rusackas commented on code in PR #41803: URL: https://github.com/apache/superset/pull/41803#discussion_r3624686351
########## superset/sql/dialects/trino.py: ########## @@ -0,0 +1,338 @@ +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you under the Apache License, Version 2.0 (the +# "License"); you may not use this file except in compliance +# with the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, +# software distributed under the License is distributed on an +# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +# KIND, either express or implied. See the License for the +# specific language governing permissions and limitations +# under the License. + +from __future__ import annotations + +import typing as t + +from sqlglot import exp +from sqlglot.dialects.trino import Trino as SqlglotTrino +from sqlglot.tokens import Token, TokenType + +# Keywords that open a block terminated by ``END`` in Trino SQL routines +# (https://trino.io/docs/current/udf/sql.html). ``CASE`` is included because +# both the ``CASE`` statement and the ``CASE`` expression are terminated by +# ``END``, so counting them keeps the depth balanced either way. +BLOCK_OPENERS: set[str] = {"BEGIN", "CASE", "IF", "LOOP", "REPEAT", "WHILE"} + +# Keywords that are also scalar functions in Trino (e.g. ``IF(a, b, c)`` and +# ``REPEAT('a', 3)``). When immediately followed by ``(`` they are function +# calls, not block openers, unless the token stream shows otherwise (see +# ``_is_paren_condition_block``). +AMBIGUOUS_OPENERS: set[str] = {"IF", "REPEAT"} + +BODY_KEYWORDS: tuple[str, str] = ("RETURN", "BEGIN") + + +def _is_paren_condition_block(tokens: t.Sequence[Token], paren_index: int) -> bool: + """ + Determine whether the parenthesized group starting at ``tokens[paren_index]`` + (an ``L_PAREN``) is a procedural block condition, e.g. ``IF (a > b) THEN``, + as opposed to a scalar function call argument list, e.g. ``IF(a, b, c)``. + + Only ``IF`` has this ambiguity: a parenthesized condition is followed by + ``THEN``, while a scalar function call's closing paren never is. + """ + depth = 0 + for i in range(paren_index, len(tokens)): + token_type = tokens[i].token_type + if token_type == TokenType.L_PAREN: + depth += 1 + elif token_type == TokenType.R_PAREN: + depth -= 1 + if depth == 0: + next_token = tokens[i + 1] if i + 1 < len(tokens) else None + return ( + next_token is not None and next_token.token_type == TokenType.THEN + ) + return False Review Comment: I don't think this holds up. `_is_paren_condition_block` returns as soon as it hits the matching closing paren, so each call only scans that one condition's span, not the rest of the stream. Profiled a routine with 3000 sequential ambiguous `IF(...)` blocks and the helper accounted for about 2% of parse time, scaling linearly. The full-stream scan only happens on unmatched parens, which isn't this repro. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
