parse.y

gcc库的原代码,对编程有很大帮助.

		{
		  resume_momentary ($2);
		  if (IS_AGGR_TYPE_CODE (TREE_CODE ($1)))
		    note_got_semicolon ($1);
		}
	| typed_declspecs initdecls ';'
		{
		  resume_momentary ($2);
		  note_list_got_semicolon ($1);
		}
	| declmods notype_initdecls ';'
		{ resume_momentary ($2); }
	| typed_declspecs ';'
		{
		  shadow_tag ($1);
		  note_list_got_semicolon ($1);
		}
	| declmods ';'
		{ warning ("empty declaration"); }
	;

/* Any kind of declarator (thus, all declarators allowed
   after an explicit typespec).  */

declarator:
	  after_type_declarator %prec EMPTY
	| notype_declarator %prec EMPTY
	;

/* This is necessary to postpone reduction of `int()()()()'.  */
fcast_or_absdcl:
	  LEFT_RIGHT %prec EMPTY
		{ $$ = build_parse_node (CALL_EXPR, NULL_TREE, empty_parms (),
					 NULL_TREE); }
	| fcast_or_absdcl LEFT_RIGHT %prec EMPTY
		{ $$ = build_parse_node (CALL_EXPR, $$, empty_parms (), 
					 NULL_TREE); }
	;

/* ANSI type-id (8.1) */
type_id:
	  typed_typespecs absdcl
		{ $$ = build_decl_list ($$, $2); }
	| nonempty_type_quals absdcl
		{ $$ = build_decl_list ($$, $2); }
	| typespec absdcl
		{ $$ = build_decl_list (get_decl_list ($$), $2); }
	| typed_typespecs %prec EMPTY
		{ $$ = build_decl_list ($$, NULL_TREE); }
	| nonempty_type_quals %prec EMPTY
		{ $$ = build_decl_list ($$, NULL_TREE); }
	;

/* Declspecs which contain at least one type specifier or typedef name.
   (Just `const' or `volatile' is not enough.)
   A typedef'd name following these is taken as a name to be declared.
   In the result, declspecs have a non-NULL TREE_VALUE, attributes do not.  */

typed_declspecs:
	  typed_typespecs %prec EMPTY
	| typed_declspecs1
	;

typed_declspecs1:
	  declmods typespec
		{ $$ = decl_tree_cons (NULL_TREE, $2, $$); }
	| typespec reserved_declspecs	%prec HYPERUNARY
		{ $$ = decl_tree_cons (NULL_TREE, $$, $2); }
	| typespec reserved_typespecquals reserved_declspecs
		{ $$ = decl_tree_cons (NULL_TREE, $$, chainon ($2, $3)); }
	| declmods typespec reserved_declspecs
		{ $$ = decl_tree_cons (NULL_TREE, $2, chainon ($3, $$)); }
	| declmods typespec reserved_typespecquals
		{ $$ = decl_tree_cons (NULL_TREE, $2, chainon ($3, $$)); }
	| declmods typespec reserved_typespecquals reserved_declspecs
		{ $$ = decl_tree_cons (NULL_TREE, $2, 
				       chainon ($3, chainon ($4, $$))); }
	;

reserved_declspecs:
	  SCSPEC
		{ if (extra_warnings)
		    warning ("`%s' is not at beginning of declaration",
			     IDENTIFIER_POINTER ($$));
		  $$ = build_decl_list (NULL_TREE, $$); }
	| reserved_declspecs typespecqual_reserved
		{ $$ = decl_tree_cons (NULL_TREE, $2, $$); }
	| reserved_declspecs SCSPEC
		{ if (extra_warnings)
		    warning ("`%s' is not at beginning of declaration",
			     IDENTIFIER_POINTER ($2));
		  $$ = decl_tree_cons (NULL_TREE, $2, $$); }
	| reserved_declspecs attributes
		{ $$ = decl_tree_cons ($2, NULL_TREE, $1); }
	| attributes
		{ $$ = decl_tree_cons ($1, NULL_TREE, NULL_TREE); }
	;

