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use peg::parser; use serde::de::{Deserialize, Deserializer, Visitor}; use std::str; use std::time::Duration; #[derive(Debug, PartialEq)] pub enum Scalar { Size(u64), Time(Duration), } impl Scalar { pub fn is_size(&self) -> bool { match self { Scalar::Size(_) => true, _ => false, } } pub fn is_time(&self) -> bool { match self { Scalar::Time(_) => true, _ => false, } } } #[derive(Debug, PartialEq)] pub enum Token { Size, Age, } #[derive(Debug, PartialEq)] pub enum Operator { Greater, GreaterEqual, Lesser, LesserEqual, Equal, NotEqual, } impl Operator { pub fn compare<T>(&self, lhs: &T, rhs: &T) -> bool where T: PartialOrd<T>, { match self { Operator::Greater => lhs > rhs, Operator::GreaterEqual => lhs >= rhs, Operator::Equal => lhs == rhs, Operator::Lesser => lhs < rhs, Operator::LesserEqual => lhs <= rhs, Operator::NotEqual => lhs != rhs, } } } #[derive(Debug, PartialEq)] pub enum Predicate { Comparison { token: Token, operator: Operator, value: Scalar, }, } impl str::FromStr for Predicate { type Err = (); fn from_str(s: &str) -> Result<Self, Self::Err> { Ok(predicates::predicate(s).unwrap()) } } struct PredicateVisitor; impl<'de> Visitor<'de> for PredicateVisitor { type Value = Predicate; fn expecting(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result { write!(f, "AAAAAAAAAAAAAA") } fn visit_str<E>(self, s: &str) -> Result<Self::Value, E> where E: serde::de::Error, { Ok(s.parse::<Predicate>().unwrap()) } } impl<'de> Deserialize<'de> for Predicate { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>, { deserializer.deserialize_str(PredicateVisitor) } } parser! { grammar predicates() for str { rule token() -> Token = "age" { Token::Age } / "size" { Token::Size } rule number() -> u64 = n:$(['0'..='9']) { n.parse().unwrap() } rule scalar_size() -> Scalar = n:number() " "? q:scalar_size_quantif() { Scalar::Size(n * q) } rule scalar_size_quantif() -> u64 = "B" { 1 } / "KB" { 2u64.pow(10) } / "MB" { 2u64.pow(10 * 2) } / "GB" { 2u64.pow(10 * 3) } rule duration_quantif() -> u64 = ("seconds" / "second" / "secs" / "sec" / "s") { 1 } / ("minutes" / "minute" / "min" / "m") { 60 } / ("hours" / "hour" / "h") { 60 * 60 } / ("days" / "day" / "d") { 24 * 60 * 60 } / ("weeks" / "week" / "w") { 7 * 24 * 60 * 60 } rule scalar_age() -> Scalar = n:number() " " q:duration_quantif() { Scalar::Time(Duration::from_secs(n as u64 * q)) } rule scalar() -> Scalar = scalar_size() / scalar_age() rule operator() -> Operator = ">" { Operator::Greater } / "<" { Operator::Lesser } / ">=" { Operator::GreaterEqual } / "<=" { Operator::LesserEqual } / "==" { Operator::Equal } / "!=" { Operator::NotEqual } pub rule predicate() -> Predicate = t:token() " " operator() " " s:scalar() { Predicate::Comparison { token: t, operator: Operator::Greater, value: s } } } } #[test] fn can_parse_size_predicate() { assert_eq!( predicates::predicate("size > 1 MB").unwrap(), Predicate::Comparison { token: Token::Size, operator: Operator::Greater, value: Scalar::Size(1024 * 1024) }, ) } #[test] fn can_parse_time_predicates() { assert_eq!( predicates::predicate("age > 1 h").unwrap(), Predicate::Comparison { token: Token::Age, operator: Operator::Greater, value: Scalar::Time(Duration::from_secs(60 * 60)) }, ) }