output.c

bison 2.0 主要可以用来做语法分析用的

      if (p->type[0] == '\0')
	fprintf (out, "  case %d: *yy0 = %s (*yy0, *yy1); break;\n",
		 n, p->name);
      else
	fprintf (out, "  case %d: yy0->%s = %s (*yy0, *yy1); break;\n",
		 n, p->type, p->name);
    }
  fputs ("]])\n\n", out);
}

/*--------------------------------------.
| Output the tokens definition to OUT.  |
`--------------------------------------*/

static void
token_definitions_output (FILE *out)
{
  int i;
  char const *sep = "";

  fputs ("m4_define([b4_tokens], \n[", out);
  for (i = 0; i < ntokens; ++i)
    {
      symbol *sym = symbols[i];
      int number = sym->user_token_number;

      /* At this stage, if there are literal aliases, they are part of
	 SYMBOLS, so we should not find symbols which are the aliases
	 here.  */
      if (number == USER_NUMBER_ALIAS)
	abort ();

      /* Skip error token.  */
      if (sym == errtoken)
	continue;

      /* If this string has an alias, then it is necessarily the alias
	 which is to be output.  */
      if (sym->alias)
	sym = sym->alias;

      /* Don't output literal chars or strings (when defined only as a
	 string).  Note that must be done after the alias resolution:
	 think about `%token 'f' "f"'.  */
      if (sym->tag[0] == '\'' || sym->tag[0] == '\"')
	continue;

      /* Don't #define nonliteral tokens whose names contain periods
	 or '$' (as does the default value of the EOF token).  */
      if (strchr (sym->tag, '.') || strchr (sym->tag, '$'))
	continue;

      fprintf (out, "%s[[[%s]], [%d]]",
	       sep, sym->tag, number);
      sep = ",\n";
    }
  fputs ("])\n\n", out);
}


/*---------------------------------------.
| Output the symbol destructors to OUT.  |
`---------------------------------------*/

static void
symbol_destructors_output (FILE *out)
{
  int i;
  char const *sep = "";

  fputs ("m4_define([b4_symbol_destructors], \n[", out);
  for (i = 0; i < nsyms; ++i)
    if (symbols[i]->destructor)
      {
	symbol *sym = symbols[i];

	/* Filename, lineno,
	   Symbol-name, Symbol-number,
	   destructor, optional typename.  */
	fprintf (out, "%s[", sep);
	sep = ",\n";
	escaped_file_name_output (out, sym->destructor_location.start.file);
	fprintf (out, ", [[%d]], [[%s]], [[%d]], [[%s]]",
		 sym->destructor_location.start.line,
		 sym->tag,
		 sym->number,
		 sym->destructor);
	if (sym->type_name)
	  fprintf (out, ", [[%s]]", sym->type_name);
	fputc (']', out);
      }
  fputs ("])\n\n", out);
}


/*------------------------------------.
| Output the symbol printers to OUT.  |
`------------------------------------*/

static void
symbol_printers_output (FILE *out)
{
  int i;
  char const *sep = "";

  fputs ("m4_define([b4_symbol_printers], \n[", out);
  for (i = 0; i < nsyms; ++i)
    if (symbols[i]->printer)
      {
	symbol *sym = symbols[i];

	/* Filename, lineno,
	   Symbol-name, Symbol-number,
	   printer, optional typename.  */
	fprintf (out, "%s[", sep);
	sep = ",\n";
	escaped_file_name_output (out, sym->printer_location.start.file);
	fprintf (out, ", [[%d]], [[%s]], [[%d]], [[%s]]",
		 sym->printer_location.start.line,
		 sym->tag,
		 sym->number,
		 sym->printer);
	if (sym->type_name)
	  fprintf (out, ", [[%s]]", sym->type_name);
	fputc (']', out);
      }
  fputs ("])\n\n", out);
}


static void
prepare_actions (void)
{
  /* Figure out the actions for the specified state, indexed by
     look-ahead token type.  */

  muscle_insert_rule_number_table ("defact", yydefact,
				   yydefact[0], 1, nstates);

  /* Figure out what to do after reducing with each rule, depending on
     the saved state from before the beginning of parsing the data
     that matched this rule.  */
  muscle_insert_state_number_table ("defgoto", yydefgoto,
				    yydefgoto[0], 1, nsyms - ntokens);


  /* Output PACT. */
  muscle_insert_base_table ("pact", base,
			     base[0], 1, nstates);
  MUSCLE_INSERT_INT ("pact_ninf", base_ninf);

  /* Output PGOTO. */
  muscle_insert_base_table ("pgoto", base,
			     base[nstates], nstates + 1, nvectors);

  muscle_insert_base_table ("table", table,
			    table[0], 1, high + 1);
  MUSCLE_INSERT_INT ("table_ninf", table_ninf);

  muscle_insert_base_table ("check", check,
			    check[0], 1, high + 1);

  /* GLR parsing slightly modifies YYTABLE and YYCHECK (and thus
     YYPACT) so that in states with unresolved conflicts, the default
     reduction is not used in the conflicted entries, so that there is
     a place to put a conflict pointer.