/* List of just storage classes and type modifiers.
   A declaration can start with just this, but then it cannot be used
   to redeclare a typedef-name.
   In the result, declspecs have a non-NULL TREE_VALUE, attributes do not.  */

declmods:
	  nonempty_type_quals %prec EMPTY
		{ TREE_STATIC ($$) = 1; }
	| SCSPEC
		{ $$ = IDENTIFIER_AS_LIST ($$); }
	| declmods TYPE_QUAL
		{ $$ = decl_tree_cons (NULL_TREE, $2, $$);
		  TREE_STATIC ($$) = 1; }
	| declmods SCSPEC
		{ if (extra_warnings && TREE_STATIC ($$))
		    warning ("`%s' is not at beginning of declaration",
			     IDENTIFIER_POINTER ($2));
		  $$ = decl_tree_cons (NULL_TREE, $2, $$);
		  TREE_STATIC ($$) = TREE_STATIC ($1); }
	| declmods attributes
		{ $$ = decl_tree_cons ($2, NULL_TREE, $1); }
	| attributes
		{ $$ = decl_tree_cons ($1, NULL_TREE, NULL_TREE); }
	;

/* Used instead of declspecs where storage classes are not allowed
   (that is, for typenames and structure components).

   C++ can takes storage classes for structure components.
   Don't accept a typedef-name if anything but a modifier precedes it.  */

typed_typespecs:
	  typespec  %prec EMPTY
		{ $$ = get_decl_list ($$); }
	| nonempty_type_quals typespec
		{ $$ = decl_tree_cons (NULL_TREE, $2, $$); }
	| typespec reserved_typespecquals
		{ $$ = decl_tree_cons (NULL_TREE, $$, $2); }
	| nonempty_type_quals typespec reserved_typespecquals
		{ $$ = decl_tree_cons (NULL_TREE, $2, chainon ($3, $$)); }
	;

reserved_typespecquals:
	  typespecqual_reserved
		{ $$ = build_decl_list (NULL_TREE, $$); }
	| reserved_typespecquals typespecqual_reserved
		{ $$ = decl_tree_cons (NULL_TREE, $2, $$); }
	;

/* A typespec (but not a type qualifier).
   Once we have seen one of these in a declaration,
   if a typedef name appears then it is being redeclared.  */

typespec: structsp
	| TYPESPEC  %prec EMPTY
	| complete_type_name
	| TYPEOF '(' expr ')'
		{ $$ = TREE_TYPE ($3);
		  if (pedantic && !in_system_header)
		    pedwarn ("ANSI C++ forbids `typeof'"); }
	| TYPEOF '(' type_id ')'
		{ $$ = groktypename ($3);
		  if (pedantic && !in_system_header)
		    pedwarn ("ANSI C++ forbids `typeof'"); }
	| SIGOF '(' expr ')'
		{ tree type = TREE_TYPE ($3);

		  if (IS_AGGR_TYPE (type))
		    {
		      sorry ("sigof type specifier");
		      $$ = type;
		    }
		  else
		    {
		      error ("`sigof' applied to non-aggregate expression");
		      $$ = error_mark_node;
		    }
		}
	| SIGOF '(' type_id ')'
		{ tree type = groktypename ($3);

		  if (IS_AGGR_TYPE (type))
		    {
		      sorry ("sigof type specifier");
		      $$ = type;
		    }
		  else
		    {
		      error("`sigof' applied to non-aggregate type");
		      $$ = error_mark_node;
		    }
		}
	;

/* A typespec that is a reserved word, or a type qualifier.  */

typespecqual_reserved: TYPESPEC
	| TYPE_QUAL
	| structsp
	;

initdecls:
	  initdcl0
	| initdecls ',' initdcl
	;

notype_initdecls:
	  notype_initdcl0
	| notype_initdecls ',' initdcl
	;

nomods_initdecls:
	  nomods_initdcl0
	| nomods_initdecls ',' initdcl
	;

maybeasm:
	  /* empty */
		{ $$ = NULL_TREE; }
	| asm_keyword '(' string ')'
		{ if (TREE_CHAIN ($3)) $3 = combine_strings ($3); $$ = $3; }
	;

