Add a serde feature for (de)serializing Selectors (#227)

Add a serde feature for serializing Selectors using CSS syntax

Author: jakubslaby09

Cargo.lock

@@ -19,6 +19,7 @@ html5ever = "0.29.0"
 indexmap = { version = "2.7.1", optional = true }
 precomputed-hash = "0.1.1"
 selectors = "0.26.0"
+serde = { version = "1.0.215", optional = true }
 tendril = "0.4.3"
 
 [dependencies.getopts]
@@ -31,6 +32,7 @@ deterministic = ["indexmap"]
 main = ["getopts"]
 atomic = []
 errors = []
+serde = ["dep:serde"]
 
 [[bin]]
 name = "scraper"

scraper/Cargo.toml

@@ -11,6 +11,9 @@ use selectors::{
     parser::{self, ParseRelative, SelectorList, SelectorParseErrorKind},
 };
 
+#[cfg(feature = "serde")]
+use serde::{de::Visitor, Deserialize, Serialize};
+
 use crate::error::SelectorErrorKind;
 use crate::ElementRef;
 
@@ -80,6 +83,36 @@ impl ToCss for Selector {
     }
 }
 
+#[cfg(feature = "serde")]
+impl Serialize for Selector {
+    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        serializer.serialize_str(&self.to_css_string())
+    }
+}
+
+#[cfg(feature = "serde")]
+impl<'de> Deserialize<'de> for Selector {
+    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        deserializer.deserialize_str(SelectorVisitor)
+    }
+}
+
+#[cfg(feature = "serde")]
+struct SelectorVisitor;
+
+#[cfg(feature = "serde")]
+impl Visitor<'_> for SelectorVisitor {
+    type Value = Selector;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        write!(formatter, "a css selector string")
+    }
+
+    fn visit_str<E: serde::de::Error>(self, v: &str) -> Result<Self::Value, E> {
+        Selector::parse(v).map_err(serde::de::Error::custom)
+    }
+}
+
 /// An implementation of `Parser` for `selectors`
 #[derive(Clone, Copy, Debug)]
 pub struct Parser;