iffyio commented on code in PR #2185:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/2185#discussion_r2759852359
##########
src/parser/mod.rs:
##########
@@ -4521,16 +4521,29 @@ impl<'a> Parser<'a> {
/// consumed and returns false
#[must_use]
pub fn parse_keywords(&mut self, keywords: &[Keyword]) -> bool {
- let index = self.index;
- for &keyword in keywords {
- if !self.parse_keyword(keyword) {
- // println!("parse_keywords aborting .. did not find {:?}",
keyword);
- // reset index and return immediately
- self.index = index;
- return false;
+ self.parse_keywords_(keywords).is_some()
+ }
+
+ /// Just like [Self::parse_keywords], but - upon success - returns the
+ /// token index of the first keyword.
+ #[must_use]
+ fn parse_keywords_(&mut self, keywords: &[Keyword]) -> Option<usize> {
Review Comment:
```suggestion
fn parse_keywords_indexed(&mut self, keywords: &[Keyword]) ->
Option<usize> {
```
##########
src/parser/mod.rs:
##########
@@ -14184,27 +14188,27 @@ impl<'a> Parser<'a> {
}
/// Parse a `CONNECT BY` clause (Oracle-style hierarchical query support).
- pub fn parse_connect_by(&mut self) -> Result<ConnectBy, ParserError> {
- let (condition, relationships) = if
self.parse_keywords(&[Keyword::CONNECT, Keyword::BY]) {
- let relationships = self.with_state(ParserState::ConnectBy,
|parser| {
- parser.parse_comma_separated(Parser::parse_expr)
- })?;
- self.expect_keywords(&[Keyword::START, Keyword::WITH])?;
- let condition = self.parse_expr()?;
- (condition, relationships)
- } else {
- self.expect_keywords(&[Keyword::START, Keyword::WITH])?;
- let condition = self.parse_expr()?;
- self.expect_keywords(&[Keyword::CONNECT, Keyword::BY])?;
- let relationships = self.with_state(ParserState::ConnectBy,
|parser| {
- parser.parse_comma_separated(Parser::parse_expr)
- })?;
- (condition, relationships)
- };
- Ok(ConnectBy {
- condition,
- relationships,
- })
+ pub fn maybe_parse_connect_by(&mut self) -> Result<Vec<ConnectByKind>,
ParserError> {
+ let mut clauses = Vec::with_capacity(2);
+ loop {
+ if let Some(idx) = self.parse_keywords_(&[Keyword::START,
Keyword::WITH]) {
Review Comment:
I see, that makes sense!
##########
src/parser/mod.rs:
##########
@@ -4521,16 +4521,29 @@ impl<'a> Parser<'a> {
/// consumed and returns false
#[must_use]
pub fn parse_keywords(&mut self, keywords: &[Keyword]) -> bool {
- let index = self.index;
- for &keyword in keywords {
- if !self.parse_keyword(keyword) {
- // println!("parse_keywords aborting .. did not find {:?}",
keyword);
- // reset index and return immediately
- self.index = index;
- return false;
+ self.parse_keywords_(keywords).is_some()
+ }
+
+ /// Just like [Self::parse_keywords], but - upon success - returns the
+ /// token index of the first keyword.
+ #[must_use]
+ fn parse_keywords_(&mut self, keywords: &[Keyword]) -> Option<usize> {
+ let start_index = self.index;
+ let mut first_keyword_index = None;
+ match keywords {
+ [keyword, keywords @ ..] if self.parse_keyword(*keyword) => {
+ first_keyword_index = Some(self.index.saturating_sub(1));
+ for &keyword in keywords {
+ if !self.parse_keyword(keyword) {
+ self.index = start_index;
+ first_keyword_index = None;
+ break;
+ }
+ }
}
+ _ => {}
}
- true
+ first_keyword_index
Review Comment:
can we rewrite to something like this to follow the previous pattern? (with
the slice matching and calling parse_keyword multiple times, makes the new
version slightly harder to follow)
```rust
let start_index = self.index;
let mut first_keyword_index = None;
for keyword in keywords {
if !self.parse_keyword(*keyword) {
self.index = start_index;
return None
}
if first_keyword_index.is_none() {
first_keyword_index = Some(self.index.saturating_sub(1));
}
}
first_keyword_index
```
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