/*

** $Id: llex.c $

** Lexical Analyzer

** See Copyright Notice in lua.h

*/

#define llex_c

#define LUA_CORE

#include "lprefix.h"

#include <locale.h>

#include <string.h>

#include "lua.h"

#include "lctype.h"

#include "ldebug.h"

#include "ldo.h"

#include "lgc.h"

#include "llex.h"

#include "lobject.h"

#include "lparser.h"

#include "lstate.h"

#include "lstring.h"

#include "ltable.h"

#include "lzio.h"

#define next(ls)  (ls->current = zgetc(ls->z))

#define currIsNewline(ls) (ls->current == '\n' || ls->current == '\r')

/* ORDER RESERVED */

static const char *const luaX_tokens [] = {

    "and", "break", "do", "else", "elseif",

    "end", "false", "for", "function", "goto", "if",

    "in", "local", "nil", "not", "or", "repeat",

    "return", "then", "true", "until", "while",

    "//", "..", "...", "==", ">=", "<=", "~=",

    "<<", ">>", "::", "<eof>",

    "<number>", "<integer>", "<name>", "<string>"

};

#define save_and_next(ls) (save(ls, ls->current), next(ls))

static l_noret lexerror (LexState *ls, const char *msg, int token);

static void save (LexState *ls, int c) {

  Mbuffer *b = ls->buff;

  if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {

    size_t newsize;

    if (luaZ_sizebuffer(b) >= MAX_SIZE/2)

      lexerror(ls, "lexical element too long", 0);

    newsize = luaZ_sizebuffer(b) * 2;

    luaZ_resizebuffer(ls->L, b, newsize);

  }

  b->buffer[luaZ_bufflen(b)++] = cast_char(c);

}

void luaX_init (lua_State *L) {

  int i;

  TString *e = luaS_newliteral(L, LUA_ENV);  /* create env name */

  luaC_fix(L, obj2gco(e));  /* never collect this name */

  for (i=0; i<NUM_RESERVED; i++) {

    TString *ts = luaS_new(L, luaX_tokens[i]);

    luaC_fix(L, obj2gco(ts));  /* reserved words are never collected */

    ts->extra = cast_byte(i+1);  /* reserved word */

  }

}

const char *luaX_token2str (LexState *ls, int token) {

  if (token < FIRST_RESERVED) {  /* single-byte symbols? */

    if (lisprint(token))

      return luaO_pushfstring(ls->L, "'%c'", token);

    else  /* control character */

      return luaO_pushfstring(ls->L, "'<\\%d>'", token);

  }

  else {

    const char *s = luaX_tokens[token - FIRST_RESERVED];

    if (token < TK_EOS)  /* fixed format (symbols and reserved words)? */

      return luaO_pushfstring(ls->L, "'%s'", s);

    else  /* names, strings, and numerals */

      return s;

  }

}

static const char *txtToken (LexState *ls, int token) {

  switch (token) {

    case TK_NAME: case TK_STRING:

    case TK_FLT: case TK_INT:

      save(ls, '\0');

      return luaO_pushfstring(ls->L, "'%s'", luaZ_buffer(ls->buff));

    default:

      return luaX_token2str(ls, token);

  }

}

static l_noret lexerror (LexState *ls, const char *msg, int token) {

  msg = luaG_addinfo(ls->L, msg, ls->source, ls->linenumber);

  if (token)

    luaO_pushfstring(ls->L, "%s near %s", msg, txtToken(ls, token));

  luaD_throw(ls->L, LUA_ERRSYNTAX);

}

l_noret luaX_syntaxerror (LexState *ls, const char *msg) {

  lexerror(ls, msg, ls->t.token);

}

/*

** Creates a new string and anchors it in scanner's table so that it

** will not be collected until the end of the compilation; by that time

** it should be anchored somewhere. It also internalizes long strings,

** ensuring there is only one copy of each unique string.  The table

** here is used as a set: the string enters as the key, while its value

** is irrelevant. We use the string itself as the value only because it

** is a TValue readily available. Later, the code generation can change

** this value.

*/

TString *luaX_newstring (LexState *ls, const char *str, size_t l) {

  lua_State *L = ls->L;

  TString *ts = luaS_newlstr(L, str, l);  /* create new string */

  TString *oldts = luaH_getstrkey(ls->h, ts);

  if (oldts != NULL)  /* string already present? */

    return oldts;  /* use it */

  else {  /* create a new entry */

    TValue *stv = s2v(L->top.p++);  /* reserve stack space for string */

    setsvalue(L, stv, ts);  /* temporarily anchor the string */

    luaH_set(L, ls->h, stv, stv);  /* t[string] = string */

    /* table is not a metatable, so it does not need to invalidate cache */

    luaC_checkGC(L);

