c-parse.y

gcc库的原代码,对编程有很大帮助.

		    pedwarn ("ANSI C forbids `&&'");
		  if (label == 0)
		    $$ = null_pointer_node;
		  else
		    {
		      TREE_USED (label) = 1;
		      $$ = build1 (ADDR_EXPR, ptr_type_node, label);
		      TREE_CONSTANT ($$) = 1;
		    }
		}
/* This seems to be impossible on some machines, so let's turn it off.
   You can use __builtin_next_arg to find the anonymous stack args.
	| '&' ELLIPSIS
		{ tree types = TYPE_ARG_TYPES (TREE_TYPE (current_function_decl));
		  $$ = error_mark_node;
		  if (TREE_VALUE (tree_last (types)) == void_type_node)
		    error ("`&...' used in function with fixed number of arguments");
		  else
		    {
		      if (pedantic)
			pedwarn ("ANSI C forbids `&...'");
		      $$ = tree_last (DECL_ARGUMENTS (current_function_decl));
		      $$ = build_unary_op (ADDR_EXPR, $$, 0);
		    } }
*/
	| SIZEOF unary_expr  %prec UNARY
		{ if (TREE_CODE ($2) == COMPONENT_REF
		      && DECL_BIT_FIELD (TREE_OPERAND ($2, 1)))
		    error ("`sizeof' applied to a bit-field");
		  $$ = c_sizeof (TREE_TYPE ($2)); }
	| SIZEOF '(' typename ')'  %prec HYPERUNARY
		{ $$ = c_sizeof (groktypename ($3)); }
	| ALIGNOF unary_expr  %prec UNARY
		{ $$ = c_alignof_expr ($2); }
	| ALIGNOF '(' typename ')'  %prec HYPERUNARY
		{ $$ = c_alignof (groktypename ($3)); }
	| REALPART cast_expr %prec UNARY
		{ $$ = build_unary_op (REALPART_EXPR, $2, 0); }
	| IMAGPART cast_expr %prec UNARY
		{ $$ = build_unary_op (IMAGPART_EXPR, $2, 0); }
	;

cast_expr:
	unary_expr
	| '(' typename ')' cast_expr  %prec UNARY
		{ tree type = groktypename ($2);
		  $$ = build_c_cast (type, $4); }
	| '(' typename ')' '{' 
		{ start_init (NULL_TREE, NULL, 0);
		  $2 = groktypename ($2);
		  really_start_incremental_init ($2); }
	  initlist_maybe_comma '}'  %prec UNARY
		{ char *name;
		  tree result = pop_init_level (0);
		  tree type = $2;
		  finish_init ();

		  if (pedantic)
		    pedwarn ("ANSI C forbids constructor expressions");
		  if (TYPE_NAME (type) != 0)
		    {
		      if (TREE_CODE (TYPE_NAME (type)) == IDENTIFIER_NODE)
			name = IDENTIFIER_POINTER (TYPE_NAME (type));
		      else
			name = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (type)));
		    }
		  else
		    name = "";
		  $$ = result;
		  if (TREE_CODE (type) == ARRAY_TYPE && TYPE_SIZE (type) == 0)
		    {
		      int failure = complete_array_type (type, $$, 1);
		      if (failure)
			abort ();
		    }
		}
	;

expr_no_commas:
	  cast_expr
	| expr_no_commas '+' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '-' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '*' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '/' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '%' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas LSHIFT expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas RSHIFT expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas ARITHCOMPARE expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas EQCOMPARE expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '&' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '|' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas '^' expr_no_commas
		{ $$ = parser_build_binary_op ($2, $1, $3); }
	| expr_no_commas ANDAND expr_no_commas
		{ $$ = parser_build_binary_op (TRUTH_ANDIF_EXPR, $1, $3); }
	| expr_no_commas OROR expr_no_commas
		{ $$ = parser_build_binary_op (TRUTH_ORIF_EXPR, $1, $3); }
	| expr_no_commas '?' xexpr ':' expr_no_commas
		{ $$ = build_conditional_expr ($1, $3, $5); }
	| expr_no_commas '=' expr_no_commas
		{ $$ = build_modify_expr ($1, NOP_EXPR, $3);
		  C_SET_EXP_ORIGINAL_CODE ($$, MODIFY_EXPR); }
	| expr_no_commas ASSIGN expr_no_commas
		{ $$ = build_modify_expr ($1, $2, $3);
		  /* This inhibits warnings in truthvalue_conversion.  */
		  C_SET_EXP_ORIGINAL_CODE ($$, ERROR_MARK); }
	;

