parse-gram.y

bison 2.0 主要可以用来做语法分析用的

%{/* Bison Grammar Parser                             -*- C -*-

   Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.

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

   This program 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 of the License, or
   (at your option) any later version.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307  USA
*/

#include "system.h"

#include "complain.h"
#include "conflicts.h"
#include "files.h"
#include "getargs.h"
#include "gram.h"
#include "muscle_tab.h"
#include "output.h"
#include "reader.h"
#include "symlist.h"

#define YYLLOC_DEFAULT(Current, Rhs, N)  (Current) = lloc_default (Rhs, N)
static YYLTYPE lloc_default (YYLTYPE const *, int);

#define YY_LOCATION_PRINT(File, Loc) \
          location_print (File, Loc)

/* Request detailed syntax error messages, and pass them to GRAM_ERROR.
   FIXME: depends on the undocumented availability of YYLLOC.  */
#undef  yyerror
#define yyerror(Msg) \
        gram_error (&yylloc, Msg)
static void gram_error (location const *, char const *);

#define YYPRINT(File, Type, Value) \
	print_token_value (File, Type, &Value)
static void print_token_value (FILE *, int, YYSTYPE const *);

static void add_param (char const *, char *, location);

symbol_class current_class = unknown_sym;
uniqstr current_type = 0;
symbol *current_lhs;
location current_lhs_location;
assoc current_assoc;
int current_prec = 0;
%}

%debug
%defines
%locations
%pure-parser
%error-verbose
%defines
%name-prefix="gram_"

%initial-action
{
  /* Bison's grammar can initial empty locations, hence a default
     location is needed. */
  @$.start.file   = @$.end.file   = current_file;
  @$.start.line   = @$.end.line   = 1;
  @$.start.column = @$.end.column = 0;
}

/* Only NUMBERS have a value.  */
%union
{
  symbol *symbol;
  symbol_list *list;
  int integer;
  char *chars;
  assoc assoc;
  uniqstr uniqstr;
};

/* Define the tokens together with their human representation.  */
%token GRAM_EOF 0 "end of file"
%token STRING     "string"
%token INT        "integer"

%token PERCENT_TOKEN       "%token"
%token PERCENT_NTERM       "%nterm"

%token PERCENT_TYPE        "%type"
%token PERCENT_DESTRUCTOR  "%destructor {...}"
%token PERCENT_PRINTER     "%printer {...}"

%token PERCENT_UNION       "%union {...}"

%token PERCENT_LEFT        "%left"
%token PERCENT_RIGHT       "%right"
%token PERCENT_NONASSOC    "%nonassoc"

%token PERCENT_PREC          "%prec"
%token PERCENT_DPREC         "%dprec"
%token PERCENT_MERGE         "%merge"


/*----------------------.
| Global Declarations.  |
`----------------------*/

%token
  PERCENT_DEBUG           "%debug"
  PERCENT_DEFAULT_PREC    "%default-prec"
  PERCENT_DEFINE          "%define"
  PERCENT_DEFINES         "%defines"
  PERCENT_ERROR_VERBOSE   "%error-verbose"
  PERCENT_EXPECT          "%expect"
  PERCENT_EXPECT_RR	  "%expect-rr"
  PERCENT_FILE_PREFIX     "%file-prefix"
  PERCENT_GLR_PARSER      "%glr-parser"
  PERCENT_INITIAL_ACTION  "%initial-action {...}"
  PERCENT_LEX_PARAM       "%lex-param {...}"
  PERCENT_LOCATIONS       "%locations"
  PERCENT_NAME_PREFIX     "%name-prefix"
  PERCENT_NO_DEFAULT_PREC "%no-default-prec"
  PERCENT_NO_LINES        "%no-lines"
  PERCENT_NONDETERMINISTIC_PARSER
                          "%nondeterministic-parser"
  PERCENT_OUTPUT          "%output"
  PERCENT_PARSE_PARAM     "%parse-param {...}"
  PERCENT_PURE_PARSER     "%pure-parser"
  PERCENT_SKELETON        "%skeleton"
  PERCENT_START           "%start"
  PERCENT_TOKEN_TABLE     "%token-table"
  PERCENT_VERBOSE         "%verbose"
  PERCENT_YACC            "%yacc"
;

