c-parse.y

gcc库的原代码,对编程有很大帮助.

		{ if (extra_warnings)
		    warning ("`%s' is not at beginning of declaration",
			     IDENTIFIER_POINTER ($2));
		  $$ = tree_cons (NULL_TREE, $2, $1); }
	;

/* 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.  */

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


/* Used instead of declspecs where storage classes are not allowed
   (that is, for typenames and structure components).
   Don't accept a typedef-name if anything but a modifier precedes it.  */

typed_typespecs:
	  typespec reserved_typespecquals
		{ $$ = tree_cons (NULL_TREE, $1, $2); }
	| nonempty_type_quals typespec reserved_typespecquals
		{ $$ = chainon ($3, tree_cons (NULL_TREE, $2, $1)); }
	;

reserved_typespecquals:  /* empty */
		{ $$ = NULL_TREE; }
	| reserved_typespecquals typespecqual_reserved
		{ $$ = tree_cons (NULL_TREE, $2, $1); }
	;

/* 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: TYPESPEC
	| structsp
	| TYPENAME
		{ /* For a typedef name, record the meaning, not the name.
		     In case of `foo foo, bar;'.  */
		  $$ = lookup_name ($1); }
	| TYPEOF '(' expr ')'
		{ $$ = TREE_TYPE ($3); }
	| TYPEOF '(' typename ')'
		{ $$ = groktypename ($3); }
	;

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

typespecqual_reserved: TYPESPEC
	| TYPE_QUAL
	| structsp
	;

initdecls:
	initdcl
	| initdecls ',' initdcl
	;

notype_initdecls:
	notype_initdcl
	| notype_initdecls ',' initdcl
	;

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

initdcl:
	  declarator maybeasm maybe_attribute '='
		{ $<ttype>$ = start_decl ($1, current_declspecs, 1,
					  $3, prefix_attributes);
		  start_init ($<ttype>$, $2, global_bindings_p ()); }
	  init
/* Note how the declaration of the variable is in effect while its init is parsed! */
		{ finish_init ();
		  finish_decl ($<ttype>5, $6, $2); }
	| declarator maybeasm maybe_attribute
		{ tree d = start_decl ($1, current_declspecs, 0,
				       $3, prefix_attributes);
		  finish_decl (d, NULL_TREE, $2); 
                }
	;

notype_initdcl:
	  notype_declarator maybeasm maybe_attribute '='
		{ $<ttype>$ = start_decl ($1, current_declspecs, 1,
					  $3, prefix_attributes);
		  start_init ($<ttype>$, $2, global_bindings_p ()); }
	  init
/* Note how the declaration of the variable is in effect while its init is parsed! */
		{ finish_init ();
		  decl_attributes ($<ttype>5, $3, prefix_attributes);
		  finish_decl ($<ttype>5, $6, $2); }
	| notype_declarator maybeasm maybe_attribute
		{ tree d = start_decl ($1, current_declspecs, 0,
				       $3, prefix_attributes);
		  finish_decl (d, NULL_TREE, $2); }
	;
/* 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 '(' 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
	;

/* Initializers.  `init' is the entry point.  */

init:
	expr_no_commas
	| '{'
		{ really_start_incremental_init (NULL_TREE);
		  /* Note that the call to clear_momentary
		     is in process_init_element.  */
		  push_momentary (); }
	  initlist_maybe_comma '}'
		{ $$ = pop_init_level (0);
		  if ($$ == error_mark_node
		      && ! (yychar == STRING || yychar == CONSTANT))
		    pop_momentary ();
		  else
		    pop_momentary_nofree (); }

	| error
		{ $$ = error_mark_node; }
	;

/* `initlist_maybe_comma' is the guts of an initializer in braces.  */
initlist_maybe_comma:
	  /* empty */
		{ if (pedantic)
		    pedwarn ("ANSI C forbids empty initializer braces"); }
	| initlist1 maybecomma
	;

initlist1:
	  initelt
	| initlist1 ',' initelt
	;