    L->top.p--;  /* remove string from stack */

  }

  return ts;

}

/*

** increment line number and skips newline sequence (any of

** \n, \r, \n\r, or \r\n)

*/

static void inclinenumber (LexState *ls) {

  int old = ls->current;

  lua_assert(currIsNewline(ls));

  next(ls);  /* skip '\n' or '\r' */

  if (currIsNewline(ls) && ls->current != old)

    next(ls);  /* skip '\n\r' or '\r\n' */

  if (++ls->linenumber >= MAX_INT)

    lexerror(ls, "chunk has too many lines", 0);

}

void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,

                    int firstchar) {

  ls->t.token = 0;

  ls->L = L;

  ls->current = firstchar;

  ls->lookahead.token = TK_EOS;  /* no look-ahead token */

  ls->z = z;

  ls->fs = NULL;

  ls->linenumber = 1;

  ls->lastline = 1;

  ls->source = source;

  ls->envn = luaS_newliteral(L, LUA_ENV);  /* get env name */

  luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);  /* initialize buffer */

}

/*

** =======================================================

** LEXICAL ANALYZER

** =======================================================

*/

static int check_next1 (LexState *ls, int c) {

  if (ls->current == c) {

    next(ls);

    return 1;

  }

  else return 0;

}

/*

** Check whether current char is in set 'set' (with two chars) and

** saves it

*/

static int check_next2 (LexState *ls, const char *set) {

  lua_assert(set[2] == '\0');

  if (ls->current == set[0] || ls->current == set[1]) {

    save_and_next(ls);

    return 1;

  }

  else return 0;

}

/* LUA_NUMBER */

/*

** This function is quite liberal in what it accepts, as 'luaO_str2num'

** will reject ill-formed numerals. Roughly, it accepts the following

** pattern:

**

**   %d(%x|%.|([Ee][+-]?))* | 0[Xx](%x|%.|([Pp][+-]?))*

**

** The only tricky part is to accept [+-] only after a valid exponent

** mark, to avoid reading '3-4' or '0xe+1' as a single number.

**

** The caller might have already read an initial dot.

*/

static int read_numeral (LexState *ls, SemInfo *seminfo) {

  TValue obj;

  const char *expo = "Ee";

  int first = ls->current;

  lua_assert(lisdigit(ls->current));

  save_and_next(ls);

  if (first == '0' && check_next2(ls, "xX"))  /* hexadecimal? */

    expo = "Pp";

  for (;;) {

    if (check_next2(ls, expo))  /* exponent mark? */

      check_next2(ls, "-+");  /* optional exponent sign */

    else if (lisxdigit(ls->current) || ls->current == '.')  /* '%x|%.' */

      save_and_next(ls);

    else break;

  }

  if (lislalpha(ls->current))  /* is numeral touching a letter? */

    save_and_next(ls);  /* force an error */

  save(ls, '\0');

  if (luaO_str2num(luaZ_buffer(ls->buff), &obj) == 0)  /* format error? */

    lexerror(ls, "malformed number", TK_FLT);

  if (ttisinteger(&obj)) {

    seminfo->i = ivalue(&obj);

    return TK_INT;

  }

  else {

    lua_assert(ttisfloat(&obj));

    seminfo->r = fltvalue(&obj);

    return TK_FLT;

  }

}

/*

** read a sequence '[=*[' or ']=*]', leaving the last bracket. If

** sequence is well formed, return its number of '='s + 2; otherwise,

** return 1 if it is a single bracket (no '='s and no 2nd bracket);

** otherwise (an unfinished '[==...') return 0.

*/

static size_t skip_sep (LexState *ls) {

  size_t count = 0;

  int s = ls->current;

  lua_assert(s == '[' || s == ']');

  save_and_next(ls);

  while (ls->current == '=') {

    save_and_next(ls);

    count++;

  }

  return (ls->current == s) ? count + 2

         : (count == 0) ? 1

         : 0;

}

static void read_long_string (LexState *ls, SemInfo *seminfo, size_t sep) {

  int line = ls->linenumber;  /* initial line (for error message) */

  save_and_next(ls);  /* skip 2nd '[' */

  if (currIsNewline(ls))  /* string starts with a newline? */

    inclinenumber(ls);  /* skip it */

  for (;;) {

    switch (ls->current) {

      case EOZ: {  /* error */

        const char *what = (seminfo ? "string" : "comment");

        const char *msg = luaO_pushfstring(ls->L,

                     "unfinished long %s (starting at line %d)", what, line);

        lexerror(ls, msg, TK_EOS);

        break;  /* to avoid warnings */

      }

      case ']': {

        if (skip_sep(ls) == sep) {

          save_and_next(ls);  /* skip 2nd ']' */

          goto endloop;

