Feature/span ents (#2599)

* Created Span.ents property

* Add tests for span.ents

* Add tests for start and end of sentence

spacy/tests/doc/test_span.py

@@ -133,3 +133,31 @@ def test_span_as_doc(doc):
     span = doc[4:10]
     span_doc = span.as_doc()
     assert span.text == span_doc.text.strip()
+
+def test_span_ents_property(doc):
+    """Test span.ents for the """
+    doc.ents = [
+        (doc.vocab.strings['PRODUCT'], 0, 1),
+        (doc.vocab.strings['PRODUCT'], 7, 8),
+        (doc.vocab.strings['PRODUCT'], 11, 14)
+    ]
+    assert len(list(doc.ents)) == 3
+    sentences = list(doc.sents)
+    assert len(sentences) == 3
+    assert len(sentences[0].ents) == 1
+    # First sentence, also tests start of sentence
+    assert sentences[0].ents[0].text == "This"
+    assert sentences[0].ents[0].label_ == "PRODUCT"
+    assert sentences[0].ents[0].start == 0
+    assert sentences[0].ents[0].end == 1
+    # Second sentence
+    assert len(sentences[1].ents) == 1
+    assert sentences[1].ents[0].text == "another"
+    assert sentences[1].ents[0].label_ == "PRODUCT"
+    assert sentences[1].ents[0].start == 7
+    assert sentences[1].ents[0].end == 8
+    # Third sentence ents, Also tests end of sentence
+    assert sentences[2].ents[0].text == "a third ."
+    assert sentences[2].ents[0].label_ == "PRODUCT"
+    assert sentences[2].ents[0].start == 11
+    assert sentences[2].ents[0].end == 14

spacy/tokens/span.pyx

@@ -302,6 +302,15 @@ cdef class Span:
                     raise RuntimeError(Errors.E038)
             return self.doc[root.l_edge:root.r_edge + 1]
 
+    property ents:
+        """RETURNS (list): A list of tokens that belong to the current span."""
+        def __get__(self):
+            ents = []
+            for ent in self.doc.ents:
+                if ent.start >= self.start and ent.end <= self.end:
+                    ents.append(ent)
+            return ents
+
     property has_vector:
         """RETURNS (bool): Whether a word vector is associated with the object.
         """