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#ifndef MODEL_H
#define MODEL_H
#include <string>
#include <list>
#include <map>
using std::list;
using std::string;
using std::map;
typedef unsigned char ClassType; // that range is enough
static const int CLS_RET_ADDR = 0;
static const int CLS_EVAL_OBJ = 1;
static const int CLS_SIM_OBJ = 0;
static const int CLS_CONS_OBJ = 1;
/** @class FrameObj
* Objects that can be held in the evaluation stack
*/
class FrameObj {
protected:
ClassType ftype; // avoid the use of dynamic_cast to improve efficiency
public:
virtual ~FrameObj() {}
bool is_ret_addr();
#ifdef DEBUG
virtual string _debug_repr() = 0;
#endif
};
class Cons;
/** @class EvalObj
* Objects that represents a value in evaluation
*/
class EvalObj : public FrameObj {
private:
ClassType otype; // avoid the use of dynamic_cast to improve efficiency
public:
EvalObj();
bool is_simple_obj();
/** External representation of this object */
virtual void prepare(Cons *pc);
virtual string ext_repr() = 0;
/**< Always true for all EvalObjs except BoolObj */
virtual bool is_true();
};
/** @class Cons
* Pair construct, which can be used to represent a list, or further
* more, a syntax tree
* (car . cdr) in Scheme
*/
class Cons : public EvalObj {
public:
EvalObj *car; /**< car (as in Scheme) */
Cons *cdr; /**< cdr (as in Scheme) */
bool skip; /**< Wether to skip the current branch */
Cons* next; /**< The next branch in effect */
Cons(EvalObj *, Cons *);
#ifdef DEBUG
void _debug_print();
string _debug_repr();
#endif
string ext_repr();
};
/** @class EmptyList
* The empty list (special situation of a list)
*/
class EmptyList: public Cons {
public:
EmptyList();
#ifdef DEBUG
string _debug_repr();
#endif
string ext_repr();
};
/** @class RetAddr
* Tracking the caller's Cons pointer
*/
class RetAddr : public FrameObj {
public:
Cons* addr; /**< The return address */
RetAddr(Cons *);
};
/** @class UnspecObj
* The "unspecified" value returned by some builtin procedures
*/
class UnspecObj: public EvalObj {
public:
UnspecObj();
#ifdef DEBUG
string _debug_repr();
#endif
string ext_repr();
};
/** @class SymObj
* Symbols
*/
class SymObj: public EvalObj {
public:
string val;
SymObj(string);
#ifdef DEBUG
string _debug_repr();
#endif
string ext_repr();
};
// Everything is cons
typedef Cons ASTList;
typedef Cons SymbolList;
typedef Cons ArgList;
class Environment;
class Continuation;
/** @class OptObj
* "Operators" in general sense
*/
class OptObj: public EvalObj {
public:
OptObj();
/**
* The function is called when an operation is needed.
* @param arg_list The argument list (the first one is the opt itself)
* @param envt The current environment (may be modified)
* @param cont The current continuation (may be modified)
* @param top_ptr Pointing to the top of the stack (may be modified)
* @return New value for pc register
*/
virtual Cons *call(ArgList *arg_list, Environment * &envt,
Continuation * &cont, FrameObj ** &top_ptr) = 0;
};
/** @class ProcObj
* User-defined procedures
*/
class ProcObj: public OptObj {
public:
/** The procedure body, a list of expressions to be evaluated */
ASTList *body;
/** The arguments, a list of Symbols */
SymbolList *para_list;
/** Pointer to the environment */
Environment *envt;
ProcObj(ASTList *, Environment *, SymbolList *);
Cons *call(ArgList *arg_list, Environment * &envt,
Continuation * &cont, FrameObj ** &top_ptr);
#ifdef DEBUG
string _debug_repr();
#endif
string ext_repr();
};
/** @class SpecialOptObj
* Special builtin syntax (`if`, `define`, `lambda`, etc.)
*/
class SpecialOptObj: public OptObj {
public:
SpecialOptObj();
};
typedef EvalObj* (*BuiltinProc)(ArgList *);
/** @class BuiltinProcObj
* Wrapping class for builtin procedures (arithmetic operators, etc.)
*/
class BuiltinProcObj: public OptObj {
private:
/** The function that tackle the inputs in effect */
BuiltinProc handler;
string name;
public:
BuiltinProcObj(BuiltinProc, string);
Cons *call(ArgList *arg_list, Environment * &envt,
Continuation * &cont, FrameObj ** &top_ptr);
};
/** @class NumberObj
* The top level abstract of numbers
*/
class NumberObj: public EvalObj {
public:
NumberObj();
};
typedef map<string, EvalObj*> Str2EvalObj;
/** @class Environment
* The environment of current evaluation, i.e. the local variable binding
*/
class Environment {
private:
Environment *prev_envt; /**< Pointer to the upper level environment */
Str2EvalObj binding; /**< Store all pairs of identifier and its
corresponding obj */
public:
Environment(Environment * = NULL);
void add_binding(SymObj *, EvalObj *);
EvalObj *get_obj(SymObj *);
bool has_obj(SymObj *);
};
class Continuation {
public:
Continuation *prev_cont;
Environment *envt;
Cons *pc;
ASTList *proc_body;
unsigned int body_cnt;
Continuation(Environment *, Cons *, Continuation *,
ASTList *, unsigned int = 0);
};
#endif
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