Allow to format signatures in docstrings

CONFIGURATION.md

@@ -75,5 +75,7 @@ This server can be configured using the `workspace/didChangeConfiguration` metho
 | `pylsp.plugins.yapf.enabled` | `boolean` | Enable or disable the plugin. | `true` |
 | `pylsp.rope.extensionModules` | `string` | Builtin and c-extension modules that are allowed to be imported and inspected by rope. | `null` |
 | `pylsp.rope.ropeFolder` | `array` of unique `string` items | The name of the folder in which rope stores project configurations and data.  Pass `null` for not using such a folder at all. | `null` |
+| `pylsp.signature.formatter` | `string` (one of: `'black'`, `'ruff'`, `None`) | Formatter to use for reformatting signatures in docstrings. | `"black"` |
+| `pylsp.signature.line_length` | `number`  | Maximum line length in signatures. | `88` |
 
 This documentation was generated from `pylsp/config/schema.json`. Please do not edit this file directly.

pylsp/_utils.py

@@ -7,6 +7,8 @@
 import os
 import pathlib
 import re
+import subprocess
+import sys
 import threading
 import time
 from typing import List, Optional
@@ -57,7 +59,7 @@ def run():
 
 
 def throttle(seconds=1):
-    """Throttles calls to a function evey `seconds` seconds."""
+    """Throttles calls to a function every `seconds` seconds."""
 
     def decorator(func):
         @functools.wraps(func)
@@ -209,8 +211,113 @@ def choose_markup_kind(client_supported_markup_kinds: List[str]):
     return "markdown"
 
 
+class Formatter:
+    command: List[str]
+
+    @property
+    def is_installed(self) -> bool:
+        """Returns whether formatter is available"""
+        if not hasattr(self, "_is_installed"):
+            self._is_installed = self._is_available_via_cli()
+        return self._is_installed
+
+    def format(self, code: str, line_length: int) -> str:
+        """Formats code"""
+        return subprocess.check_output(
+            [
+                sys.executable,
+                "-m",
+                *self.command,
+                "--line-length",
+                str(line_length),
+                "-",
+            ],
+            input=code,
+            text=True,
+        ).strip()
+
+    def _is_available_via_cli(self) -> bool:
+        try:
+            subprocess.check_output(
+                [
+                    sys.executable,
+                    "-m",
+                    *self.command,
+                    "--help",
+                ],
+            )
+            return True
+        except subprocess.CalledProcessError:
+            return False
+
+
+class RuffFormatter(Formatter):
+    command = ["ruff", "format"]
+
+
+class BlackFormatter(Formatter):
+    command = ["black"]
+
+
+formatters = {"ruff": RuffFormatter(), "black": BlackFormatter()}
+
+
+def removeprefix(text: str, prefix: str) -> str:
+    if text.startswith(prefix):
+        return text[len(prefix) :]
+    return text
+
+
+def removesuffix(text: str, suffix: str) -> str:
+    if suffix and text.endswith(suffix):
+        return text[: -len(suffix)]
+    return text
+
+
+def format_signature(signature: str, config: dict, signature_formatter: str) -> str:
+    """Formats signature using ruff or black if either is available."""
+    as_func = f"def {signature.strip()}:\n    pass"
+    line_length = config.get("line_length", 88)
+    formatter = formatters[signature_formatter]
+    if formatter.is_installed:
+        try:
+            return (
+                # TODO: replace with str.removeprefix and str.removesuffix
+                # once Python 3.8 support is no longer required
+                removesuffix(
+                    removeprefix(
+                        formatter.format(as_func, line_length=line_length), "def "
+                    ),
+                    ":\n    pass",
+                )
+            )
+        except subprocess.CalledProcessError as e:
+            log.warning("Signature formatter failed %s", e)
+    else:
+        log.warning(
+            "Formatter %s was requested but it does not appear to be installed",
+            signature_formatter,
+        )
+    return signature
+
+
+def convert_signatures_to_markdown(signatures: List[str], config: dict) -> str:
+    signature_formatter = config.get("formatter", "black")
+    if signature_formatter:
+        signatures = [
+            format_signature(
+                signature, signature_formatter=signature_formatter, config=config
+            )
+            for signature in signatures
+        ]
+    return wrap_signature("\n".join(signatures))
+
+
 def format_docstring(
-    contents: str, markup_kind: str, signatures: Optional[List[str]] = None
+    contents: str,
+    markup_kind: str,
+    signatures: Optional[List[str]] = None,
+    signature_config: Optional[dict] = None,
 ):
     """Transform the provided docstring into a MarkupContent object.
 
