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authorTeddy <ted.sybil@gmail.com>2013-08-09 12:41:49 +0800
committerTeddy <ted.sybil@gmail.com>2013-08-09 12:41:49 +0800
commit01b2c905872ff38d5d8291f2f8de92c2771f183f (patch)
treebd3622d29d29cc1f7205a79eca9a15ee377c719a /builtin.cpp
parent0c606491335e99017897a7710461214412243dd7 (diff)
removed `skip` field from Pair, use `next` to make jumps insteadskip_removal
Diffstat (limited to 'builtin.cpp')
-rw-r--r--builtin.cpp121
1 files changed, 61 insertions, 60 deletions
diff --git a/builtin.cpp b/builtin.cpp
index 7c5f3c7..27b3ee7 100644
--- a/builtin.cpp
+++ b/builtin.cpp
@@ -543,59 +543,53 @@ void SpecialOptIf::prepare(Pair *pc) {
throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS)
state = 0; // Prepared
+ Pair *first, *second, *third;
+
if (pc->cdr->is_pair_obj())
- pc = TO_PAIR(pc->cdr);
+ first = TO_PAIR(pc->cdr);
else
IF_EXP_ERR;
-// if (pc == empty_list)
-// IF_EXP_ERR;
-
- pc->skip = false;
- if (pc->cdr->is_pair_obj())
- pc = TO_PAIR(pc->cdr);
+ if (first->cdr->is_pair_obj())
+ second = TO_PAIR(first->cdr);
else
IF_EXP_ERR;
- // if (pc == empty_list)
- // IF_EXP_ERR;
- pc->skip = true;
- if (pc->cdr != empty_list)
+ if (second->cdr != empty_list)
{
- if (pc->cdr->is_pair_obj())
+ if (second->cdr->is_pair_obj())
{
- TO_PAIR(pc->cdr)->skip = true;
- if (TO_PAIR(pc->cdr)->cdr != empty_list)
+ third = TO_PAIR(second->cdr);
+ if (third->cdr != empty_list)
IF_EXP_ERR;
}
else
IF_EXP_ERR;
}
+ pc->next = first;
+ first->next = NULL; // skip <consequence> and <alternative>
}
void SpecialOptIf::pre_call(ArgList *args, Pair *pc,
Environment *envt) {
- // static_cast because it's a call invocation
- pc = TO_PAIR(TO_PAIR(pc->car)->cdr);
+ // prepare has guaranteed ...
+ pc = TO_PAIR(pc->car);
+ Pair *first = TO_PAIR(pc->cdr);
+ Pair *second = TO_PAIR(first->cdr);
+ Pair *third = TO_PAIR(second->cdr);
// Condition evaluated and the decision is made
state = 1;
if (TO_PAIR(args->cdr)->car->is_true())
{
- pc->skip = true;
- pc = TO_PAIR(pc->cdr);
- pc->skip = false;
- if (pc->cdr != empty_list)
- TO_PAIR(pc->cdr)->skip = true; // Eval the former
+ pc->next = second;
+ second->next = NULL;
}
else
{
- pc->skip = true;
- pc = TO_PAIR(pc->cdr);
- pc->skip = true;
- if (pc->cdr != empty_list)
- TO_PAIR(pc->cdr)->skip = false; //Eval the latter
+ pc->next = third;
+ third->next = NULL;
}
}
@@ -628,7 +622,7 @@ ReprCons *SpecialOptIf::get_repr_cons() {
}
SpecialOptLambda::SpecialOptLambda() : SpecialOptObj("lambda") {}
-#define FILL_MARKS(pc, flag) \
+#define CHECK_COM(pc) \
do \
{ \
EvalObj *nptr; \
@@ -638,7 +632,6 @@ do \
if ((nptr = ptr->cdr)->is_pair_obj()) \
ptr = TO_PAIR(nptr); \
else break; \
- ptr->skip = flag; \
} \
if (ptr->cdr != empty_list) \
throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS); \
@@ -673,7 +666,8 @@ while (0)
void SpecialOptLambda::prepare(Pair *pc) {
// Do not evaluate anything
- FILL_MARKS(pc, true);
+ CHECK_COM(pc);
+ pc->next = NULL;
}
Pair *SpecialOptLambda::call(ArgList *args, Environment * &envt,
@@ -684,22 +678,22 @@ Pair *SpecialOptLambda::call(ArgList *args, Environment * &envt,
// TODO: remove the following two lines?