/* `initelt' is a single element of an initializer.
   It may use braces.  */
initelt:
	expr_no_commas
		{ process_init_element ($1); }
	| '{' 
		{ push_init_level (0); }
	  initlist_maybe_comma '}'
		{ process_init_element (pop_init_level (0)); }
	| error
	/* These are for labeled elements.  The syntax for an array element
	   initializer conflicts with the syntax for an Objective-C message,
	   so don't include these productions in the Objective-C grammar.  */
	| '[' expr_no_commas ELLIPSIS expr_no_commas ']' '='
		{ set_init_index ($2, $4); }
	  initelt
	| '[' expr_no_commas ']' '='
		{ set_init_index ($2, NULL_TREE); }
	  initelt
	| '[' expr_no_commas ']'
		{ set_init_index ($2, NULL_TREE); }
	  initelt
	| identifier ':'
		{ set_init_label ($1); }
	  initelt
	| '.' identifier '='
		{ set_init_label ($2); }
	  initelt
	;

nested_function:
	  declarator
		{ push_c_function_context ();
		  if (! start_function (current_declspecs, $1,
					prefix_attributes, NULL_TREE, 1))
		    {
		      pop_c_function_context ();
		      YYERROR1;
		    }
		  reinit_parse_for_function (); }
	   xdecls
		{ store_parm_decls (); }
/* This used to use compstmt_or_error.
   That caused a bug with input `f(g) int g {}',
   where the use of YYERROR1 above caused an error
   which then was handled by compstmt_or_error.
   There followed a repeated execution of that same rule,
   which called YYERROR1 again, and so on.  */
	  compstmt
		{ finish_function (1);
		  pop_c_function_context (); }
	;

notype_nested_function:
	  notype_declarator
		{ push_c_function_context ();
		  if (! start_function (current_declspecs, $1,
					prefix_attributes, NULL_TREE, 1))
		    {
		      pop_c_function_context ();
		      YYERROR1;
		    }
		  reinit_parse_for_function (); }
	  xdecls
		{ store_parm_decls (); }
/* This used to use compstmt_or_error.
   That caused a bug with input `f(g) int g {}',
   where the use of YYERROR1 above caused an error
   which then was handled by compstmt_or_error.
   There followed a repeated execution of that same rule,
   which called YYERROR1 again, and so on.  */
	  compstmt
		{ finish_function (1);
		  pop_c_function_context (); }
	;

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

declarator:
	  after_type_declarator
	| notype_declarator
	;

/* A declarator that is allowed only after an explicit typespec.  */

after_type_declarator:
	  '(' after_type_declarator ')'
		{ $$ = $2; }
	| after_type_declarator '(' parmlist_or_identifiers  %prec '.'
		{ $$ = build_nt (CALL_EXPR, $1, $3, NULL_TREE); }
/*	| after_type_declarator '(' error ')'  %prec '.'
		{ $$ = build_nt (CALL_EXPR, $1, NULL_TREE, NULL_TREE);
		  poplevel (0, 0, 0); }  */
	| after_type_declarator '[' expr ']'  %prec '.'
		{ $$ = build_nt (ARRAY_REF, $1, $3); }
	| after_type_declarator '[' ']'  %prec '.'
		{ $$ = build_nt (ARRAY_REF, $1, NULL_TREE); }
	| '*' type_quals after_type_declarator  %prec UNARY
		{ $$ = make_pointer_declarator ($2, $3); }
	| attributes setattrs after_type_declarator
		{ $$ = $3; }
	| TYPENAME
	;

/* Kinds of declarator that can appear in a parameter list
   in addition to notype_declarator.  This is like after_type_declarator
   but does not allow a typedef name in parentheses as an identifier
   (because it would conflict with a function with that typedef as arg).  */

parm_declarator:
	  parm_declarator '(' parmlist_or_identifiers  %prec '.'
		{ $$ = build_nt (CALL_EXPR, $1, $3, NULL_TREE); }
/*	| parm_declarator '(' error ')'  %prec '.'
		{ $$ = build_nt (CALL_EXPR, $1, NULL_TREE, NULL_TREE);
		  poplevel (0, 0, 0); }  */
	| parm_declarator '[' expr ']'  %prec '.'
		{ $$ = build_nt (ARRAY_REF, $1, $3); }
	| parm_declarator '[' ']'  %prec '.'
		{ $$ = build_nt (ARRAY_REF, $1, NULL_TREE); }
	| '*' type_quals parm_declarator  %prec UNARY
		{ $$ = make_pointer_declarator ($2, $3); }
	| attributes setattrs parm_declarator
		{ $$ = $3; }
	| TYPENAME
	;

