(L, i);
    luaL_arg_check(L, uchar(c) == c, i, l_s("invalid value"));
    luaL_putchar(&b, uchar(c));
  }
  luaL_pushresult(&b);
  return 1;
}



/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/

#ifndef MAX_CAPTURES
#define MAX_CAPTURES 32  /* arbitrary limit */
#endif


#define CAP_UNFINISHED	(-1)
#define CAP_POSITION	(-2)

typedef struct MatchState {
  const l_char *src_init;  /* init of source string */
  const l_char *src_end;  /* end (`\0') of source string */
  int level;  /* total number of captures (finished or unfinished) */
  struct {
    const l_char *init;
    sint32 len;
  } capture[MAX_CAPTURES];
  lua_State *L;
} MatchState;


#define ESC		l_c('%')
#define SPECIALS	l_s("^$*+?.([%-")


static int check_capture (MatchState *ms, int l) {
  l -= l_c('1');
  if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
    lua_error(ms->L, l_s("invalid capture index"));
  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;
  lua_error(ms->L, l_s("invalid pattern capture"));
  return 0;  /* to avoid warnings */
}


static const l_char *luaI_classend (MatchState *ms, const l_char *p) {
  switch (*p++) {
    case ESC:
      if (*p == l_c('\0'))
        lua_error(ms->L, l_s("malformed pattern (ends with `%')"));
      return p+1;
    case l_c('['):
      if (*p == l_c('^')) p++;
      do {  /* look for a `]' */
        if (*p == l_c('\0'))
          lua_error(ms->L, l_s("malformed pattern (missing `]')"));
        if (*(p++) == ESC && *p != l_c('\0'))
          p++;  /* skip escapes (e.g. `%]') */
      } while (*p != l_c(']'));
      return p+1;
    default:
      return p;
  }
}


static int match_class (l_charint c, l_charint cl) {
  int res;
  switch (tolower(cl)) {
    case l_c('a') : res = isalpha(c); break;
    case l_c('c') : res = iscntrl(c); break;
    case l_c('d') : res = isdigit(c); break;
    case l_c('l') : res = islower(c); break;
    case l_c('p') : res = ispunct(c); break;
    case l_c('s') : res = isspace(c); break;
    case l_c('u') : res = isupper(c); break;
    case l_c('w') : res = isalnum(c); break;
    case l_c('x') : res = isxdigit(c); break;
    case l_c('z') : res = (c == 0); break;
    default: return (cl == c);
  }
  return (islower(cl) ? res : !res);
}


static int matchbracketclass (l_charint c, const l_char *p, const l_char *ec) {
  int sig = 1;
  if (*(p+1) == l_c('^')) {
    sig = 0;
    p++;  /* skip the `^' */
  }
  while (++p < ec) {
    if (*p == ESC) {
      p++;
      if (match_class(c, *p))
        return sig;
    }
    else if ((*(p+1) == l_c('-')) && (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 luaI_singlematch (l_charint c, const l_char *p, const l_char *ep) {
  switch (*p) {
    case l_c('.'):  /* matches any char */
      return 1;
    case ESC:
      return match_class(c, *(p+1));
    case l_c('['):
      return matchbracketclass(c, p, ep-1);
    default:
      return (uchar(*p) == c);
  }
}


static const l_char *match (MatchState *ms, const l_char *s, const l_char *p);


static const l_char *matchbalance (MatchState *ms, const l_char *s,
                                   const l_char *p) {
  if (*p == 0 || *(p+1) == 0)
    lua_error(ms->L, l_s("unbalanced pattern"));
  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 l_char *max_expand (MatchState *ms, const l_char *s,
                                 const l_char *p, const l_char *ep) {
  sint32 i = 0;  /* counts maximum expand for item */
  while ((s+i)<ms->src_end && luaI_singlematch(uchar(*(s+i)), p, ep))
    i++;
  /* keeps trying to match with the maximum repetitions */
  while (i>=0) {
    const l_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 l_char *min_expand (MatchState *ms, const l_char *s,
                                 const l_char *p, const l_char *ep) {
  for (;;) {
    const l_char *res = match(ms, s, ep+1);
    if (res != NULL)
      return res;
    else if (s<ms->src_end && luaI_singlematch(uchar(*s), p, ep))
      s++;  /* try with one more repetition */
    else return NULL;
  }
}


