java-layers.py revision 8858d2a731f432786b7548b5f63ac93be81eb986 
1#!/usr/bin/env python
2
3import os
4import re
5import sys
6
7def fail_with_usage():
8  sys.stderr.write("usage: java-layers.py DEPENDENCY_FILE SOURCE_DIRECTORIES...\n")
9  sys.stderr.write("\n")
10  sys.stderr.write("Enforces layering between java packages.  Scans\n")
11  sys.stderr.write("DIRECTORY and prints errors when the packages violate\n")
12  sys.stderr.write("the rules defined in the DEPENDENCY_FILE.\n")
13  sys.stderr.write("\n")
14  sys.stderr.write("Prints a warning when an unknown package is encountered\n")
15  sys.stderr.write("on the assumption that it should fit somewhere into the\n")
16  sys.stderr.write("layering.\n")
17  sys.stderr.write("\n")
18  sys.stderr.write("DEPENDENCY_FILE format\n")
19  sys.stderr.write("  - # starts comment\n")
20  sys.stderr.write("  - Lines consisting of two java package names:  The\n")
21  sys.stderr.write("    first package listed must not contain any references\n")
22  sys.stderr.write("    to any classes present in the second package, or any\n")
23  sys.stderr.write("    of its dependencies.\n")
24  sys.stderr.write("  - Lines consisting of one java package name:  The\n")
25  sys.stderr.write("    packge is assumed to be a high level package and\n")
26  sys.stderr.write("    nothing may depend on it.\n")
27  sys.stderr.write("  - Lines consisting of a dash (+) followed by one java\n")
28  sys.stderr.write("    package name: The package is considered a low level\n")
29  sys.stderr.write("    package and may not import any of the other packages\n")
30  sys.stderr.write("    listed in the dependency file.\n")
31  sys.stderr.write("  - Lines consisting of a plus (-) followed by one java\n")
32  sys.stderr.write("    package name: The package is considered \'legacy\'\n")
33  sys.stderr.write("    and excluded from errors.\n")
34  sys.stderr.write("\n")
35  sys.exit(1)
36
37class Dependency:
38  def __init__(self, filename, lineno, lower, top, lowlevel, legacy):
39    self.filename = filename
40    self.lineno = lineno
41    self.lower = lower
42    self.top = top
43    self.lowlevel = lowlevel
44    self.legacy = legacy
45    self.uppers = []
46    self.transitive = set()
47
48  def matches(self, imp):
49    for d in self.transitive:
50      if imp.startswith(d):
51        return True
52    return False
53
54class Dependencies:
55  def __init__(self, deps):
56    def recurse(obj, dep, visited):
57      global err
58      if dep in visited:
59        sys.stderr.write("%s:%d: Circular dependency found:\n"
60            % (dep.filename, dep.lineno))
61        for v in visited:
62          sys.stderr.write("%s:%d:    Dependency: %s\n"
63              % (v.filename, v.lineno, v.lower))
64        err = True
65        return
66      visited.append(dep)
67      for upper in dep.uppers:
68        obj.transitive.add(upper)
69        if upper in deps:
70          recurse(obj, deps[upper], visited)
71    self.deps = deps
72    self.parts = [(dep.lower.split('.'),dep) for dep in deps.itervalues()]
73    # transitive closure of dependencies
74    for dep in deps.itervalues():
75      recurse(dep, dep, [])
76    # disallow everything from the low level components
77    for dep in deps.itervalues():
78      if dep.lowlevel:
79        for d in deps.itervalues():
80          if dep != d and not d.legacy:
81            dep.transitive.add(d.lower)
82    # disallow the 'top' components everywhere but in their own package
83    for dep in deps.itervalues():
84      if dep.top and not dep.legacy:
85        for d in deps.itervalues():
86          if dep != d and not d.legacy:
87            d.transitive.add(dep.lower)
88    for dep in deps.itervalues():
89      dep.transitive = set([x+"." for x in dep.transitive])
90    if False:
91      for dep in deps.itervalues():
92        print "-->", dep.lower, "-->", dep.transitive
93
94  # Lookup the dep object for the given package.  If pkg is a subpackage
95  # of one with a rule, that one will be returned.  If no matches are found,
96  # None is returned.
97  def lookup(self, pkg):
98    # Returns the number of parts that match
99    def compare_parts(parts, pkg):
100      if len(parts) > len(pkg):
101        return 0
102      n = 0
103      for i in range(0, len(parts)):
104        if parts[i] != pkg[i]:
105          return 0
106        n = n + 1
107      return n
108    pkg = pkg.split(".")
