* src/reader.c (grammar_rule_begin, previous_rule, current_rule):

[bison.git] / src / lex.c

/* Token-reader for Bison's input parser,
   Copyright (C) 1984, 1986, 1989, 1992, 2000, 2001, 2002
   Free Software Foundation, Inc.

   This file is part of Bison, the GNU Compiler Compiler.

   Bison is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   Bison is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with Bison; see the file COPYING.  If not, write to
   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "system.h"
#include "getargs.h"
#include "files.h"
#include "symtab.h"
#include "options.h"
#include "lex.h"
#include "complain.h"
#include "gram.h"
#include "quote.h"

/* Buffer for storing the current token.  */
static struct obstack token_obstack;
const char *token_buffer = NULL;

symbol_t *symval = NULL;
int numval;

/* A token to be reread, see unlex and lex. */
static token_t unlexed = tok_undef;
static symbol_t *unlexed_symval = NULL;
static const char *unlexed_token_buffer = NULL;

void
lex_init (void)
{
  obstack_init (&token_obstack);
  unlexed = tok_undef;
}


void
lex_free (void)
{
  obstack_free (&token_obstack, NULL);
}


int
skip_white_space (void)
{
  int c;
  int inside;

  c = getc (finput);

  for (;;)
    {
      int cplus_comment;

      switch (c)
	{
	case '/':
	  /* FIXME: Should probably be merged with copy_comment.  */
	  c = getc (finput);
	  if (c != '*' && c != '/')
	    {
	      complain (_("unexpected `/' found and ignored"));
	      break;
	    }
	  cplus_comment = (c == '/');

	  c = getc (finput);

	  inside = 1;
	  while (inside)
	    {
	      if (!cplus_comment && c == '*')
		{
		  while (c == '*')
		    c = getc (finput);

		  if (c == '/')
		    {
		      inside = 0;
		      c = getc (finput);
		    }
		}
	      else if (c == '\n')
		{
		  lineno++;
		  if (cplus_comment)
		    inside = 0;
		  c = getc (finput);
		}
	      else if (c == EOF)
		fatal (_("unterminated comment"));
	      else
		c = getc (finput);
	    }

	  break;

	case '\n':
	  lineno++;

	case ' ':
	case '\t':
	case '\f':
	  c = getc (finput);
	  break;

	default:
	  return c;
	}
    }
}


/*-----------------------------------------------------.
| Do a getc, but give error message if EOF encountered |
`-----------------------------------------------------*/

int
xgetc (FILE *f)
{
  int c = getc (f);
  if (c == EOF)
    fatal (_("unexpected end of file"));
  return c;
}


/*---------------------------------------------------------------.
| Read one literal character from FINPUT, process \-escapes, and |
| return the character.                                          |
`---------------------------------------------------------------*/

char
literalchar (void)
{
  int c;
  int res;

  c = xgetc (finput);
  if (c == '\n')
    {
      complain (_("unescaped newline in constant"));
      ungetc (c, finput);
      res = '?';
    }
  else if (c != '\\')
    {
      res = c;
    }
  else
    {
      c = xgetc (finput);
      if (c == 't')
	res = '\t';
      else if (c == 'n')
	res = '\n';
      else if (c == 'a')
	res = '\007';
      else if (c == 'r')
	res = '\r';
      else if (c == 'f')
	res = '\f';
      else if (c == 'b')
	res = '\b';
      else if (c == 'v')
	res = '\013';
      else if (c == '\\')
	res = '\\';
      else if (c == '\'')
	res = '\'';
      else if (c == '\"')
	res = '\"';
      else if (c <= '7' && c >= '0')
	{
	  res = 0;
	  while (c <= '7' && c >= '0')
	    {
	      res = (res * 8) + (c - '0');
	      if (res >= 256 || res < 0)
		{
		  complain (_("octal value outside range 0...255: `\\%o'"),
			    res);
		  res &= 0xFF;
		  break;
		}
	      c = xgetc (finput);
	    }
	  ungetc (c, finput);
	}
      else if (c == 'x')
	{
	  c = xgetc (finput);
	  res = 0;
	  while (1)
	    {
	      if (c >= '0' && c <= '9')
		res *= 16, res += c - '0';
	      else if (c >= 'a' && c <= 'f')
		res *= 16, res += c - 'a' + 10;
	      else if (c >= 'A' && c <= 'F')
		res *= 16, res += c - 'A' + 10;
	      else
		break;
	      if (res >= 256 || res < 0)
		{
		  complain (_("hexadecimal value above 255: `\\x%x'"), res);
		  res &= 0xFF;
		  break;
		}
	      c = xgetc (finput);
	    }
	  ungetc (c, finput);
	}
      else
	{
	  char badchar [] = "c";
	  badchar[0] = c;
	  complain (_("unknown escape sequence: `\\' followed by `%s'"),
		    quote (badchar));
	  res = '?';
	}
    }				/* has \ */

  return res;
}


void
unlex (token_t token)
{
  unlexed = token;
  unlexed_token_buffer = token_buffer;
  unlexed_symval = symval;
}

