layout/redactgraph.c

   1 /**/
   2
   3 static void extendsplits(void) {
   4   /*
   5    * Whenever we have a node which has one or more moveable feature
   6    * subsegments, part of the same moveable feature, on one side, and
   7    * fixed portion of the same segment on the other, we eliminate
   8    * the fixed portion and add its length to both the moveables,
   9    * so that we have one subsegspec for the whole of each position:
  10    *
  11    *    <---l---> <----l'--->             <---------(l+l')------>
  12    *
  13    *   *----A1---*----A1/P0--*  becomes  *--------A1/P0----------*
  14    *              `---A1/P1---*           `-------A1/P1-----------*
  15    *
  16    *              <----l''--->            <---------(l+l'')------>
  17    */
  18
  19   for (;;) {
  20     pass++;
  21     for (node=nodes_head; node; node=node->next) {
  22       for (rightside=0; rightside<2; rightside++) {
  23         trace("extendsplit pass %d node ",pass); trace_node(node);
  24         trace("/%d ",rightside);
  25         if ((n= count_edges(&node->sides[!rightside])) != 1) {
  26           trace("no: lhs edges=%d\n", n);
  27           goto no_extend_this;
  28         }
  29         leftedge= node->sides[!rightside].head;
  30         if (leftedge->edge->movfeatpos) {
  31           trace("no: lhs moveable\n");
  32           goto no_extend_this;
  33         }
  34         if (!node->sides[rightside].head) {
  35           trace("no: rhs absent\n");
  36           goto no_extend_this;
  37         }
  38         for (rightedge= node->sides[rightside].head;
  39              rightedge;
  40              rightedge= rightedge->next) {
  41           if (!rightedge->edge->movfeatpos) {
  42             trace("no: rhs fixed ("); trace_edgeend(rightedge); trace(")\n");
  43             goto no_extend_this;
  44           }
  45           if (strcmp(leftedge->edge->segment, rightedge->edge->segment)) {
  46             trace("no: lhs seg %s, rhs seg %s (",
  47                   leftedge->edge->segment
  48                   rightedge->edge->segment);
  49             trace_edgeend(rightedge); trace(")\n");
  50             goto no_extend_this;
  51           }
  52         }
  53         goto extend_this;
  54
  55       no_extend_this:;
  56       }
  57     }
  58     return;
  59
  60   extend_this:
  61     trace("yes, lhs "); trace_edgeend(leftedge); trace(":\n");
  62     for (rightedge= node->sides[rightside].head;
  63          rightedge;
  64          rightedge= rightedge->next) {
  65       rightedge->edge->distance += leftedge->edge->distance;
  66       edge_replumb(rightedge, edgeend_otherend(leftedge)->node);
  67     }
  68     edge_delete(leftedge->edge);
  69     node_surely_orphaned(node);
  70     trace(" extendsplit operation complete\n");
  71   }
  72 }
  73
  74 static EdgeEnd *edgeend_otherend(EdgeEnd *thisend) {
  75   return &thisend->edge->ends[!thisend->end];
  76 }
  77
  78 static void elimtrivial(void) {
  79   /* Eliminate trivial nodes: ones which have only two edges, which
  80    * come in on opposite sides, have the same subsegspec, and with the
  81    * two ends identically aligned.
  82    */
  83   for (node=nodes_head; node; node=next_node) {
  84     next_node=node->next;
  85     trace("elimtrivial node "); trace_node(node); trace(" ");
  86     if (!(count_edges(&node->sides[0])==1 &&
  87           count_edges(&node->sides[1])==1)) {
  88       trace("no, a non-unitary side\n");
  89       continue;
  90     }
  91     leftedge= node->sides[0].head;
  92     rightedge= node->sides[0].head;
  93     if (strcmp(leftedge->edge.segment,rightedge->edge.segment)) {
  94       trace("no, segments differ\n");
  95       continue;
  96     }
  97     if (!!leftedge->edge.movfeatpos != !!rightedge->edge.movfeatpos ||
  98         strcmp(leftedge->edge.movfeatpos, rightedge->edge.movfeatpos)) {
  99       trace("no, movfeatpos's differ\n");
 100       continue;
 101     }
 102     if (leftedge->end == rightedge->end) {
 103       trace("no, opposite alignment\n");
 104       continue;
 105     }
 106     trace(" yes:\n");
 107     rightedge->edge->distance += leftedge->edge->distance;
 108     edge_replumb(rightedge, edgeend_otherend(leftedge)->node);
 109     edge_delete(leftedge->edge);
 110     node_surely_orphaned(node);
 111     trace(" elimtrivial operation complete\n");
 112   }
 113 }