From db4acddd22634b2873b7085ffc60df1ee726e5f3 Mon Sep 17 00:00:00 2001 From: Teddy Date: Thu, 15 Aug 2013 22:46:51 +0800 Subject: more docs --- TODO.rst | 4 ++-- eval.cpp | 52 ++++++++++++++++++++++++++++++++++++++-------------- eval.h | 3 +-- model.cpp | 8 ++++---- model.h | 2 +- 5 files changed, 46 insertions(+), 23 deletions(-) diff --git a/TODO.rst b/TODO.rst index 1befc72..c978575 100644 --- a/TODO.rst +++ b/TODO.rst @@ -1,7 +1,7 @@ - Documents and comment - - model - - eval + - model --- done + - eval --- done - builtin - gc - types diff --git a/eval.cpp b/eval.cpp index c6ded6e..918311e 100644 --- a/eval.cpp +++ b/eval.cpp @@ -1,13 +1,18 @@ +#include "consts.h" #include "eval.h" #include "builtin.h" #include "exc.h" -#include "consts.h" #include "gc.h" + #include +static const int EVAL_STACK_SIZE = 262144; extern Pair *empty_list; + +/** The stack for evaluating expressions */ EvalObj *eval_stack[EVAL_STACK_SIZE]; +/** Add all kinds of built-in facilities before the evaluation */ void Evaluator::add_builtin_routines() { #define ADD_ENTRY(name, rout) \ @@ -103,6 +108,9 @@ Evaluator::Evaluator() { add_builtin_routines(); } +/** + * Initiate the `next` pointer of an s-expression (a list) + */ inline bool make_exec(Pair *ptr) { if (ptr == empty_list) return true; EvalObj *nptr; @@ -117,11 +125,15 @@ inline bool make_exec(Pair *ptr) { return ptr->cdr == empty_list; } +/** + * Push a new stack frame according to current pc + */ inline void push(Pair * &pc, EvalObj ** &top_ptr, Environment * &envt, Continuation * &cont) { if (pc->car->is_simple_obj()) // Not an opt invocation { - *top_ptr++ = gc.attach(envt->get_obj(pc->car)); // Objectify the symbol + // Objectify the symbol + *top_ptr++ = gc.attach(envt->get_obj(pc->car)); pc = pc->next; // Move to the next instruction } else // Operational Invocation @@ -136,59 +148,71 @@ inline void push(Pair * &pc, EvalObj ** &top_ptr, gc.attach(cont); *top_ptr++ = gc.attach(cont); } - else cont->tail = false; + else cont->tail = false; // tail recursion opt if (!make_exec(TO_PAIR(pc->car))) + // not a valid an invocation throw TokenError(pc->car->ext_repr(), RUN_ERR_WRONG_NUM_OF_ARGS); - // static_cast because of is_simple_obj() is false - cont->prog = pc = TO_PAIR(pc->car); // Go deeper to enter the call + // dive into the call + cont->prog = pc = TO_PAIR(pc->car); + // "pre-call" for some `SpecialObj` envt->get_obj(pc->car)->prepare(pc); } } +/** + * The main routine for the evaluation + */ EvalObj *Evaluator::run_expr(Pair *prog) { + EvalObj **top_ptr = eval_stack; Pair *pc = prog; Continuation *bcont = new Continuation(NULL, NULL, NULL), // dummy cont *cont = bcont; - gc.attach(cont); + #ifdef GC_DEBUG fprintf(stderr, "Start the evaluation...\n"); #endif + + // attach current cont and the whole s-expression tree, so they will not be + // garbage-collected + gc.attach(cont); + gc.attach(prog); // envt is this->envt push(pc, top_ptr, envt, cont); - gc.attach(prog); - while (cont != bcont) + // (cont != bcont) Still need to evaluate at least one level of invocation + while (cont != bcont) { if (top_ptr == eval_stack + EVAL_STACK_SIZE) throw TokenError("Evaluation", RUN_ERR_STACK_OVERFLOW); if (pc) push(pc, top_ptr, envt, cont); - else + else // All arguments are evaluated { Pair *args = empty_list; while (*(--top_ptr) != cont) { EvalObj* obj = static_cast(*top_ptr); gc.expose(obj); - args = new Pair(obj, args); + // old args is auto attached due to the constructor of `Pair` + args = new Pair(obj, args); } - //gc.expose(*top_ptr); - //< static_cast because the while condition + // manually protect the head pointer gc.attach(args); if ((args->car)->is_opt_obj()) { OptObj *opt = static_cast(args->car); -// printf("%s\n", args->ext_repr().c_str()); pc = opt->call(args, envt, cont, top_ptr, cont->prog); } else throw TokenError((args->car)->ext_repr(), SYN_ERR_CAN_NOT_APPLY); -// gc.collect(); +// gc.collect(); THIS IS DEPRECATED BECAUSE IT'S NOT A SAFE POINT +// ANYMORE DUE TO THE TAIL RECURSION OPT } } + // remove the protection gc.expose(prog); gc.expose(cont); // static_cast because the previous while condition diff --git a/eval.h b/eval.h index a824748..c0e03e1 100644 --- a/eval.h +++ b/eval.h @@ -3,9 +3,8 @@ #include "model.h" #include "types.h" -const int EVAL_STACK_SIZE = 262144; /** @class Evaluator - * A runtime platform of interpreting + * A realtime interpreting platform */ class Evaluator { private: diff --git a/model.cpp b/model.cpp index 3e5c9fa..12aa665 100644 --- a/model.cpp +++ b/model.cpp @@ -1,11 +1,11 @@ -#include - -#include "model.h" -#include "exc.h" #include "consts.h" +#include "model.h" #include "types.h" +#include "exc.h" #include "gc.h" +#include + static const int REPR_STACK_SIZE = 262144; extern EmptyList *empty_list; extern GarbageCollector gc; diff --git a/model.h b/model.h index ab5dcc6..225cb37 100644 --- a/model.h +++ b/model.h @@ -118,7 +118,7 @@ class EvalObj : public FrameObj {/*{{{*/ */ class ParseBracket : public FrameObj {/*{{{*/ public: - /** The type of the bracket */ + /** The type of the bracket (to distingiush '(' and '#(' ) */ unsigned char btype; /** Construct a ParseBracket object */ ParseBracket(unsigned char btype); -- cgit v1.2.3-70-g09d2