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u3: adds generic noun traversal u3a_walk_fore()

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This commit is contained in:
Joe Bryan 2019-11-19 16:32:33 -08:00
parent d8970b9cf5
commit c9c1c62825
2 changed files with 144 additions and 0 deletions
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17
pkg/urbit/include/noun/allocate.h
View File

@ -505,4 +505,21 @@
u3_noun
u3a_mint(c3_w* sal_w, c3_w len_w);
/* u3a_walk_fore(): preorder traversal, visits ever limb of a noun.
**
** cells are visited *before* their heads and tails
** and can shortcircuit traversal by returning [c3n]
*/
void
u3a_walk_fore(u3_noun a,
void* ptr_v,
void (*pat_f)(u3_atom, void*),
c3_o (*cel_f)(u3_noun, void*));
/* u3a_walk_fore_unsafe(): u3a_walk_fore(), without overflow checks
*/
void
u3a_walk_fore_unsafe(u3_noun a,
void* ptr_v,
void (*pat_f)(u3_atom, void*),
c3_o (*cel_f)(u3_noun, void*));

127
pkg/urbit/noun/allocate.c
View File

@ -2193,3 +2193,130 @@ u3a_lop(c3_w lab_w)
{
}
#endif
/* u3a_walk_fore(): preorder traversal, visits ever limb of a noun.
**
** cells are visited *before* their heads and tails
** and can shortcircuit traversal by returning [c3n]
*/
void
u3a_walk_fore(u3_noun a,
void* ptr_v,
void (*pat_f)(u3_atom, void*),
c3_o (*cel_f)(u3_noun, void*))
{
// initialize signed stack offsets (relative to N or S road)
//
c3_o nor_o = u3a_is_north(u3R);
c3_ys mov_ys, off_ys;
{
c3_y wis_y = c3_wiseof(u3_noun);
mov_ys = ( c3y == nor_o ? -wis_y : wis_y );
off_ys = ( c3y == nor_o ? 0 : -wis_y );
}
// set stack root, push argument
//
u3_noun *top, *don;
{
don = u3to(u3_noun, u3R->cap_p + off_ys);
u3R->cap_p += mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
*top = a;
}
while ( top != don ) {
// visit an atom, then pop the stack
//
if ( c3y == u3a_is_atom(a) ) {
pat_f(a, ptr_v);
u3R->cap_p -= mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
}
// vist a cell, if c3n, pop the stack
//
else if ( c3n == cel_f(a, ptr_v) ) {
u3R->cap_p -= mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
}
// otherwise, push the tail and continue into the head
//
else {
*top = u3t(a);
u3R->cap_p += mov_ys;
if ( c3y == nor_o ) {
if( !(u3R->cap_p > u3R->hat_p) ) {
u3m_bail(c3__meme);
}
}
else {
if( !(u3R->cap_p < u3R->hat_p) ) {
u3m_bail(c3__meme);
}
}
top = u3to(u3_noun, u3R->cap_p + off_ys);
*top = u3h(a);
}
a = *top;
}
}
/* u3a_walk_fore_unsafe(): u3a_walk_fore(), without overflow checks
*/
void
u3a_walk_fore_unsafe(u3_noun a,
void* ptr_v,
void (*pat_f)(u3_atom, void*),
c3_o (*cel_f)(u3_noun, void*))
{
// initialize signed stack offsets (relative to N or S road)
//
c3_ys mov_ys, off_ys;
{
c3_y wis_y = c3_wiseof(u3_noun);
c3_o nor_o = u3a_is_north(u3R);
mov_ys = ( c3y == nor_o ? -wis_y : wis_y );
off_ys = ( c3y == nor_o ? 0 : -wis_y );
}
// set stack root, push argument
//
u3_noun *top, *don;
{
don = u3to(u3_noun, u3R->cap_p + off_ys);
u3R->cap_p += mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
*top = a;
}
while ( top != don ) {
// visit an atom, then pop the stack
//
if ( c3y == u3a_is_atom(a) ) {
pat_f(a, ptr_v);
u3R->cap_p -= mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
}
// vist a cell, if c3n, pop the stack
//
else if ( c3n == cel_f(a, ptr_v) ) {
u3R->cap_p -= mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
}
// otherwise, push the tail and continue into the head
//
else {
*top = u3t(a);
u3R->cap_p += mov_ys;
top = u3to(u3_noun, u3R->cap_p + off_ys);
*top = u3h(a);
}
a = *top;
}
}