* src/nullable.h: New file.

[bison.git] / src / lex.c

/* Token-reader for Bison's input parser,
   Copyright (C) 1984, 1986, 1989, 1992, 2000 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 "getopt.h"		/* for optarg */
#include "symtab.h"
#include "lex.h"
#include "alloc.h"
#include "complain.h"

/*spec_outfile is declared in files.h, for -o */

extern int translations;

/* functions from main.c */
extern char *printable_version PARAMS ((int));

/* Buffer for storing the current token.  */
char *token_buffer;

/* Allocated size of token_buffer, not including space for terminator.  */
int maxtoken;

bucket *symval;
int numval;

static int unlexed;		/* these two describe a token to be reread */
static bucket *unlexed_symval;	/* by the next call to lex */


void
init_lex (void)
{
  maxtoken = 100;
  token_buffer = NEW2 (maxtoken + 1, char);
  unlexed = -1;
}


char *
grow_token_buffer (char *p)
{
  int offset = p - token_buffer;
  maxtoken *= 2;
  token_buffer = (char *) xrealloc (token_buffer, maxtoken + 1);
  return token_buffer + offset;
}


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

  c = getc (finput);

  for (;;)
    {
      int cplus_comment;

      switch (c)
	{
	case '/':
	  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 */
static 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.       |
| Append the normalized string version of the char to *PP.  Assign  |
| the character code to *PCODE. Return 1 unless the character is an |
| unescaped `term' or \n report error for \n                        |
`------------------------------------------------------------------*/

static int
literalchar (char **pp, int *pcode, char term)
{
  int c;
  char *p;
  int code;
  int wasquote = 0;

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

  /* now fill token_buffer with the canonical name for this character
     as a literal token.  Do not use what the user typed,
     so that `\012' and `\n' can be interchangeable.  */

  p = *pp;
  if (code == term && wasquote)
    *p++ = code;
  else if (code == '\\')
    {
      *p++ = '\\';
      *p++ = '\\';
    }
  else if (code == '\'')
    {
      *p++ = '\\';
      *p++ = '\'';
    }
  else if (code == '\"')
    {
      *p++ = '\\';
      *p++ = '\"';
    }
  else if (code >= 040 && code < 0177)
    *p++ = code;
  else if (code == '\t')
    {
      *p++ = '\\';
      *p++ = 't';
    }
  else if (code == '\n')
    {
      *p++ = '\\';
      *p++ = 'n';
    }
  else if (code == '\r')
    {
      *p++ = '\\';
      *p++ = 'r';
    }
  else if (code == '\v')
    {
      *p++ = '\\';
      *p++ = 'v';
    }
  else if (code == '\b')
    {
      *p++ = '\\';
      *p++ = 'b';
    }
  else if (code == '\f')
    {
      *p++ = '\\';
      *p++ = 'f';
    }
  else
    {
      *p++ = '\\';
      *p++ = code / 0100 + '0';
      *p++ = ((code / 010) & 07) + '0';
      *p++ = (code & 07) + '0';
    }
  *pp = p;
  *pcode = code;
  return !wasquote;
}


void
unlex (int token)
{
  unlexed = token;
  unlexed_symval = symval;
}


int
lex (void)
{
  int c;
  char *p;

  if (unlexed >= 0)
    {
      symval = unlexed_symval;
      c = unlexed;
      unlexed = -1;
      return c;
    }

  c = skip_white_space ();
  *token_buffer = c;		/* for error messages (token buffer always valid) */
  token_buffer[1] = 0;

  switch (c)
    {
    case EOF:
      strcpy (token_buffer, "EOF");
      return ENDFILE;

    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 '_':

      p = token_buffer;
      while (isalnum (c) || c == '_' || c == '.')
	{
	  if (p == token_buffer + maxtoken)
	    p = grow_token_buffer (p);

	  *p++ = c;
	  c = getc (finput);
	}

      *p = 0;
      ungetc (c, finput);
      symval = getsym (token_buffer);
      return IDENTIFIER;

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

	p = token_buffer;
	while (isdigit (c))
	  {
	    if (p == token_buffer + maxtoken)
	      p = grow_token_buffer (p);

	    *p++ = c;
	    numval = numval * 10 + c - '0';
	    c = getc (finput);
	  }
	*p = 0;
	ungetc (c, finput);
	return NUMBER;
      }

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

      translations = -1;
      {
	int code, discode;
	char discard[10], *dp;

	p = token_buffer;
	*p++ = '\'';
	literalchar (&p, &code, '\'');

	c = getc (finput);
	if (c != '\'')
	  {
	    complain (_("use \"...\" for multi-character literal tokens"));
	    while (1)
	      {
		dp = discard;
		if (!literalchar (&dp, &discode, '\''))
		  break;
	      }
	  }
	*p++ = '\'';
	*p = 0;
	symval = getsym (token_buffer);
	symval->class = STOKEN;
	if (!symval->user_token_number)
	  symval->user_token_number = code;
	return IDENTIFIER;
      }

