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Diffstat (limited to 'model.h')
| -rw-r--r-- | model.h | 226 |
1 files changed, 226 insertions, 0 deletions
@@ -0,0 +1,226 @@ +#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 |