datafusion-sqlparse/examples/acme_parser.rs
2018-09-01 08:11:26 -06:00

80 lines
2 KiB
Rust

use std::str::Chars;
use std::iter::Peekable;
extern crate datafusion_sql;
use datafusion_sql::ansi::tokenizer::ANSISQLTokenizer;
use datafusion_sql::tokenizer::*;
use datafusion_sql::parser::*;
///
/// This example demonstrates building a custom ACME parser that extends the generic parser
/// by adding support for a factorial operator !!
///
#[derive(Debug,PartialEq)]
enum AcmeToken {
/// Factorial operator `!!`
Factorial
}
#[derive(Debug)]
enum AcmeOperator {
Factorial
}
#[derive(Debug)]
enum AcmeTokenizerError {
}
struct AcmeTokenizer {
generic: ANSISQLTokenizer
}
/// The ACME tokenizer looks for the factorial operator `!!` but delegates everything else
impl SQLTokenizer<AcmeToken> for AcmeTokenizer {
fn peek_token(&self, chars: &mut Peekable<Chars>) -> Result<Option<SQLToken<AcmeToken>>, TokenizerError<AcmeToken>> {
unimplemented!()
}
fn next_token(&self, chars: &mut Peekable<Chars>) -> Result<Option<SQLToken<AcmeToken>>, TokenizerError<AcmeToken>> {
match chars.peek() {
Some(&ch) => match ch {
'!' => {
chars.next(); // consume the first `!`
match chars.peek() {
Some(&ch) => match ch {
'!' => {
chars.next(); // consume the second `!`
Ok(Some(SQLToken::Custom(AcmeToken::Factorial)))
},
_ => Err(TokenizerError::UnexpectedChar(ch,Position::new(0,0)))
},
None => Ok(Some(SQLToken::Not))
}
},
_ => self.generic.next_token(chars)
}
_ => self.generic.next_token(chars)
}
}
}
fn main() {
let sql = "1 + !! 5 * 2";
let mut acme_tokenizer = AcmeTokenizer {
generic: ANSISQLTokenizer { }
};
let tokens = tokenize(&sql, &mut acme_tokenizer).unwrap();
println!("tokens = {:?}", tokens);
}