parse.y

gcc库的原代码,对编程有很大帮助.

/* YACC parser for C++ syntax.
   Copyright (C) 1988, 1989, 1993, 1994, 1995 Free Software Foundation, Inc.
   Hacked by Michael Tiemann ([e-mail])

This file is part of GNU CC.

GNU CC 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.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


/* This grammar is based on the GNU CC grammar.  */

/* Note: Bison automatically applies a default action of "$$ = $1" for
   all derivations; this is applied before the explicit action, if one
   is given.  Keep this in mind when reading the actions.  */

%{
/* Cause the `yydebug' variable to be defined.  */
#define YYDEBUG 1

#include "config.h"

#include <stdio.h>
#include <errno.h>

#include "tree.h"
#include "input.h"
#include "flags.h"
#include "lex.h"
#include "cp-tree.h"
#include "output.h"

/* Since parsers are distinct for each language, put the language string
   definition here.  (fnf) */
char *language_string = "GNU C++";

extern tree void_list_node;
extern struct obstack permanent_obstack;

#ifndef errno
extern int errno;
#endif

extern int end_of_file;
extern int current_class_depth;

/* FSF LOCAL dje prefix attributes */
extern tree strip_attrs		PROTO((tree));
/* END FSF LOCAL */

void yyerror ();

/* Like YYERROR but do call yyerror.  */
#define YYERROR1 { yyerror ("syntax error"); YYERROR; }

#define OP0(NODE) (TREE_OPERAND (NODE, 0))
#define OP1(NODE) (TREE_OPERAND (NODE, 1))

/* Contains the statement keyword (if/while/do) to include in an
   error message if the user supplies an empty conditional expression.  */
static char *cond_stmt_keyword;

/* Nonzero if we have an `extern "C"' acting as an extern specifier.  */
int have_extern_spec;
int used_extern_spec;

void yyhook ();

/* Cons up an empty parameter list.  */
#ifdef __GNUC__
__inline
#endif
static tree
empty_parms ()
{
  tree parms;

  if (strict_prototype)
    parms = void_list_node;
  else
    parms = NULL_TREE;
  return parms;
}
%}

%start program

%union {long itype; tree ttype; char *strtype; enum tree_code code; }

/* All identifiers that are not reserved words
   and are not declared typedefs in the current block */
%token IDENTIFIER

/* All identifiers that are declared typedefs in the current block.
   In some contexts, they are treated just like IDENTIFIER,
   but they can also serve as typespecs in declarations.  */
%token TYPENAME

/* Reserved words that specify storage class.
   yylval contains an IDENTIFIER_NODE which indicates which one.  */
%token SCSPEC

/* Reserved words that specify type.
   yylval contains an IDENTIFIER_NODE which indicates which one.  */
%token TYPESPEC

/* Reserved words that qualify type: "const" or "volatile".
   yylval contains an IDENTIFIER_NODE which indicates which one.  */
%token TYPE_QUAL

/* Character or numeric constants.
   yylval is the node for the constant.  */
%token CONSTANT

/* String constants in raw form.
   yylval is a STRING_CST node.  */
%token STRING

/* "...", used for functions with variable arglists.  */
%token ELLIPSIS

/* the reserved words */
/* SCO include files test "ASM", so use something else. */
%token SIZEOF ENUM /* STRUCT UNION */ IF ELSE WHILE DO FOR SWITCH CASE DEFAULT
%token BREAK CONTINUE RETURN GOTO ASM_KEYWORD GCC_ASM_KEYWORD TYPEOF ALIGNOF
%token SIGOF
%token ATTRIBUTE EXTENSION LABEL

/* the reserved words... C++ extensions */
%token <ttype> AGGR
%token <itype> VISSPEC
%token DELETE NEW OVERLOAD THIS OPERATOR CXX_TRUE CXX_FALSE
%token NAMESPACE TYPENAME_KEYWORD USING
%token LEFT_RIGHT TEMPLATE
%token TYPEID DYNAMIC_CAST STATIC_CAST REINTERPRET_CAST CONST_CAST
%token <itype> SCOPE

/* Define the operator tokens and their precedences.
   The value is an integer because, if used, it is the tree code
   to use in the expression made from the operator.  */

%left EMPTY			/* used to resolve s/r with epsilon */

%left error

/* Add precedence rules to solve dangling else s/r conflict */
%nonassoc IF
%nonassoc ELSE

%left IDENTIFIER TYPENAME PTYPENAME SCSPEC TYPESPEC TYPE_QUAL ENUM AGGR ELLIPSIS TYPEOF SIGOF OPERATOR NSNAME TYPENAME_KEYWORD

%left '{' ',' ';'

%nonassoc THROW
%right <code> ':'
%right <code> ASSIGN '='
%right <code> '?'
%left <code> OROR
%left <code> ANDAND
%left <code> '|'
%left <code> '^'
%left <code> '&'
%left <code> MIN_MAX
%left <code> EQCOMPARE
%left <code> ARITHCOMPARE '<' '>'
%left <code> LSHIFT RSHIFT
%left <code> '+' '-'
%left <code> '*' '/' '%'
%left <code> POINTSAT_STAR DOT_STAR
%right <code> UNARY PLUSPLUS MINUSMINUS '~'
%left HYPERUNARY
%left <ttype> PAREN_STAR_PAREN LEFT_RIGHT
%left <code> POINTSAT '.' '(' '['

