Method unparse_expr

crates/ruff_python_parser/src/parser/statement.rs:1128–1171

We are permissive than the original implementation because we would allow whitespace between the expression and the suffix while the IPython implementation doesn't allow it. For example, `foo ?` would be valid in our case but invalid for IPython.

(parser: &mut Parser, expr: &Expr, buffer: &mut String)

        // between the expression and the suffix while the IPython implementation doesn't allow it.
        // For example, `foo ?` would be valid in our case but invalid for IPython.
        fn unparse_expr(parser: &mut Parser, expr: &Expr, buffer: &mut String) {
            match expr {
                Expr::Name(ast::ExprName { id, .. }) => {
                    buffer.push_str(id.as_str());
                }
                Expr::Subscript(ast::ExprSubscript { value, slice, .. }) => {
                    unparse_expr(parser, value, buffer);
                    buffer.push('[');

                    if let Expr::NumberLiteral(ast::ExprNumberLiteral {
                        value: ast::Number::Int(integer),
                        ..
                    }) = &**slice
                    {
                        let _ = write!(buffer, "{integer}");
                    } else {
                        parser.add_error(
                            ParseErrorType::OtherError(
                                "Only integer literals are allowed in subscript expressions in help end escape command"
                                    .to_string()
                            ),
                            slice.range(),
                        );
                        buffer.push_str(parser.src_text(slice.range()));
                    }

                    buffer.push(']');
                }
                Expr::Attribute(ast::ExprAttribute { value, attr, .. }) => {
                    unparse_expr(parser, value, buffer);
                    buffer.push('.');
                    buffer.push_str(attr.as_str());
                }
                _ => {
                    parser.add_error(
                        ParseErrorType::OtherError(
                            "Expected name, subscript or attribute expression in help end escape command"
                                .to_string()
                        ),
                        expr,
                    );
                }
            }
        }

        let start = self.node_start();
        self.bump(TokenKind::Question);