Teach the Vim plugin to respect pyproject.toml (issue 414) (#1273)

Creates two separate functions:

1) abspath_pyproject_toml: find the absolute path to pyproject.toml
2) parse_pyproject_toml: finds black-specific toml config

Co-authored-by: Samuel Roeca <samuel.roeca@gmail.com>

black.py

@@ -213,6 +213,23 @@ def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> b
     return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
 
 
+def find_pyproject_toml(path_search_start: str) -> Optional[str]:
+    """Find the absolute filepath to a pyproject.toml if it exists"""
+    path_project_root = find_project_root(path_search_start)
+    path_pyproject_toml = path_project_root / "pyproject.toml"
+    return str(path_pyproject_toml) if path_pyproject_toml.is_file() else None
+
+
+def parse_pyproject_toml(path_config: str) -> Dict[str, Any]:
+    """Parse a pyproject toml file, pulling out relevant parts for Black
+
+    If parsing fails, will raise a toml.TomlDecodeError
+    """
+    pyproject_toml = toml.load(path_config)
+    config = pyproject_toml.get("tool", {}).get("black", {})
+    return {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
+
+
 def read_pyproject_toml(
     ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None]
 ) -> Optional[str]:
@@ -223,16 +240,12 @@ def read_pyproject_toml(
     """
     assert not isinstance(value, (int, bool)), "Invalid parameter type passed"
     if not value:
-        root = find_project_root(ctx.params.get("src", ()))
-        path = root / "pyproject.toml"
-        if path.is_file():
-            value = str(path)
-        else:
+        value = find_pyproject_toml(ctx.params.get("src", ()))
+        if value is None:
             return None
 
     try:
-        pyproject_toml = toml.load(value)
-        config = pyproject_toml.get("tool", {}).get("black", {})
+        config = parse_pyproject_toml(value)
     except (toml.TomlDecodeError, OSError) as e:
         raise click.FileError(
             filename=value, hint=f"Error reading configuration file: {e}"
@@ -243,9 +256,7 @@ def read_pyproject_toml(
 
     if ctx.default_map is None:
         ctx.default_map = {}
-    ctx.default_map.update(  # type: ignore  # bad types in .pyi
-        {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
-    )
+    ctx.default_map.update(config)  # type: ignore  # bad types in .pyi
     return value
 
 

plugin/black.vim

@@ -41,10 +41,34 @@ if !exists("g:black_skip_string_normalization")
 endif
 
 python3 << endpython3
+import collections
 import os
 import sys
 import vim
 
+
+class Flag(collections.namedtuple("FlagBase", "name, cast")):
+  @property
+  def var_name(self):
+    return self.name.replace("-", "_")
+
+  @property
+  def vim_rc_name(self):
+    name = self.var_name
+    if name == "line_length":
+      name = name.replace("_", "")
+    if name == "string_normalization":
+      name = "skip_" + name
+    return "g:black_" + name
+
+
+FLAGS = [
+  Flag(name="line_length", cast=int),
+  Flag(name="fast", cast=bool),
+  Flag(name="string_normalization", cast=bool),
+]
+
+
 def _get_python_binary(exec_prefix):
   try:
     default = vim.eval("g:pymode_python").strip()
@@ -108,15 +132,20 @@ if _initialize_black_env():
 
 def Black():
   start = time.time()
-  fast = bool(int(vim.eval("g:black_fast")))
+  configs = get_configs()
   mode = black.FileMode(
-    line_length=int(vim.eval("g:black_linelength")),
-    string_normalization=not bool(int(vim.eval("g:black_skip_string_normalization"))),
+    line_length=configs["line_length"],
+    string_normalization=configs["string_normalization"],
     is_pyi=vim.current.buffer.name.endswith('.pyi'),
   )
+
   buffer_str = '\n'.join(vim.current.buffer) + '\n'
   try:
-    new_buffer_str = black.format_file_contents(buffer_str, fast=fast, mode=mode)
+    new_buffer_str = black.format_file_contents(
+      buffer_str,
+      fast=configs["fast"],
+      mode=mode,
+    )
   except black.NothingChanged:
     print(f'Already well formatted, good job. (took {time.time() - start:.4f}s)')
   except Exception as exc:
@@ -138,6 +167,19 @@ def Black():
         window.cursor = (len(window.buffer), 0)
     print(f'Reformatted in {time.time() - start:.4f}s.')
 
+def get_configs():
+  path_pyproject_toml = black.find_pyproject_toml(vim.eval("fnamemodify(getcwd(), ':t')"))
+  if path_pyproject_toml:
+    toml_config = black.parse_pyproject_toml(path_pyproject_toml)
+  else:
+    toml_config = {}
+
+  return {
+    flag.var_name: toml_config.get(flag.name, flag.cast(vim.eval(flag.vim_rc_name)))
+    for flag in FLAGS
+  }
+
+
 def BlackUpgrade():
   _initialize_black_env(upgrade=True)