initdcl0:
	  declarator exception_specification_opt maybeasm maybe_attribute '='
		{ split_specs_attrs ($<ttype>0, &current_declspecs,
				     &prefix_attributes);
		  if (TREE_CODE (current_declspecs) != TREE_LIST)
		    current_declspecs = get_decl_list (current_declspecs);
		  if (have_extern_spec && !used_extern_spec)
		    {
		      current_declspecs = decl_tree_cons
			(NULL_TREE, get_identifier ("extern"), 
			 current_declspecs);
		      used_extern_spec = 1;
		    }
		  $<itype>5 = suspend_momentary ();
		  $<ttype>$ = start_decl ($<ttype>1, current_declspecs, 1, $2);
		  cplus_decl_attributes ($<ttype>$, $4, prefix_attributes); }
	  init
/* Note how the declaration of the variable is in effect while its init is parsed! */
		{ cp_finish_decl ($<ttype>6, $7, $3, 0, LOOKUP_ONLYCONVERTING);
		  $$ = $<itype>5; }
	| declarator exception_specification_opt maybeasm maybe_attribute
		{ tree d;
		  split_specs_attrs ($<ttype>0, &current_declspecs,
				     &prefix_attributes);
		  if (TREE_CODE (current_declspecs) != TREE_LIST)
		    current_declspecs = get_decl_list (current_declspecs);
		  if (have_extern_spec && !used_extern_spec)
		    {
		      current_declspecs = decl_tree_cons
			(NULL_TREE, get_identifier ("extern"), 
			 current_declspecs);
		      used_extern_spec = 1;
		    }
		  $$ = suspend_momentary ();
		  d = start_decl ($<ttype>1, current_declspecs, 0, $2);
		  cplus_decl_attributes (d, $4, prefix_attributes);
		  cp_finish_decl (d, NULL_TREE, $3, 0, 0); }
	;

initdcl:
	  declarator exception_specification_opt maybeasm maybe_attribute '='
		{ $<ttype>$ = start_decl ($<ttype>1, current_declspecs, 1, $2);
		  cplus_decl_attributes ($<ttype>$, $4, prefix_attributes); }
	  init
/* Note how the declaration of the variable is in effect while its init is parsed! */
		{ cp_finish_decl ($<ttype>6, $7, $3, 0, LOOKUP_ONLYCONVERTING); }
	| declarator exception_specification_opt maybeasm maybe_attribute
		{ $<ttype>$ = start_decl ($<ttype>1, current_declspecs, 0, $2);
		  cplus_decl_attributes ($<ttype>$, $4, prefix_attributes);
		  cp_finish_decl ($<ttype>$, NULL_TREE, $3, 0, 0); }
	;

notype_initdcl0:
	  notype_declarator exception_specification_opt maybeasm maybe_attribute '='
		{ split_specs_attrs ($<ttype>0, &current_declspecs,
				     &prefix_attributes);
		  $<itype>5 = suspend_momentary ();
		  $<ttype>$ = start_decl ($<ttype>1, current_declspecs, 1, $2);
		  cplus_decl_attributes ($<ttype>$, $4, prefix_attributes); }
	  init
/* Note how the declaration of the variable is in effect while its init is parsed! */
		{ cp_finish_decl ($<ttype>6, $7, $3, 0, LOOKUP_ONLYCONVERTING);
		  $$ = $<itype>5; }
	| notype_declarator exception_specification_opt maybeasm maybe_attribute
		{ tree d;
		  split_specs_attrs ($<ttype>0, &current_declspecs,
				     &prefix_attributes);
		  $$ = suspend_momentary ();
		  d = start_decl ($<ttype>1, current_declspecs, 0, $2);
		  cplus_decl_attributes (d, $4, prefix_attributes);
		  cp_finish_decl (d, NULL_TREE, $3, 0, 0); }
	;

nomods_initdcl0:
	  notype_declarator exception_specification_opt maybeasm maybe_attribute '='
		{ current_declspecs = NULL_TREE;
		  prefix_attributes = NULL_TREE;
		  $<itype>5 = suspend_momentary ();
		  $<ttype>$ = start_decl ($1, current_declspecs, 1, $2);
		  cplus_decl_attributes ($<ttype>$, $4, prefix_attributes); }
	  init
/* Note how the declaration of the variable is in effect while its init is parsed! */
		{ cp_finish_decl ($<ttype>6, $7, $3, 0, LOOKUP_ONLYCONVERTING);
		  $$ = $<itype>5; }
	| notype_declarator exception_specification_opt maybeasm maybe_attribute
		{ tree d;
		  current_declspecs = NULL_TREE;
		  prefix_attributes = NULL_TREE;
		  $$ = suspend_momentary ();
		  d = start_decl ($1, current_declspecs, 0, $2);
		  cplus_decl_attributes (d, $4, prefix_attributes);
		  cp_finish_decl (d, NULL_TREE, $3, 0, 0); }
	;

