Assorted code simplification and doc improvements #131
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To use the new helper effectively, a few related changes were required: - Each of the parse_..._list functions (`parse_cte_list`, `parse_order_by_expr_list`, `parse_select_list`) was replaced with a version that parses a single element of the list (e.g. `parse_cte`), with their callers now using `self.parse_comma_separated(Parser::parse_<one_element>)?` - `parse_with_options` now parses the WITH keyword and a separate `parse_sql_option` function (named after the struct it produces) was added to parse a single k=v option. - `parse_list_of_ids` is gone, with the '.'-separated parsing moved to `parse_object_name`. Custom comma-separated parsing is still used in: - parse_transaction_modes (where the comma separator is optional) - parse_columns (allows optional trailing comma, before the closing ')')
It used to consume the `RParen` closing the encompassing `OVER (`, even when no window frame was parsed, which confused me a bit, even though I wrote it initially. After fixing that, I took the opportunity to reduce nesting and duplication a bit.
The note about WindowFrameBound::Following being only valid "in WindowFrame::end_bound" was both - confusing, as it was based on the ANSI SQL syntax the parser doesn't adhere to -- though it sounded like a promise about the AST one could expect to get from the parser - and incomplete, as the reality is that the bounds validation the SQL engine might want to perform is more complex. For example Postgres documentation says <https://www.postgresql.org/docs/11/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS>: > Restrictions are that frame_start cannot be UNBOUNDED FOLLOWING, > frame_end cannot be UNBOUNDED PRECEDING, and the frame_end choice > cannot appear earlier in the above list of frame_start and frame_end > options than the frame_start choice does — for example RANGE BETWEEN > CURRENT ROW AND offset PRECEDING is not allowed. But, for example, > ROWS BETWEEN 7 PRECEDING AND 8 PRECEDING is allowed, even though it > would never select any rows.
Pull Request Test Coverage Report for Build 413
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Including some follow-ups to #124 and #50 and
parse_comma_separated(03efcf6)