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/*
* Copyright © 2019 Broadcom
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "util/set.h"
#include "util/dag.h"
/**
* Adds a directed edge from the parent node to the child.
*
* Both nodes should have been initialized with dag_init_node(). The edge
* list may contain multiple edges to the same child with different data.
*/
void
dag_add_edge(struct dag_node *parent, struct dag_node *child, void *data)
{
util_dynarray_foreach(&parent->edges, struct dag_edge, edge) {
if (edge->child == child && edge->data == data)
return;
}
/* Remove the child as a DAG head. */
list_delinit(&child->link);
struct dag_edge edge = {
.child = child,
.data = data,
};
util_dynarray_append(&parent->edges, struct dag_edge, edge);
child->parent_count++;
}
/* Removes a single edge from the graph, promoting the child to a DAG head.
*
* Note that calling this other than through dag_prune_head() means that you
* need to be careful when iterating the edges of remaining nodes for NULL
* children.
*/
void
dag_remove_edge(struct dag *dag, struct dag_edge *edge)
{
if (!edge->child)
return;
struct dag_node *child = edge->child;
child->parent_count--;
if (child->parent_count == 0)
list_addtail(&child->link, &dag->heads);
edge->child = NULL;
edge->data = NULL;
}
/**
* Removes a DAG head from the graph, and moves any new dag heads into the
* heads list.
*/
void
dag_prune_head(struct dag *dag, struct dag_node *node)
{
assert(!node->parent_count);
list_delinit(&node->link);
util_dynarray_foreach(&node->edges, struct dag_edge, edge) {
dag_remove_edge(dag, edge);
}
}
/**
* Initializes DAG node (probably embedded in some other datastructure in the
* user).
*/
void
dag_init_node(struct dag *dag, struct dag_node *node)
{
util_dynarray_init(&node->edges, dag);
list_addtail(&node->link, &dag->heads);
}
struct dag_traverse_bottom_up_state {
struct set *seen;
void *data;
};
static void
dag_traverse_bottom_up_node(struct dag_node *node,
void (*cb)(struct dag_node *node,
void *data),
struct dag_traverse_bottom_up_state *state)
{
if (_mesa_set_search(state->seen, node))
return;
util_dynarray_foreach(&node->edges, struct dag_edge, edge) {
dag_traverse_bottom_up_node(edge->child, cb, state);
}
cb(node, state->data);
_mesa_set_add(state->seen, node);
}
/**
* Walks the DAG from leaves to the root, ensuring that each node is only seen
* once its children have been, and each node is only traversed once.
*/
void
dag_traverse_bottom_up(struct dag *dag, void (*cb)(struct dag_node *node,
void *data), void *data)
{
struct dag_traverse_bottom_up_state state = {
.seen = _mesa_pointer_set_create(NULL),
.data = data,
};
list_for_each_entry(struct dag_node, node, &dag->heads, link) {
dag_traverse_bottom_up_node(node, cb, &state);
}
ralloc_free(state.seen);
}
/**
* Creates an empty DAG datastructure.
*/
struct dag *
dag_create(void *mem_ctx)
{
struct dag *dag = rzalloc(mem_ctx, struct dag);
list_inithead(&dag->heads);
return dag;
}