if (pc->cdr == empty_list)
throw TokenError(name, SYN_ERR_EMPTY_PARA_LIST);
- if (TO_PAIR(pc->cdr)->cdr == empty_list)
+ Pair *first = TO_PAIR(pc->cdr);
+ // <body> is expected
+ if (first->cdr == empty_list)
throw TokenError(name, SYN_ERR_MISS_OR_EXTRA_EXP);
-
- // Clear the flag to avoid side-effects (e.g. proc calling)
- FILL_MARKS(pc, false);
+
+ // Restore the next pointer
+ pc->next = TO_PAIR(pc->cdr); // CHECK_COM made it always okay
- pc = TO_PAIR(pc->cdr); // Now pointintg to params
- if (pc->car->is_simple_obj())
- CHECK_SYMBOL(pc->car);
+ if (first->car->is_simple_obj())
+ CHECK_SYMBOL(first->car);
else
- CHECK_PARA_LIST(pc->car);
- EvalObj *params = pc->car;
+ CHECK_PARA_LIST(first->car);
+ EvalObj *params = first->car;
// store a list of expressions inside <body>
-
- Pair *body = TO_PAIR(pc->cdr); // Truncate the expression list
+ Pair *body = TO_PAIR(first->cdr); // Truncate the expression list
for (Pair *ptr = body; ptr != empty_list; ptr = TO_PAIR(ptr->cdr))
ptr->next = NULL; // Make each expression an orphan
@@ -716,16 +710,22 @@ SpecialOptDefine::SpecialOptDefine() : SpecialOptObj("define") {}
void SpecialOptDefine::prepare(Pair *pc) {
if (!pc->cdr->is_pair_obj())
throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS);
-
- if (TO_PAIR(pc->cdr)->car->is_simple_obj()) // Simple value assignment
+ Pair *first = TO_PAIR(pc->cdr), *second;
+ if (first->car->is_simple_obj()) // Simple value assignment
{
- pc = TO_PAIR(pc->cdr);
- if (!pc->cdr->is_pair_obj())
+ if (!first->cdr->is_pair_obj())
+ throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS);
+ second = TO_PAIR(first->cdr);
+ if (second->cdr != empty_list)
throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS);
- pc->skip = true; // Skip the identifier
- TO_PAIR(pc->cdr)->skip = false;
- } // Procedure definition
- else FILL_MARKS(pc, true); // Skip all parts
+ pc->next = second; // Skip the identifier
+ second->next = NULL;
+ } // Procedure definition
+ else
+ {
+ CHECK_COM(pc);
+ pc->next = NULL; // Skip all parts
+ }
}
Pair *SpecialOptDefine::call(ArgList *args, Environment * &envt,
@@ -739,7 +739,6 @@ Pair *SpecialOptDefine::call(ArgList *args, Environment * &envt,
{
if (!first->is_sym_obj())
throw TokenError(first->ext_repr(), SYN_ERR_NOT_AN_ID);
- ARGS_EXACTLY_TWO;
id = static_cast<SymObj*>(first);
obj = TO_PAIR(args->cdr)->car;
}
@@ -758,8 +757,9 @@ Pair *SpecialOptDefine::call(ArgList *args, Environment * &envt,
id = static_cast<SymObj*>(plst->car);
EvalObj *params = plst->cdr;
- // Clear the flag to avoid side-effects (e.g. proc calling)
- FILL_MARKS(pc, false);
+
+ // Restore the next pointer
+ pc->next = TO_PAIR(pc->cdr);
Pair *body = TO_PAIR(TO_PAIR(pc->cdr)->cdr); // Truncate the expression list
@@ -784,16 +784,17 @@ void SpecialOptSet::prepare(Pair *pc) {
if (!pc->cdr->is_pair_obj())
throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS);
- pc = TO_PAIR(pc->cdr);
-
- pc->skip = true; // Skip the identifier
+ Pair *first = TO_PAIR(pc->cdr), *second;
- if (!pc->cdr->is_pair_obj())
+ if (!first->is_pair_obj())
throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS);
- pc = TO_PAIR(pc->cdr);
+ second = TO_PAIR(pc->cdr);
+ if (second->cdr != empty_list)
+ throw TokenError(name, RUN_ERR_WRONG_NUM_OF_ARGS);
- pc->skip = false;
+ pc->next = second;
+ second->next = NULL;
}
Pair *SpecialOptSet::call(ArgList *args, Environment * &envt,
@@ -804,7 +805,6 @@ Pair *SpecialOptSet::call(ArgList *args, Environment * &envt,
if (!first->is_sym_obj())
throw TokenError(first->ext_repr(), SYN_ERR_NOT_AN_ID);
- ARGS_EXACTLY_TWO;
SymObj *id = static_cast<SymObj*>(first);
@@ -824,7 +824,8 @@ SpecialOptQuote::SpecialOptQuote() : SpecialOptObj("quote") {}
void SpecialOptQuote::prepare(Pair *pc) {
// Do not evaluate anything
- FILL_MARKS(pc, true);
+ CHECK_COM(pc);
+ pc->next = NULL;
}
Pair *SpecialOptQuote::call(ArgList *args, Environment * &envt,
@@ -832,7 +833,7 @@ Pair *SpecialOptQuote::call(ArgList *args, Environment * &envt,
Pair *ret_addr = static_cast<RetAddr*>(*top_ptr)->addr;
Pair *pc = static_cast<Pair*>(ret_addr->car);
// revert
- FILL_MARKS(pc, false);
+ pc->next = TO_PAIR(pc->cdr);
*top_ptr++ = TO_PAIR(pc->cdr)->car;
return ret_addr->next;
}
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