%token TYPE            "type"
%token EQUAL           "="
%token SEMICOLON       ";"
%token PIPE            "|"
%token ID              "identifier"
%token ID_COLON        "identifier:"
%token PERCENT_PERCENT "%%"
%token PROLOGUE        "%{...%}"
%token EPILOGUE        "epilogue"
%token BRACED_CODE     "{...}"


%type <chars> STRING string_content
	      "%destructor {...}"
	      "%initial-action {...}"
	      "%lex-param {...}"
	      "%parse-param {...}"
	      "%printer {...}"
	      "%union {...}"
	      BRACED_CODE action
	      PROLOGUE EPILOGUE
%type <uniqstr> TYPE
%type <integer> INT
%type <symbol> ID ID_COLON symbol string_as_id
%type <assoc> precedence_declarator
%type <list>  symbols.1
%%

input:
  declarations "%%" grammar epilogue.opt
;


	/*------------------------------------.
	| Declarations: before the first %%.  |
	`------------------------------------*/

declarations:
  /* Nothing */
| declarations declaration
;

declaration:
  grammar_declaration
| PROLOGUE                                 { prologue_augment ($1, @1); }
| "%debug"                                 { debug_flag = true; }
| "%define" string_content string_content  { muscle_insert ($2, $3); }
| "%defines"                               { defines_flag = true; }
| "%error-verbose"                         { error_verbose = true; }
| "%expect" INT                            { expected_sr_conflicts = $2; }
| "%expect-rr" INT 			   { expected_rr_conflicts = $2; }
| "%file-prefix" "=" string_content        { spec_file_prefix = $3; }
| "%glr-parser"
  {
    nondeterministic_parser = true;
    glr_parser = true;
  }
| "%initial-action {...}"
  {
    muscle_code_grow ("initial_action", $1, @1);
  }
| "%lex-param {...}"			   { add_param ("lex_param", $1, @1); }
| "%locations"                             { locations_flag = true; }
| "%name-prefix" "=" string_content        { spec_name_prefix = $3; }
| "%no-lines"                              { no_lines_flag = true; }
| "%nondeterministic-parser" 		   { nondeterministic_parser = true; }
| "%output" "=" string_content             { spec_outfile = $3; }
| "%parse-param {...}"			   { add_param ("parse_param", $1, @1); }
| "%pure-parser"                           { pure_parser = true; }
| "%skeleton" string_content               { skeleton = $2; }
| "%token-table"                           { token_table_flag = true; }
| "%verbose"                               { report_flag = report_states; }
| "%yacc"                                  { yacc_flag = true; }
| /*FIXME: Err?  What is this horror doing here? */ ";"
;

grammar_declaration:
  precedence_declaration
| symbol_declaration
| "%start" symbol
    {
      grammar_start_symbol_set ($2, @2);
    }
| "%union {...}"
    {
      typed = true;
      MUSCLE_INSERT_INT ("stype_line", @1.start.line);
      muscle_insert ("stype", $1);
    }
| "%destructor {...}" symbols.1
    {
      symbol_list *list;
      for (list = $2; list; list = list->next)
	symbol_destructor_set (list->sym, $1, @1);
      symbol_list_free ($2);
    }
| "%printer {...}" symbols.1
    {
      symbol_list *list;
      for (list = $2; list; list = list->next)
	symbol_printer_set (list->sym, $1, list->location);
      symbol_list_free ($2);
    }
| "%default-prec"
    {
      default_prec = true;
    }
| "%no-default-prec"
    {
      default_prec = false;
    }
;

