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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:
/// 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
}Metadata
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