diogo/yap-6.3
Archived
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

deb

Browse Source
This commit is contained in:
Vitor Santos Costa 2019-02-06 15:08:25 +00:00
parent 4092003cd6
commit 933db5bc7e
2 changed files with 153 additions and 254 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

393
C/terms.c
View File

@ -68,15 +68,6 @@ static int expand_vts(int args USES_REGS) {
}
static inline void clean_tr(tr_fr_ptr TR0 USES_REGS) {
if (TR != TR0) {
do {
Term p = TrailTerm(--TR);
RESET_VARIABLE(p);
} while (TR != TR0);
}
}
#if 0
static inline void clean_dirty_tr(tr_fr_ptr TR0 USES_REGS) {
tr_fr_ptr pt0 = TR;
while (pt0 != TR0) {
Term p = TrailTerm(--pt0);
@ -95,42 +86,7 @@ static inline void clean_dirty_tr(tr_fr_ptr TR0 USES_REGS) {
TR = TR0;
}
/// @brief recover original term while fixing direct refs.
///
/// @param USES_REGS
///
static inline void clean_complex_tr(tr_fr_ptr TR0 USES_REGS) {
tr_fr_ptr pt0 = TR;
while (pt0 != TR0) {
Term p = TrailTerm(--pt0);
if (IsApplTerm(p)) {
/// pt: points to the address of the new term we may want to fix.
CELL *pt = RepAppl(p);
if (pt >= HB && pt < HR) { /// is it new?
Term v = pt[0];
if (IsApplTerm(v)) {
/// yes, more than a single ref
*pt = (CELL)RepAppl(v);
}
#ifndef FROZEN_STACKS
pt0--;
#endif /* FROZEN_STACKS */
continue;
}
#ifdef FROZEN_STACKS
pt[0] = TrailVal(pt0);
#else
pt[0] = TrailTerm(pt0 - 1);
pt0--;
#endif /* FROZEN_STACKS */
} else {
RESET_VARIABLE(p);
}
}
TR = TR0;
}
#endif
typedef struct {
Term old_var;
Term new_var;
@ -143,82 +99,93 @@ typedef struct non_single_struct_t {
} non_singletons_t;
#define WALK_COMPLEX_TERM__(LIST0, STRUCT0, PRIMI0) \
int lvl = push_text_stack(); \
\
struct non_single_struct_t *to_visit = Malloc( \
1024 * sizeof(struct non_single_struct_t)), \
*to_visit0 = to_visit, \
*to_visit_max = to_visit + 1024; \
\
restart: \
while (pt0 < pt0_end) { \
register CELL d0; \
register CELL *ptd0; \
do{ \
CELL d0; \
CELL *ptd0; \
restart:\
while (pt0 < pt0_end) { \
++pt0; \
ptd0 = pt0; \
ptd0 = pt0; \
d0 = *ptd0; \
list_loop: \
fprintf(stderr,"%ld at %s\n", to_visit-to_visit0, __FUNCTION__);\
deref_head(d0, var_in_term_unk); \
fprintf(stderr, "%ld at %s\n", to_visit - to_visit0, __FUNCTION__); \
deref_head(d0, var_in_term_unk); \
var_in_term_nvar : { \
if (IsPairTerm(d0)) { \
if (to_visit + 32 >= to_visit_max) { \
goto aux_overflow; \
} \
ptd0 = RepPair(d0); \
d0 = ptd0[0]; \
LIST0; \
if (*ptd0 == TermFreeTerm) \
if (d0 == TermFreeTerm) \
goto restart; \
to_visit->pt0 = pt0; \
to_visit->pt0_end = pt0_end; \
to_visit->ptd0 = ptd0; \
to_visit->d0 = *ptd0; \
to_visit->ptd0 = ptd0; \
to_visit->d0 = d0; \
to_visit++; \
d0 = ptd0[0]; \
*ptd0 = TermFreeTerm; \
*ptd0 = TermFreeTerm; \
pt0 = ptd0; \
pt0_end = pt0 + 1; \
goto list_loop; \
goto list_loop; \
} else if (IsApplTerm(d0)) { \
register Functor f; \
/* store the terms to visit */ \
ptd0 = RepAppl(d0); \
f = (Functor)(d0 = *ptd0); \
ptd0 = RepAppl(d0); \
f = (Functor)(d0 = *ptd0); \
\
if (to_visit + 32 >= to_visit_max) { \
goto aux_overflow; \
} \
STRUCT0; \
if (IsExtensionFunctor(f) || IsAtomTerm((CELL)f)) { \
if (IsExtensionFunctor(f) || f == FunctorDollarVar || IsAtomTerm((CELL)f)) { \
\
goto restart; \
continue; \
} \