109    matched = 0
110    result = None
111    for (parts,dep) in self.parts:
112      x = compare_parts(parts, pkg)
113      if x > matched:
114        matched = x
115        result = dep
116    return result
117
118def parse_dependency_file(filename):
119  global err
120  f = file(filename)
121  lines = f.readlines()
122  f.close()
123  def lineno(s, i):
124    i[0] = i[0] + 1
125    return (i[0],s)
126  n = [0]
127  lines = [lineno(x,n) for x in lines]
128  lines = [(n,s.split("#")[0].strip()) for (n,s) in lines]
129  lines = [(n,s) for (n,s) in lines if len(s) > 0]
130  lines = [(n,s.split()) for (n,s) in lines]
131  deps = {}
132  for n,words in lines:
133    if len(words) == 1:
134      lower = words[0]
135      top = True
136      legacy = False
137      lowlevel = False
138      if lower[0] == '+':
139        lower = lower[1:]
140        top = False
141        lowlevel = True
142      elif lower[0] == '-':
143        lower = lower[1:]
144        legacy = True
145      if lower in deps:
146        sys.stderr.write(("%s:%d: Package '%s' already defined on"
147            + " line %d.\n") % (filename, n, lower, deps[lower].lineno))
148        err = True
149      else:
150        deps[lower] = Dependency(filename, n, lower, top, lowlevel, legacy)
151    elif len(words) == 2:
152      lower = words[0]
153      upper = words[1]
154      if lower in deps:
155        dep = deps[lower]
156        if dep.top:
157          sys.stderr.write(("%s:%d: Can't add dependency to top level package "
158            + "'%s'\n") % (filename, n, lower))
159          err = True
160      else:
161        dep = Dependency(filename, n, lower, False, False, False)
162        deps[lower] = dep
163      dep.uppers.append(upper)
164    else:
165      sys.stderr.write("%s:%d: Too many words on line starting at \'%s\'\n" % (
166          filename, n, words[2]))
167      err = True
168  return Dependencies(deps)
169
170def find_java_files(srcs):
171  result = []
172  for d in srcs:
173    if d[0] == '@':
174      f = file(d[1:])
175      result.extend([fn for fn in [s.strip() for s in f.readlines()]
176          if len(fn) != 0])
177      f.close()
178    else:
179      for root, dirs, files in os.walk(d):
180        result.extend([os.sep.join((root,f)) for f in files
181            if f.lower().endswith(".java")])
182  return result
183
184COMMENTS = re.compile("//.*?\n|/\*.*?\*/", re.S)
185PACKAGE = re.compile("package\s+(.*)")
186IMPORT = re.compile("import\s+(.*)")
187
188def examine_java_file(deps, filename):
189  global err
190  # Yes, this is a crappy java parser.  Write a better one if you want to.
191  f = file(filename)
192  text = f.read()
193  f.close()
194  text = COMMENTS.sub("", text)
195  index = text.find("{")
196  if index < 0:
197    sys.stderr.write(("%s: Error: Unable to parse java. Can't find class "
198        + "declaration.\n") % filename)
199    err = True
200    return
201  text = text[0:index]
202  statements = [s.strip() for s in text.split(";")]
203  # First comes the package declaration.  Then iterate while we see import
204  # statements.  Anything else is either bad syntax that we don't care about
205  # because the compiler will fail, or the beginning of the class declaration.
206  m = PACKAGE.match(statements[0])
207  if not m:
208    sys.stderr.write(("%s: Error: Unable to parse java. Missing package "
209        + "statement.\n") % filename)
210    err = True
211    return
212  pkg = m.group(1)
213  imports = []
214  for statement in statements[1:]:
215    m = IMPORT.match(statement)
216    if not m:
217      break
218    imports.append(m.group(1))
219  # Do the checking
220  if False:
221    print filename
222    print "'%s' --> %s" % (pkg, imports)
223  dep = deps.lookup(pkg)
224  if not dep:
225    sys.stderr.write(("%s: Error: Package does not appear in dependency file: "
226      + "%s\n") % (filename, pkg))
227    err = True
228    return
229  for imp in imports:
230    if dep.matches(imp):
231      sys.stderr.write("%s: Illegal import in package '%s' of '%s'\n"
232          % (filename, pkg, imp))
233      err = True
234
235err = False
236
237def main(argv):
238  if len(argv) < 3:
239    fail_with_usage()
240  deps = parse_dependency_file(argv[1])
241
242  if err:
243    sys.exit(1)
244
245  java = find_java_files(argv[2:])
246  for filename in java:
247    examine_java_file(deps, filename)
248
249  if err:
250    sys.stderr.write("%s: Using this file as dependency file.\n" % argv[1])
251    sys.exit(1)
252
253  sys.exit(0)
254
255if __name__ == "__main__":
256  main(sys.argv)
257
258