parse.y

gcc库的原代码,对编程有很大帮助.

		  else
		    $$ = do_identifier ($$);
		}		
	| CONSTANT
	| boolean.literal
	| string
		{ $$ = combine_strings ($$); }
	| '(' expr ')'
		{ char class;
		  $$ = $2;
		  class = TREE_CODE_CLASS (TREE_CODE ($$));
		  if (class == 'e' || class == '1'
		      || class == '2' || class == '<')
                    /* This inhibits warnings in truthvalue_conversion. */
		    C_SET_EXP_ORIGINAL_CODE ($$, ERROR_MARK); }
	| '(' expr_or_declarator ')'
		{ char class;
		  $$ = reparse_decl_as_expr (NULL_TREE, $2);
		  class = TREE_CODE_CLASS (TREE_CODE ($$));
		  if (class == 'e' || class == '1'
		      || class == '2' || class == '<')
                    /* This inhibits warnings in truthvalue_conversion. */
		    C_SET_EXP_ORIGINAL_CODE ($$, ERROR_MARK); }
	| '(' error ')'
		{ $$ = error_mark_node; }
	| '('
		{ if (current_function_decl == 0)
		    {
		      error ("braced-group within expression allowed only inside a function");
		      YYERROR;
		    }
		  keep_next_level ();
		  $<ttype>$ = expand_start_stmt_expr (); }
	  compstmt ')'
		{ tree rtl_exp;
		  if (pedantic)
		    pedwarn ("ANSI C++ forbids braced-groups within expressions");
		  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 '(' nonnull_exprlist ')'
                { /* [eichin:19911016.1902EST] */
                  $<ttype>$ = build_x_function_call ($1, $3, current_class_decl); 
                  /* here we instantiate_class_template as needed... */
                  do_pending_templates ();
                } template_instantiate_some {
                  if (TREE_CODE ($<ttype>5) == CALL_EXPR
                      && TREE_TYPE ($<ttype>5) != void_type_node)
	            $$ = require_complete_type ($<ttype>5);
                  else
                    $$ = $<ttype>5;
                }
	| primary LEFT_RIGHT
                {
		  $$ = build_x_function_call ($$, NULL_TREE, current_class_decl);
		  if (TREE_CODE ($$) == CALL_EXPR
		      && TREE_TYPE ($$) != void_type_node)
		    $$ = require_complete_type ($$);
                }
	| primary '[' expr ']'
		{ $$ = grok_array_decl ($$, $3); }
	| primary PLUSPLUS
		{ /* If we get an OFFSET_REF, turn it into what it really
		     means (e.g., a COMPONENT_REF).  This way if we've got,
		     say, a reference to a static member that's being operated
		     on, we don't end up trying to find a member operator for
		     the class it's in.  */
		  if (TREE_CODE ($$) == OFFSET_REF)
		    $$ = resolve_offset_ref ($$);
		  $$ = build_x_unary_op (POSTINCREMENT_EXPR, $$); }
	| primary MINUSMINUS
		{ if (TREE_CODE ($$) == OFFSET_REF)
		    $$ = resolve_offset_ref ($$);
		  $$ = build_x_unary_op (POSTDECREMENT_EXPR, $$); }
	/* C++ extensions */
	| THIS
		{ if (current_class_decl)
		    {
#ifdef WARNING_ABOUT_CCD
		      TREE_USED (current_class_decl) = 1;
#endif
		      $$ = current_class_decl;
		    }
		  else if (current_function_decl
			   && DECL_STATIC_FUNCTION_P (current_function_decl))
		    {
		      error ("`this' is unavailable for static member functions");
		      $$ = error_mark_node;
		    }
		  else
		    {
		      if (current_function_decl)
			error ("invalid use of `this' in non-member function");
		      else
			error ("invalid use of `this' at top level");
		      $$ = error_mark_node;
		    }
		}
	| TYPE_QUAL '(' nonnull_exprlist ')'
		{
		  tree type;
		  tree id = $$;

