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// Copyright 2018 sqlparser-rs contributors. All rights reserved.
// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// This file is derived from the sqlparser-rs project, available at
// https://github.com/andygrove/sqlparser-rs. It was incorporated
// directly into Materialize on December 21, 2019.
//
// Licensed 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 in the LICENSE file at the
// root of this repository, or online 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.
use std::fmt;
use std::str::FromStr;
use uncased::UncasedStr;
// The `Keyword` type and the keyword constants are automatically generated from
// the list in keywords.txt by the crate's build script.
//
// We go to the trouble of code generation primarily to create a "perfect hash
// function" at compile time via the phf crate, which enables very fast,
// case-insensitive keyword parsing. From there it's easy to generate a few
// more convenience functions and accessors.
//
// If the only keywords were `Insert` and `Select`, we'd generate the following
// code:
//
// pub enum Keyword {
// Insert,
// Select,
// }
//
// pub const INSERT: Keyword = Keyword::Insert;
// pub const SELECT: Keyword = Keyword::Select;
//
// impl Keyword {
// pub fn as_str(&self) -> &'static str {
// match self {
// Keyword::Insert => "INSERT",
// Keyword::Select => "SELECT",
// }
// }
// }
//
// static KEYWORDS: phf::Map<&'static UncasedStr, Keyword> = { /* ... */ };
//
include!(concat!(env!("OUT_DIR"), "/keywords.rs"));
impl Keyword {
/// Reports whether this keyword requires quoting when used as an
/// identifier in any context.
///
/// The only exception to the rule is when the keyword follows `AS` in a
/// column or table alias.
pub fn is_reserved(self) -> bool {
matches!(
self,
// Keywords that can appear at the top-level of a SELECT statement.
WITH | SELECT | FROM | WHERE | GROUP | HAVING | ORDER | LIMIT | OFFSET | FETCH | OPTIONS | RETURNING |
// Set operations.
UNION | EXCEPT | INTERSECT
)
}
/// Reports whether this keyword requires quoting when used as a table
/// alias.
///
/// Note that this rule is only applies when the table alias is "bare";
/// i.e., when the table alias is not preceded by `AS`.
///
/// Ensures that `FROM <table_name> <table_alias>` can be parsed
/// unambiguously.
pub fn is_reserved_in_table_alias(self) -> bool {
matches!(
self,
// These keywords are ambiguous when used as a table alias, as they
// conflict with the syntax for joins.
ON | JOIN | INNER | CROSS | FULL | LEFT | RIGHT | NATURAL | USING |
// Needed for UPDATE.
SET |
// `OUTER` is not strictly ambiguous, but it prevents `a OUTER JOIN
// b` from parsing as `a AS outer JOIN b`, instead producing a nice
// syntax error.
OUTER
) || self.is_reserved()
}
/// Reports whether this keyword requires quoting when used as a column
/// alias.
///
///
/// Note that this rule is only applies when the column alias is "bare";
/// i.e., when the column alias is not preceded by `AS`.
///
/// Ensures that `SELECT <column_name> <column_alias>` can be parsed
/// unambiguously.
pub fn is_reserved_in_column_alias(self) -> bool {
matches!(
self,
// These timelike keywords conflict with interval timeframe
// suffixes. They are not strictly ambiguous, but marking them
// reserved prevents e.g. `SELECT pg_catalog.interval '1' year` from
// parsing as `SELECT pg_catalog.interval '1' AS YEAR`.
YEAR | MONTH | DAY | HOUR | MINUTE | SECOND
) || self.is_reserved()
}
/// Reports whether a keyword is considered reserved in any context:
/// either in table aliases, column aliases, or in all contexts.
pub fn is_sometimes_reserved(self) -> bool {
self.is_reserved()
|| self.is_reserved_in_table_alias()
|| self.is_reserved_in_column_alias()
}
}
impl FromStr for Keyword {
type Err = ();
fn from_str(s: &str) -> Result<Keyword, ()> {
match KEYWORDS.get(UncasedStr::new(s)) {
Some(kw) => Ok(*kw),
None => Err(()),
}
}
}
impl fmt::Display for Keyword {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(self.as_str())
}
}