Add basic Goto Implementation Request support

CONFIGURATION.md

@@ -72,6 +72,7 @@ This server can be configured using the `workspace/didChangeConfiguration` metho
 | `pylsp.plugins.rope_autoimport.memory` | `boolean` | Make the autoimport database memory only. Drastically increases startup time. | `false` |
 | `pylsp.plugins.rope_completion.enabled` | `boolean` | Enable or disable the plugin. | `false` |
 | `pylsp.plugins.rope_completion.eager` | `boolean` | Resolve documentation and detail eagerly. | `false` |
+| `pylsp.plugins.rope_implementation.enabled` | `boolean` | Enable or disable the plugin. | `true` |
 | `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` |

README.md

@@ -15,7 +15,7 @@ pip install python-lsp-server
 This will expose the command `pylsp` on your PATH. Confirm that installation succeeded by running `pylsp --help`.
 
 If the respective dependencies are found, the following optional providers will be enabled:
-- [Rope](https://github.com/python-rope/rope) for Completions and renaming
+- [Rope](https://github.com/python-rope/rope) for Completions, Goto Implementation, and renaming
 - [Pyflakes](https://github.com/PyCQA/pyflakes) linter to detect various errors
 - [McCabe](https://github.com/PyCQA/mccabe) linter for complexity checking
 - [pycodestyle](https://github.com/PyCQA/pycodestyle) linter for style checking
@@ -151,7 +151,7 @@ pip install 'python-lsp-server[websockets]'
 * Code Linting
 * Code actions
 * Signature Help
-* Go to definition
+* Go to definition or implementation
 * Hover
 * Find References
 * Document Symbols

pylsp/config/schema.json

@@ -487,6 +487,11 @@
       "default": false,
       "description": "Resolve documentation and detail eagerly."
     },
+    "pylsp.plugins.rope_implementation.enabled": {
+      "type": "boolean",
+      "default": true,
+      "description": "Enable or disable the plugin."
+    },
     "pylsp.plugins.yapf.enabled": {
       "type": "boolean",
       "default": true,

pylsp/hookspecs.py

@@ -93,6 +93,11 @@ def pylsp_hover(config, workspace, document, position) -> None:
     pass
 
 
+@hookspec
+def pylsp_implementations(config, workspace, document, position) -> None:
+    pass
+
+
 @hookspec
 def pylsp_initialize(config, workspace) -> None:
     pass

pylsp/plugins/rope_implementation.py

@@ -0,0 +1,70 @@
+# Copyright 2017-2020 Palantir Technologies, Inc.
+# Copyright 2021- Python Language Server Contributors.
+import logging
+import os
+from typing import Any
+
+from rope.base.project import Project
+from rope.base.resources import Resource
+from rope.contrib.findit import Location, find_implementations
+
+from pylsp import hookimpl, uris
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def pylsp_settings():
+    # Default to enabled (no reason not to)
+    return {"plugins": {"rope_implementation": {"enabled": True}}}
+
+
+@hookimpl
+def pylsp_implementations(config, workspace, document, position):
+    offset = document.offset_at_position(position)
+    rope_config = config.settings(document_path=document.path).get("rope", {})
+    rope_project = workspace._rope_project_builder(rope_config)
+    rope_resource = document._rope_resource(rope_config)
+
+    impls = find_implementations(rope_project, rope_resource, offset)
+
+    return [
+        {
+            "uri": uris.uri_with(
+                document.uri,
+                path=os.path.join(workspace.root_path, impl.resource.path),
+            ),
+            "range": _rope_location_to_range(impl, rope_project),
+        }
+        for impl in impls
+    ]
+
+
+def _rope_location_to_range(
+    location: Location, rope_project: Project
+) -> dict[str, Any]:
+    # NOTE: This assumes the result is confined to a single line, which should
+    # always be the case here because Python doesn't allow splitting up
+    # identifiers across more than one line.
+    start_column, end_column = _rope_region_to_columns(
+        location.region, location.lineno, location.resource, rope_project
+    )
+    return {
+        "start": {"line": location.lineno - 1, "character": start_column},
+        "end": {"line": location.lineno - 1, "character": end_column},
+    }
+
+
+def _rope_region_to_columns(
+    offsets: tuple[int, int], line: int, rope_resource: Resource, rope_project: Project
+) -> tuple[int, int]:
+    """
+    Convert pair of offsets from start of file to columns within line.
+
+    Assumes both offsets reside within the same line and will return nonsense
+    for the end offset if this isn't the case.
+    """
+    line_start_offset = rope_project.get_pymodule(rope_resource).lines.get_line_start(
+        line
+    )
+    return offsets[0] - line_start_offset, offsets[1] - line_start_offset

pylsp/python_lsp.py

@@ -280,6 +280,7 @@ def capabilities(self):
                 "commands": flatten(self._hook("pylsp_commands"))
             },
             "hoverProvider": True,
+            "implementationProvider": True,  # only when Rope is installed
             "referencesProvider": True,
             "renameProvider": True,
             "foldingRangeProvider": True,
@@ -436,6 +437,9 @@ def highlight(self, doc_uri, position):
     def hover(self, doc_uri, position):
         return self._hook("pylsp_hover", doc_uri, position=position) or {"contents": ""}
 
+    def implementations(self, doc_uri, position):
+        return flatten(self._hook("pylsp_implementations", doc_uri, position=position))
+
     @_utils.debounce(LINT_DEBOUNCE_S, keyed_by="doc_uri")
     def lint(self, doc_uri, is_saved) -> None:
         # Since we're debounced, the document may no longer be open
@@ -762,6 +766,12 @@ def m_text_document__definition(self, textDocument=None, position=None, **_kwarg
             return self._cell_document__definition(document, position, **_kwargs)
         return self.definitions(textDocument["uri"], position)
 