/*-----------------------------------------------------------------.
| We just read `<' from FIN.  Store in TOKEN_BUFFER, the type name |
| specified between the `<...>'.                                   |
`-----------------------------------------------------------------*/

void
read_type_name (FILE *fin)
{
  int c = getc (fin);

  while (c != '>')
    {
      if (c == EOF)
	fatal (_("unterminated type name at end of file"));
      if (c == '\n')
	{
	  complain (_("unterminated type name"));
	  ungetc (c, fin);
	  break;
	}

      obstack_1grow (&token_obstack, c);
      c = getc (fin);
    }
  obstack_1grow (&token_obstack, '\0');
  token_buffer = obstack_finish (&token_obstack);
}


token_t
lex (void)
{
  int c;

  /* Just to make sure. */
  token_buffer = NULL;

  if (unlexed != tok_undef)
    {
      token_t res = unlexed;
      symval = unlexed_symval;
      token_buffer = unlexed_token_buffer;
      unlexed = tok_undef;
      return res;
    }

  c = skip_white_space ();

  switch (c)
    {
    case EOF:
      token_buffer = "EOF";
      return tok_eof;

    case 'A':    case 'B':    case 'C':    case 'D':    case 'E':
    case 'F':    case 'G':    case 'H':    case 'I':    case 'J':
    case 'K':    case 'L':    case 'M':    case 'N':    case 'O':
    case 'P':    case 'Q':    case 'R':    case 'S':    case 'T':
    case 'U':    case 'V':    case 'W':    case 'X':    case 'Y':
    case 'Z':
    case 'a':    case 'b':    case 'c':    case 'd':    case 'e':
    case 'f':    case 'g':    case 'h':    case 'i':    case 'j':
    case 'k':    case 'l':    case 'm':    case 'n':    case 'o':
    case 'p':    case 'q':    case 'r':    case 's':    case 't':
    case 'u':    case 'v':    case 'w':    case 'x':    case 'y':
    case 'z':
    case '.':    case '_':

      while (isalnum (c) || c == '_' || c == '.')
	{
	  obstack_1grow (&token_obstack, c);
	  c = getc (finput);
	}
      obstack_1grow (&token_obstack, '\0');
      token_buffer = obstack_finish (&token_obstack);
      ungetc (c, finput);
      symval = getsym (token_buffer);
      return tok_identifier;

    case '0':    case '1':    case '2':    case '3':    case '4':
    case '5':    case '6':    case '7':    case '8':    case '9':
      {
	numval = 0;

	while (isdigit (c))
	  {
	    obstack_1grow (&token_obstack, c);
	    numval = numval * 10 + c - '0';
	    c = getc (finput);
	  }
	obstack_1grow (&token_obstack, '\0');
	token_buffer = obstack_finish (&token_obstack);
	ungetc (c, finput);
	return tok_number;
      }

    case '\'':
      /* parse the literal token and compute character code in  code  */

      {
	int code = literalchar ();

	obstack_1grow (&token_obstack, '\'');
	obstack_1grow (&token_obstack, code);

	c = getc (finput);
	if (c != '\'')
	  {
	    complain (_("use \"...\" for multi-character literal tokens"));
	    while (literalchar () != '\'')
	      /* Skip. */;
	  }
	obstack_1grow (&token_obstack, '\'');
	obstack_1grow (&token_obstack, '\0');
	token_buffer = obstack_finish (&token_obstack);
	symval = getsym (token_buffer);
	symbol_class_set (symval, token_sym);
	symbol_user_token_number_set (symval, code);
	return tok_identifier;
      }

    case '\"':
      /* parse the literal string token and treat as an identifier */

      {
	int code;

	obstack_1grow (&token_obstack, '\"');
	/* Read up to and including ".  */
	do
	  {
	    code = literalchar ();
	    obstack_1grow (&token_obstack, code);
	  }
	while (code != '\"');
	obstack_1grow (&token_obstack, '\0');
	token_buffer = obstack_finish (&token_obstack);

	symval = getsym (token_buffer);
	symbol_class_set (symval, token_sym);
	return tok_identifier;
      }

    case ',':
      token_buffer = ",";
      return tok_comma;

    case ':':
      token_buffer = ":";
      return tok_colon;

    case ';':
      token_buffer = ";";
      return tok_semicolon;

    case '|':
      token_buffer = "|";
      return tok_bar;

    case '{':
      token_buffer = "{";
      return tok_left_curly;

