Bug 1384400 - Add input to output mappings to mozpack.FileRegistry. r=gps

This is necessary because the existing manifests don't expose full
dependency information.  I needed to avoid the existing dependency
files because those code paths need to know the output destination of
the manifest in order to parse the Make dependency files; trying to
adapt this system is more complicated than just preprocessing each
file to extract dependency information directly.

MozReview-Commit-ID: 5m0SEqmhJMM

--HG--
extra : rebase_source : 1ff6a1a51bc76efa78eb564cd8e572777dace0f6

python/mozbuild/mozpack/copier.py

@@ -16,6 +16,7 @@ from mozpack.files import (
 import mozpack.path as mozpath
 import errno
 from collections import (
+    defaultdict,
     Counter,
     OrderedDict,
 )
@@ -153,6 +154,34 @@ class FileRegistry(object):
         '''
         return set(k for k, v in self._required_directories.items() if v > 0)
 
+    def output_to_inputs_tree(self):
+        '''
+        Return a dictionary mapping each output path to the set of its
+        required input paths.
+
+        All paths are normalized.
+        '''
+        tree = {}
+        for output, file in self:
+            output = mozpath.normpath(output)
+            tree[output] = set(mozpath.normpath(f) for f in file.inputs())
+        return tree
+
+    def input_to_outputs_tree(self):
+        '''
+        Return a dictionary mapping each input path to the set of
+        impacted output paths.
+
+        All paths are normalized.
+        '''
+        tree = defaultdict(set)
+        for output, file in self:
+            output = mozpath.normpath(output)
+            for input in file.inputs():
+                input = mozpath.normpath(input)
+                tree[input].add(output)
+        return dict(tree)
+
 
 class FileRegistrySubtree(object):
     '''A proxy class to give access to a subtree of an existing FileRegistry.

python/mozbuild/mozpack/files.py

@@ -234,6 +234,12 @@ class BaseFile(object):
         '''
         return None
 
+    def inputs(self):
+        '''
+        Return an iterable of the input file paths that impact this output file.
+        '''
+        raise NotImplementedError('BaseFile.inputs() not implemented.')
+
 
 class File(BaseFile):
     '''
@@ -261,6 +267,9 @@ class File(BaseFile):
     def size(self):
         return os.stat(self.path).st_size
 
+    def inputs(self):
+        return (self.path,)
+
 
 class ExecutableFile(File):
     '''
@@ -474,6 +483,9 @@ class ExistingFile(BaseFile):
             errors.fatal("Required existing file doesn't exist: %s" %
                 dest.path)
 
+    def inputs(self):
+        return ()
+
 
 class PreprocessedFile(BaseFile):
     '''
@@ -490,6 +502,17 @@ class PreprocessedFile(BaseFile):
         self.silence_missing_directive_warnings = \
             silence_missing_directive_warnings
 
+    def inputs(self):
+        pp = Preprocessor(defines=self.defines, marker=self.marker)
+        pp.setSilenceDirectiveWarnings(self.silence_missing_directive_warnings)
+
+        with open(self.path, 'rU') as input:
+            with open(os.devnull, 'w') as output:
+                pp.processFile(input=input, output=output)
+
+        # This always yields at least self.path.
+        return pp.includes
+
     def copy(self, dest, skip_if_older=True):
         '''
         Invokes the preprocessor to create the destination file.
@@ -565,6 +588,9 @@ class GeneratedFile(BaseFile):
     def size(self):
         return len(self.content)
 
+    def inputs(self):
+        return ()
+
 
 class DeflatedFile(BaseFile):
     '''