Refactor the dot graph generation out of cros_generate_deps_graphs

dot_helper.py

Index: dot_helper.py
diff --git a/dot_helper.py b/dot_helper.py
new file mode 100644
index 0000000000000000000000000000000000000000..d22f901f92fb19a2cb630793e8e52f89e14657a6
--- /dev/null
+++ b/dot_helper.py
@@ -0,0 +1,116 @@
+#!/usr/bin/python
+# Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Helper functions for building graphs with dot."""
+
+import subprocess
+
+class Subgraph(object):
+  """A subgraph in dot. Contains nodes, arcs, and other subgraphs."""
+
+  _valid_ranks = set(['source', 'sink', 'same', 'min', 'max', None])
+
+  def __init__(self, rank=None):
+    self.SetRank(rank)
+    self._nodes = []
+    self._subgraphs = []
+    self._arcs = set()
+
+  def SetRank(self, rank):
+    """Sets the rank for the nodes in the graph.
+
+    Can be one of 'source', 'sink', 'same', 'min', 'max' or None. See dot
+    documentation at http://www.graphviz.org/Documentation.php for exact
+    semantics."""
+    assert(rank in self._valid_ranks)
+    self._rank = rank
+
+  def AddNode(self, id, name=None, color=None, href=None):
+    """Adds a node to the subgraph."""
+    tags = {}
+    if name:
+      tags['label'] = name
+    if color:
+      tags['color'] = color
+      tags['fontcolor'] = color
+    if href:
+      tags['href'] = href
+    self._nodes.append({'id': id, 'tags': tags})
+
+  def AddSubgraph(self, subgraph):
+    """Adds a subgraph to the subgraph."""
+    self._subgraphs.append(subgraph)
+
+  def AddNewSubgraph(self, rank=None):
+    """Adds a new subgraph to the subgraph. The new subgraph is returned."""
+    subgraph = Subgraph(rank)
+    self.AddSubgraph(subgraph)
+    return subgraph
+
+  def AddArc(self, node_from, node_to):
+    """Adds an arc between two nodes."""
+    self._arcs.add((node_from, node_to))
+
+  def _GenNodes(self):
+    """Generates the code for all the nodes."""
+    lines = []
+    for node in self._nodes:
+      tags = ['%s="%s"' % (k, v) for (k, v) in node['tags'].iteritems()]
+      lines.append('"%s" [%s];' % (node['id'], ', '.join(tags)))
+    return lines
+
+  def _GenSubgraphs(self):
+    """Generates the code for all the subgraphs contained in this subgraph."""
+    lines = []
+    for subgraph in self._subgraphs:
+      lines += subgraph.Gen();
+    return lines
+
+  def _GenArcs(self):
+    """Generates the code for all the arcs."""
+    lines = []
+    for node_from, node_to in self._arcs:
+      lines.append('"%s" -> "%s";' % (node_from, node_to))
+    return lines
+
+  def _GenInner(self):
+    """Generates the code for the inner contents of the subgraph."""
+    lines = []
+    if self._rank:
+      lines.append('rank=%s;' % self._rank)
+    lines += self._GenSubgraphs()
+    lines += self._GenNodes()
+    lines += self._GenArcs()
+    return lines
+
+  def Gen(self):
+    """Generates the code for the subgraph."""
+    return ['subgraph {'] + self._GenInner() + ['}']
+
+
+class Graph(Subgraph):
+  """A top-level graph in dot. It's basically a subgraph with a name."""
+
+  def __init__(self, name):
+    Subgraph.__init__(self)
+    self._name = name
+
+  def Gen(self):
+    """Generates the code for the graph."""
+    return ['digraph "%s" {' % self._name,
+            'graph [name="%s"];' % self._name] + self._GenInner() + ['}']
+
+
+def GenerateImage(lines, filename, format='svg', save_dot_filename=None):
+  """Generates the image by calling dot on the input lines."""
+  data = '\n'.join(lines)
+  proc = subprocess.Popen(['dot', '-T' + format, '-o' + filename],
+                          stdin=subprocess.PIPE)
+  proc.communicate(data)
+
+  if save_dot_filename:
+    file = open(save_dot_filename, 'w')
+    file.write(data)
+    file.close()