+    def m_text_document__implementation(self, textDocument=None, position=None, **_kwargs):
+        # textDocument here is just a dict with a uri
+        workspace = self._match_uri_to_workspace(textDocument["uri"])
+        document = workspace.get_document(textDocument["uri"])
+        return self.implementations(textDocument["uri"], position)
+
     def m_text_document__document_highlight(
         self, textDocument=None, position=None, **_kwargs
     ):

pyproject.toml

@@ -80,6 +80,7 @@ pyflakes = "pylsp.plugins.pyflakes_lint"
 pylint = "pylsp.plugins.pylint_lint"
 rope_completion = "pylsp.plugins.rope_completion"
 rope_autoimport = "pylsp.plugins.rope_autoimport"
+rope_implementation = "pylsp.plugins.rope_implementation"
 yapf = "pylsp.plugins.yapf_format"
 
 [project.scripts]

test/data/implementations_examples/example.py

@@ -0,0 +1,29 @@
+from abc import ABC, abstractmethod
+
+class Animal(ABC):
+    @abstractmethod
+    def breathe(self):
+        pass
+
+    @property
+    @abstractmethod
+    def size(self) -> str:
+        pass
+
+class WingedAnimal(Animal):
+    @abstractmethod
+    def fly(self, destination):
+        pass
+
+class Bird(WingedAnimal):
+    def breathe(self):
+        print("*inhales like a bird*")
+
+    def fly(self, destination):
+        print("*flies like a bird*")
+
+    @property
+    def size(self) -> str:
+        return "bird-sized"
+
+print("not a method at all")

test/plugins/test_implementations.py

@@ -0,0 +1,104 @@
+# Copyright 2017-2020 Palantir Technologies, Inc.
+# Copyright 2021- Python Language Server Contributors.
+
+from collections.abc import Iterable
+from importlib.resources import as_file, files
+from pathlib import Path
+
+import pytest
+from rope.base.exceptions import BadIdentifierError
+
+from pylsp import uris
+from pylsp.config.config import Config
+from pylsp.plugins.rope_implementation import pylsp_implementations
+from pylsp.workspace import Workspace
+
+
+# We use a real file because the part of Rope that this feature uses
+# (`rope.findit.find_implementations`) *always* loads files from the
+# filesystem, in contrast to e.g. `code_assist` which takes a `source` argument
+# that can be more easily faked.
+# An alternative to using real files would be `unittest.mock.patch`, but that
+# ends up being more trouble than it's worth...
+@pytest.fixture
+def examples_dir_path() -> Iterable[Path]:
+    with as_file(files("test.data.implementations_examples")) as path:
+        yield path
+
+
+@pytest.fixture
+def doc_uri(examples_dir_path: Path) -> str:
+    return uris.from_fs_path(str(examples_dir_path / "example.py"))
+
+
+# Similarly to the above, we need our workspace to point to the actual location
+# on the filesystem containing the example modules, so we override the fixture:
+@pytest.fixture
+def workspace(examples_dir_path: Path, endpoint) -> None:
+    ws = Workspace(uris.from_fs_path(str(examples_dir_path)), endpoint)
+    ws._config = Config(ws.root_uri, {}, 0, {})
+    yield ws
+    ws.close()
+
+
+def test_implementations(config, workspace, doc_uri) -> None:
+    # Over 'fly' in WingedAnimal.fly
+    cursor_pos = {"line": 14, "character": 8}
+
+    # The implementation of 'Bird.fly'
+    def_range = {
+        "start": {"line": 21, "character": 8},
+        "end": {"line": 21, "character": 11},
+    }
+
+    doc = workspace.get_document(doc_uri)
+    assert [{"uri": doc_uri, "range": def_range}] == pylsp_implementations(
+        config, workspace, doc, cursor_pos
+    )
+
+
+def test_implementations_skipping_one_class(config, workspace, doc_uri) -> None:
+    # Over 'Animal.breathe'
+    cursor_pos = {"line": 4, "character": 8}
+
+    # The implementation of 'breathe', skipping intermediate classes
+    def_range = {
+        "start": {"line": 18, "character": 8},
+        "end": {"line": 18, "character": 15},
+    }
+
+    doc = workspace.get_document(doc_uri)
+    assert [{"uri": doc_uri, "range": def_range}] == pylsp_implementations(
+        config, workspace, doc, cursor_pos
+    )
+
+
+@pytest.mark.xfail(
+    reason="not implemented upstream (Rope)", strict=True, raises=BadIdentifierError
+)
+def test_property_implementations(config, workspace, doc_uri) -> None:
+    # Over 'Animal.size'
+    cursor_pos = {"line": 9, "character": 9}
+
+    # The property implementation 'Bird.size'
+    def_range = {
+        "start": {"line": 25, "character": 8},
+        "end": {"line": 25, "character": 12},
+    }
+
+    doc = workspace.get_document(doc_uri)
+    assert [{"uri": doc_uri, "range": def_range}] == pylsp_implementations(
+        config, workspace, doc, cursor_pos
+    )
+
+
+def test_implementations_not_a_method(config, workspace, doc_uri) -> None:
+    # Over 'print(...)' call => Rope error because not a method.
+    cursor_pos = {"line": 28, "character": 0}
+
+    doc = workspace.get_document(doc_uri)
+
+    # This exception is turned into an empty result set automatically in upper
+    # layers, so we just check that it is raised to document this behavior:
+    with pytest.raises(BadIdentifierError):
+        pylsp_implementations(config, workspace, doc, cursor_pos)