Experiment with flattening graphs for textual edit distance based match

Signed-off-by: Nir Izraeli <nirizr@gmail.com>

idaplugin/rematch/collectors/flat_graph.py

@@ -0,0 +1,61 @@
+import idaapi
+
+from .vector import Vector
+
+
+class FlatGraphVector(Vector):
+  type = 'flatgraph_editdistance'
+  type_version = 0
+
+  def __init__(self, *args, **kwargs):
+    super(FlatGraphVector, self).__init__(*args, **kwargs)
+    self.flow_chart = idaapi.FlowChart(idaapi.get_func(self.offset))
+    self.visited = set()
+    self.items = list[self.flow_chart.size]
+
+  def _bb_size(self, bb):
+    if bb.endEA > bb.startEA:
+      return bb.endEA - bb.startEA
+
+    raise ValueError("while flattening graph, a basicblock that ends before "
+                     "it starts encountered at {:x}".format(self.offset))
+
+  def _bb_value(self, bb):
+    # TODO: this should be something that's uncorellated with the order of
+    #  basic blocks
+    return self._bb_size(bb)
+
+  def _append_bbs(self, *bbs):
+    for bb in bbs:
+      self.items.append(self._bb_value(bb))
+
+  def _find_head(self):
+    def is_head(bb):
+      return len(bb.preds()) == 0
+
+    heads = filter(is_head, self.flow_chart)
+    if len(heads) == 1:
+      return heads[0]
+
+    msg = ("flattening graphs with head count other than 1 is not supported, "
+           "got {} head-count for {:x}".format(len(heads), self.offset))
+    raise ValueError(msg)
+
+  def _sort_siblings(self, siblings):
+    return sorted(siblings, key=self._bb_size)
+
+  def _recurse_bb(self, bb):
+    if bb in self.visited:
+      return []
+
+    self.visited.add(bb)
+    siblings = self._sort_siblings(bb.succs())
+    self._append_bbs(*siblings)
+
+    for sibling in siblings:
+      self._recurse_siblings(sibling)
+
+  def _data(self):
+    head = self._find_head()
+    self._recurse_bb(head)
+    return self.items