static const l_char *start_capture (MatchState *ms, const l_char *s,
                                    const l_char *p, int what) {
  const l_char *res;
  int level = ms->level;
  if (level >= MAX_CAPTURES) lua_error(ms->L, l_s("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 l_char *end_capture (MatchState *ms, const l_char *s,
                                  const l_char *p) {
  int l = capture_to_close(ms);
  const l_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 l_char *match_capture (MatchState *ms, const l_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 l_char *match (MatchState *ms, const l_char *s, const l_char *p) {
  init: /* using goto's to optimize tail recursion */
  switch (*p) {
    case l_c('('):  /* start capture */
      if (*(p+1) == l_c(')'))  /* position capture? */
        return start_capture(ms, s, p+2, CAP_POSITION);
      else
        return start_capture(ms, s, p+1, CAP_UNFINISHED);
    case l_c(')'):  /* end capture */
      return end_capture(ms, s, p+1);
    case ESC:  /* may be %[0-9] or %b */
      if (isdigit(uchar(*(p+1)))) {  /* capture? */
        s = match_capture(ms, s, *(p+1));
        if (s == NULL) return NULL;
        p+=2; goto init;  /* else return match(ms, s, p+2) */
      }
      else if (*(p+1) == l_c('b')) {  /* balanced string? */
        s = matchbalance(ms, s, p+2);
        if (s == NULL) return NULL;
        p+=4; goto init;  /* else return match(ms, s, p+4); */
      }
      else goto dflt;  /* case default */
    case l_c('\0'):  /* end of pattern */
      return s;  /* match succeeded */
    case l_c('$'):
      if (*(p+1) == l_c('\0'))  /* is the `$' 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 l_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 l_c('?'): {  /* optional */
          const l_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 l_c('*'):  /* 0 or more repetitions */
          return max_expand(ms, s, p, ep);
        case l_c('+'):  /* 1 or more repetitions */
          return (m ? max_expand(ms, s+1, p, ep) : NULL);
        case l_c('-'):  /* 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 l_char *lmemfind (const l_char *s1, size_t l1,
                               const l_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 l_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 l_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) lua_error(ms->L, l_s("unfinished capture"));
  if (l == CAP_POSITION)
    lua_pushnumber(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) {
  int i;
  luaL_checkstack(ms->L, ms->level, l_s("too many 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 l_char *s = luaL_check_lstr(L, 1, &l1);
  const l_char *p = luaL_check_lstr(L, 2, &l2);
  sint32 init = posrelat(luaL_opt_long(L, 3, 1), l1) - 1;
  luaL_arg_check(L, 0 <= init && (size_t)init <= l1, 3, l_s("out of range"));
  if (lua_gettop(L) > 3 ||  /* extra argument? */
      strpbrk(p, SPECIALS) == NULL) {  /* or no special characters? */
    const l_char *s2 = lmemfind(s+init, l1-init, p, l2);
    if (s2) {
      lua_pushnumber(L, s2-s+1);
      lua_pushnumber(L, s2-s+l2);
      return 2;
    }
  }
  else {
    MatchState ms;
    int anchor = (*p == l_c('^')) ? (p++, 1) : 0;
    const l_char *s1=s+init;
    ms.L = L;
    ms.src_init = s;
    ms.src_end = s+l1;
    do {
      const l_char *res;
      ms.level = 0;
      if ((res=match(&ms, s1, p)) != NULL) {
        lua_pushnumber(L, s1-s+1);  /* start */
        lua_pushnumber(L, res-s);   /* end */
        return push_captures(&ms) + 2;
      }
    } while (s1++<ms.src_end && !anchor);
  }
  lua_pushnil(L);  /* not found */
  return 1;
}


