/*

** $Id: llex.c,v 1.119 2003/03/24 12:39:34 roberto Exp $

** Lexical Analyzer

** See Copyright Notice in lua.h

*/





#include <ctype.h>

#include <string.h>



#define llex_c



#include "lua.h"



#include "ldo.h"

#include "llex.h"

#include "lobject.h"

#include "lparser.h"

#include "lstate.h"

#include "lstring.h"

#include "lzio.h"







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







/* ORDER RESERVED */

static const char *const token2string [] = {

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

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

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

    "return", "then", "true", "until", "while", "*name",

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

    "*number", "*string", "<eof>"

};





void luaX_init (lua_State *L) {

  int i;

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

    TString *ts = luaS_new(L, token2string[i]);

    luaS_fix(ts);  /* reserved words are never collected */

    lua_assert(strlen(token2string[i])+1 <= TOKEN_LEN);

    ts->tsv.reserved = cast(lu_byte, i+1);  /* reserved word */

  }

}





#define MAXSRC          80





void luaX_checklimit (LexState *ls, int val, int limit, const char *msg) {

  if (val > limit) {

    msg = luaO_pushfstring(ls->L, "too many %s (limit=%d)", msg, limit);

    luaX_syntaxerror(ls, msg);

  }

}





void luaX_errorline (LexState *ls, const char *s, const char *token, int line) {

  lua_State *L = ls->L;

  char buff[MAXSRC];

  luaO_chunkid(buff, getstr(ls->source), MAXSRC);

  luaO_pushfstring(L, "%s:%d: %s near `%s'", buff, line, s, token); 

  luaD_throw(L, LUA_ERRSYNTAX);

}





static void luaX_error (LexState *ls, const char *s, const char *token) {

  luaX_errorline(ls, s, token, ls->linenumber);

}





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

  const char *lasttoken;

  switch (ls->t.token) {

    case TK_NAME:

      lasttoken = getstr(ls->t.seminfo.ts);

      break;

    case TK_STRING:

    case TK_NUMBER:

      lasttoken = luaZ_buffer(ls->buff);

      break;

    default:

      lasttoken = luaX_token2str(ls, ls->t.token);

      break;

  }

  luaX_error(ls, msg, lasttoken);

}





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

  if (token < FIRST_RESERVED) {

    lua_assert(token == (unsigned char)token);

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

  }

  else

    return token2string[token-FIRST_RESERVED];

}





static void luaX_lexerror (LexState *ls, const char *s, int token) {

  if (token == TK_EOS)

    luaX_error(ls, s, luaX_token2str(ls, token));

  else

    luaX_error(ls, s, luaZ_buffer(ls->buff));

}





static void inclinenumber (LexState *LS) {

  next(LS);  /* skip `\n' */

  ++LS->linenumber;

  luaX_checklimit(LS, LS->linenumber, MAX_INT, "lines in a chunk");

}





void luaX_setinput (lua_State *L, LexState *LS, ZIO *z, TString *source) {

  LS->L = L;

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

  LS->z = z;

  LS->fs = NULL;

  LS->linenumber = 1;

  LS->lastline = 1;

  LS->source = source;

  next(LS);  /* read first char */

  if (LS->current == '#') {

    do {  /* skip first line */

      next(LS);

    } while (LS->current != '\n' && LS->current != EOZ);

  }

}







/*

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

** LEXICAL ANALYZER

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

*/





/* use buffer to store names, literal strings and numbers */



/* extra space to allocate when growing buffer */

#define EXTRABUFF	32



/* maximum number of chars that can be read without checking buffer size */

#define MAXNOCHECK	5



#define checkbuffer(LS, len)	\

    if (((len)+MAXNOCHECK)*sizeof(char) > luaZ_sizebuffer((LS)->buff)) \

      luaZ_openspace((LS)->L, (LS)->buff, (len)+EXTRABUFF)