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

      translations = -1;
      {
	int code;		/* ignored here */
	p = token_buffer;
	*p++ = '\"';
	while (literalchar (&p, &code, '\"'))	/* read up to and including " */
	  {
	    if (p >= token_buffer + maxtoken - 4)
	      p = grow_token_buffer (p);
	  }
	*p = 0;

	symval = getsym (token_buffer);
	symval->class = STOKEN;

	return IDENTIFIER;
      }

    case ',':
      return COMMA;

    case ':':
      return COLON;

    case ';':
      return SEMICOLON;

    case '|':
      return BAR;

    case '{':
      return LEFT_CURLY;

    case '=':
      do
	{
	  c = getc (finput);
	  if (c == '\n')
	    lineno++;
	}
      while (c == ' ' || c == '\n' || c == '\t');

      if (c == '{')
	{
	  strcpy (token_buffer, "={");
	  return LEFT_CURLY;
	}
      else
	{
	  ungetc (c, finput);
	  return ILLEGAL;
	}

    case '<':
      p = token_buffer;
      c = getc (finput);
      while (c != '>')
	{
	  if (c == EOF)
	    fatal (_("unterminated type name at end of file"));
	  if (c == '\n')
	    {
	      complain (_("unterminated type name"));
	      ungetc (c, finput);
	      break;
	    }

	  if (p == token_buffer + maxtoken)
	    p = grow_token_buffer (p);

	  *p++ = c;
	  c = getc (finput);
	}
      *p = 0;
      return TYPENAME;


    case '%':
      return parse_percent_token ();

    default:
      return ILLEGAL;
    }
}

/* the following table dictates the action taken for the various %
   directives.  A setflag value causes the named flag to be set.  A
   retval action returns the code.  */
struct percent_table_struct
{
  const char *name;
  void *setflag;
  int retval;
}
percent_table[] =
{
  { "token", NULL, TOKEN },
  { "term", NULL, TOKEN },
  { "nterm", NULL, NTERM },
  { "type", NULL, TYPE },
  { "guard", NULL, GUARD },
  { "union", NULL, UNION },
  { "expect", NULL, EXPECT },
  { "thong", NULL, THONG },
  { "start", NULL, START },
  { "left", NULL, LEFT },
  { "right", NULL, RIGHT },
  { "nonassoc", NULL, NONASSOC },
  { "binary", NULL, NONASSOC },
  { "semantic_parser", NULL, SEMANTIC_PARSER },
  { "pure_parser", NULL, PURE_PARSER },
  { "prec", NULL, PREC },
  { "no_lines", &nolinesflag, NOOP},	/* -l */
  { "raw", &rawtoknumflag, NOOP },	/* -r */
  { "token_table", &toknumflag, NOOP},	/* -k */
#if 0
    /* These can be utilized after main is reoganized so
       open_files() is deferred 'til after read_declarations().
       But %{ and %union both put information into files
       that have to be opened before read_declarations().
     */
  { "yacc", &fixed_outfiles, NOOP},			/* -y */
  { "fixed_output_files", &fixed_outfiles, NOOP},	/* -y */
  { "defines", &definesflag, NOOP},			/* -d */
  { "no_parser", &noparserflag, NOOP},			/* -n */
  { "output_file", &spec_outfile, SETOPT},		/* -o */
  { "file_prefix", &spec_file_prefix, SETOPT},		/* -b */
  { "name_prefix", &spec_name_prefix, SETOPT},		/* -p */
    /* These would be acceptable, but they do not affect processing */
  { "verbose", &verboseflag, NOOP},			/* -v */
  { "debug", &debugflag, NOOP},				/* -t */
/*    {"help", <print usage stmt>, NOOP}, *//* -h */
/*    {"version", <print version number> ,  NOOP}, *//* -V */
#endif
  { NULL, NULL, ILLEGAL}
};

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

int
parse_percent_token (void)
{
  int c;
  char *p;
  struct percent_table_struct *tx;

  p = token_buffer;
  c = getc (finput);
  *p++ = '%';
  *p++ = c;			/* for error msg */
  *p = 0;

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

    case '{':
      return PERCENT_LEFT_CURLY;

    case '<':
      return LEFT;

    case '>':
      return RIGHT;

    case '2':
      return NONASSOC;

    case '0':
      return TOKEN;

    case '=':
      return PREC;
    }
  if (!isalpha (c))
    return ILLEGAL;

  p = token_buffer;
  *p++ = '%';
  while (isalpha (c) || c == '_' || c == '-')
    {
      if (p == token_buffer + maxtoken)
	p = grow_token_buffer (p);

      if (c == '-')
	c = '_';
      *p++ = c;
      c = getc (finput);
    }

  ungetc (c, finput);

  *p = 0;

  /* table lookup % directive */
  for (tx = percent_table; tx->name; tx++)
    if (strcmp (token_buffer + 1, tx->name) == 0)
      break;
  if (tx->retval == SETOPT)
    {
      *((char **) (tx->setflag)) = optarg;
      return NOOP;
    }
  if (tx->setflag)
    {
      *((int *) (tx->setflag)) = 1;
      return NOOP;
    }
  return tx->retval;
}