Treat match and case as soft keywords in lambda assignments (#4623)

Author: charliermarsh

parser/src/parser.rs

@@ -604,6 +604,8 @@ match match:
     case 1: pass
     case 2:
         pass
+match = lambda query: query == event
+print(match(12))
 "#,
             "<test>",
         )

parser/src/snapshots/rustpython_parser__parser__tests__match_as_identifier.snap

@@ -1671,4 +1671,240 @@ expression: parse_ast
             ],
         },
     },
+    Located {
+        location: Location {
+            row: 21,
+            column: 0,
+        },
+        end_location: Some(
+            Location {
+                row: 21,
+                column: 36,
+            },
+        ),
+        custom: (),
+        node: Assign {
+            targets: [
+                Located {
+                    location: Location {
+                        row: 21,
+                        column: 0,
+                    },
+                    end_location: Some(
+                        Location {
+                            row: 21,
+                            column: 5,
+                        },
+                    ),
+                    custom: (),
+                    node: Name {
+                        id: "match",
+                        ctx: Store,
+                    },
+                },
+            ],
+            value: Located {
+                location: Location {
+                    row: 21,
+                    column: 8,
+                },
+                end_location: Some(
+                    Location {
+                        row: 21,
+                        column: 36,
+                    },
+                ),
+                custom: (),
+                node: Lambda {
+                    args: Arguments {
+                        posonlyargs: [],
+                        args: [
+                            Located {
+                                location: Location {
+                                    row: 21,
+                                    column: 15,
+                                },
+                                end_location: Some(
+                                    Location {
+                                        row: 21,
+                                        column: 20,
+                                    },
+                                ),
+                                custom: (),
+                                node: ArgData {
+                                    arg: "query",
+                                    annotation: None,
+                                    type_comment: None,
+                                },
+                            },
+                        ],
+                        vararg: None,
+                        kwonlyargs: [],
+                        kw_defaults: [],
+                        kwarg: None,
+                        defaults: [],
+                    },
+                    body: Located {
+                        location: Location {
+                            row: 21,
+                            column: 22,
+                        },
+                        end_location: Some(
+                            Location {
+                                row: 21,
+                                column: 36,
+                            },
+                        ),
+                        custom: (),
+                        node: Compare {
+                            left: Located {
+                                location: Location {
+                                    row: 21,
+                                    column: 22,
+                                },
+                                end_location: Some(
+                                    Location {
+                                        row: 21,
+                                        column: 27,
+                                    },
+                                ),
+                                custom: (),
+                                node: Name {
+                                    id: "query",
+                                    ctx: Load,
+                                },
+                            },
+                            ops: [
+                                Eq,
+                            ],
+                            comparators: [
+                                Located {
+                                    location: Location {
+                                        row: 21,
+                                        column: 31,
+                                    },
+                                    end_location: Some(
+                                        Location {
+                                            row: 21,
+                                            column: 36,
+                                        },
+                                    ),
+                                    custom: (),
+                                    node: Name {
+                                        id: "event",
+                                        ctx: Load,
+                                    },
+                                },
+                            ],
+                        },
+                    },
+                },
+            },
+            type_comment: None,
+        },
+    },
+    Located {
+        location: Location {
+            row: 22,
+            column: 0,
+        },
+        end_location: Some(
+            Location {
+                row: 22,
+                column: 16,
+            },
+        ),
+        custom: (),
+        node: Expr {
+            value: Located {
+                location: Location {
+                    row: 22,
+                    column: 0,
+                },
+                end_location: Some(
+                    Location {
+                        row: 22,
+                        column: 16,
+                    },
+                ),
+                custom: (),
+                node: Call {
+                    func: Located {
+                        location: Location {
+                            row: 22,
+                            column: 0,
+                        },
+                        end_location: Some(
+                            Location {
+                                row: 22,
+                                column: 5,
+                            },
+                        ),
+                        custom: (),
+                        node: Name {
+                            id: "print",
+                            ctx: Load,
+                        },
+                    },
+                    args: [
+                        Located {
+                            location: Location {
+                                row: 22,
+                                column: 6,
+                            },
+                            end_location: Some(
+                                Location {
+                                    row: 22,
+                                    column: 15,
+                                },
+                            ),
+                            custom: (),
+                            node: Call {
+                                func: Located {
+                                    location: Location {
+                                        row: 22,
+                                        column: 6,
+                                    },
+                                    end_location: Some(
+                                        Location {
+                                            row: 22,
+                                            column: 11,
+                                        },
+                                    ),
+                                    custom: (),
+                                    node: Name {
+                                        id: "match",
+                                        ctx: Load,
+                                    },
+                                },
+                                args: [
+                                    Located {
+                                        location: Location {
+                                            row: 22,
+                                            column: 12,
+                                        },
+                                        end_location: Some(
+                                            Location {
+                                                row: 22,
+                                                column: 14,
+                                            },
+                                        ),
+                                        custom: (),
+                                        node: Constant {
+                                            value: Int(
+                                                12,
+                                            ),
+                                            kind: None,
+                                        },
+                                    },
+                                ],
+                                keywords: [],
+                            },
+                        },
+                    ],
+                    keywords: [],
+                },
+            },
+        },
+    },
 ]

parser/src/soft_keywords.rs

@@ -59,11 +59,15 @@ where
                     let mut nesting = 0;
                     let mut first = true;
                     let mut seen_colon = false;
+                    let mut seen_lambda = false;
                     while let Some(Ok((_, tok, _))) = self.underlying.peek() {
                         match tok {
                             Tok::Newline => break,
+                            Tok::Lambda if nesting == 0 => seen_lambda = true,
                             Tok::Colon if nesting == 0 => {
-                                if !first {
+                                if seen_lambda {
+                                    seen_lambda = false;
+                                } else if !first {
                                     seen_colon = true;
                                 }
                             }