#define save(LS, c, l) \

	(luaZ_buffer((LS)->buff)[l++] = cast(char, c))

#define save_and_next(LS, l)  (save(LS, LS->current, l), next(LS))





static size_t readname (LexState *LS) {

  size_t l = 0;

  checkbuffer(LS, l);

  do {

    checkbuffer(LS, l);

    save_and_next(LS, l);

  } while (isalnum(LS->current) || LS->current == '_');

  save(LS, '\0', l);

  return l-1;

}





/* LUA_NUMBER */

static void read_numeral (LexState *LS, int comma, SemInfo *seminfo) {

  size_t l = 0;

  checkbuffer(LS, l);

  if (comma) save(LS, '.', l);

  while (isdigit(LS->current)) {

    checkbuffer(LS, l);

    save_and_next(LS, l);

  }

  if (LS->current == '.') {

    save_and_next(LS, l);

    if (LS->current == '.') {

      save_and_next(LS, l);

      save(LS, '\0', l);

      luaX_lexerror(LS,

                 "ambiguous syntax (decimal point x string concatenation)",

                 TK_NUMBER);

    }

  }

  while (isdigit(LS->current)) {

    checkbuffer(LS, l);

    save_and_next(LS, l);

  }

  if (LS->current == 'e' || LS->current == 'E') {

    save_and_next(LS, l);  /* read `E' */

    if (LS->current == '+' || LS->current == '-')

      save_and_next(LS, l);  /* optional exponent sign */

    while (isdigit(LS->current)) {

      checkbuffer(LS, l);

      save_and_next(LS, l);

    }

  }

  save(LS, '\0', l);

  if (!luaO_str2d(luaZ_buffer(LS->buff), &seminfo->r))

    luaX_lexerror(LS, "malformed number", TK_NUMBER);

}





static void read_long_string (LexState *LS, SemInfo *seminfo) {

  int cont = 0;

  size_t l = 0;

  checkbuffer(LS, l);

  save(LS, '[', l);  /* save first `[' */

  save_and_next(LS, l);  /* pass the second `[' */

  if (LS->current == '\n')  /* string starts with a newline? */

    inclinenumber(LS);  /* skip it */

  for (;;) {

    checkbuffer(LS, l);

    switch (LS->current) {

      case EOZ:

        save(LS, '\0', l);

        luaX_lexerror(LS, (seminfo) ? "unfinished long string" :

                                   "unfinished long comment", TK_EOS);

        break;  /* to avoid warnings */

      case '[':

        save_and_next(LS, l);

        if (LS->current == '[') {

          cont++;

          save_and_next(LS, l);

        }

        continue;

      case ']':

        save_and_next(LS, l);

        if (LS->current == ']') {

          if (cont == 0) goto endloop;

          cont--;

          save_and_next(LS, l);

        }

        continue;

      case '\n':

        save(LS, '\n', l);

        inclinenumber(LS);

        if (!seminfo) l = 0;  /* reset buffer to avoid wasting space */

        continue;

      default:

        save_and_next(LS, l);

    }

  } endloop:

  save_and_next(LS, l);  /* skip the second `]' */

  save(LS, '\0', l);

  if (seminfo)

    seminfo->ts = luaS_newlstr(LS->L, luaZ_buffer(LS->buff) + 2, l - 5);

}





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

  size_t l = 0;

  checkbuffer(LS, l);

  save_and_next(LS, l);

  while (LS->current != del) {

    checkbuffer(LS, l);

    switch (LS->current) {

      case EOZ:

        save(LS, '\0', l);

        luaX_lexerror(LS, "unfinished string", TK_EOS);

        break;  /* to avoid warnings */

      case '\n':

        save(LS, '\0', l);

        luaX_lexerror(LS, "unfinished string", TK_STRING);

        break;  /* to avoid warnings */

      case '\\':

        next(LS);  /* do not save the `\' */

        switch (LS->current) {

          case 'a': save(LS, '\a', l); next(LS); break;

          case 'b': save(LS, '\b', l); next(LS); break;

          case 'f': save(LS, '\f', l); next(LS); break;

          case 'n': save(LS, '\n', l); next(LS); break;

          case 'r': save(LS, '\r', l); next(LS); break;

          case 't': save(LS, '\t', l); next(LS); break;

          case 'v': save(LS, '\v', l); next(LS); break;

          case '\n': save(LS, '\n', l); inclinenumber(LS); break;