primary:
	IDENTIFIER
		{
		  $$ = lastiddecl;
		  if (!$$ || $$ == error_mark_node)
		    {
		      if (yychar == YYEMPTY)
			yychar = YYLEX;
		      if (yychar == '(')
			{
			    {
			      /* Ordinary implicit function declaration.  */
			      $$ = implicitly_declare ($1);
			      assemble_external ($$);
			      TREE_USED ($$) = 1;
			    }
			}
		      else if (current_function_decl == 0)
			{
			  error ("`%s' undeclared here (not in a function)",
				 IDENTIFIER_POINTER ($1));
			  $$ = error_mark_node;
			}
		      else
			{
			    {
			      if (IDENTIFIER_GLOBAL_VALUE ($1) != error_mark_node
				  || IDENTIFIER_ERROR_LOCUS ($1) != current_function_decl)
				{
				  error ("`%s' undeclared (first use this function)",
					 IDENTIFIER_POINTER ($1));

				  if (! undeclared_variable_notice)
				    {
				      error ("(Each undeclared identifier is reported only once");
				      error ("for each function it appears in.)");
				      undeclared_variable_notice = 1;
				    }
				}
			      $$ = error_mark_node;
			      /* Prevent repeated error messages.  */
			      IDENTIFIER_GLOBAL_VALUE ($1) = error_mark_node;
			      IDENTIFIER_ERROR_LOCUS ($1) = current_function_decl;
			    }
			}
		    }
		  else if (TREE_TYPE ($$) == error_mark_node)
		    $$ = error_mark_node;
		  else if (C_DECL_ANTICIPATED ($$))
		    {
		      /* The first time we see a build-in function used,
			 if it has not been declared.  */
		      C_DECL_ANTICIPATED ($$) = 0;
		      if (yychar == YYEMPTY)
			yychar = YYLEX;
		      if (yychar == '(')
			{
			  /* Omit the implicit declaration we
			     would ordinarily do, so we don't lose
			     the actual built in type.
			     But print a diagnostic for the mismatch.  */
			    if (TREE_CODE ($$) != FUNCTION_DECL)
			      error ("`%s' implicitly declared as function",
				     IDENTIFIER_POINTER (DECL_NAME ($$)));
			  else if ((TYPE_MODE (TREE_TYPE (TREE_TYPE ($$)))
				    != TYPE_MODE (integer_type_node))
				   && (TREE_TYPE (TREE_TYPE ($$))
				       != void_type_node))
			    pedwarn ("type mismatch in implicit declaration for built-in function `%s'",
				     IDENTIFIER_POINTER (DECL_NAME ($$)));
			  /* If it really returns void, change that to int.  */
			  if (TREE_TYPE (TREE_TYPE ($$)) == void_type_node)
			    TREE_TYPE ($$)
			      = build_function_type (integer_type_node,
						     TYPE_ARG_TYPES (TREE_TYPE ($$)));
			}
		      else
			pedwarn ("built-in function `%s' used without declaration",
				 IDENTIFIER_POINTER (DECL_NAME ($$)));

		      /* Do what we would ordinarily do when a fn is used.  */
		      assemble_external ($$);
		      TREE_USED ($$) = 1;
		    }
		  else
		    {
		      assemble_external ($$);
		      TREE_USED ($$) = 1;
		    }

		  if (TREE_CODE ($$) == CONST_DECL)
		    {
		      $$ = DECL_INITIAL ($$);
		      /* This is to prevent an enum whose value is 0
			 from being considered a null pointer constant.  */
		      $$ = build1 (NOP_EXPR, TREE_TYPE ($$), $$);
		      TREE_CONSTANT ($$) = 1;
		    }
		}
	| CONSTANT
	| string
		{ $$ = combine_strings ($1); }
	| '(' expr ')'
		{ char class = TREE_CODE_CLASS (TREE_CODE ($2));
		  if (class == 'e' || class == '1'
		      || class == '2' || class == '<')
		    C_SET_EXP_ORIGINAL_CODE ($2, ERROR_MARK);
		  $$ = $2; }
	| '(' error ')'
		{ $$ = error_mark_node; }
	| '('
		{ if (current_function_decl == 0)
		    {
		      error ("braced-group within expression allowed only inside a function");
		      YYERROR;
		    }
		  /* We must force a BLOCK for this level
		     so that, if it is not expanded later,
		     there is a way to turn off the entire subtree of blocks
		     that are contained in it.  */
		  keep_next_level ();
		  push_iterator_stack ();
		  push_label_level ();
		  $<ttype>$ = expand_start_stmt_expr (); }
	  compstmt ')'
		{ tree rtl_exp;
		  if (pedantic)
		    pedwarn ("ANSI C forbids braced-groups within expressions");
		  pop_iterator_stack ();
		  pop_label_level ();
		  rtl_exp = expand_end_stmt_expr ($<ttype>2);
		  /* The statements have side effects, so the group does.  */
		  TREE_SIDE_EFFECTS (rtl_exp) = 1;

