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/*************************************************************************
* Copyright (c) 2011 AT&T Intellectual Property
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-v10.html
*
* Contributors: Details at https://graphviz.org
*************************************************************************/
#include <circogen/blocktree.h>
#include <stdbool.h>
#include <util/agxbuf.h>
#include <util/debug.h>
#include <util/gv_math.h>
#include <util/list.h>
static void addNode(block_t * bp, Agnode_t * n)
{
agsubnode(bp->sub_graph, n,1);
BLOCK(n) = bp;
}
static Agraph_t *makeBlockGraph(Agraph_t * g, circ_state * state)
{
agxbuf name = {0};
agxbprint(&name, "_block_%d", state->blockCount++);
Agraph_t *subg = agsubg(g, agxbuse(&name), 1);
agxbfree(&name);
agbindrec(subg, "Agraphinfo_t", sizeof(Agraphinfo_t), true); //node custom data
return subg;
}
static block_t *makeBlock(Agraph_t * g, circ_state * state)
{
Agraph_t *subg = makeBlockGraph(g, state);
block_t *bp = mkBlock(subg);
return bp;
}
typedef LIST(Agedge_t *) estack_t;
/* Current scheme adds articulation point to first non-trivial child
* block. If none exists, it will be added to its parent's block, if
* non-trivial, or else given its own block.
*
* FIX:
* This should be modified to:
* - allow user to specify which block gets a node, perhaps on per-node basis.
* - if an articulation point is not used in one of its non-trivial blocks,
* dummy edges should be added to preserve biconnectivity
* - turn on user-supplied blocks.
* - Post-process to move articulation point to largest block
*/
static void dfs(Agraph_t *g, Agnode_t *u, circ_state *state, bool isRoot,
estack_t *stk) {
LOWVAL(u) = VAL(u) = state->orderCount++;
for (Agedge_t *e = agfstedge(g, u); e; e = agnxtedge(g, e, u)) {
Agnode_t *v = aghead (e);
if (v == u) {
v = agtail(e);
if (!EDGEORDER(e)) EDGEORDER(e) = -1;
}
else {
if (!EDGEORDER(e)) EDGEORDER(e) = 1;
}
if (VAL(v) == 0) { /* Since VAL(root) == 0, it gets treated as artificial cut point */
PARENT(v) = u;
LIST_PUSH_BACK(stk, e);
dfs(g, v, state, false, stk);
LOWVAL(u) = imin(LOWVAL(u), LOWVAL(v));
if (LOWVAL(v) >= VAL(u)) { /* u is an articulation point */
block_t *block = NULL;
Agnode_t *np;
Agedge_t *ep;
do {
ep = LIST_POP_BACK(stk);
if (EDGEORDER(ep) == 1)
np = aghead (ep);
else
np = agtail (ep);
if (!BLOCK(np)) {
if (!block)
block = makeBlock(g, state);
addNode(block, np);
}
} while (ep != e);
if (block) { /* If block != NULL, it's not empty */
if (!BLOCK(u) && blockSize (block) > 1)
addNode(block, u);
if (isRoot && BLOCK(u) == block)
insertBlock(&state->bl, block);
else
appendBlock(&state->bl, block);
}
}
} else if (PARENT(u) != v) {
LOWVAL(u) = imin(LOWVAL(u), VAL(v));
}
}
if (isRoot && !BLOCK(u)) {
block_t *block = makeBlock(g, state);
addNode(block, u);
insertBlock(&state->bl, block);
}
}
static void find_blocks(Agraph_t * g, circ_state * state)
{
Agnode_t *root = NULL;
/* check to see if there is a node which is set to be the root
*/
if (state->rootname) {
root = agfindnode(g, state->rootname);
}
if (!root && state->N_root) {
for (Agnode_t *n = agfstnode(g); n; n = agnxtnode(g, n)) {
if (late_bool(ORIGN(n), state->N_root, false)) {
root = n;
break;
}
}
}
if (!root)
root = agfstnode(g);
GV_DEBUG("root = %s", agnameof(root));
estack_t stk = {0};
dfs(g, root, state, true, &stk);
LIST_FREE(&stk);
}
/* Construct block tree by peeling nodes from block list in state.
* When done, return root. The block list is empty
* FIX: use largest block as root
*/
block_t *createBlocktree(Agraph_t * g, circ_state * state)
{
block_t *next;
find_blocks(g, state);
block_t *bp = state->bl.first; // if root chosen, will be first
/* Otherwise, just pick first as root */
block_t *root = bp;
/* Find node with minimum VAL value to find parent block */
/* FIX: Should be some way to avoid search below. */
for (bp = bp->next; bp; bp = next) {
Agnode_t *n;
Agnode_t *parent;
Agnode_t *child;
Agraph_t *subg = bp->sub_graph;
child = n = agfstnode(subg);
int min = VAL(n);
parent = PARENT(n);
for (n = agnxtnode(subg, n); n; n = agnxtnode(subg, n)) {
if (VAL(n) < min) {
child = n;
min = VAL(n);
parent = PARENT(n);
}
}
SET_PARENT(parent);
CHILD(bp) = child;
next = bp->next; /* save next since list insertion destroys it */
appendBlock(&BLOCK(parent)->children, bp);
}
initBlocklist(&state->bl); /* zero out list */
return root;
}
void freeBlocktree(block_t * bp)
{
for (block_t *child = bp->children.first, *next; child; child = next) {
next = child->next;
freeBlocktree(child);
}
freeBlock(bp);
}
#ifdef DEBUG
static void indent(int i)
{
while (i--)
fputs(" ", stderr);
}
void print_blocktree(block_t * sn, int depth)
{
indent(depth);
Agraph_t *g = sn->sub_graph;
fprintf(stderr, "%s:", agnameof(g));
for (Agnode_t *n = agfstnode(g); n; n = agnxtnode(g, n)) {
fprintf(stderr, " %s", agnameof(n));
}
fputs("\n", stderr);
depth++;
for (block_t *child = sn->children.first; child; child = child->next) {
print_blocktree(child, depth);
}
}
#endif
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