to_visit->pt0 = pt0; \
to_visit->pt0_end = pt0_end; \
to_visit->ptd0 = ptd0; \
to_visit->d0 = d0; \
to_visit->ptd0 = ptd0; \
to_visit->d0 = d0; \
to_visit++; \
\
*ptd0 = TermNil; \
Term d1 = ArityOfFunctor(f); \
pt0 = ptd0; \
pt0_end = ptd0 + d1; \
goto restart; \
*ptd0 = TermNil; \
Term d1 = ArityOfFunctor(f); \
pt0 = ptd0; \
pt0_end = ptd0 + d1; \
continue; \
} else { \
PRIMI0; \
goto restart; \
continue; \
} \
} \
derefa_body(d0, ptd0, var_in_term_unk, var_in_term_nvar);
#define WALK_COMPLEX_TERM() WALK_COMPLEX_TERM__({}, {}, {})
#define END_WALK() goto restart;}
#define END_WALK() \
}\
}\
/* Do we still have compound terms to visit */ \
if (to_visit > to_visit0) {\
to_visit--;\
\
pt0 = to_visit->pt0;\
pt0_end = to_visit->pt0_end;\
*to_visit->ptd0 = to_visit->d0;\
} \
} while (to_visit>to_visit0); \
pop_text_stack(lvl);
#define def_aux_overflow() \
aux_overflow : { \
size_t d1 = to_visit - to_visit0; \
size_t d2 = to_visit_max - to_visit0; \
size_t d2 = to_visit_max - to_visit0; \
to_visit0 = \
Realloc(to_visit0, (d2 + 128) * sizeof(struct non_single_struct_t)); \
to_visit = to_visit0 + d1; \
@ -253,25 +220,26 @@ typedef struct non_single_struct_t {
}
#define CYC_LIST \
if (*ptd0 == TermFreeTerm) { \
while (to_visit > to_visit0) { \
if (d0 == TermFreeTerm) { \
fprintf(stderr,"+%ld at %s\n", to_visit-to_visit0, __FUNCTION__);\
while (to_visit > to_visit0) { \
to_visit--; \
CELL *ptd0 = to_visit->ptd0; \
*ptd0 = to_visit->d0; \
to_visit->ptd0[0] = \
to_visit->d0; \
} \
pop_text_stack(lvl); fprintf(stderr,"<%ld at %s\n", to_visit-to_visit0, __FUNCTION__);\
return true; \
}
#define CYC_APPL \
if (IsAtomTerm((CELL)f)) { \
if (IsAtomTerm((CELL)f)) { \
while (to_visit > to_visit0) { \
to_visit--; \
CELL *ptd0 = to_visit->ptd0; \
*ptd0 = to_visit->d0; \
} \
pop_text_stack(lvl); fprintf(stderr,"<%d at %s\n", to_visit-to_visit0, __FUNCTION__);\
return true; \
to_visit--; \
to_visit->ptd0[0] = \
to_visit->d0; \
} \
fprintf(stderr,"<%ld at %s\n", to_visit-to_visit0, __FUNCTION__);\
return true; \
}
/**
@ -280,21 +248,11 @@ typedef struct non_single_struct_t {
static Term cyclic_complex_term(register CELL *pt0,
register CELL *pt0_end USES_REGS) {
int lvl = push_text_stack(); \
WALK_COMPLEX_TERM__(CYC_LIST, CYC_APPL, {});
/* leave an empty slot to fill in later */
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
pop_text_stack(lvl);
return false;
@ -332,6 +290,7 @@ static Int cyclic_term(USES_REGS1) /* cyclic_term(+T) */
static bool ground_complex_term(register CELL *pt0,
register CELL *pt0_end USES_REGS) {
int lvl = push_text_stack(); \
WALK_COMPLEX_TERM();
/* leave an empty slot to fill in later */
while (to_visit > to_visit0) {
@ -345,15 +304,7 @@ static bool ground_complex_term(register CELL *pt0,
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
pop_text_stack(lvl);
return true;
@ -388,9 +339,10 @@ static Int ground(USES_REGS1) /* ground(+T) */
static Int var_in_complex_term(register CELL *pt0, register CELL *pt0_end,
Term v USES_REGS) {
int lvl = push_text_stack(); \
WALK_COMPLEX_TERM();
if ((CELL)d0 == v) { /* we found it */
if ((CELL)ptd0 == v) { /* we found it */
/* Do we still have compound terms to visit */
while (to_visit > to_visit0) {
to_visit--;
