Merge pkg_resource_overrides branch.

1 files changed, 106 insertions, 0 deletions

diff --git a/repoze/bfg/resource.py b/repoze/bfg/resource.py
new file mode 100644
index 000000000..00e30170d
--- /dev/null
+++ b/repoze/bfg/resource.py
@@ -0,0 +1,106 @@
+import pkg_resources
+from zope.component import queryUtility
+from zope.interface import implements
+
+from repoze.bfg.interfaces import IPackageOverrides
+
+class OverrideProvider(pkg_resources.DefaultProvider):
+    def __init__(self, module):
+        pkg_resources.DefaultProvider.__init__(self, module)
+        self.module_name = module.__name__
+
+    def _get_overrides(self):
+        overrides = queryUtility(IPackageOverrides, self.module_name)
+        return overrides
+    
+    def get_resource_filename(self, manager, resource_name):
+        """ Return a true filesystem path for resource_name,
+        co-ordinating the extraction with manager, if the resource
+        must be unpacked to the filesystem.
+        """
+        overrides = self._get_overrides()
+        if overrides is not None:
+            filename = overrides.get_filename(resource_name)
+            if filename is not None:
+                return filename
+        return pkg_resources.DefaultProvider.get_resource_filename(
+            self, manager, resource_name)
+    
+    def get_resource_stream(self, manager, resource_name):
+        """ Return a readable file-like object for resource_name."""
+        overrides = self._get_overrides()
+        if overrides is not None:
+            stream =  overrides.get_stream(resource_name)
+            if stream is not None:
+                return stream
+        return pkg_resources.DefaultProvider.get_resource_stream(
+            self, manager, resource_name)
+
+    def get_resource_string(self, manager, resource_name):
+        """ Return a string containing the contents of resource_name."""
+        overrides = self._get_overrides()
+        if overrides is not None:
+            string = overrides.get_string(resource_name)
+            if string is not None:
+                return string
+        return pkg_resources.DefaultProvider.get_resource_string(
+            self, manager, resource_name)
+
+class PackageOverrides:
+    implements(IPackageOverrides)
+    def __init__(self, overridden_package):
+        self.overrides = []
+        self.overridden_package = overridden_package
+
+    def insert(self, path, package, prefix):
+        if path.endswith('/'):
+            override = DirectoryOverride(path, package, prefix)
+        else:
+            override = FileOverride(path, package, prefix)
+        self.overrides.insert(0, override)
+        return override
+
+    def search_path(self, resource_name):
+        for override in self.overrides:
+            o = override(resource_name)
+            if o is not None:
+                package, name = o
+                yield package, name
+
+    def get_filename(self, resource_name):
+        for package, rname in self.search_path(resource_name):
+            if pkg_resources.resource_exists(package, rname):
+                return pkg_resources.resource_filename(package, rname)
+
+    def get_stream(self, resource_name):
+        for package, rname in self.search_path(resource_name):
+            if pkg_resources.resource_exists(package, rname):
+                return pkg_resources.resource_stream(package, rname)
+
+    def get_string(self, resource_name):
+        for package, rname in self.search_path(resource_name):
+            if pkg_resources.resource_exists(package, rname):
+                return pkg_resources.resource_string(package, rname)
+
+class DirectoryOverride:
+    def __init__(self, path, package, prefix):
+        self.path = path
+        self.package = package
+        self.prefix = prefix
+        self.pathlen = len(self.path)
+
+    def __call__(self, resource_name):
+        if resource_name.startswith(self.path):
+            name = '%s%s' % (self.prefix, resource_name[self.pathlen:])
+            return self.package, name
+
+class FileOverride:
+    def __init__(self, path, package, prefix):
+        self.path = path
+        self.package = package
+        self.prefix = prefix
+
+    def __call__(self, resource_name):
+        if resource_name == self.path:
+            return self.package, self.prefix
+