/* A declarator allowed whether or not there has been
   an explicit typespec.  These cannot redeclare a typedef-name.  */

notype_declarator:
	  notype_declarator '(' parmlist_or_identifiers  %prec '.'
		{ $$ = build_nt (CALL_EXPR, $1, $3, NULL_TREE); }
/*	| notype_declarator '(' error ')'  %prec '.'
		{ $$ = build_nt (CALL_EXPR, $1, NULL_TREE, NULL_TREE);
		  poplevel (0, 0, 0); }  */
	| '(' notype_declarator ')'
		{ $$ = $2; }
	| '*' type_quals notype_declarator  %prec UNARY
		{ $$ = make_pointer_declarator ($2, $3); }
	| notype_declarator '[' expr ']'  %prec '.'
		{ $$ = build_nt (ARRAY_REF, $1, $3); }
	| notype_declarator '[' ']'  %prec '.'
		{ $$ = build_nt (ARRAY_REF, $1, NULL_TREE); }
	| attributes setattrs notype_declarator
		{ $$ = $3; }
	| IDENTIFIER
	;

structsp:
	  STRUCT identifier '{'
		{ $$ = start_struct (RECORD_TYPE, $2);
		  /* Start scope of tag before parsing components.  */
		}
	  component_decl_list '}' maybe_attribute 
		{ $$ = finish_struct ($<ttype>4, $5, $7); }
	| STRUCT '{' component_decl_list '}' maybe_attribute
		{ $$ = finish_struct (start_struct (RECORD_TYPE, NULL_TREE),
				      $3, $5);
		}
	| STRUCT identifier
		{ $$ = xref_tag (RECORD_TYPE, $2); }
	| UNION identifier '{'
		{ $$ = start_struct (UNION_TYPE, $2); }
	  component_decl_list '}' maybe_attribute
		{ $$ = finish_struct ($<ttype>4, $5, $7); }
	| UNION '{' component_decl_list '}' maybe_attribute
		{ $$ = finish_struct (start_struct (UNION_TYPE, NULL_TREE),
				      $3, $5);
		}
	| UNION identifier
		{ $$ = xref_tag (UNION_TYPE, $2); }
	| ENUM identifier '{'
		{ $<itype>3 = suspend_momentary ();
		  $$ = start_enum ($2); }
	  enumlist maybecomma_warn '}' maybe_attribute
		{ $$ = finish_enum ($<ttype>4, nreverse ($5), $8);
		  resume_momentary ($<itype>3); }
	| ENUM '{'
		{ $<itype>2 = suspend_momentary ();
		  $$ = start_enum (NULL_TREE); }
	  enumlist maybecomma_warn '}' maybe_attribute
		{ $$ = finish_enum ($<ttype>3, nreverse ($4), $7);
		  resume_momentary ($<itype>2); }
	| ENUM identifier
		{ $$ = xref_tag (ENUMERAL_TYPE, $2); }
	;

maybecomma:
	  /* empty */
	| ','
	;

maybecomma_warn:
	  /* empty */
	| ','
		{ if (pedantic) pedwarn ("comma at end of enumerator list"); }
	;

component_decl_list:
	  component_decl_list2
		{ $$ = $1; }
	| component_decl_list2 component_decl
		{ $$ = chainon ($1, $2);
		  pedwarn ("no semicolon at end of struct or union"); }
	;

component_decl_list2:	/* empty */
		{ $$ = NULL_TREE; }
	| component_decl_list2 component_decl ';'
		{ $$ = chainon ($1, $2); }