     This means that YYCONFLP and YYCONFL are nonsense for a non-GLR
     parser, so we could avoid accidents by not writing them out in
     that case.  Nevertheless, it seems even better to be able to use
     the GLR skeletons even without the non-deterministic tables.  */
  muscle_insert_unsigned_int_table ("conflict_list_heads", conflict_table,
				    conflict_table[0], 1, high + 1);
  muscle_insert_unsigned_int_table ("conflicting_rules", conflict_list,
				    0, 1, conflict_list_cnt);
}


/*---------------------------.
| Call the skeleton parser.  |
`---------------------------*/

static void
output_skeleton (void)
{
  FILE *in;
  FILE *out;
  int filter_fd[2];
  char const *argv[6];
  pid_t pid;

  /* Compute the names of the package data dir and skeleton file.
     Test whether m4sugar.m4 is readable, to check for proper
     installation.  A faulty installation can cause deadlock, so a
     cheap sanity check is worthwhile.  */
  char const m4sugar[] = "m4sugar/m4sugar.m4";
  char *full_m4sugar;
  char *full_cm4;
  char *full_skeleton;
  char const *p;
  char const *m4 = (p = getenv ("M4")) ? p : M4;
  char const *pkgdatadir = (p = getenv ("BISON_PKGDATADIR")) ? p : PKGDATADIR;
  size_t skeleton_size = strlen (skeleton) + 1;
  size_t pkgdatadirlen = strlen (pkgdatadir);
  while (pkgdatadirlen && pkgdatadir[pkgdatadirlen - 1] == '/')
    pkgdatadirlen--;
  full_skeleton = xmalloc (pkgdatadirlen + 1
			   + (skeleton_size < sizeof m4sugar
			      ? sizeof m4sugar : skeleton_size));
  strcpy (full_skeleton, pkgdatadir);
  full_skeleton[pkgdatadirlen] = '/';
  strcpy (full_skeleton + pkgdatadirlen + 1, m4sugar);
  full_m4sugar = xstrdup (full_skeleton);
  strcpy (full_skeleton + pkgdatadirlen + 1, "c.m4");
  full_cm4 = xstrdup (full_skeleton);
  strcpy (full_skeleton + pkgdatadirlen + 1, skeleton);
  xfclose (xfopen (full_m4sugar, "r"));

  /* Create an m4 subprocess connected to us via two pipes.  */

  if (trace_flag & trace_tools)
    fprintf (stderr, "running: %s %s - %s %s\n",
	     m4, full_m4sugar, full_cm4, full_skeleton);

  argv[0] = m4;
  argv[1] = full_m4sugar;
  argv[2] = "-";
  argv[3] = full_cm4;
  argv[4] = full_skeleton;
  argv[5] = NULL;

  init_subpipe ();
  pid = create_subpipe (argv, filter_fd);
  free (full_m4sugar);
  free (full_cm4);
  free (full_skeleton);

  out = fdopen (filter_fd[0], "w");
  if (! out)
    error (EXIT_FAILURE, get_errno (), "fdopen");

  /* Output the definitions of all the muscles.  */
  fputs ("m4_init()\n", out);

  user_actions_output (out);
  merger_output (out);
  token_definitions_output (out);
  symbol_destructors_output (out);
  symbol_printers_output (out);

  muscles_m4_output (out);

  fputs ("m4_wrap([m4_divert_pop(0)])\n", out);
  fputs ("m4_divert_push(0)dnl\n", out);
  xfclose (out);

  /* Read and process m4's output.  */
  timevar_push (TV_M4);
  in = fdopen (filter_fd[1], "r");
  if (! in)
    error (EXIT_FAILURE, get_errno (), "fdopen");
  scan_skel (in);
  xfclose (in);
  reap_subpipe (pid, m4);
  timevar_pop (TV_M4);
}

static void
prepare (void)
{
  /* Flags. */
  MUSCLE_INSERT_BOOL ("debug", debug_flag);
  MUSCLE_INSERT_BOOL ("defines_flag", defines_flag);
  MUSCLE_INSERT_BOOL ("error_verbose", error_verbose);
  MUSCLE_INSERT_BOOL ("locations_flag", locations_flag);
  MUSCLE_INSERT_BOOL ("pure", pure_parser);
  MUSCLE_INSERT_BOOL ("synclines_flag", !no_lines_flag);

  /* File names.  */
  MUSCLE_INSERT_STRING ("prefix", spec_name_prefix ? spec_name_prefix : "yy");

  /* User Code.  */
  obstack_1grow (&pre_prologue_obstack, 0);
  obstack_1grow (&post_prologue_obstack, 0);
  muscle_insert ("pre_prologue", obstack_finish (&pre_prologue_obstack));
  muscle_insert ("post_prologue", obstack_finish (&post_prologue_obstack));

  /* Find the right skeleton file.  */
  if (!skeleton)
    {
      if (glr_parser || nondeterministic_parser)
	skeleton = "glr.c";
      else
	skeleton = "yacc.c";
    }

  /* Parse the skeleton file and output the needed parsers.  */
  MUSCLE_INSERT_C_STRING ("skeleton", skeleton);
}


/*----------------------------------------------------------.
| Output the parsing tables and the parser code to ftable.  |
`----------------------------------------------------------*/

void
output (void)
{
  obstack_init (&format_obstack);

  prepare_symbols ();
  prepare_rules ();
  prepare_states ();
  prepare_actions ();

  prepare ();

  /* Process the selected skeleton file.  */
  output_skeleton ();

  obstack_free (&format_obstack, NULL);
  obstack_free (&pre_prologue_obstack, NULL);
  obstack_free (&post_prologue_obstack, NULL);
}