@ -452,7 +404,9 @@ static Term vars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
register tr_fr_ptr TR0 = TR;
CELL *InitialH = HR;
CELL output = AbsPair(HR);
int lvl = push_text_stack();
push_text_stack(); \
WALK_COMPLEX_TERM();
/* do or pt2 are unbound */
*ptd0 = TermNil;
@ -471,18 +425,8 @@ static Term vars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
}
}
TrailTerm(TR++) = (CELL)ptd0;
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
END_WALK();
clean_tr(TR0 PASS_REGS);
pop_text_stack(lvl);
@ -658,9 +602,9 @@ static Term attvars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
register tr_fr_ptr TR0 = TR;
CELL *InitialH = HR;
CELL output = inp;
int lvl = push_text_stack(); \
WALK_COMPLEX_TERM();
if (IsAttVar(ptd0)) {
/* do or pt2 are unbound */
attvar_record *a0 = RepAttVar(ptd0);
@ -685,22 +629,11 @@ static Term attvars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
pt0_end = &RepAttVar(ptd0)->Atts;
pt0 = pt0_end - 1;
}
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
END_WALK();
clean_tr(TR0 PASS_REGS);
pop_text_stack(lvl);
fprintf(stderr,"<%ld at %s\n", to_visit-to_visit0, __FUNCTION__);
if (HR != InitialH) {
/* close the list */
Term t2 = Deref(inp);
@ -712,7 +645,8 @@ static Term attvars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
}
}
return (output);
fprintf(stderr,"<%ld at %s\n", to_visit-to_visit0, __FUNCTION__);
return (output);
def_aux_overflow();
def_global_overflow();
@ -753,16 +687,16 @@ static Term new_vars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
Term inp USES_REGS) {
register tr_fr_ptr TR0 = TR;
CELL *InitialH = HR;
int lvl = push_text_stack(); \
HB=ASP;
CELL output = TermNil;
{
while (!IsVarTerm(inp) && IsPairTerm(inp)) {
Term t = HeadOfTerm(inp);
if (IsVarTerm(t)) {
YapBind( VarOfTerm(t), TermFoundVar );
if ((tr_fr_ptr)LOCAL_TrailTop - TR < 1024) {
int lvl = push_text_stack();
if (!Yap_growtrail((TR - TR0) * sizeof(tr_fr_ptr *), true)) {
goto trail_overflow;
}
@ -785,15 +719,6 @@ static Term new_vars_in_complex_term(register CELL *pt0, register CELL *pt0_end,
goto global_overflow;
}
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
}
clean_tr(TR0 PASS_REGS);
pop_text_stack(lvl);
@ -856,6 +781,7 @@ static Term vars_within_complex_term(register CELL *pt0, register CELL *pt0_end,
tr_fr_ptr TR0 = TR;
CELL *InitialH = HR;
CELL output = AbsPair(HR);
int lvl = push_text_stack();
while (!IsVarTerm(inp) && IsPairTerm(inp)) {
Term t = HeadOfTerm(inp);
@ -873,16 +799,6 @@ static Term vars_within_complex_term(register CELL *pt0, register CELL *pt0_end,
WALK_COMPLEX_TERM__({}, {}, FOUND_VAR());
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
clean_tr(TR0 PASS_REGS);
pop_text_stack(lvl);
@ -931,7 +847,7 @@ static Term free_vars_in_complex_term(CELL *pt0, CELL *pt0_end,
tr_fr_ptr TR0 USES_REGS) {
Term o = TermNil;
CELL *InitialH = HR;
int lvl = push_text_stack();
WALK_COMPLEX_TERM();
/* do or pt2 are unbound */
*ptd0 = TermNil;
@ -952,19 +868,8 @@ static Term free_vars_in_complex_term(CELL *pt0, CELL *pt0_end,
}
}
TrailTerm(TR++) = (CELL)ptd0;
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
clean_tr(TR0 PASS_REGS);
pop_text_stack(lvl);
