statement.h

一个编译器修改的例子

#ifndef STATEMENT_H
#define STATEMENT_H

typedef struct statement Statement;

#include "bool.h"
#include "expression.h"
#include "list.h"
#include "scope.h"
#include "token.h"


typedef enum
{
    assignment_stat = 40,
    compound_stat,
    delete_stat,
    expr_stat,
    for_stat,
    if_stat,
    repeat_stat,
    return_stat,
    while_stat
}
Stat_subtype;


/* Statements are stored in 'Statement'-type structures. The subtype field
 * indicates the type of the statement (listed in Stat_subtype)
 * Depending on this type, the union un may contain fields specific
 * to that type of statement. For instance, an assignment statement
 * has two expressions pointing to the lvalue and rvalue, and a loop
 * statement has a condition expression to evaluate and another statement
 * to execute.  These fields should be accessed using the ASSIGNMENT_STAT,
 * COMPOUND_STAT, etc defines!
 */

struct statement
{
    Stat_subtype	subtype;

    union
    {
	struct
	{
	    Expression	*lvalue;
	    Expression	*rvalue;
	}
	assignment_stat;

	struct
	{
	    List	*declarations;
	    List	*statements;
	    Scope	*scope;
	    Bool	must_delete_scope;
	}
	compound_stat;

	struct
	{
	    Expression	*expression;
	}
	delete_stat, expr_stat;

	struct for_stat
	{
	    Expression	*loop_variable;
	    Expression	*begin_value;
	    Expression	*end_value;
	    Expression	*increment_value;
	    Statement	*body;
	}
	for_stat;

	struct if_stat
	{
	    Expression	*condition;
	    Statement	*then_body;
	    Statement	*else_body;	/* 0 if no else-part */
	}
	if_stat;

	struct loop_stat
	{
	    Statement	*body;
	    Expression	*condition;
	}
	loop_stat;

	struct return_stat
	{
	    Expression	*return_value;	/* 0 if no return value */
	    Token	*token;
	}
	return_stat;
    }
    un;
};


#define ASSIGNMENT_STAT(s)	((s)->un.assignment_stat)
#define COMPOUND_STAT(s)	((s)->un.compound_stat)
#define DELETE_STAT(s)		((s)->un.delete_stat)
#define EXPR_STAT(s)		((s)->un.expr_stat)
#define FOR_STAT(s)		((s)->un.for_stat)
#define IF_STAT(s)		((s)->un.if_stat)
#define LOOP_STAT(s)		((s)->un.loop_stat)
#define RETURN_STAT(s)		((s)->un.return_stat)


Statement *new_assignment_statement(Expression *lvalue,
				    Expression *rvalue);

Statement *new_compound_statement(List  *declarations,
				  List  *statements,
				  Scope *scope);

Statement *new_delete_statement(Expression *expression);

Statement *new_expression_statement(Expression *expression);

Statement *new_for_statement(Expression *loop_variable,
			     Expression *begin_value,
			     Expression *end_value,
			     Expression *increment_value,
			     Statement  *body);

Statement *new_if_statement(Expression *condition,
			    Statement  *then_body,
			    Statement  *else_body);

Statement *new_repeat_statement(Statement  *body,
				Expression *condition);

Statement *new_return_statement(Expression *return_value, Token *);

Statement *new_while_statement(Expression *condition,
			       Statement  *body);

void	  delete_statement(Statement *);

void	  type_check_statement(Statement *, Declaration *subprog);

void	  generate_statement(Statement *);

#endif