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      1 #!/usr/bin/env python
      2 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
      3 # Use of this source code is governed by a BSD-style license that can be
      4 # found in the LICENSE file.
      5 
      6 """Prints paths between gyp targets.
      7 """
      8 
      9 import json
     10 import os
     11 import sys
     12 import time
     13 
     14 from collections import deque
     15 
     16 def usage():
     17   print """\
     18 Usage:
     19   tools/gyp-explain.py [--dot] chrome_dll# gtest#
     20 """
     21 
     22 
     23 def GetPath(graph, fro, to):
     24   """Given a graph in (node -> list of successor nodes) dictionary format,
     25   yields all paths from |fro| to |to|, starting with the shortest."""
     26   # Storing full paths in the queue is a bit wasteful, but good enough for this.
     27   q = deque([(fro, [])])
     28   while q:
     29     t, path = q.popleft()
     30     if t == to:
     31       yield path + [t]
     32     for d in graph[t]:
     33       q.append((d, path + [t]))
     34 
     35 
     36 def MatchNode(graph, substring):
     37   """Given a dictionary, returns the key that matches |substring| best. Exits
     38   if there's not one single best match."""
     39   candidates = []
     40   for target in graph:
     41     if substring in target:
     42       candidates.append(target)
     43 
     44   if not candidates:
     45     print 'No targets match "%s"' % substring
     46     sys.exit(1)
     47   if len(candidates) > 1:
     48     print 'More than one target matches "%s": %s' % (
     49         substring, ' '.join(candidates))
     50     sys.exit(1)
     51   return candidates[0]
     52 
     53 
     54 def EscapeForDot(string):
     55   suffix = '#target'
     56   if string.endswith(suffix):
     57     string = string[:-len(suffix)]
     58   string = string.replace('\\', '\\\\')
     59   return '"' + string + '"'
     60 
     61 
     62 def GenerateDot(fro, to, paths):
     63   """Generates an input file for graphviz's dot program."""
     64   prefixes = [os.path.commonprefix(path) for path in paths]
     65   prefix = os.path.commonprefix(prefixes)
     66   print '// Build with "dot -Tpng -ooutput.png this_file.dot"'
     67   # "strict" collapses common paths.
     68   print 'strict digraph {'
     69   for path in paths:
     70     print (' -> '.join(EscapeForDot(item[len(prefix):]) for item in path)), ';'
     71   print '}'
     72 
     73 
     74 def Main(argv):
     75   # Check that dump.json exists and that it's not too old.
     76   dump_json_dirty = False
     77   try:
     78     st = os.stat('dump.json')
     79     file_age_s = time.time() - st.st_mtime
     80     if file_age_s > 2 * 60 * 60:
     81       print 'dump.json is more than 2 hours old.'
     82       dump_json_dirty = True
     83   except OSError:
     84     print 'dump.json not found.'
     85     dump_json_dirty = True
     86 
     87   if dump_json_dirty:
     88     print 'Run'
     89     print '    GYP_GENERATORS=dump_dependency_json build/gyp_chromium'
     90     print 'first, then try again.'
     91     sys.exit(1)
     92 
     93   g = json.load(open('dump.json'))
     94 
     95   if len(argv) not in (3, 4):
     96     usage()
     97     sys.exit(1)
     98 
     99   generate_dot = argv[1] == '--dot'
    100   if generate_dot:
    101     argv.pop(1)
    102 
    103   fro = MatchNode(g, argv[1])
    104   to = MatchNode(g, argv[2])
    105 
    106   paths = list(GetPath(g, fro, to))
    107   if len(paths) > 0:
    108     if generate_dot:
    109       GenerateDot(fro, to, paths)
    110     else:
    111       print 'These paths lead from %s to %s:' % (fro, to)
    112       for path in paths:
    113         print ' -> '.join(path)
    114   else:
    115     print 'No paths found from %s to %s.' % (fro, to)
    116 
    117 
    118 if __name__ == '__main__':
    119   Main(sys.argv)
    120