Add formatting of type alias statements

crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/type_alias.py

@@ -1,4 +1,4 @@
-# Copied from https://github.com/RustPython/Parser/blob/704eb40108239a8faf9bd1d4217e8dad0ac7edb3/parser/src/parser.rs#L901-L936
+# basic usage
 
 type X = int
 type X = int | str
@@ -10,6 +10,17 @@
 type X[T: int, *Ts, **P] = (T, Ts, P)
 type X[T: (int, str), *Ts, **P] = (T, Ts, P)
 
+# long name
+type Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx = int
+type Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx[A] = int
+type Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx[Aaaaaaaaaaaaaaaaaaaaaaaaaaaa] = int
+type Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx[Aaaaaaaaaaaaaaaaaaaaaaaaaaaa, Bbbbbbbbbbbbb] = int
+type Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx = Tttttttttttttttttttttttttttttttttttttttttttttttttttttttt
+
+# long value
+type X = Ttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt
+type X = Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb | Ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
+
 # soft keyword as alias name
 type type = int
 type match = int
@@ -36,3 +47,44 @@
     [T] = T
 type X[T] \
     = T
+
+# type leading comment
+type X = ( # trailing open paren comment
+    # value leading comment
+    int # value trailing comment
+    # leading close paren comment
+) # type trailing comment
+
+
+# type leading comment
+type X = (
+    # value leading comment
+    int # value trailing comment
+
+    # leading close paren comment
+)
+
+# type parameters
+type type_params_single_line[aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbb, ccccccccccccccccc] = int
+type type_params_arguments_on_their_own_line[aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbb, ccccccccccc, ddddddddddddd, eeeeeee] = int
+type type_params_argument_per_line[aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbb, ccccccccccccccccc, ddddddddddddd, eeeeeeeeeeeeeeee, ffffffffffff] = int
+type type_params_trailing_comma[a, b,] = int
+type type_params_comments[ # trailing open bracket comment
+    # leading comment
+    A,
+
+    # in between comment
+
+    B,
+    # another leading comment
+    C,
+    D, # trailing comment
+    # leading close bracket comment
+] = int  # trailing value comment
+type type_params_all_kinds[type_var, *type_var_tuple, **param_spec] = int
+
+# type variable bounds
+type bounds_single_line[T: (aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbb, ccccccccccccccccc)] = T
+type bounds_arguments_on_their_own_line[T: (aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbb, ccccccccccc, ddddddddddddd, eeeeeee)] = T
+type bounds_argument_per_line[T: (aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbb, ccccccccccccccccc, ddddddddddddd, eeeeeeeeeeeeeeee, ffffffffffff)] = T
+type bounds_trailing_comma[T: (a, b,)] = T

crates/ruff_python_formatter/src/lib.rs

@@ -188,6 +188,7 @@ impl Format<PyFormatContext<'_>> for NotYetImplemented {
 pub(crate) struct NotYetImplementedCustomText(&'static str);
 
 /// Formats a placeholder for nodes that have not yet been implemented
+#[allow(dead_code)]
 pub(crate) const fn not_yet_implemented_custom_text(
     text: &'static str,
 ) -> NotYetImplementedCustomText {

crates/ruff_python_formatter/src/statement/stmt_type_alias.rs

@@ -1,17 +1,37 @@
-use crate::{not_yet_implemented_custom_text, FormatNodeRule, PyFormatter};
+use crate::expression::maybe_parenthesize_expression;
+use crate::expression::parentheses::Parenthesize;
+use crate::AsFormat;
+use crate::{FormatNodeRule, PyFormatter};
+use ruff_formatter::prelude::{space, text};
 use ruff_formatter::{write, Buffer, FormatResult};
 use ruff_python_ast::StmtTypeAlias;
 
 #[derive(Default)]
 pub struct FormatStmtTypeAlias;
 
 impl FormatNodeRule<StmtTypeAlias> for FormatStmtTypeAlias {
-    fn fmt_fields(&self, _item: &StmtTypeAlias, f: &mut PyFormatter) -> FormatResult<()> {
+    fn fmt_fields(&self, item: &StmtTypeAlias, f: &mut PyFormatter) -> FormatResult<()> {
+        let StmtTypeAlias {
+            name,
+            type_params,
+            value,
+            range: _,
+        } = item;
+
+        write!(f, [text("type"), space(), name.as_ref().format()])?;
+
+        if let Some(type_params) = type_params {
+            write!(f, [type_params.format()])?;
+        }
+
         write!(
             f,
-            [not_yet_implemented_custom_text(
-                "type NOT_YET_IMPLEMENTED_type_alias = int"
-            )]
+            [
+                space(),
+                text("="),
+                space(),
+                maybe_parenthesize_expression(value, item, Parenthesize::IfBreaks)
+            ]
         )
     }
 }