symbol_declaration:
  "%nterm" { current_class = nterm_sym; } symbol_defs.1
    {
      current_class = unknown_sym;
      current_type = NULL;
    }
| "%token" { current_class = token_sym; } symbol_defs.1
    {
      current_class = unknown_sym;
      current_type = NULL;
    }
| "%type" TYPE symbols.1
    {
      symbol_list *list;
      for (list = $3; list; list = list->next)
	symbol_type_set (list->sym, $2, @2);
      symbol_list_free ($3);
    }
;

precedence_declaration:
  precedence_declarator type.opt symbols.1
    {
      symbol_list *list;
      ++current_prec;
      for (list = $3; list; list = list->next)
	{
	  symbol_type_set (list->sym, current_type, @2);
	  symbol_precedence_set (list->sym, current_prec, $1, @1);
	}
      symbol_list_free ($3);
      current_type = NULL;
    }
;

precedence_declarator:
  "%left"     { $$ = left_assoc; }
| "%right"    { $$ = right_assoc; }
| "%nonassoc" { $$ = non_assoc; }
;

type.opt:
  /* Nothing. */ { current_type = NULL; }
| TYPE           { current_type = $1; }
;

/* One or more nonterminals to be %typed. */

symbols.1:
  symbol            { $$ = symbol_list_new ($1, @1); }
| symbols.1 symbol  { $$ = symbol_list_prepend ($1, $2, @2); }
;

/* One token definition.  */
symbol_def:
  TYPE
     {
       current_type = $1;
     }
| ID
     {
       symbol_class_set ($1, current_class, @1);
       symbol_type_set ($1, current_type, @1);
     }
| ID INT
    {
      symbol_class_set ($1, current_class, @1);
      symbol_type_set ($1, current_type, @1);
      symbol_user_token_number_set ($1, $2, @2);
    }
| ID string_as_id
    {
      symbol_class_set ($1, current_class, @1);
      symbol_type_set ($1, current_type, @1);
      symbol_make_alias ($1, $2, @$);
    }
| ID INT string_as_id
    {
      symbol_class_set ($1, current_class, @1);
      symbol_type_set ($1, current_type, @1);
      symbol_user_token_number_set ($1, $2, @2);
      symbol_make_alias ($1, $3, @$);
    }
;

/* One or more symbol definitions. */
symbol_defs.1:
  symbol_def
| symbol_defs.1 symbol_def
;


	/*------------------------------------------.
	| The grammar section: between the two %%.  |
	`------------------------------------------*/

grammar:
  rules_or_grammar_declaration
| grammar rules_or_grammar_declaration
;

/* As a Bison extension, one can use the grammar declarations in the
   body of the grammar.  */
rules_or_grammar_declaration:
  rules
| grammar_declaration ";"
    {
      if (yacc_flag)
	complain_at (@$, _("POSIX forbids declarations in the grammar"));
    }
| error ";"
    {
      yyerrok;
    }
;

rules:
  ID_COLON { current_lhs = $1; current_lhs_location = @1; } rhses.1
;

rhses.1:
  rhs                { grammar_rule_end (@1); }
| rhses.1 "|" rhs    { grammar_rule_end (@3); }
| rhses.1 ";"
;

rhs:
  /* Nothing.  */
    { grammar_rule_begin (current_lhs, current_lhs_location); }
| rhs symbol
    { grammar_current_rule_symbol_append ($2, @2); }
| rhs action
    { grammar_current_rule_action_append ($2, @2); }
| rhs "%prec" symbol
    { grammar_current_rule_prec_set ($3, @3); }
| rhs "%dprec" INT
    { grammar_current_rule_dprec_set ($3, @3); }
| rhs "%merge" TYPE
    { grammar_current_rule_merge_set ($3, @3); }
;

symbol:
  ID              { $$ = $1; }
| string_as_id    { $$ = $1; }
;

action:
  BRACED_CODE
   { $$ = $1; }
;

/* A string used as an ID: we have to keep the quotes. */
string_as_id:
  STRING
    {
      $$ = symbol_get ($1, @1);
      symbol_class_set ($$, token_sym, @1);
    }
;