        }

        break;

      }

      case '\n': case '\r': {

        save(ls, '\n');

        inclinenumber(ls);

        if (!seminfo) luaZ_resetbuffer(ls->buff);  /* avoid wasting space */

        break;

      }

      default: {

        if (seminfo) save_and_next(ls);

        else next(ls);

      }

    }

  } endloop:

  if (seminfo)

    seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + sep,

                                     luaZ_bufflen(ls->buff) - 2 * sep);

}

static void esccheck (LexState *ls, int c, const char *msg) {

  if (!c) {

    if (ls->current != EOZ)

      save_and_next(ls);  /* add current to buffer for error message */

    lexerror(ls, msg, TK_STRING);

  }

}

static int gethexa (LexState *ls) {

  save_and_next(ls);

  esccheck (ls, lisxdigit(ls->current), "hexadecimal digit expected");

  return luaO_hexavalue(ls->current);

}

static int readhexaesc (LexState *ls) {

  int r = gethexa(ls);

  r = (r << 4) + gethexa(ls);

  luaZ_buffremove(ls->buff, 2);  /* remove saved chars from buffer */

  return r;

}

static unsigned long readutf8esc (LexState *ls) {

  unsigned long r;

  int i = 4;  /* chars to be removed: '\', 'u', '{', and first digit */

  save_and_next(ls);  /* skip 'u' */

  esccheck(ls, ls->current == '{', "missing '{'");

  r = gethexa(ls);  /* must have at least one digit */

  while (cast_void(save_and_next(ls)), lisxdigit(ls->current)) {

    i++;

    esccheck(ls, r <= (0x7FFFFFFFu >> 4), "UTF-8 value too large");

    r = (r << 4) + luaO_hexavalue(ls->current);

  }

  esccheck(ls, ls->current == '}', "missing '}'");

  next(ls);  /* skip '}' */

  luaZ_buffremove(ls->buff, i);  /* remove saved chars from buffer */

  return r;

}

static void utf8esc (LexState *ls) {

  char buff[UTF8BUFFSZ];

  int n = luaO_utf8esc(buff, readutf8esc(ls));

  for (; n > 0; n--)  /* add 'buff' to string */

    save(ls, buff[UTF8BUFFSZ - n]);

}

static int readdecesc (LexState *ls) {

  int i;

  int r = 0;  /* result accumulator */

  for (i = 0; i < 3 && lisdigit(ls->current); i++) {  /* read up to 3 digits */

    r = 10*r + ls->current - '0';

    save_and_next(ls);

  }

  esccheck(ls, r <= UCHAR_MAX, "decimal escape too large");

  luaZ_buffremove(ls->buff, i);  /* remove read digits from buffer */

  return r;

}

static void read_string (LexState *ls, int del, SemInfo *seminfo) {

  save_and_next(ls);  /* keep delimiter (for error messages) */

  while (ls->current != del) {

    switch (ls->current) {

      case EOZ:

        lexerror(ls, "unfinished string", TK_EOS);

        break;  /* to avoid warnings */

      case '\n':

      case '\r':

        lexerror(ls, "unfinished string", TK_STRING);

        break;  /* to avoid warnings */

      case '\\': {  /* escape sequences */

        int c;  /* final character to be saved */

        save_and_next(ls);  /* keep '\\' for error messages */

        switch (ls->current) {

          case 'a': c = '\a'; goto read_save;

          case 'b': c = '\b'; goto read_save;

          case 'f': c = '\f'; goto read_save;

          case 'n': c = '\n'; goto read_save;

          case 'r': c = '\r'; goto read_save;

          case 't': c = '\t'; goto read_save;

          case 'v': c = '\v'; goto read_save;

          case 'x': c = readhexaesc(ls); goto read_save;

          case 'u': utf8esc(ls);  goto no_save;

          case '\n': case '\r':

            inclinenumber(ls); c = '\n'; goto only_save;

          case '\\': case '\"': case '\'':

            c = ls->current; goto read_save;

          case EOZ: goto no_save;  /* will raise an error next loop */

          case 'z': {  /* zap following span of spaces */

            luaZ_buffremove(ls->buff, 1);  /* remove '\\' */

            next(ls);  /* skip the 'z' */

            while (lisspace(ls->current)) {

              if (currIsNewline(ls)) inclinenumber(ls);

              else next(ls);

            }

            goto no_save;

          }

          default: {

            esccheck(ls, lisdigit(ls->current), "invalid escape sequence");

            c = readdecesc(ls);  /* digital escape '\ddd' */

            goto only_save;

