Parses a slice expression. See:
(&mut self)
| 1082 | /// |
| 1083 | /// See: <https://docs.python.org/3/reference/expressions.html#slicings> |
| 1084 | fn parse_slice(&mut self) -> Expr { |
| 1085 | const UPPER_END_SET: TokenSet = |
| 1086 | TokenSet::new([TokenKind::Comma, TokenKind::Colon, TokenKind::Rsqb]) |
| 1087 | .union(NEWLINE_EOF_SET); |
| 1088 | const STEP_END_SET: TokenSet = |
| 1089 | TokenSet::new([TokenKind::Comma, TokenKind::Rsqb]).union(NEWLINE_EOF_SET); |
| 1090 | |
| 1091 | // test_err named_expr_slice |
| 1092 | // # even after 3.9, an unparenthesized named expression is not allowed in a slice |
| 1093 | // lst[x:=1:-1] |
| 1094 | // lst[1:x:=1] |
| 1095 | // lst[1:3:x:=1] |
| 1096 | |
| 1097 | // test_err named_expr_slice_parse_error |
| 1098 | // # parse_options: {"target-version": "3.8"} |
| 1099 | // # before 3.9, only emit the parse error, not the unsupported syntax error |
| 1100 | // lst[x:=1:-1] |
| 1101 | |
| 1102 | let start = self.node_start(); |
| 1103 | |
| 1104 | let lower = if self.at_expr() { |
| 1105 | let lower = |
| 1106 | self.parse_named_expression_or_higher(ExpressionContext::starred_conditional()); |
| 1107 | |
| 1108 | // This means we're in a subscript. |
| 1109 | if self.at_ts(NEWLINE_EOF_SET.union([TokenKind::Rsqb, TokenKind::Comma].into())) { |
| 1110 | // test_ok parenthesized_named_expr_index_py38 |
| 1111 | // # parse_options: {"target-version": "3.8"} |
| 1112 | // lst[(x:=1)] |
| 1113 | |
| 1114 | // test_ok unparenthesized_named_expr_index_py39 |
| 1115 | // # parse_options: {"target-version": "3.9"} |
| 1116 | // lst[x:=1] |
| 1117 | |
| 1118 | // test_err unparenthesized_named_expr_index_py38 |
| 1119 | // # parse_options: {"target-version": "3.8"} |
| 1120 | // lst[x:=1] |
| 1121 | if lower.is_unparenthesized_named_expr() { |
| 1122 | self.add_unsupported_syntax_error( |
| 1123 | UnsupportedSyntaxErrorKind::UnparenthesizedNamedExpr( |
| 1124 | UnparenthesizedNamedExprKind::SequenceIndex, |
| 1125 | ), |
| 1126 | lower.range(), |
| 1127 | ); |
| 1128 | } |
| 1129 | return lower.expr; |
| 1130 | } |
| 1131 | |
| 1132 | // Now we know we're in a slice. |
| 1133 | if !lower.is_parenthesized { |
| 1134 | match lower.expr { |
| 1135 | Expr::Starred(_) => { |
| 1136 | self.add_error(ParseErrorType::InvalidStarredExpressionUsage, &lower); |
| 1137 | } |
| 1138 | Expr::Named(_) => { |
| 1139 | self.add_error(ParseErrorType::UnparenthesizedNamedExpression, &lower); |
| 1140 | } |
| 1141 | _ => {} |
no test coverage detected