    case '=':
      obstack_1grow (&token_obstack, c);
      do
	{
	  c = getc (finput);
	  obstack_1grow (&token_obstack, c);
	  if (c == '\n')
	    lineno++;
	}
      while (c == ' ' || c == '\n' || c == '\t');
      obstack_1grow (&token_obstack, '\0');
      token_buffer = obstack_finish (&token_obstack);

      if (c == '{')
	{
	  return tok_left_curly;
	}
      else
	{
	  ungetc (c, finput);
	  return tok_illegal;
	}

    case '<':
      read_type_name (finput);
      return tok_typename;

    case '%':
      return parse_percent_token ();

    default:
      obstack_1grow (&token_obstack, c);
      obstack_1grow (&token_obstack, '\0');
      token_buffer = obstack_finish (&token_obstack);
      return tok_illegal;
    }
}

/* This function is a strcmp, which doesn't differentiate `-' and `_'
   chars.  */

static int
option_strcmp (const char *left, const char *right)
{
  const unsigned char *l, *r;
  int c;

  assert (left);
  assert (right);
  l = (const unsigned char *)left;
  r = (const unsigned char *)right;
  while (((c = *l - *r++) == 0 && *l != '\0')
	 || ((*l == '-' || *l == '_') && (*r == '_' || *r == '-')))
    l++;
  return c;
}

/* Parse a token which starts with %.
   Assumes the % has already been read and discarded.  */

token_t
parse_percent_token (void)
{
  const struct option_table_s *tx = NULL;
  const char *arg = NULL;
  /* Where the ARG was found in token_buffer. */
  size_t arg_offset = 0;

  int c = getc (finput);
  obstack_1grow (&token_obstack, '%');
  obstack_1grow (&token_obstack, c);

  if (!isalpha (c))
    {
      obstack_1grow (&token_obstack, '\0');
      token_buffer = obstack_finish (&token_obstack);

      switch (c)
	{
	case '%':
	  return tok_two_percents;

	case '{':
	  return tok_percent_left_curly;

	  /* The following guys are here for backward compatibility with
	     very ancient Yacc versions.  The paper of Johnson mentions
	     them (as ancient :).  */
	case '<':
	  return tok_left;

	case '>':
	  return tok_right;

	case '2':
	  return tok_nonassoc;

	case '0':
	  return tok_token;

	case '=':
	  return tok_prec;

	default:
	  return tok_illegal;
	}
    }

  while (c = getc (finput), isalpha (c) || c == '_' || c == '-')
    {
      if (c == '_')
	c = '-';
      obstack_1grow (&token_obstack, c);
    }

  /* %DIRECTIVE="ARG".  Separate into
     TOKEN_BUFFER = `%DIRECTIVE\0ARG\0'.
     This is a bit hackish, but once we move to a Bison parser,
     things will be cleaned up.  */
  if (c == '=')
    {
      /* End of the directive.  We skip the `='. */
      obstack_1grow (&token_obstack, '\0');
      /* Fetch the ARG if present. */
      c = getc (finput);
      if (c == '"')
	{
	  int code;
	  arg_offset = obstack_object_size (&token_obstack);
	  /* Read up to and including `"'.  Do not append the closing
	     `"' in the output: it's not part of the ARG.  */
	  while ((code = literalchar ()) != '"')
	    obstack_1grow (&token_obstack, code);
	}
      /* else: should be an error. */
    }
  else
    ungetc (c, finput);

  obstack_1grow (&token_obstack, '\0');
  token_buffer = obstack_finish (&token_obstack);
  if (arg_offset)
    arg = token_buffer + arg_offset;

  /* table lookup % directive */
  for (tx = option_table; tx->name; tx++)
    if ((tx->access == opt_percent || tx->access == opt_both)
	&& option_strcmp (token_buffer + 1, tx->name) == 0)
      break;

  if (arg && tx->ret_val != tok_stropt)
    fatal (_("`%s' supports no argument: %s"), token_buffer, quote (arg));


  switch (tx->ret_val)
    {
    case tok_stropt:
      assert (tx->flag);
      if (arg)
	{
	  char **flag = (char **) tx->flag;
	  /* Keep only the first assignment: command line options have
	     already been processed, and we want them to have
	     precedence.  Side effect: if this %-option is used
	     several times, only the first is honored.  Bah.  */
	  if (!*flag)
	    *flag = xstrdup (arg);
	}
      else
	fatal (_("`%s' requires an argument"), token_buffer);
      return tok_noop;
      break;

    case tok_intopt:
      assert (tx->flag);
      *((int *) (tx->flag)) = 1;
      return tok_noop;
      break;

    case tok_obsolete:
      fatal (_("`%s' is no longer supported"), token_buffer);
      return tok_noop;
      break;

    default:
      return tx->ret_val;
      break;
    }
  abort ();
}