		  if (TREE_CODE ($3) == BLOCK)
		    {
		      /* Make a BIND_EXPR for the BLOCK already made.  */
		      $$ = build (BIND_EXPR, TREE_TYPE (rtl_exp),
				  NULL_TREE, rtl_exp, $3);
		      /* Remove the block from the tree at this point.
			 It gets put back at the proper place
			 when the BIND_EXPR is expanded.  */
		      delete_block ($3);
		    }
		  else
		    $$ = $3;
		}
	| primary '(' exprlist ')'   %prec '.'
		{ $$ = build_function_call ($1, $3); }
	| primary '[' expr ']'   %prec '.'
		{ $$ = build_array_ref ($1, $3); }
	| primary '.' identifier
		{
		    $$ = build_component_ref ($1, $3);
		}
	| primary POINTSAT identifier
		{
                  tree expr = build_indirect_ref ($1, "->");

                    $$ = build_component_ref (expr, $3);
		}
	| primary PLUSPLUS
		{ $$ = build_unary_op (POSTINCREMENT_EXPR, $1, 0); }
	| primary MINUSMINUS
		{ $$ = build_unary_op (POSTDECREMENT_EXPR, $1, 0); }
	;

/* Produces a STRING_CST with perhaps more STRING_CSTs chained onto it.  */
string:
	  STRING
	| string STRING
		{ $$ = chainon ($1, $2); }
	;


xdecls:
	/* empty */
	| datadecls
	| datadecls ELLIPSIS
		/* ... is used here to indicate a varargs function.  */
		{ c_mark_varargs ();
		  if (pedantic)
		    pedwarn ("ANSI C does not permit use of `varargs.h'"); }
	;

/* The following are analogous to lineno_decl, decls and decl
   except that they do not allow nested functions.
   They are used for old-style parm decls.  */
lineno_datadecl:
	  save_filename save_lineno datadecl
		{ }
	;

datadecls:
	lineno_datadecl
	| errstmt
	| datadecls lineno_datadecl
	| lineno_datadecl errstmt
	;

datadecl:
	typed_declspecs setspecs initdecls ';'
		{ current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| declmods setspecs notype_initdecls ';'
		{ current_declspecs = TREE_VALUE (declspec_stack);	
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| typed_declspecs ';'
		{ shadow_tag_warned ($1, 1);
		  pedwarn ("empty declaration"); }
	| declmods ';'
		{ pedwarn ("empty declaration"); }
	;

/* This combination which saves a lineno before a decl
   is the normal thing to use, rather than decl itself.
   This is to avoid shift/reduce conflicts in contexts
   where statement labels are allowed.  */
lineno_decl:
	  save_filename save_lineno decl
		{ }
	;

decls:
	lineno_decl
	| errstmt
	| decls lineno_decl
	| lineno_decl errstmt
	;

/* records the type and storage class specs to use for processing
   the declarators that follow.
   Maintains a stack of outer-level values of current_declspecs,
   for the sake of parm declarations nested in function declarators.  */
setspecs: /* empty */
		{ $$ = suspend_momentary ();
		  pending_xref_error ();
		  declspec_stack = tree_cons (prefix_attributes,
					      current_declspecs,
					      declspec_stack);
		  current_declspecs = $<ttype>0; 
		  prefix_attributes = NULL_TREE; }
	;

setattrs: /* empty */
		{ prefix_attributes = chainon (prefix_attributes, $<ttype>0); }
	;

decl:
	typed_declspecs setspecs initdecls ';'
		{ current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| declmods setspecs notype_initdecls ';'
		{ current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| typed_declspecs setspecs nested_function
		{ current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| declmods setspecs notype_nested_function
		{ current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| typed_declspecs ';'
		{ shadow_tag ($1); }
	| declmods ';'
		{ pedwarn ("empty declaration"); }
	;

/* 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.  */

typed_declspecs:
	  typespec reserved_declspecs
		{ $$ = tree_cons (NULL_TREE, $1, $2); }
	| declmods typespec reserved_declspecs
		{ $$ = chainon ($3, tree_cons (NULL_TREE, $2, $1)); }
	;

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