%right SCOPE			/* C++ extension */
%nonassoc NEW DELETE TRY CATCH

%type <code> unop

%type <ttype> identifier IDENTIFIER TYPENAME CONSTANT expr nonnull_exprlist
%type <ttype> paren_expr_or_null nontrivial_exprlist
%type <ttype> expr_no_commas cast_expr unary_expr primary string STRING
%type <ttype> typed_declspecs reserved_declspecs boolean.literal
%type <ttype> typed_typespecs reserved_typespecquals
%type <ttype> declmods typespec typespecqual_reserved
%type <ttype> SCSPEC TYPESPEC TYPE_QUAL nonempty_type_quals maybe_type_qual
%type <itype> initdecls notype_initdecls initdcl	/* C++ modification */
%type <ttype> init initlist maybeasm maybe_init
%type <ttype> asm_operands nonnull_asm_operands asm_operand asm_clobbers
%type <ttype> maybe_attribute attributes attribute attribute_list attrib
%type <ttype> any_word

%type <ttype> compstmt implicitly_scoped_stmt

%type <ttype> declarator notype_declarator after_type_declarator
%type <ttype> direct_notype_declarator direct_after_type_declarator

%type <ttype> structsp opt.component_decl_list component_decl_list
%type <ttype> component_decl component_decl_1 components notype_components
%type <ttype> component_declarator component_declarator0
%type <ttype> notype_component_declarator notype_component_declarator0
%type <ttype> after_type_component_declarator after_type_component_declarator0
%type <ttype> enumlist enumerator
%type <ttype> type_id absdcl type_quals
%type <ttype> direct_abstract_declarator conversion_declarator
%type <ttype> new_type_id new_declarator direct_new_declarator
%type <ttype> xexpr parmlist parms parm bad_parm full_parm
%type <ttype> identifiers_or_typenames
%type <ttype> fcast_or_absdcl regcast_or_absdcl
%type <ttype> expr_or_declarator complex_notype_declarator
%type <ttype> notype_unqualified_id unqualified_id qualified_id
%type <ttype> overqualified_id notype_qualified_id any_id
%type <ttype> complex_direct_notype_declarator functional_cast
%type <ttype> named_parm complex_parmlist typed_declspecs1 parms_comma

/* C++ extensions */
%token <ttype> TYPENAME_ELLIPSIS PTYPENAME
%token <ttype> PRE_PARSED_FUNCTION_DECL EXTERN_LANG_STRING ALL
%token <ttype> PRE_PARSED_CLASS_DECL
%type <ttype> fn.def1 /* Not really! */
%type <ttype> fn.def2 return_id
%type <itype> ctor_initializer_opt
%type <ttype> named_class_head named_class_head_sans_basetype
%type <ttype> named_complex_class_head_sans_basetype
%type <ttype> unnamed_class_head
%type <ttype> class_head base_class_list
%type <itype> base_class_access_list
%type <ttype> base_class maybe_base_class_list base_class.1
%type <ttype> exception_specification_opt ansi_raise_identifier ansi_raise_identifiers
%type <ttype> operator_name
%type <ttype> object aggr
%type <itype> new delete
/* %type <ttype> primary_no_id */
%type <ttype> nonmomentary_expr maybe_parmlist
%type <itype> initdcl0 notype_initdcl0 member_init_list
%type <ttype> template_header template_parm_list template_parm
%type <ttype> template_type_parm
%type <ttype> template_type template_arg_list template_arg
%type <ttype> template_instantiation template_type_name tmpl.2
%type <ttype> template_instantiate_once template_instantiate_some
%type <itype> fn_tmpl_end
/* %type <itype> try_for_typename */
%type <ttype> condition xcond paren_cond_or_null
%type <ttype> type_name nested_name_specifier nested_type ptr_to_mem
%type <ttype> qualified_type_name complete_type_name notype_identifier
%type <ttype> complex_type_name nested_name_specifier_1
%type <itype> nomods_initdecls nomods_initdcl0
%type <ttype> new_initializer new_placement specialization type_specifier_seq
%type <ttype> using_decl .poplevel

/* in order to recognize aggr tags as defining and thus shadowing. */
%token TYPENAME_DEFN IDENTIFIER_DEFN PTYPENAME_DEFN
%type <ttype> named_class_head_sans_basetype_defn 
%type <ttype> identifier_defn IDENTIFIER_DEFN TYPENAME_DEFN PTYPENAME_DEFN

%token NSNAME
%type <ttype> NSNAME

/* Used in lex.c for parsing pragmas.  */
%token END_OF_LINE

/* lex.c and pt.c depends on this being the last token.  Define
   any new tokens before this one!  */
%token END_OF_SAVED_INPUT