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

          default: {

            if (!isdigit(LS->current))

              save_and_next(LS, l);  /* handles \\, \", \', and \? */

            else {  /* \xxx */

              int c = 0;

              int i = 0;

              do {

                c = 10*c + (LS->current-'0');

                next(LS);

              } while (++i<3 && isdigit(LS->current));

              if (c > UCHAR_MAX) {

                save(LS, '\0', l);

                luaX_lexerror(LS, "escape sequence too large", TK_STRING);

              }

              save(LS, c, l);

            }

          }

        }

        break;

      default:

        save_and_next(LS, l);

    }

  }

  save_and_next(LS, l);  /* skip delimiter */

  save(LS, '\0', l);

  seminfo->ts = luaS_newlstr(LS->L, luaZ_buffer(LS->buff) + 1, l - 3);

}





int luaX_lex (LexState *LS, SemInfo *seminfo) {

  for (;;) {

    switch (LS->current) {



      case '\n': {

        inclinenumber(LS);

        continue;

      }

      case '-': {

        next(LS);

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

        /* else is a comment */

        next(LS);

        if (LS->current == '[' && (next(LS), LS->current == '['))

          read_long_string(LS, NULL);  /* long comment */

        else  /* short comment */

          while (LS->current != '\n' && LS->current != EOZ)

            next(LS);

        continue;

      }

      case '[': {

        next(LS);

        if (LS->current != '[') return '[';

        else {

          read_long_string(LS, seminfo);

          return TK_STRING;

        }

      }

      case '=': {

        next(LS);

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

        else { next(LS); return TK_EQ; }

      }

      case '<': {

        next(LS);

        if (LS->current != '=') return '<';

        else { next(LS); return TK_LE; }

      }

      case '>': {

        next(LS);

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

        else { next(LS); return TK_GE; }

      }

      case '~': {

        next(LS);

        if (LS->current != '=') return '~';

        else { next(LS); return TK_NE; }

      }

      case '"':

      case '\'': {

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

        return TK_STRING;

      }

      case '.': {

        next(LS);

        if (LS->current == '.') {

          next(LS);

          if (LS->current == '.') {

            next(LS);

            return TK_DOTS;   /* ... */

          }

          else return TK_CONCAT;   /* .. */

        }

        else if (!isdigit(LS->current)) return '.';

        else {

          read_numeral(LS, 1, seminfo);

          return TK_NUMBER;

        }

      }

      case EOZ: {

        return TK_EOS;

      }

      default: {

        if (isspace(LS->current)) {

          next(LS);

          continue;

        }

        else if (isdigit(LS->current)) {

          read_numeral(LS, 0, seminfo);

          return TK_NUMBER;

        }

        else if (isalpha(LS->current) || LS->current == '_') {

          /* identifier or reserved word */

          size_t l = readname(LS);

          TString *ts = luaS_newlstr(LS->L, luaZ_buffer(LS->buff), l);

          if (ts->tsv.reserved > 0)  /* reserved word? */

            return ts->tsv.reserved - 1 + FIRST_RESERVED;

          seminfo->ts = ts;

          return TK_NAME;

        }

        else {

          int c = LS->current;

          if (iscntrl(c))

            luaX_error(LS, "invalid control char",

                           luaO_pushfstring(LS->L, "char(%d)", c));

          next(LS);

          return c;  /* single-char tokens (+ - / ...) */

        }

      }

    }

  }

}



#undef next

