Add regex test to expression language (fixes #162)

src/value/attr_value/attr_value_expr.rs

@@ -17,6 +17,7 @@ pub enum BinOp {
     GT,
     LT,
     Elvis,
+    RegexMatch,
 }
 
 impl std::fmt::Display for BinOp {
@@ -34,6 +35,7 @@ impl std::fmt::Display for BinOp {
             BinOp::GT => write!(f, ">"),
             BinOp::LT => write!(f, "<"),
             BinOp::Elvis => write!(f, "?:"),
+            BinOp::RegexMatch => write!(f, "=~"),
         }
     }
 }
@@ -156,6 +158,10 @@ impl AttrValExpr {
                     BinOp::GT => PrimVal::from(a.as_f64()? > b.as_f64()?),
                     BinOp::LT => PrimVal::from(a.as_f64()? < b.as_f64()?),
                     BinOp::Elvis => PrimVal::from(if a.0.is_empty() { b } else { a }),
+                    BinOp::RegexMatch => {
+                        let regex = regex::Regex::new(&b.as_string()?)?;
+                        PrimVal::from(regex.is_match(&a.as_string()?))
+                    }
                 })
             }
             AttrValExpr::UnaryOp(op, a) => {

src/value/attr_value/parser.rs

@@ -111,6 +111,7 @@ fn parse_term1(i: &str) -> IResult<&str, AttrValExpr, VerboseError<&str>> {
         map(preceded(tag("!="), parse_term2), |x| (BinOp::NotEquals, x)),
         map(preceded(tag(">"), parse_term2), |x| (BinOp::GT, x)),
         map(preceded(tag("<"), parse_term2), |x| (BinOp::LT, x)),
+        map(preceded(tag("=~"), parse_term2), |x| (BinOp::RegexMatch, x)),
     )))(i)?;
 
     let exprs = remainder.into_iter().fold(initial, |acc, (op, expr)| AttrValExpr::BinOp(box acc, op, box expr));