%{
/* List of types and structure classes of the current declaration.  */
static tree current_declspecs;
/* List of prefix attributes in effect.
   Prefix attributes are parsed by the reserved_declspecs and declmods
   rules.  They create a list that contains *both* declspecs and attrs.  */
/* ??? It is not clear yet that all cases where an attribute can now appear in
   a declspec list have been updated.  */
static tree prefix_attributes;

/* When defining an aggregate, this is the most recent one being defined.  */
static tree current_aggr;

/* Tell yyparse how to print a token's value, if yydebug is set.  */

#define YYPRINT(FILE,YYCHAR,YYLVAL) yyprint(FILE,YYCHAR,YYLVAL)
extern void yyprint ();
extern tree combine_strings		PROTO((tree));
%}

%%
program: /* empty */
	| extdefs
		{
		  /* In case there were missing closebraces,
		     get us back to the global binding level.  */
		  while (! global_bindings_p ())
		    poplevel (0, 0, 0);
		  finish_file ();
		}
	;

/* the reason for the strange actions in this rule
 is so that notype_initdecls when reached via datadef
 can find a valid list of type and sc specs in $0. */

extdefs:
	  { $<ttype>$ = NULL_TREE; } lang_extdef
		{ $<ttype>$ = NULL_TREE; }
	| extdefs lang_extdef
		{ $<ttype>$ = NULL_TREE; }
	;

extdefs_opt:
	  extdefs
	| /* empty */
	;

.hush_warning:
		{ have_extern_spec = 1;
		  used_extern_spec = 0;
		  $<ttype>$ = NULL_TREE; }
	;
.warning_ok:
		{ have_extern_spec = 0; }
	;

asm_keyword:
	  ASM_KEYWORD
	| GCC_ASM_KEYWORD
	;

lang_extdef:
	  { if (pending_lang_change) do_pending_lang_change(); }
	  extdef
	  { if (! toplevel_bindings_p () && ! pseudo_global_level_p())
	      pop_everything (); }
	;

extdef:
	  fndef
		{ if (pending_inlines) do_pending_inlines (); }
	| datadef
		{ if (pending_inlines) do_pending_inlines (); }
	| template_def
		{ if (pending_inlines) do_pending_inlines (); }
	| overloaddef
	| asm_keyword '(' string ')' ';'
		{ if (TREE_CHAIN ($3)) $3 = combine_strings ($3);
		  assemble_asm ($3); }
	| extern_lang_string '{' extdefs_opt '}'
		{ pop_lang_context (); }
	| extern_lang_string .hush_warning fndef .warning_ok
		{ if (pending_inlines) do_pending_inlines ();
		  pop_lang_context (); }
	| extern_lang_string .hush_warning datadef .warning_ok
		{ if (pending_inlines) do_pending_inlines ();
		  pop_lang_context (); }
	| NAMESPACE identifier '{'
		{ push_namespace ($2); }
	  extdefs_opt '}'
		{ pop_namespace (); }
	| NAMESPACE '{'
		{ push_namespace (NULL_TREE); }
	  extdefs_opt '}'
		{ pop_namespace (); }
	| NAMESPACE identifier '=' any_id ';'
		{ do_namespace_alias ($2, $4); }
	| using_decl ';'
		{ do_toplevel_using_decl ($1); }
	| USING NAMESPACE any_id ';'
		{ do_using_directive ($3); }
	;

using_decl:
	  USING qualified_id
		{ $$ = $2; }
	| USING global_scope qualified_id
		{ $$ = $3; }
	| USING global_scope unqualified_id
		{ $$ = $3; }
	;

any_id:
	  unqualified_id
	| qualified_id
	| global_scope qualified_id
		{ $$ = $2; }
	| global_scope unqualified_id
		{ $$ = $2; }
	;

extern_lang_string:
	EXTERN_LANG_STRING
		{ push_lang_context ($1); }
	| extern_lang_string EXTERN_LANG_STRING
		{ if (current_lang_name != $2)
		    cp_error ("use of linkage spec `%D' is different from previous spec `%D'", $2, current_lang_name);
		  pop_lang_context (); push_lang_context ($2); }
	;

template_header:
	  TEMPLATE '<'
		{ begin_template_parm_list (); }
	  template_parm_list '>'
		{ $$ = end_template_parm_list ($4); }
	;

template_parm_list:
	  template_parm
		{ $$ = process_template_parm (NULL_TREE, $1); }
	| template_parm_list ',' template_parm
		{ $$ = process_template_parm ($1, $3); }
	;

template_type_parm:
	  aggr
		{ 
		  $$ = build_tree_list ($1, NULL_TREE);
		 ttpa:
		  if (TREE_PURPOSE ($$) == signature_type_node)
		    sorry ("signature as template type parameter");
		  else if (TREE_PURPOSE ($$) != class_type_node)
		    pedwarn ("template type parameters must use the keyword `class'");
		}
	| aggr identifier
		{ $$ = build_tree_list ($1, $2); goto ttpa; }
	| TYPENAME_KEYWORD
		{ $$ = build_tree_list (class_type_node, NULL_TREE); }
	| TYPENAME_KEYWORD identifier
		{ $$ = build_tree_list (class_type_node, $2); }
	;