		  /* This is a C cast in C++'s `functional' notation.  */
		  if ($3 == error_mark_node)
		    {
		      $$ = error_mark_node;
		      break;
		    }
#if 0
		  if ($3 == NULL_TREE)
		    {
		      error ("cannot cast null list to type `%s'",
		             IDENTIFIER_POINTER (TYPE_NAME (id)));
		      $$ = error_mark_node;
		      break;
		    }
#endif
#if 0
		  /* type is not set! (mrs) */
		  if (type == error_mark_node)
		    $$ = error_mark_node;
		  else
#endif
		    {
		      if (id == ridpointers[(int) RID_CONST])
		        type = build_type_variant (integer_type_node, 1, 0);
		      else if (id == ridpointers[(int) RID_VOLATILE])
		        type = build_type_variant (integer_type_node, 0, 1);
#if 0
		      /* should not be able to get here (mrs) */
		      else if (id == ridpointers[(int) RID_FRIEND])
		        {
		          error ("cannot cast expression to `friend' type");
		          $$ = error_mark_node;
		          break;
		        }
#endif
		      else my_friendly_abort (79);
		      $$ = build_c_cast (type, build_compound_expr ($3), 1);
		    }
		}
	| functional_cast
	| DYNAMIC_CAST '<'
		{ dont_allow_type_definitions = "inside dynamic_cast"; }
	  type_id '>'
		{ dont_allow_type_definitions = 0; }
	  '(' expr ')'
		{ tree type = groktypename ($4);
		  $$ = build_dynamic_cast (type, $8); }
	| STATIC_CAST '<'
		{ dont_allow_type_definitions = "inside static_cast"; }
	  type_id '>'
		{ dont_allow_type_definitions = 0; }
	  '(' expr ')'
		{ tree type = groktypename ($4);
		  $$ = build_static_cast (type, $8); }
	| REINTERPRET_CAST '<'
		{ dont_allow_type_definitions = "inside reinterpret_cast"; }
	  type_id '>'
		{ dont_allow_type_definitions = 0; }
	  '(' expr ')'
		{ tree type = groktypename ($4);
		  $$ = build_reinterpret_cast (type, $8); }
	| CONST_CAST '<'
		{ dont_allow_type_definitions = "inside const_cast"; }
	  type_id '>'
		{ dont_allow_type_definitions = 0; }
	  '(' expr ')'
		{ tree type = groktypename ($4);
		  $$ = build_const_cast (type, $8); }
	| TYPEID '(' expr ')'
		{ $$ = build_typeid ($3); }
	| TYPEID '(' type_id ')'
		{ tree type = groktypename ($3);
		  $$ = get_typeid (TYPE_MAIN_VARIANT (type)); }
	| global_scope IDENTIFIER
		{
		do_scoped_id:
		  $$ = IDENTIFIER_GLOBAL_VALUE ($2);
		  if (yychar == YYEMPTY)
		    yychar = YYLEX;
		  if (! $$)
		    {
		      if (yychar == '(' || yychar == LEFT_RIGHT)
			$$ = implicitly_declare ($2);
		      else
			{
			  if (IDENTIFIER_GLOBAL_VALUE ($2) != error_mark_node)
			    error ("undeclared variable `%s' (first use here)",
				   IDENTIFIER_POINTER ($2));
			  $$ = error_mark_node;
			  /* Prevent repeated error messages.  */
			  IDENTIFIER_GLOBAL_VALUE ($2) = error_mark_node;
			}
		    }
		  else
		    {
		      if (TREE_CODE ($$) == ADDR_EXPR)
			assemble_external (TREE_OPERAND ($$, 0));
		      else
			assemble_external ($$);
		      TREE_USED ($$) = 1;
		    }
		  if (TREE_CODE ($$) == CONST_DECL)
		    {
		      /* XXX CHS - should we set TREE_USED of the constant? */
		      $$ = DECL_INITIAL ($$);
		      /* 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;
		    }

