reader.c

bison源代码.bison 是替代yacc的语法分析程序生成器. yacc是 Yet Another Compiler Compiler的缩写. bison又是什么呐 是一个生成可以分析文本文件结构

    }
}



/* read in a %left, %right or %nonassoc declaration and record its information.  */
/* assoc is either LEFT_ASSOC, RIGHT_ASSOC or NON_ASSOC.  */

void
parse_assoc_decl (assoc)
int assoc;
{
  register int k;
  register char *name = NULL;
  register int prev = 0;

  lastprec++;  /* Assign a new precedence level, never 0.  */

  for (;;)
    {
      register int t;

      if(ungetc(skip_white_space(), finput) == '%')
	return;

      t = lex();

      switch (t)
	{

	case TYPENAME:
	  k = strlen(token_buffer);
	  name = NEW2(k + 1, char);
	  strcpy(name, token_buffer);
	  break;

	case COMMA:
	  break;

	case IDENTIFIER:
	  if (symval->prec != 0)
	    warns("redefining precedence of %s", symval->tag);
	  symval->prec = lastprec;
	  symval->assoc = assoc;
	  if (symval->class == SNTERM)
	    warns("symbol %s redefined", symval->tag);
	  symval->class = STOKEN;
	  if (name)
	    { /* record the type, if one is specified */
	      if (symval->type_name == NULL)
		symval->type_name = name;
	      else if (strcmp(name, symval->type_name) != 0)
		warns("type redeclaration for %s", symval->tag);
	    }
	  break;

	case NUMBER:
	  if (prev == IDENTIFIER)
            {
	      symval->user_token_number = numval;
	      translations = 1;
            }
          else	  
            {
	      warns("invalid text (%s) - number should be after identifier", 
			token_buffer);
	      skip_to_char('%');
            }
	  break;

	case SEMICOLON:
	  return;

	default:
	  warns("unexpected item: %s", token_buffer);
	  skip_to_char('%');
	}

      prev = t;

    }
}



/* copy the union declaration into fattrs (and fdefines),
   where it is made into the
   definition of YYSTYPE, the type of elements of the parser value stack.  */

void
parse_union_decl()
{
  register int c;
  register int count;
  register int in_comment;
  int cplus_comment;

  if (typed)
    warn("multiple %union declarations");

  typed = 1;

  if (!nolinesflag)
    fprintf(fattrs, "\n#line %d \"%s\"\n", lineno, infile);
  else
    fprintf(fattrs, "\n");

  fprintf(fattrs, "typedef union");
  if (fdefines)
    fprintf(fdefines, "typedef union");

  count = 0;
  in_comment = 0;

  c = getc(finput);

  while (c != EOF)
    {
      putc(c, fattrs);
      if (fdefines)
	putc(c, fdefines);

      switch (c)
	{
	case '\n':
	  lineno++;
	  break;

	case '/':
	  c = getc(finput);
	  if (c != '*' && c != '/')
	    ungetc(c, finput);
	  else
	    {
	      putc(c, fattrs);
	      if (fdefines)
		putc(c, fdefines);
	      cplus_comment = (c == '/');
	      in_comment = 1;
	      c = getc(finput);
	      while (in_comment)
		{
		  putc(c, fattrs);
		  if (fdefines)
		    putc(c, fdefines);

		  if (c == '\n')
		    {
		      lineno++;
		      if (cplus_comment)
			{
			  in_comment = 0;
			  break;
			}
		    }
		  if (c == EOF)
		    fatal("unterminated comment at end of file");

		  if (!cplus_comment && c == '*')
		    {
		      c = getc(finput);
		      if (c == '/')
			{
			  putc('/', fattrs);
			  if (fdefines)
			    putc('/', fdefines);
			  in_comment = 0;
			}
		    }
		  else
		    c = getc(finput);
		}
	    }
	  break;


	case '{':
	  count++;
	  break;

	case '}':
	  if (count == 0)
	    warn ("unmatched close-brace (`}')");
	  count--;
	  if (count <= 0)
	    {
	      fprintf(fattrs, " YYSTYPE;\n");
	      if (fdefines)
		fprintf(fdefines, " YYSTYPE;\n");
	      /* JF don't choke on trailing semi */
	      c=skip_white_space();
	      if(c!=';') ungetc(c,finput);
	      return;
	    }
	}

      c = getc(finput);
    }
}

/* parse the declaration %expect N which says to expect N
   shift-reduce conflicts.  */

void
parse_expect_decl()
{
  register int c;
  register int count;
  char buffer[20];

  c = getc(finput);
  while (c == ' ' || c == '\t')
    c = getc(finput);

  count = 0;
  while (c >= '0' && c <= '9')
    {
      if (count < 20)
	buffer[count++] = c;
      c = getc(finput);
    }
  buffer[count] = 0;

  ungetc (c, finput);

  if (count <= 0 || count > 10)
	warn("argument of %expect is not an integer");
  expected_conflicts = atoi (buffer);
}

