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/* SPDX-License-Identifier: GPL-2.0-or-later */
/** \file
* \ingroup bmesh
*
* BMesh Walker API.
*/
#include <stdlib.h>
#include <string.h> /* for memcpy */
#include "BLI_listbase.h"
#include "BLI_utildefines.h"
#include "bmesh.h"
#include "bmesh_walkers_private.h"
/**
* NOTE(@joeedh): Details on design.
*
* Original design: walkers directly emulation recursive functions.
* functions save their state onto a #BMWalker.worklist, and also add new states
* to implement recursive or looping behavior.
* Generally only one state push per call with a specific state is desired.
*
* basic design pattern: the walker step function goes through its
* list of possible choices for recursion, and recurses (by pushing a new state)
* using the first non-visited one. This choice is the flagged as visited using the #GHash.
* Each step may push multiple new states onto the #BMWalker.worklist at once.
*
* - Walkers use tool flags, not header flags.
* - Walkers now use #GHash for storing visited elements,
* rather than stealing flags. #GHash can be rewritten
* to be faster if necessary, in the far future :) .
* - tools should ALWAYS have necessary error handling
* for if walkers fail.
*/
void *BMW_begin(BMWalker *walker, void *start)
{
BLI_assert(((BMHeader *)start)->htype & walker->begin_htype);
walker->begin(walker, start);
return BMW_current_state(walker) ? walker->step(walker) : NULL;
}
void BMW_init(BMWalker *walker,
BMesh *bm,
int type,
short mask_vert,
short mask_edge,
short mask_face,
BMWFlag flag,
int layer)
{
memset(walker, 0, sizeof(BMWalker));
walker->layer = layer;
walker->flag = flag;
walker->bm = bm;
walker->mask_vert = mask_vert;
walker->mask_edge = mask_edge;
walker->mask_face = mask_face;
walker->visit_set = BLI_gset_ptr_new("bmesh walkers");
walker->visit_set_alt = BLI_gset_ptr_new("bmesh walkers sec");
if (UNLIKELY(type >= BMW_MAXWALKERS || type < 0)) {
fprintf(stderr,
"%s: Invalid walker type in BMW_init; type: %d, "
"searchmask: (v:%d, e:%d, f:%d), flag: %u, layer: %d\n",
__func__,
type,
mask_vert,
mask_edge,
mask_face,
flag,
layer);
BLI_assert(0);
return;
}
if (type != BMW_CUSTOM) {
walker->begin_htype = bm_walker_types[type]->begin_htype;
walker->begin = bm_walker_types[type]->begin;
walker->yield = bm_walker_types[type]->yield;
walker->step = bm_walker_types[type]->step;
walker->structsize = bm_walker_types[type]->structsize;
walker->order = bm_walker_types[type]->order;
walker->valid_mask = bm_walker_types[type]->valid_mask;
/* safety checks */
/* if this raises an error either the caller is wrong or
* 'bm_walker_types' needs updating */
BLI_assert(mask_vert == 0 || (walker->valid_mask & BM_VERT));
BLI_assert(mask_edge == 0 || (walker->valid_mask & BM_EDGE));
BLI_assert(mask_face == 0 || (walker->valid_mask & BM_FACE));
}
walker->worklist = BLI_mempool_create(walker->structsize, 0, 128, BLI_MEMPOOL_NOP);
BLI_listbase_clear(&walker->states);
}
void BMW_end(BMWalker *walker)
{
BLI_mempool_destroy(walker->worklist);
BLI_gset_free(walker->visit_set, NULL);
BLI_gset_free(walker->visit_set_alt, NULL);
}
void *BMW_step(BMWalker *walker)
{
BMHeader *head;
head = BMW_walk(walker);
return head;
}
int BMW_current_depth(BMWalker *walker)
{
return walker->depth;
}
void *BMW_walk(BMWalker *walker)
{
void *current = NULL;
while (BMW_current_state(walker)) {
current = walker->step(walker);
if (current) {
return current;
}
}
return NULL;
}
void *BMW_current_state(BMWalker *walker)
{
BMwGenericWalker *currentstate = walker->states.first;
if (currentstate) {
/* Automatic update of depth. For most walkers that
* follow the standard "Step" pattern of:
* - read current state
* - remove current state
* - push new states
* - return walk result from just-removed current state
* this simple automatic update should keep track of depth
* just fine. Walkers that deviate from that pattern may
* need to manually update the depth if they care about
* keeping it correct. */
walker->depth = currentstate->depth + 1;
}
return currentstate;
}
void BMW_state_remove(BMWalker *walker)
{
void *oldstate;
oldstate = BMW_current_state(walker);
BLI_remlink(&walker->states, oldstate);
BLI_mempool_free(walker->worklist, oldstate);
}
void *BMW_state_add(BMWalker *walker)
{
BMwGenericWalker *newstate;
newstate = BLI_mempool_alloc(walker->worklist);
newstate->depth = walker->depth;
switch (walker->order) {
case BMW_DEPTH_FIRST:
BLI_addhead(&walker->states, newstate);
break;
case BMW_BREADTH_FIRST:
BLI_addtail(&walker->states, newstate);
break;
default:
BLI_assert(0);
break;
}
return newstate;
}
void BMW_reset(BMWalker *walker)
{
while (BMW_current_state(walker)) {
BMW_state_remove(walker);
}
walker->depth = 0;
BLI_gset_clear(walker->visit_set, NULL);
BLI_gset_clear(walker->visit_set_alt, NULL);
}
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