niebayes opened a new issue, #1593:
URL: https://github.com/apache/datafusion-sqlparser-rs/issues/1593
We have designed an SQL parser using sqlparser's `Parser`, and we wish to
implement two helper methods for consuming tokens—similar to
`Parser::consume_token` and `Parser::consume_tokens`—but with the ability to
accept string inputs and perform case-insensitive matching.
However, since the Parser does not provide a method to mutate the
`Parser::index`, we are unable to correctly implement our own `consume_tokens`
because we need to revert the parser state if consumption fails mid-way.
We propose adding and exposing a new method in sqlparser's `Parser`, such as
`set_index` or `index_mut`, to allow users to mutate the index.
The expected implementation of our `consume_token` and `consume_tokens`:
``` rust
/// Consumes the next token if it matches the expected token, otherwise
return false.
///
/// Note, the matching is not case sensitive.
fn consume_token(&mut self, expected: &str) -> bool {
if self.parser.peek_token().to_string().to_uppercase() ==
*expected.to_uppercase() {
self.parser.next_token();
true
} else {
false
}
}
/// If the current and subsequent tokens exactly match the `tokens`
sequence, consume them and returns true.
/// Otherwise, no tokens are consumed and returns false
///
/// Note, the matching is not case sensitive.
fn consume_tokens(&mut self, tokens: &[&str]) -> bool {
let index = self.parser.index();
for token in tokens {
if !self.consume_token(*token) {
// Or: `*self.parser.index_mut() = index;`
self.parser.set_index(index);
return false;
}
}
true
}
```
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