@ -980,7 +885,7 @@ static Term free_vars_in_complex_term(CELL *pt0, CELL *pt0_end,
static Term bind_vars_in_complex_term(CELL *pt0, CELL *pt0_end,
tr_fr_ptr TR0 USES_REGS) {
CELL *InitialH = HR;
int lvl = push_text_stack();
WALK_COMPLEX_TERM();
/* do or pt2 are unbound */
*ptd0 = TermFoundVar;
@ -997,16 +902,8 @@ static Term bind_vars_in_complex_term(CELL *pt0, CELL *pt0_end,
}
}
TrailTerm(TR++) = (CELL)ptd0;
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->ptd0;
*pt0 = to_visit->d0;
goto list_loop;
}
END_WALK();
pop_text_stack(lvl);
return TermNil;
@ -1083,22 +980,12 @@ static Term non_singletons_in_complex_term(CELL *pt0, CELL *pt0_end USES_REGS) {
CELL *InitialH = HR;
HB = (CELL *)ASP;
CELL output = AbsPair(HR);
int lvl = push_text_stack();
WALK_COMPLEX_TERM__({}, {}, FOUND_VAR_AGAIN());
/* do or pt2 are unbound */
YapBind(ptd0,TermFoundVar);
goto restart;
END_WALK();
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
}
clean_tr(TR0 PASS_REGS);
@ -1164,6 +1051,7 @@ static Int numbervars_in_complex_term(CELL *pt0, CELL *pt0_end, Int numbv,
tr_fr_ptr TR0 = TR;
CELL *InitialH = HR;
int lvl = push_text_stack();
WALK_COMPLEX_TERM__({}, {}, {});
@ -1181,23 +1069,8 @@ static Int numbervars_in_complex_term(CELL *pt0, CELL *pt0_end, Int numbv,
/* next make sure noone will see this as a variable again */
YapBind(ptd0, d0);
continue;
END_WALK();
/* Do we still have compound terms to visit */
while (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
pt0_end = to_visit->pt0_end;
CELL *ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
if (pt0 >= pt0_end)
continue;
goto restart;
}
pop_text_stack(lvl);
return numbv;
@ -1267,7 +1140,7 @@ static Int p_numbervars(USES_REGS1) {
}
static int max_numbered_var(CELL *pt0, CELL *pt0_end, Int *maxp USES_REGS) {
int lvl = push_text_stack();
WALK_COMPLEX_TERM__({}, MAX_NUMBERED, {});
END_WALK();
/* Do we still have compound terms to visit */
@ -1333,49 +1206,62 @@ static Term UNFOLD_LOOP(Term t, Term *b) {
static Term *loops_in_complex_term(CELL *pt0, CELL *pt0_end,
Term *listp USES_REGS) {
int lvl = push_text_stack();
CELL *ptf0 = HR;
tr_fr_ptr TR0 = TR;
struct non_single_struct_t *to_visit = Malloc(
1024 * sizeof(struct non_single_struct_t)),
*to_visit0 = to_visit,
*to_visit_max = to_visit + 1024;
CELL *ptd0;
CELL *ptf0 = HR,
*ptf = HR;
restart:
while (pt0 < pt0_end) {
*to_visit_max = to_visit + 1024;
do{
CELL *ptd0,
*ptf = HR;
CELL d0;
restart:
while (pt0 < pt0_end) {
++pt0;
ptd0 = pt0;
d0 = *ptd0;
list_loop:
fprintf(stderr,"%d at %s\n", to_visit-to_visit0, __FUNCTION__);
{
fprintf(stderr,"%ld at %s\n", to_visit-to_visit0, __FUNCTION__);
deref_head(d0, vars_in_term_unk);
vars_in_term_nvar:
if (IsPairTerm(d0)) {
if (to_visit + 32 >= to_visit_max) {
goto aux_overflow;
}
CELL *ptd0 = RepPair(d0);
ptd0 = RepPair(d0);
d0 = ptd0[0];
if (IsAtomTerm(d0) && (CELL *)AtomOfTerm(d0) >= (CELL *)to_visit0 &&
(CELL *)AtomOfTerm(d0) < (CELL *)to_visit) {
// LIST0;
struct non_single_struct_t *v0 =
if (listp) {
CELL *pt = VarOfTerm(d0);
if (pt &&pt >= ptf &&
pt < HR) {
// LIST0;
*ptf++ = UNFOLD_LOOP(AbsPair(pt), listp);
continue;
} else {
*ptf++ = AbsPair(HR);
MaBind( ptd0, AbsPair(ptf - 1));
}
} else {
struct non_single_struct_t *v0 =
(struct non_single_struct_t *)AtomOfTerm(d0);
