1 files changed, 57 insertions, 0 deletions
diff --git a/lbup/_path.py b/lbup/_path.py
new file mode 100644
index 0000000..26c67f8
--- /dev/null
+++ b/lbup/_path.py
@@ -0,0 +1,57 @@
+class AbsPath:
+    _components = None
+
+    def __init__(self, path = None, components = None):
+        if path is not None and components is not None:
+            raise ValueError('Both path and components provided')
+
+        if path is not None:
+            if isinstance(path, str):
+                path = path.encode('utf-8')
+            if len(path) < 1 or not path.startswith(b'/'):
+                raise ValueError('Path does not look like valid absolute path', path)
+            components = list(filter(lambda x: len(x) > 0 and x != b'.', path[1:].split(b'/')))
+            if b'..' in components:
+                raise ValueError('Parent references are not allowed', path)
+
+        self._components = components
+
+    def __bytes__(self):
+        return self.path
+    def __repr__(self):
+        return self.path.decode('utf-8', errors = 'backslashreplace')
+
+    def __contains__(self, item):
+        c  = self.components
+        ci = item.components
+        if len(ci) >= len(c) and ci[:len(c)] == c:
+            return True
+        return False
+
+    def __eq__(self, other):
+        return self.components == other.components
+
+    def __len__(self):
+        return len(self.components)
+
+    @property
+    def path(self):
+        return b'/' + b'/'.join(self.components)
+
+    @property
+    def components(self):
+        """
+        Return a list of path components.
+
+        Note that root does not count as a component, so a path of b'/' returns
+        an empty list.
+        """
+        return self._components
+
+    def reparent(self, src, dst):
+        if not self in src:
+            raise ValueError('Path not in parent', self, src)
+        tail = self.components[len(src):]
+        return AbsPath(components = dst.components + tail)
+
+ROOT = AbsPath('/')