          }

        }

       read_save:

         next(ls);

         /* go through */

       only_save:

         luaZ_buffremove(ls->buff, 1);  /* remove '\\' */

         save(ls, c);

         /* go through */

       no_save: break;

      }

      default:

        save_and_next(ls);

    }

  }

  save_and_next(ls);  /* skip delimiter */

  seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1,

                                   luaZ_bufflen(ls->buff) - 2);

}

static int llex (LexState *ls, SemInfo *seminfo) {

  luaZ_resetbuffer(ls->buff);

  for (;;) {

    switch (ls->current) {

      case '\n': case '\r': {  /* line breaks */

        inclinenumber(ls);

        break;

      }

      case ' ': case '\f': case '\t': case '\v': {  /* spaces */

        next(ls);

        break;

      }

      case '-': {  /* '-' or '--' (comment) */

        next(ls);

        if (ls->current != '-') return '-';

        /* else is a comment */

        next(ls);

        if (ls->current == '[') {  /* long comment? */

          size_t sep = skip_sep(ls);

          luaZ_resetbuffer(ls->buff);  /* 'skip_sep' may dirty the buffer */

          if (sep >= 2) {

            read_long_string(ls, NULL, sep);  /* skip long comment */

            luaZ_resetbuffer(ls->buff);  /* previous call may dirty the buff. */

            break;

          }

        }

        /* else short comment */

        while (!currIsNewline(ls) && ls->current != EOZ)

          next(ls);  /* skip until end of line (or end of file) */

        break;

      }

      case '[': {  /* long string or simply '[' */

        size_t sep = skip_sep(ls);

        if (sep >= 2) {

          read_long_string(ls, seminfo, sep);

          return TK_STRING;

        }

        else if (sep == 0)  /* '[=...' missing second bracket? */

          lexerror(ls, "invalid long string delimiter", TK_STRING);

        return '[';

      }

      case '=': {

        next(ls);

        if (check_next1(ls, '=')) return TK_EQ;  /* '==' */

        else return '=';

      }

      case '<': {

        next(ls);

        if (check_next1(ls, '=')) return TK_LE;  /* '<=' */

        else if (check_next1(ls, '<')) return TK_SHL;  /* '<<' */

        else return '<';

      }

      case '>': {

        next(ls);

        if (check_next1(ls, '=')) return TK_GE;  /* '>=' */

        else if (check_next1(ls, '>')) return TK_SHR;  /* '>>' */

        else return '>';

      }

      case '/': {

        next(ls);

        if (check_next1(ls, '/')) return TK_IDIV;  /* '//' */

        else return '/';

      }

      case '~': {

        next(ls);

        if (check_next1(ls, '=')) return TK_NE;  /* '~=' */

        else return '~';

      }

      case ':': {

        next(ls);

        if (check_next1(ls, ':')) return TK_DBCOLON;  /* '::' */

        else return ':';

      }

      case '"': case '\'': {  /* short literal strings */

        read_string(ls, ls->current, seminfo);

        return TK_STRING;

      }

      case '.': {  /* '.', '..', '...', or number */

        save_and_next(ls);

        if (check_next1(ls, '.')) {

          if (check_next1(ls, '.'))

            return TK_DOTS;   /* '...' */

          else return TK_CONCAT;   /* '..' */

        }

        else if (!lisdigit(ls->current)) return '.';

        else return read_numeral(ls, seminfo);

      }

      case '0': case '1': case '2': case '3': case '4':

      case '5': case '6': case '7': case '8': case '9': {

        return read_numeral(ls, seminfo);

      }

      case EOZ: {

        return TK_EOS;

      }

      default: {

        if (lislalpha(ls->current)) {  /* identifier or reserved word? */

          TString *ts;

          do {

            save_and_next(ls);

          } while (lislalnum(ls->current));

          ts = luaX_newstring(ls, luaZ_buffer(ls->buff),

                                  luaZ_bufflen(ls->buff));

          seminfo->ts = ts;

          if (isreserved(ts))  /* reserved word? */

            return ts->extra - 1 + FIRST_RESERVED;

          else {

            return TK_NAME;

          }

        }

        else {  /* single-char tokens ('+', '*', '%', '{', '}', ...) */

          int c = ls->current;

          next(ls);

          return c;

        }

      }

    }

  }

}

void luaX_next (LexState *ls) {

  ls->lastline = ls->linenumber;

  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 = llex(ls, &ls->t.seminfo);  /* read next token */

}

int luaX_lookahead (LexState *ls) {

  lua_assert(ls->lookahead.token == TK_EOS);

  ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);

  return ls->lookahead.token;

}