if (listp) {
*ptf++ = UNFOLD_LOOP(AbsPair(v0->ptf-1), listp);
} else {
*ptf++ = BREAK_LOOP(to_visit - v0);
}
if (IsAtomTerm(d0) && v0 >= to_visit0 &&
(CELL *)AtomOfTerm(d0) < (CELL *)to_visit) {
// LIST0;
*ptf++ = BREAK_LOOP(to_visit - v0);
continue;
}
*ptf++ = AbsPair(HR);
to_visit->pt0 = pt0;
to_visit->pt0_end = pt0_end;
} else {
*ptf++ = AbsPair(HR);
to_visit->ptd0 = ptd0;
to_visit->ptf = ptf;
to_visit->d0 = d0 = *ptd0;
*ptd0 = MkAtomTerm((AtomEntry *)to_visit);
}
}
to_visit->pt0 = pt0;
to_visit->pt0_end = pt0_end;
to_visit->ptf = ptf;
to_visit++;
pt0 = ptd0;
pt0_end = pt0 + 1;
@ -1389,30 +1275,43 @@ static Term *loops_in_complex_term(CELL *pt0, CELL *pt0_end,
/* store the terms to visit */
ptd0 = RepAppl(d0);
f = (Functor)(*ptd0);
if (IsExtensionFunctor(f)) {
if (IsExtensionFunctor(f) || f == FunctorDollarVar) {
*ptf++ = d0;
continue;
}
if (IsAtomTerm((CELL)f)) {
struct non_single_struct_t *v0 = (struct non_single_struct_t *)AtomOfTerm(*ptd0);
if (listp) {
*ptf++ = UNFOLD_LOOP(AbsAppl(v0->ptf-1), listp);
if (listp) {
CELL *pt = (CELL *)f;
if (IsVarTerm(d0) && pt >= ptf0 &&
pt < HR) {
// LIST0;
*ptf++ = UNFOLD_LOOP(AbsAppl(pt), listp);
continue;
} else {
*ptf++ = AbsAppl(HR);
MaBind( pt, AbsAppl(ptf - 1));
}
} else {
struct non_single_struct_t *v0 =
(struct non_single_struct_t *)AtomOfTerm(d0);
if (IsAtomTerm(d0) && v0 >= to_visit0 &&
v0 < to_visit) {
// LIST0;
*ptf++ = BREAK_LOOP(to_visit - v0);
continue;
} else {
*ptf++ = BREAK_LOOP(to_visit - v0);
}
continue;
*ptf++ = AbsAppl(HR);
to_visit->ptd0 = ptd0;
to_visit->d0 = d0;
*ptd0 = MkAtomTerm((AtomEntry *)to_visit);
}
}
// STRUCT0;
if (to_visit + 32 >= to_visit_max) {
goto aux_overflow;
}
*ptf++ = AbsAppl(HR);
to_visit->pt0 = pt0;
to_visit->pt0_end = pt0_end;
to_visit->ptd0 = ptd0;
to_visit->d0 = *ptd0;
to_visit->ptf = ptf;
*ptd0 = MkAtomTerm((AtomEntry *)to_visit);
to_visit++;
pt0 = ptd0;
pt0_end = ptd0 + (ArityOfFunctor(f));
@ -1422,25 +1321,27 @@ static Term *loops_in_complex_term(CELL *pt0, CELL *pt0_end,
} else {
*ptf++ = d0;
}
goto restart;
continue;
}
derefa_body(d0, ptd0, vars_in_term_unk, vars_in_term_nvar);
*ptf++ = *ptd0;
goto restart;
}
continue;
}
/* Do we still have compound terms to visit */
if (to_visit > to_visit0) {
to_visit--;
while (to_visit > to_visit0) {
to_visit--;
pt0 = to_visit->pt0;
ptf = to_visit->ptf;
pt0_end = to_visit->pt0_end;
ptd0 = to_visit->ptd0;
*ptd0 = to_visit->d0;
goto restart;
pt0 = to_visit->pt0;
ptf = to_visit->ptf;
pt0_end = to_visit->pt0_end;
to_visit->ptd0[0] = to_visit->d0;
}
} while (to_visit > to_visit0) ;
fprintf(stderr,"exit %ld at %s\n", to_visit-to_visit0, __FUNCTION__);
if (listp) {
clean_tr(TR0);
}
fprintf(stderr,"exit %d at %s\n", to_visit-to_visit0, __FUNCTION__);
pop_text_stack(lvl);
return ptf0;

2
regression/cyclics.yap
View File

@ -95,13 +95,11 @@ d(X) :- X:=: f(_,A/[A]), A:=: f(B,[X,g(A)]), B:=:[C|B], C:=:[X].
end :- writeln('....'), fail.
/*
e(X,Y) :- X :=: t(_A,B,_C,D), Y :=: [B,E].
e(X,Y) :- X :=: t(_A,_B,_C,_D), Y :=: [_,_E].
e(X,Y) :- X :=: t(A,_B,C,_D), Y :=: [ A,C].
e(X,Y) :- X :=: t(A,[X,_D]), Y :=: [A,_C,_E].
e(X,Y) :- X :=: t(A,[X,C]), Y :=: [A,C,_E].
*/
e(X,Y) :- X :=: t(A,X,_B,[X,C,_D]), Y :=: [A,C,_E].
a(no, no).