/* that's all of parsing the declaration section */

/* Get the data type (alternative in the union) of the value for symbol n in rule rule.  */

char *
get_type_name(n, rule)
int n;
symbol_list *rule;
{
  static char *msg = "invalid $ value";

  register int i;
  register symbol_list *rp;

  if (n < 0)
    {
      warn(msg);
      return NULL;
    }

  rp = rule;
  i = 0;

  while (i < n)
    {
      rp = rp->next;
      if (rp == NULL || rp->sym == NULL)
	{
	  warn(msg);
	  return NULL;
	}
      i++;
    }

  return (rp->sym->type_name);
}


/* after %guard is seen in the input file,
copy the actual guard into the guards file.
If the guard is followed by an action, copy that into the actions file.
stack_offset is the number of values in the current rule so far,
which says where to find $0 with respect to the top of the stack,
for the simple parser in which the stack is not popped until after the guard is run.  */

void
copy_guard(rule, stack_offset)
symbol_list *rule;
int stack_offset;
{
  register int c;
  register int n;
  register int count;
  register int match;
  register int ended;
  register char *type_name;
  int brace_flag = 0;
  int cplus_comment;

  /* offset is always 0 if parser has already popped the stack pointer */
  if (semantic_parser) stack_offset = 0;

  fprintf(fguard, "\ncase %d:\n", nrules);
  if (!nolinesflag)
    fprintf(fguard, "#line %d \"%s\"\n", lineno, infile);
  putc('{', fguard);

  count = 0;
  c = getc(finput);

  while (brace_flag ? (count > 0) : (c != ';'))
    {
      switch (c)
	{
	case '\n':
	  putc(c, fguard);
	  lineno++;
	  break;

	case '{':
	  putc(c, fguard);
	  brace_flag = 1;
	  count++;
	  break;

	case '}':
	  putc(c, fguard);
	  if (count > 0)
	    count--;
	  else 
	    {
	      warn("unmatched right brace (`}')");
	      c = getc(finput);	/* skip it */
	    }
          break;

	case '\'':
	case '"':
	  match = c;
	  putc(c, fguard);
	  c = getc(finput);

	  while (c != match)
	    {
	      if (c == EOF)
		fatal("unterminated string at end of file");
	      if (c == '\n') 
		{
		  warn("unterminated string");
		  ungetc(c, finput);
		  c = match;		/* invent terminator */
		  continue;
		}

	      putc(c, fguard);
	      
	      if (c == '\\')
		{
		  c = getc(finput);
		  if (c == EOF)
		    fatal("unterminated string");
		  putc(c, fguard);
		  if (c == '\n')
		    lineno++;
		}

	      c = getc(finput);
	    }

	  putc(c, fguard);
	  break;

	case '/':
	  putc(c, fguard);
	  c = getc(finput);
	  if (c != '*' && c != '/')
	    continue;

	  cplus_comment = (c == '/');
	  putc(c, fguard);
	  c = getc(finput);

	  ended = 0;
	  while (!ended)
	    {
	      if (!cplus_comment && c == '*')
		{
		  while (c == '*')
		    {
		      putc(c, fguard);
		      c = getc(finput);
		    }

		  if (c == '/')
		    {
		      putc(c, fguard);
		      ended = 1;
		    }
		}
	      else if (c == '\n')
		{
		  lineno++;
		  putc(c, fguard);
		  if (cplus_comment)
		    ended = 1;
		  else
		    c = getc(finput);
		}
	      else if (c == EOF)
		fatal("unterminated comment");
	      else
		{
		  putc(c, fguard);
		  c = getc(finput);
		}
	    }

	  break;

	case '$':
	  c = getc(finput);
	  type_name = NULL;

	  if (c == '<')
	    {
	      register char *cp = token_buffer;

	      while ((c = getc(finput)) != '>' && c > 0)
		*cp++ = c;
	      *cp = 0;
	      type_name = token_buffer;

	      c = getc(finput);
	    }

	  if (c == '$')
	    {
	      fprintf(fguard, "yyval");
	      if (!type_name) type_name = rule->sym->type_name;
	      if (type_name)
		fprintf(fguard, ".%s", type_name);
	      if(!type_name && typed)
		warns("$$ of `%s' has no declared type", rule->sym->tag);
	    }

	  else if (isdigit(c) || c == '-')
	    {
	      ungetc (c, finput);
	      n = read_signed_integer(finput);
	      c = getc(finput);

	      if (!type_name && n > 0)
		type_name = get_type_name(n, rule);

	      fprintf(fguard, "yyvsp[%d]", n - stack_offset);
	      if (type_name)
		fprintf(fguard, ".%s", type_name);
	      if(!type_name && typed)
		warnss("$%s of `%s' has no declared type", int_to_string(n), rule->sym->tag);
	      continue;
	    }
	  else
	    warni("$%s is invalid", printable_version(c));

	  break;

