From 862da5e7932bda6ceee3091c915b782a8215cc83 Mon Sep 17 00:00:00 2001
From: Ines Montani <ines@ines.io>
Date: Tue, 22 May 2018 18:29:45 +0200
Subject: [PATCH] Support pipeline factories via entry points (#2348)

---
 spacy/errors.py   |  2 ++
 spacy/language.py |  7 ++++++-
 spacy/util.py     | 13 +++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/spacy/errors.py b/spacy/errors.py
index b812a6f76..ad0518fca 100644
--- a/spacy/errors.py
+++ b/spacy/errors.py
@@ -46,6 +46,8 @@ class Warnings(object):
             "use context-sensitive tensors. You can always add your own word "
             "vectors, or use one of the larger models instead if available.")
     W008 = ("Evaluating {obj}.similarity based on empty vectors.")
+    W009 = ("Custom factory '{name}' provided by entry points of another "
+            "package overwrites built-in factory.")
 
 
 @add_codes
diff --git a/spacy/language.py b/spacy/language.py
index be331e72d..e1e01d0ca 100644
--- a/spacy/language.py
+++ b/spacy/language.py
@@ -28,7 +28,7 @@ from .lang.punctuation import TOKENIZER_INFIXES
 from .lang.tokenizer_exceptions import TOKEN_MATCH
 from .lang.tag_map import TAG_MAP
 from .lang.lex_attrs import LEX_ATTRS, is_stop
-from .errors import Errors
+from .errors import Errors, Warnings, user_warning
 from . import util
 from . import about
 
@@ -139,6 +139,11 @@ class Language(object):
             100,000 characters in one text.
         RETURNS (Language): The newly constructed object.
         """
+        user_factories = util.get_entry_points('spacy_factories')
+        for factory in user_factories.keys():
+            if factory in self.factories:
+                user_warning(Warnings.W009.format(name=factory))
+        self.factories.update(user_factories)
         self._meta = dict(meta)
         self._path = None
         if vocab is True:
diff --git a/spacy/util.py b/spacy/util.py
index b80142c38..80adf7257 100644
--- a/spacy/util.py
+++ b/spacy/util.py
@@ -220,6 +220,19 @@ def get_package_path(name):
     return Path(pkg.__file__).parent
 
 
+def get_entry_points(key):
+    """Get registered entry points from other packages for a given key, e.g.
+    'spacy_factories' and return them as a dictionary, keyed by name.
+
+    key (unicode): Entry point name.
+    RETURNS (dict): Entry points, keyed by name.
+    """
+    result = {}
+    for entry_point in pkg_resources.iter_entry_points(key):
+        result[entry_point.name] = entry_point.load()
+    return result
+
+
 def is_in_jupyter():
     """Check if user is running spaCy from a Jupyter notebook by detecting the
     IPython kernel. Mainly used for the displaCy visualizer.