Update pyls hover to specify language of signature.

LSP supports `MarkedString[]` to specify render engine. We can definitely
say that function signature should be rendered as python. For the docstring,
as we have no good way of parsing it to guess the engine, we can pass it
as markdown.

Author: mpanarin

pyls/plugins/hover.py

@@ -1,5 +1,6 @@
 # Copyright 2017 Palantir Technologies, Inc.
 import logging
+from jedi.api.classes import Signature
 from pyls import hookimpl, _utils
 
 log = logging.getLogger(__name__)
@@ -10,9 +11,26 @@ def pyls_hover(document, position):
     definitions = document.jedi_script(position).goto_definitions()
     word = document.word_at_position(position)
 
-    # Find an exact match for a completion
-    for d in definitions:
-        if d.name == word:
-            return {'contents': _utils.format_docstring(d.docstring()) or ''}
+    # Find first exact matching definition
+    definition = next((x for x in definitions if x.name == word), None)
 
-    return {'contents': ''}
+    if not definition:
+        return {'contents': ''}
+
+    # raw docstring returns only doc, without signature
+    doc = _utils.format_docstring(definition.docstring(raw=True))
+
+    # Find first exact matching signature
+    signature = next((x.to_string() for x in definition.get_signatures() if x.name == word), '')
+
+    contents = []
+    if signature:
+        contents.append({
+            'language': 'python',
+            'value': signature,
+        })
+    if doc:
+        contents.append(doc)
+    if not contents:
+        return {'contents': ''}
+    return {'contents': contents}

setup.py

@@ -36,7 +36,7 @@
         'future>=0.14.0',
         'futures; python_version<"3.2"',
         'backports.functools_lru_cache; python_version<"3.2"',
-        'jedi>=0.13.2,<0.15,!=0.14.0',
+        'jedi>=0.15.0',
         'python-jsonrpc-server>=0.1.0',
         'pluggy'
     ],

test/plugins/test_hover.py

@@ -21,7 +21,7 @@ def test_hover():
     doc = Document(DOC_URI, DOC)
 
     assert {
-        'contents': 'main()\n\nhello world'
+        'contents': [{'language': 'python', 'value': 'main()'}, 'hello world']
     } == pyls_hover(doc, hov_position)
 
     assert {'contents': ''} == pyls_hover(doc, no_hov_position)