Fix for bug 1911

diff --git a/lib/circogen/blocktree.c b/lib/circogen/blocktree.c
index 6f303b2cf968063ba44687b914ff9eccd395de86..60f0aa5f42429b55a7d5141958cd9cdbd63a01e1 100644 (file)
--- a/lib/circogen/blocktree.c
+++ b/lib/circogen/blocktree.c
@@ -80,6 +80,20 @@ pop (estack* s)
 }
 
 
+/* dfs:
+ *
+ * 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, int isRoot, estack* stk)
 {
     Agedge_t *e;
@@ -96,7 +110,7 @@ static void dfs(Agraph_t * g, Agnode_t * u, circ_state * state, int isRoot, esta
            if (!EDGEORDER(e)) EDGEORDER(e) = 1;
        }
 
-        if (VAL(v) == 0) {
+        if (VAL(v) == 0) {   /* Since VAL(root) == 0, it gets treated as artificial cut point */
            PARENT(v) = u;
             push(stk, e);
             dfs(g, v, state, 0, stk);
@@ -118,7 +132,7 @@ static void dfs(Agraph_t * g, Agnode_t * u, circ_state * state, int isRoot, esta
                    }
                 } while (ep != e);
                if (block) {    /* If block != NULL, it's not empty */
-                   if (blockSize (block) > 1)
+                   if (!BLOCK(u) && blockSize (block) > 1)
                        addNode(block, u);
                    if (isRoot && (BLOCK(u) == block))
                        insertBlock(&state->bl, block);