	case '@':
	  c = getc(finput);
	  if (isdigit(c) || c == '-')
	    {
	      ungetc (c, finput);
	      n = read_signed_integer(finput);
	      c = getc(finput);
	    }
	  else
	    {
	      warni("@%s is invalid", printable_version(c));
	      n = 1;
	    }

	  fprintf(fguard, "yylsp[%d]", n - stack_offset);
	  yylsp_needed = 1;

	  continue;

	case EOF:
	  fatal("unterminated %%guard clause");

	default:
	  putc(c, fguard);
	}

      if (c != '}' || count != 0)
	c = getc(finput);
    }

  c = skip_white_space();

  fprintf(fguard, ";\n    break;}");
  if (c == '{')
    copy_action(rule, stack_offset);
  else if (c == '=')
    {
      c = getc(finput);	/* why not skip_white_space -wjh */
      if (c == '{')
	copy_action(rule, stack_offset);
    }
  else
    ungetc(c, finput);
}



/* Assuming that a { has just been seen, copy everything up to the matching }
into the actions file.
stack_offset is the number of values in the current rule so far,
which says where to find $0 with respect to the top of the stack.  */

void
copy_action(rule, stack_offset)
symbol_list *rule;
int stack_offset;
{
  register int c;
  register int n;
  register int count;
  register int match;
  register int ended;
  register char *type_name;
  int cplus_comment;

  /* offset is always 0 if parser has already popped the stack pointer */
  if (semantic_parser) stack_offset = 0;

  fprintf(faction, "\ncase %d:\n", nrules);
  if (!nolinesflag)
    fprintf(faction, "#line %d \"%s\"\n", lineno, infile);
  putc('{', faction);

  count = 1;
  c = getc(finput);

  while (count > 0)
    {
      while (c != '}')
        {
          switch (c)
	    {
	    case '\n':
	      putc(c, faction);
	      lineno++;
	      break;

	    case '{':
	      putc(c, faction);
	      count++;
	      break;

	    case '\'':
	    case '"':
	      match = c;
	      putc(c, faction);
	      c = getc(finput);

	      while (c != match)
		{
		  if (c == '\n')
		    {
		      warn("unterminated string");
		      ungetc(c, finput);
		      c = match;
		      continue;
		    }
		  else if (c == EOF)
		    fatal("unterminated string at end of file");

		  putc(c, faction);

		  if (c == '\\')
		    {
		      c = getc(finput);
		      if (c == EOF)
			fatal("unterminated string");
		      putc(c, faction);
		      if (c == '\n')
			lineno++;
		    }

		  c = getc(finput);
		}

	      putc(c, faction);
	      break;

	    case '/':
	      putc(c, faction);
	      c = getc(finput);
	      if (c != '*' && c != '/')
		continue;

	      cplus_comment = (c == '/');
	      putc(c, faction);
	      c = getc(finput);

	      ended = 0;
	      while (!ended)
		{
		  if (!cplus_comment && c == '*')
		    {
		      while (c == '*')
		        {
			  putc(c, faction);
			  c = getc(finput);
			}

		      if (c == '/')
			{
			  putc(c, faction);
			  ended = 1;
			}
		    }
		  else if (c == '\n')
		    {
		      lineno++;
		      putc(c, faction);
		      if (cplus_comment)
			ended = 1;
		      else
		        c = getc(finput);
		    }
		  else if (c == EOF)
		    fatal("unterminated comment");
		  else
		    {
		      putc(c, faction);
		      c = getc(finput);
		    }
		}

	      break;

	    case '$':
	      c = getc(finput);
	      type_name = NULL;

	      if (c == '<')
		{
		  register char *cp = token_buffer;

		  while ((c = getc(finput)) != '>' && c > 0)
		    *cp++ = c;
		  *cp = 0;
		  type_name = token_buffer;
		  value_components_used = 1;

		  c = getc(finput);
		}
	      if (c == '$')
		{
		  fprintf(faction, "yyval");
		  if (!type_name) type_name = get_type_name(0, rule);
		  if (type_name)
		    fprintf(faction, ".%s", type_name);
		  if(!type_name && typed)	
		    warns("$$ of `%s' has no declared type", rule->sym->tag);
		}
	      else if (isdigit(c) || c == '-')
		{
		  ungetc (c, finput);
		  n = read_signed_integer(finput);
		  c = getc(finput);

		  if (!type_name && n > 0)
		    type_name = get_type_name(n, rule);

		  fprintf(faction, "yyvsp[%d]", n - stack_offset);
		  if (type_name)
		    fprintf(faction, ".%s", type_name);
		  if(!type_name && typed)	
		    warnss("$%s of `%s' has no declared type", 
				int_to_string(n), rule->sym->tag);
		  continue;
		}
	      else
		warni("$%s is invalid", printable_version(c));

	      break;

	    case '@':
	      c = getc(finput);
	      if (isdigit(c) || c == '-')
		{
		  ungetc (c, finput);
		  n = read_signed_integer(finput);
		  c = getc(finput);
		}
	      else
		{
		  warn("invalid @-construct");
		  n = 1;
		}