		}
	| global_scope operator_name
		{
		  got_scope = NULL_TREE;
		  if (TREE_CODE ($2) == IDENTIFIER_NODE)
		    goto do_scoped_id;
		  $$ = $2;
		}
	| overqualified_id %prec HYPERUNARY
		{ $$ = build_offset_ref (OP0 ($$), OP1 ($$)); }
	| overqualified_id '(' nonnull_exprlist ')'
		{ $$ = build_member_call (OP0 ($$), OP1 ($$), $3); }
	| overqualified_id LEFT_RIGHT
		{ $$ = build_member_call (OP0 ($$), OP1 ($$), NULL_TREE); }
	| object unqualified_id  %prec UNARY
		{ got_object = NULL_TREE;
		  $$ = build_component_ref ($$, $2, NULL_TREE, 1); }
	| object overqualified_id %prec UNARY
		{ got_object = NULL_TREE;
		  $$ = build_object_ref ($$, OP0 ($2), OP1 ($2)); }
	| object unqualified_id '(' nonnull_exprlist ')'
		{
		  got_object = NULL_TREE;
#if 0
		  /* This is a future direction of this code, but because
		     build_x_function_call cannot always undo what is done
		     in build_component_ref entirely yet, we cannot do this. */
		  $$ = build_x_function_call (build_component_ref ($$, $2, NULL_TREE, 1), $4, $$);
		  if (TREE_CODE ($$) == CALL_EXPR
		      && TREE_TYPE ($$) != void_type_node)
		    $$ = require_complete_type ($$);
#else
		  $$ = build_method_call ($$, $2, $4, NULL_TREE,
					  (LOOKUP_NORMAL|LOOKUP_AGGR));
#endif
		}
	| object unqualified_id LEFT_RIGHT
		{
		  got_object = NULL_TREE;
#if 0
		  /* This is a future direction of this code, but because
		     build_x_function_call cannot always undo what is done
		     in build_component_ref entirely yet, we cannot do this. */
		  $$ = build_x_function_call (build_component_ref ($$, $2, NULL_TREE, 1), NULL_TREE, $$);
		  if (TREE_CODE ($$) == CALL_EXPR
		      && TREE_TYPE ($$) != void_type_node)
		    $$ = require_complete_type ($$);
#else
		  $$ = build_method_call ($$, $2, NULL_TREE, NULL_TREE,
					  (LOOKUP_NORMAL|LOOKUP_AGGR));
#endif
		}
	| object overqualified_id '(' nonnull_exprlist ')'
		{
		  got_object = NULL_TREE;
		  if (IS_SIGNATURE (IDENTIFIER_TYPE_VALUE (OP0 ($2))))
		    {
		      warning ("signature name in scope resolution ignored");
		      $$ = build_method_call ($$, OP1 ($2), $4, NULL_TREE,
					      (LOOKUP_NORMAL|LOOKUP_AGGR));
		    }
		  else
		    $$ = build_scoped_method_call ($$, OP0 ($2), OP1 ($2), $4);
		}
	| object overqualified_id LEFT_RIGHT
		{
		  got_object = NULL_TREE;
		  if (IS_SIGNATURE (IDENTIFIER_TYPE_VALUE (OP0 ($2))))
		    {
		      warning ("signature name in scope resolution ignored");
		      $$ = build_method_call ($$, OP1 ($2), NULL_TREE, NULL_TREE,
					      (LOOKUP_NORMAL|LOOKUP_AGGR));
		    }
		  else
		    $$ = build_scoped_method_call ($$, OP0 ($2), OP1 ($2), NULL_TREE);
		}
	/* p->int::~int() is valid -- 12.4 */
	| object '~' TYPESPEC LEFT_RIGHT
		{
		  got_object = NULL_TREE;
		  if (IDENTIFIER_GLOBAL_VALUE ($3)
		      && (TREE_CODE (TREE_TYPE ($1)) 
			  != TREE_CODE (TREE_TYPE (IDENTIFIER_GLOBAL_VALUE ($3)))))
		    cp_error ("`%E' is not of type `%T'", $1, $3);
		  $$ = convert (void_type_node, $1);
		}
	| object TYPESPEC SCOPE '~' TYPESPEC LEFT_RIGHT
		{
		  got_object = NULL_TREE;
		  if ($2 != $5)
		    cp_error ("destructor specifier `%T::~%T()' must have matching names", $2, $5);
		  if (TREE_CODE (TREE_TYPE ($1))
		      != TREE_CODE (TREE_TYPE (IDENTIFIER_GLOBAL_VALUE ($2))))
		    cp_error ("`%E' is not of type `%T'", $1, $2);
		  $$ = convert (void_type_node, $1);
		}
	| object error
		{
		  got_object = NULL_TREE;
		  $$ = error_mark_node;
		}
	;