@@ -232,7 +339,10 @@ def format_docstring(
             value = escape_markdown(contents)
 
         if signatures:
-            value = wrap_signature("\n".join(signatures)) + "\n\n" + value
+            wrapped_signatures = convert_signatures_to_markdown(
+                signatures, config=signature_config or {}
+            )
+            value = wrapped_signatures + "\n\n" + value
 
         return {"kind": "markdown", "value": value}
     value = contents

pylsp/config/schema.json

@@ -511,6 +511,24 @@
       },
       "uniqueItems": true,
       "description": "The name of the folder in which rope stores project configurations and data.  Pass `null` for not using such a folder at all."
+    },
+    "pylsp.signature.formatter": {
+      "type": [
+        "string",
+        "null"
+      ],
+      "enum": [
+        "black",
+        "ruff",
+        null
+      ],
+      "default": "black",
+      "description": "Formatter to use for reformatting signatures in docstrings."
+    },
+    "pylsp.signature.line_length": {
+      "type": "number",
+      "default": 88,
+      "description": "Maximum line length in signatures."
     }
   }
 }

pylsp/plugins/hover.py

@@ -10,6 +10,7 @@
 
 @hookimpl
 def pylsp_hover(config, document, position):
+    signature_config = config.settings().get("signature", {})
     code_position = _utils.position_to_jedi_linecolumn(document, position)
     definitions = document.jedi_script(use_document_path=True).infer(**code_position)
     word = document.word_at_position(position)
@@ -46,5 +47,6 @@ def pylsp_hover(config, document, position):
             definition.docstring(raw=True),
             preferred_markup_kind,
             signatures=[signature] if signature else None,
+            signature_config=signature_config,
         )
     }

pylsp/plugins/jedi_completion.py

@@ -40,8 +40,9 @@ def pylsp_completions(config, document, position):
     """Get formatted completions for current code position"""
     settings = config.plugin_settings("jedi_completion", document_path=document.path)
     resolve_eagerly = settings.get("eager", False)
-    code_position = _utils.position_to_jedi_linecolumn(document, position)
+    signature_config = config.settings().get("signature", {})
 
+    code_position = _utils.position_to_jedi_linecolumn(document, position)
     code_position["fuzzy"] = settings.get("fuzzy", False)
     completions = document.jedi_script(use_document_path=True).complete(**code_position)
 
@@ -88,6 +89,7 @@ def pylsp_completions(config, document, position):
             resolve=resolve_eagerly,
             resolve_label_or_snippet=(i < max_to_resolve),
             snippet_support=snippet_support,
+            signature_config=signature_config,
         )
         for i, c in enumerate(completions)
     ]
@@ -103,6 +105,7 @@ def pylsp_completions(config, document, position):
                     resolve=resolve_eagerly,
                     resolve_label_or_snippet=(i < max_to_resolve),
                     snippet_support=snippet_support,
+                    signature_config=signature_config,
                 )
                 completion_dict["kind"] = lsp.CompletionItemKind.TypeParameter
                 completion_dict["label"] += " object"
@@ -118,6 +121,7 @@ def pylsp_completions(config, document, position):
                     resolve=resolve_eagerly,
                     resolve_label_or_snippet=(i < max_to_resolve),
                     snippet_support=snippet_support,
+                    signature_config=signature_config,
                 )
                 completion_dict["kind"] = lsp.CompletionItemKind.TypeParameter
                 completion_dict["label"] += " object"
@@ -137,7 +141,11 @@ def pylsp_completions(config, document, position):
 