/* the * rules are dummies to accept the Apollo extended syntax
   so that the header files compile. */
maybe_attribute:
      /* empty */
  		{ $$ = NULL_TREE; }
	| attributes
		{ $$ = $1; }
	;
 
attributes:
      attribute
		{ $$ = $1; }
	| attributes attribute
		{ $$ = chainon ($1, $2); }
	;

attribute:
      ATTRIBUTE '(' '(' attribute_list ')' ')'
		{ $$ = $4; }
	;

attribute_list:
      attrib
		{ $$ = $1; }
	| attribute_list ',' attrib
		{ $$ = chainon ($1, $3); }
	;
 
attrib:
    /* empty */
		{ $$ = NULL_TREE; }
	| any_word
		{ $$ = build_tree_list ($1, NULL_TREE); }
	| any_word '(' IDENTIFIER ')'
		{ $$ = build_tree_list ($1, build_tree_list (NULL_TREE, $3)); }
	| any_word '(' IDENTIFIER ',' nonnull_exprlist ')'
		{ $$ = build_tree_list ($1, tree_cons (NULL_TREE, $3, $5)); }
	| any_word '(' nonnull_exprlist ')'
		{ $$ = build_tree_list ($1, $3); }
	;

/* This still leaves out most reserved keywords,
   shouldn't we include them?  */

any_word:
	  identifier
	| SCSPEC
	| TYPESPEC
	| TYPE_QUAL
	;

/* A nonempty list of identifiers, including typenames.  */
identifiers_or_typenames:
	identifier
		{ $$ = build_tree_list (NULL_TREE, $1); }
	| identifiers_or_typenames ',' identifier
		{ $$ = chainon ($1, build_tree_list (NULL_TREE, $3)); }
	;

maybe_init:
	%prec EMPTY /* empty */
		{ $$ = NULL_TREE; }
	| '=' init
		{ $$ = $2; }

init:
	  expr_no_commas %prec '='
	| '{' '}'
		{ $$ = build_nt (CONSTRUCTOR, NULL_TREE, NULL_TREE);
		  TREE_HAS_CONSTRUCTOR ($$) = 1; }
	| '{' initlist '}'
		{ $$ = build_nt (CONSTRUCTOR, NULL_TREE, nreverse ($2));
		  TREE_HAS_CONSTRUCTOR ($$) = 1; }
	| '{' initlist ',' '}'
		{ $$ = build_nt (CONSTRUCTOR, NULL_TREE, nreverse ($2));
		  TREE_HAS_CONSTRUCTOR ($$) = 1; }
	| error
		{ $$ = NULL_TREE; }
	;

/* This chain is built in reverse order,
   and put in forward order where initlist is used.  */
initlist:
	  init
		{ $$ = build_tree_list (NULL_TREE, $$); }
	| initlist ',' init
		{ $$ = tree_cons (NULL_TREE, $3, $$); }
	/* These are for labeled elements.  */
	| '[' expr_no_commas ']' init
		{ $$ = build_tree_list ($2, $4); }
	| initlist ',' CASE expr_no_commas ':' init
		{ $$ = tree_cons ($4, $6, $$); }
	| identifier ':' init
		{ $$ = build_tree_list ($$, $3); }
	| initlist ',' identifier ':' init
		{ $$ = tree_cons ($3, $5, $$); }
	;

structsp:
	  ENUM identifier '{'
		{ $<itype>3 = suspend_momentary ();
		  $$ = start_enum ($2); }
	  enumlist maybecomma_warn '}'
		{ $$ = finish_enum ($<ttype>4, $5);
		  resume_momentary ((int) $<itype>3);
		  check_for_missing_semicolon ($<ttype>4); }
	| ENUM identifier '{' '}'
		{ $$ = finish_enum (start_enum ($2), NULL_TREE);
		  check_for_missing_semicolon ($$); }
	| ENUM '{'
		{ $<itype>2 = suspend_momentary ();
		  $$ = start_enum (make_anon_name ()); }
	  enumlist maybecomma_warn '}'
		{ $$ = finish_enum ($<ttype>3, $4);
		  resume_momentary ((int) $<itype>1);
		  check_for_missing_semicolon ($<ttype>3); }
	| ENUM '{' '}'
		{ $$ = finish_enum (start_enum (make_anon_name()), NULL_TREE);
		  check_for_missing_semicolon ($$); }
	| ENUM identifier
		{ $$ = xref_tag (enum_type_node, $2, NULL_TREE, 1); }
	| ENUM complex_type_name
		{ $$ = xref_tag (