/* Not needed for now.

primary_no_id:
	  '(' expr ')'
		{ $$ = $2; }
	| '(' error ')'
		{ $$ = error_mark_node; }
	| '('
		{ if (current_function_decl == 0)
		    {
		      error ("braced-group within expression allowed only inside a function");
		      YYERROR;
		    }
		  $<ttype>$ = expand_start_stmt_expr (); }
	  compstmt ')'
		{ if (pedantic)
		    pedwarn ("ANSI C++ forbids braced-groups within expressions");
		  $$ = expand_end_stmt_expr ($<ttype>2); }
	| primary_no_id '(' nonnull_exprlist ')'
		{ $$ = build_x_function_call ($$, $3, current_class_decl); }
	| primary_no_id LEFT_RIGHT
		{ $$ = build_x_function_call ($$, NULL_TREE, current_class_decl); }
	| primary_no_id '[' expr ']'
		{ goto do_array; }
	| primary_no_id PLUSPLUS
		{ $$ = build_x_unary_op (POSTINCREMENT_EXPR, $$); }
	| primary_no_id MINUSMINUS
		{ $$ = build_x_unary_op (POSTDECREMENT_EXPR, $$); }
	| SCOPE IDENTIFIER
		{ goto do_scoped_id; }
	| SCOPE operator_name
		{ if (TREE_CODE ($2) == IDENTIFIER_NODE)
		    goto do_scoped_id;
		  goto do_scoped_operator;
		}
	;
*/

new:	  NEW
		{ $$ = 0; }
	| global_scope NEW
		{ got_scope = NULL_TREE; $$ = 1; }
	;

delete:	  DELETE
		{ $$ = 0; }
	| global_scope delete
		{ got_scope = NULL_TREE; $$ = 1; }
	;

boolean.literal:
	  CXX_TRUE
		{ $$ = boolean_true_node; }
	| CXX_FALSE
		{ $$ = boolean_false_node; }
	;

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

nodecls:
	  /* empty */
		{
		  if (! current_function_parms_stored)
		    store_parm_decls ();
		  setup_vtbl_ptr ();
		  /* Always keep the BLOCK node associated with the outermost
		     pair of curley braces of a function.  These are needed
		     for correct operation of dwarfout.c.  */
		  keep_next_level ();
		}
	;

object:	  primary '.'
		{ got_object = TREE_TYPE ($$); }
	| primary POINTSAT
		{
		  $$ = build_x_arrow ($$); 
		  got_object = TREE_TYPE ($$);
		}
	;

decl:
	/* Normal case: make this fast.  */
	  typespec declarator ';'
		{ tree d = get_decl_list ($1);
		  int yes = suspend_momentary ();
		  d = start_decl ($2, d, 0, NULL_TREE);
		  cp_finish_decl (d, NULL_TREE, NULL_TREE, 0, 0);
		  resume_momentary (yes);
		  if (IS_AGGR_TYPE_CODE (TREE_CODE ($1)))
		    note_got_semicolon ($1);
		}
	| typed_declspecs declarator ';'
		{ tree d, specs, attrs;
		  int yes;
		  split_specs_attrs ($1, &specs, &attrs);
		  yes = suspend_momentary ();
		  d = start_decl ($2, specs, 0, NULL_TREE);
		  cplus_decl_attributes (d, NULL_TREE, attrs);
		  cp_finish_decl (d, NULL_TREE, NULL_TREE, 0, 0);
		  resume_momentary (yes);
		  note_list_got_semicolon ($1);
		}
	| typespec initdecls ';'