feat: serialize AST to json (#94)

* feat: serialize AST to json

* chore: make header check happy again

* feat: implement serialize for vectorSelector and call

* test: improve converage

* feat: implement serialization for more

* test: cover more expression

* fix: subquery

* refactor: address review comments

Cargo.toml

@@ -31,6 +31,12 @@ lazy_static = "1.4.0"
 lrlex = "0.13.5"
 lrpar = "0.13.5"
 regex = "1"
+serde = { version = "1", optional = true }
+serde_json = { version = "1", optional = true }
+
+[features]
+default = []
+ser = ["serde", "serde_json"]
 
 [build-dependencies]
 cfgrammar = "0.13.5"

src/label/matcher.rs

@@ -24,6 +24,7 @@ use crate::util::join_vector;
 pub enum MatchOp {
     Equal,
     NotEqual,
+    // TODO: do we need regex here?
     Re(Regex),
     NotRe(Regex),
 }
@@ -64,9 +65,21 @@ impl Hash for MatchOp {
     }
 }
 
+#[cfg(feature = "ser")]
+impl serde::Serialize for MatchOp {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        serializer.serialize_str(&self.to_string())
+    }
+}
+
 // Matcher models the matching of a label.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "ser", derive(serde::Serialize))]
 pub struct Matcher {
+    #[cfg_attr(feature = "ser", serde(rename = "type"))]
     pub op: MatchOp,
     pub name: String,
     pub value: String,
@@ -183,8 +196,10 @@ fn try_escape_for_repeat_re(re: &str) -> String {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ser", derive(serde::Serialize))]
 pub struct Matchers {
     pub matchers: Vec<Matcher>,
+    #[cfg_attr(feature = "ser", serde(skip_serializing_if = "<[_]>::is_empty"))]
     pub or_matchers: Vec<Vec<Matcher>>,
 }
 

src/label/mod.rs

@@ -73,6 +73,23 @@ impl fmt::Display for Labels {
     }
 }
 
+#[cfg(feature = "ser")]
+impl serde::Serialize for Labels {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        use serde::ser::SerializeSeq;
+        let mut seq = serializer.serialize_seq(Some(self.labels.len()))?;
+
+        for l in &self.labels {
+            seq.serialize_element(&l)?;
+        }
+
+        seq.end()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;