static void add_s (MatchState *ms, luaL_Buffer *b) {
  lua_State *L = ms->L;
  if (lua_isstring(L, 3)) {
    const l_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);
    lua_rawcall(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 l_char *src = luaL_check_lstr(L, 1, &srcl);
  const l_char *p = luaL_check_string(L, 2);
  int max_s = luaL_opt_int(L, 4, srcl+1);
  int anchor = (*p == l_c('^')) ? (p++, 1) : 0;
  int n = 0;
  MatchState ms;
  luaL_Buffer b;
  luaL_arg_check(L,
    lua_gettop(L) >= 3 && (lua_isstring(L, 3) || lua_isfunction(L, 3)),
    3, l_s("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 l_char *e;
    ms.level = 0;
    e = match(&ms, src, p);
    if (e) {
      n++;
      add_s(&ms, &b);
    }
    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, 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 l_char *s = luaL_check_lstr(L, arg, &l);
  luaL_putchar(b, l_c('"'));
  while (l--) {
    switch (*s) {
      case l_c('"'):  case l_c('\\'):  case l_c('\n'):
        luaL_putchar(b, l_c('\\'));
        luaL_putchar(b, *s);
        break;
      case l_c('\0'): luaL_addlstring(b, l_s("\\000"), 4); break;
      default: luaL_putchar(b, *s);
    }
    s++;
  }
  luaL_putchar(b, l_c('"'));
}


static const l_char *scanformat (lua_State *L, const l_char *strfrmt,
                                 l_char *form, int *hasprecision) {
  const l_char *p = strfrmt;
  while (strchr(l_s("-+ #0"), *p)) p++;  /* skip flags */
  if (isdigit(uchar(*p))) p++;  /* skip width */
  if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
  if (*p == l_c('.')) {
    p++;
    *hasprecision = 1;
    if (isdigit(uchar(*p))) p++;  /* skip precision */
    if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
  }
  if (isdigit(uchar(*p)))
    lua_error(L, l_s("invalid format (width or precision too long)"));
  if (p-strfrmt+2 > MAX_FORMAT)  /* +2 to include `%' and the specifier */
    lua_error(L, l_s("invalid format (too long)"));
  form[0] = l_c('%');
  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 l_char *strfrmt = luaL_check_lstr(L, arg, &sfl);
  const l_char *strfrmt_end = strfrmt+sfl;
  luaL_Buffer b;
  luaL_buffinit(L, &b);
  while (strfrmt < strfrmt_end) {
    if (*strfrmt != l_c('%'))
      luaL_putchar(&b, *strfrmt++);
    else if (*++strfrmt == l_c('%'))
      luaL_putchar(&b, *strfrmt++);  /* %% */
    else { /* format item */
      l_char form[MAX_FORMAT];  /* to store the format (`%...') */
      l_char buff[MAX_ITEM];  /* to store the formatted item */
      int hasprecision = 0;
      if (isdigit(uchar(*strfrmt)) && *(strfrmt+1) == l_c('$'))
        lua_error(L, l_s("obsolete `format' option (d$)"));
      arg++;
      strfrmt = scanformat(L, strfrmt, form, &hasprecision);
      switch (*strfrmt++) {
        case l_c('c'):  case l_c('d'):  case l_c('i'):
          sprintf(buff, form, luaL_check_int(L, arg));
          break;
        case l_c('o'):  case l_c('u'):  case l_c('x'):  case l_c('X'):
          sprintf(buff, form, (unsigned int)luaL_check_number(L, arg));
          break;
        case l_c('e'):  case l_c('E'): case l_c('f'):
        case l_c('g'): case l_c('G'):
          sprintf(buff, form, luaL_check_number(L, arg));
          break;
        case l_c('q'):
          luaI_addquoted(L, &b, arg);
          continue;  /* skip the `addsize' at the end */
        case l_c('s'): {
          size_t l;
          const l_char *s = luaL_check_lstr(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' */
          lua_error(L, l_s("invalid option in `format'"));
      }
      luaL_addlstring(&b, buff, strlen(buff));
    }
  }
  luaL_pushresult(&b);
  return 1;
}


static const luaL_reg strlib[] = {
{l_s("strlen"), str_len},
{l_s("strsub"), str_sub},
{l_s("strlower"), str_lower},
{l_s("strupper"), str_upper},
{l_s("strchar"), str_char},
{l_s("strrep"), str_rep},
{l_s("strbyte"), str_byte},
{l_s("format"), str_format},
{l_s("strfind"), str_find},
{l_s("gsub"), str_gsub}
};


/*
** Open string library
*/
LUALIB_API int lua_strlibopen (lua_State *L) {
  luaL_openl(L, strlib);
  return 0;
}