namespace and uri extensions

1 files changed, 36 insertions, 12 deletions

diff --git a/bsfs/namespace/namespace.py b/bsfs/namespace/namespace.py
index 8080f5d..f652dcd 100644
--- a/bsfs/namespace/namespace.py
+++ b/bsfs/namespace/namespace.py
@@ -29,29 +29,55 @@ class Namespace():
     # namespace prefix.
     prefix: URI
 
-    def __init__(self, prefix: URI):
-        self.prefix = URI(prefix)
+    # fragment separator.
+    fsep: str
+
+    # path separator.
+    psep: str
+
+    def __init__(self, prefix: URI, fsep: str = '#', psep: str = '/'):
+        # ensure prefix type
+        prefix = URI(prefix)
+        # truncate fragment separator
+        while prefix.endswith(fsep):
+            prefix = URI(prefix[:-1])
+        # truncate path separator
+        while prefix.endswith(psep):
+            prefix = URI(prefix[:-1])
+        # store members
+        self.prefix = prefix
+        self.fsep = fsep
+        self.psep = psep
 
     def __eq__(self, other: typing.Any) -> bool:
-        return isinstance(other, type(self)) and self.prefix == other.prefix
+        return isinstance(other, type(self)) \
+           and self.prefix == other.prefix \
+           and self.fsep == other.fsep \
+           and self.psep == other.psep
 
     def __hash__(self) -> int:
-        return hash((type(self), self.prefix))
+        return hash((type(self), self.prefix, self.fsep, self.psep))
 
     def __str__(self) -> str:
         return f'{typename(self)}({self.prefix})'
 
     def __repr__(self) -> str:
-        return f'{typename(self)}({self.prefix})'
+        return f'{typename(self)}({self.prefix}, {self.fsep}, {self.psep})'
 
     def __getattr__(self, fragment: str) -> URI:
         """Return prefix + fragment."""
-        return URI(self.prefix + fragment)
+        return URI(self.prefix + self.fsep + fragment)
 
     def __getitem__(self, fragment: str) -> URI:
         """Alias for getattr(self, fragment)."""
         return self.__getattr__(fragment)
 
+    def __add__(self, value: typing.Any) -> 'Namespace':
+        """Concatenate another namespace to this one."""
+        if not isinstance(value, str):
+            return NotImplemented
+        return Namespace(self.prefix + self.psep + value, self.fsep, self.psep)
+
 
 class ClosedNamespace(Namespace):
     """Namespace that covers a restricted set of URIs."""
@@ -59,8 +85,8 @@ class ClosedNamespace(Namespace):
     # set of permissible fragments.
     fragments: typing.Set[str]
 
-    def __init__(self, prefix: URI, *args: str):
-        super().__init__(prefix)
+    def __init__(self, prefix: URI, *args: str, fsep: str = '#', psep: str = '/'):
+        super().__init__(prefix, fsep, psep)
         self.fragments = set(args)
 
     def __eq__(self, other: typing.Any) -> bool:
@@ -70,11 +96,9 @@ class ClosedNamespace(Namespace):
         return hash((type(self), self.prefix, tuple(sorted(self.fragments))))
 
     def __getattr__(self, fragment: str) -> URI:
-        """Return prefix + fragment.
-        Raises a KeyError if the fragment is not allowed in this namespace.
-        """
+        """Return prefix + fragment or raise a KeyError if the fragment is not part of this namespace."""
         if fragment not in self.fragments:
-            raise KeyError('fragment')
+            raise KeyError(f'{fragment} is not a valid fragment of namespace {self.prefix}')
         return super().__getattr__(fragment)
 
 ## EOF ##