/* A string used for its contents.  Strip the quotes. */
string_content:
  STRING
    {
      $$ = $1 + 1;
      $$[strlen ($$) - 1] = '\0';
    };


epilogue.opt:
  /* Nothing.  */
| "%%" EPILOGUE
    {
      muscle_code_grow ("epilogue", $2, @2);
      scanner_last_string_free ();
    }
;

%%


/* Return the location of the left-hand side of a rule whose
   right-hand side is RHS[1] ... RHS[N].  Ignore empty nonterminals in
   the right-hand side, and return an empty location equal to the end
   boundary of RHS[0] if the right-hand side is empty.  */

static YYLTYPE
lloc_default (YYLTYPE const *rhs, int n)
{
  int i;
  YYLTYPE loc;

  /* SGI MIPSpro 7.4.1m miscompiles "loc.start = loc.end = rhs[n].end;".
     The bug is fixed in 7.4.2m, but play it safe for now.  */
  loc.start = rhs[n].end;
  loc.end = rhs[n].end;

  /* Ignore empty nonterminals the start of the the right-hand side.
     Do not bother to ignore them at the end of the right-hand side,
     since empty nonterminals have the same end as their predecessors.  */
  for (i = 1; i <= n; i++)
    if (! equal_boundaries (rhs[i].start, rhs[i].end))
      {
	loc.start = rhs[i].start;
	break;
      }

  return loc;
}


/* Add a lex-param or a parse-param (depending on TYPE) with
   declaration DECL and location LOC.  */

static void
add_param (char const *type, char *decl, location loc)
{
  static char const alphanum[26 + 26 + 1 + 10] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "_"
    "0123456789";
  char const *name_start = NULL;
  char *p;

  /* Stop on last actual character.  */
  for (p = decl; p[1]; p++)
    if ((p == decl
	 || ! memchr (alphanum, p[-1], sizeof alphanum))
	&& memchr (alphanum, p[0], sizeof alphanum - 10))
      name_start = p;

  /* Strip the surrounding '{' and '}', and any blanks just inside
     the braces.  */
  while (*--p == ' ' || *p == '\t')
    continue;
  p[1] = '\0';
  while (*++decl == ' ' || *decl == '\t')
    continue;

  if (! name_start)
    complain_at (loc, _("missing identifier in parameter declaration"));
  else
    {
      char *name;
      size_t name_len;

      for (name_len = 1;
	   memchr (alphanum, name_start[name_len], sizeof alphanum);
	   name_len++)
	continue;

      name = xmalloc (name_len + 1);
      memcpy (name, name_start, name_len);
      name[name_len] = '\0';
      muscle_pair_list_grow (type, decl, name);
      free (name);
    }

  scanner_last_string_free ();
}

/*----------------------------------------------------.
| When debugging the parser, display tokens' values.  |
`----------------------------------------------------*/

static void
print_token_value (FILE *file, int type, YYSTYPE const *value)
{
  fputc (' ', file);
  switch (type)
    {
    case ID:
      fprintf (file, " = %s", value->symbol->tag);
      break;

    case INT:
      fprintf (file, " = %d", value->integer);
      break;

    case STRING:
      fprintf (file, " = \"%s\"", value->chars);
      break;

    case TYPE:
      fprintf (file, " = <%s>", value->uniqstr);
      break;

    case BRACED_CODE:
    case PERCENT_DESTRUCTOR:
    case PERCENT_LEX_PARAM:
    case PERCENT_PARSE_PARAM:
    case PERCENT_PRINTER:
    case PERCENT_UNION:
    case PROLOGUE:
    case EPILOGUE:
      fprintf (file, " = {{ %s }}", value->chars);
      break;

    default:
      fprintf (file, "unknown token type");
      break;
    }
}

static void
gram_error (location const *loc, char const *msg)
{
  complain_at (*loc, "%s", msg);
}

char const *
token_name (int type)
{
  return yytname[type];
}