 
 @hookimpl
-def pylsp_completion_item_resolve(config, completion_item, document):
+def pylsp_completion_item_resolve(
+    config,
+    completion_item,
+    document,
+):
     """Resolve formatted completion for given non-resolved completion"""
     shared_data = document.shared_data["LAST_JEDI_COMPLETIONS"].get(
         completion_item["label"]
@@ -152,7 +160,12 @@ def pylsp_completion_item_resolve(config, completion_item, document):
 
     if shared_data:
         completion, data = shared_data
-        return _resolve_completion(completion, data, markup_kind=preferred_markup_kind)
+        return _resolve_completion(
+            completion,
+            data,
+            markup_kind=preferred_markup_kind,
+            signature_config=config.settings().get("signature", {}),
+        )
     return completion_item
 
 
@@ -207,13 +220,14 @@ def use_snippets(document, position):
     return expr_type not in _IMPORTS and not (expr_type in _ERRORS and "import" in code)
 
 
-def _resolve_completion(completion, d, markup_kind: str):
+def _resolve_completion(completion, d, markup_kind: str, signature_config: dict):
     completion["detail"] = _detail(d)
     try:
         docs = _utils.format_docstring(
             d.docstring(raw=True),
             signatures=[signature.to_string() for signature in d.get_signatures()],
             markup_kind=markup_kind,
+            signature_config=signature_config,
         )
     except Exception:
         docs = ""
@@ -228,6 +242,7 @@ def _format_completion(
     resolve=False,
     resolve_label_or_snippet=False,
     snippet_support=False,
+    signature_config=None,
 ):
     completion = {
         "label": _label(d, resolve_label_or_snippet),
@@ -237,7 +252,9 @@ def _format_completion(
     }
 
     if resolve:
-        completion = _resolve_completion(completion, d, markup_kind)
+        completion = _resolve_completion(
+            completion, d, markup_kind, signature_config=signature_config
+        )
 
     # Adjustments for file completions
     if d.type == "path":

pyproject.toml

@@ -19,6 +19,7 @@ dependencies = [
     "pluggy>=1.0.0",
     "python-lsp-jsonrpc>=1.1.0,<2.0.0",
     "ujson>=3.0.0",
+    "black"
 ]
 dynamic = ["version"]
 

test/plugins/test_hover.py

@@ -10,7 +10,7 @@
 DOC_URI = uris.from_fs_path(__file__)
 DOC = """
 
-def main():
+def main(a: float, b: float):
     \"\"\"hello world\"\"\"
     pass
 """
@@ -79,13 +79,47 @@ def test_hover(workspace) -> None:
 
     doc = Document(DOC_URI, workspace, DOC)
 
-    contents = {"kind": "markdown", "value": "```python\nmain()\n```\n\n\nhello world"}
+    contents = {
+        "kind": "markdown",
+        "value": "```python\nmain(a: float, b: float)\n```\n\n\nhello world",
+    }
 
     assert {"contents": contents} == pylsp_hover(doc._config, doc, hov_position)
 
     assert {"contents": ""} == pylsp_hover(doc._config, doc, no_hov_position)
 
 
+def test_hover_signature_formatting(workspace) -> None:
+    # Over 'main' in def main():
+    hov_position = {"line": 2, "character": 6}
+
+    doc = Document(DOC_URI, workspace, DOC)
+    # setting low line length should trigger reflow to multiple lines
+    doc._config.update({"signature": {"line_length": 10}})
+
+    contents = {
+        "kind": "markdown",
+        "value": "```python\nmain(\n    a: float,\n    b: float,\n)\n```\n\n\nhello world",
+    }
+
+    assert {"contents": contents} == pylsp_hover(doc._config, doc, hov_position)
+
+
+def test_hover_signature_formatting_opt_out(workspace) -> None:
+    # Over 'main' in def main():
+    hov_position = {"line": 2, "character": 6}
+
+    doc = Document(DOC_URI, workspace, DOC)
+    doc._config.update({"signature": {"line_length": 10, "formatter": None}})
+
+    contents = {
+        "kind": "markdown",
+        "value": "```python\nmain(a: float, b: float)\n```\n\n\nhello world",
+    }
+
+    assert {"contents": contents} == pylsp_hover(doc._config, doc, hov_position)
+
+
 def test_document_path_hover(workspace_other_root_path, tmpdir) -> None:
     # Create a dummy module out of the workspace's root_path and try to get
     # a definition on it in another file placed next to it.