Function parse_is_null_expression

crates/gitql-parser/src/parser.rs:1399–1437

(
    context: &mut ParserContext,
    env: &mut Environment,
    tokens: &[Token],
    position: &mut usize,
)

}

pub(crate) fn parse_is_null_expression(
    context: &mut ParserContext,
    env: &mut Environment,
    tokens: &[Token],
    position: &mut usize,
) -> Result<Box<dyn Expr>, Box<Diagnostic>> {
    let expression = parse_in_expression(context, env, tokens, position)?;
    if is_current_token(tokens, position, TokenKind::Is) {
        let is_location = tokens[*position].location;

        // Consume `IS` keyword
        *position += 1;

        let has_not_keyword = if is_current_token(tokens, position, TokenKind::Not) {
            // Consume `NOT` keyword
            *position += 1;
            true
        } else {
            false
        };

        if is_current_token(tokens, position, TokenKind::Null) {
            // Consume `Null` keyword
            *position += 1;

            return Ok(Box::new(IsNullExpr {
                argument: expression,
                has_not: has_not_keyword,
            }));
        }

        return Err(
            Diagnostic::error("Expects `NULL` Keyword after `IS` or `IS NOT`")
                .with_location(is_location)
                .as_boxed(),
        );
    }
    Ok(expression)
}

fn parse_in_expression(
    context: &mut ParserContext,