feat(encoding)!: EncodeExemplarValue does not consume ExemplarValueEncoder

see #135.

this adjusts the parameter of `encode()` so that it only mutably borrows
the encoder.

Signed-off-by: katelyn martin <me+cratelyn@katelyn.world>

Author: cratelyn

src/encoding.rs

@@ -691,29 +691,29 @@ impl<'a> CounterValueEncoder<'a> {
 /// An encodable exemplar value.
 pub trait EncodeExemplarValue {
     /// Encode the given instance in the OpenMetrics text encoding.
-    fn encode(&self, encoder: ExemplarValueEncoder) -> Result<(), std::fmt::Error>;
+    fn encode(&self, encoder: &mut ExemplarValueEncoder) -> Result<(), std::fmt::Error>;
 }
 
 impl EncodeExemplarValue for f64 {
-    fn encode(&self, mut encoder: ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
+    fn encode(&self, encoder: &mut ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
         encoder.encode(*self)
     }
 }
 
 impl EncodeExemplarValue for u64 {
-    fn encode(&self, mut encoder: ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
+    fn encode(&self, encoder: &mut ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
         encoder.encode(*self as f64)
     }
 }
 
 impl EncodeExemplarValue for f32 {
-    fn encode(&self, mut encoder: ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
+    fn encode(&self, encoder: &mut ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
         encoder.encode(*self as f64)
     }
 }
 
 impl EncodeExemplarValue for u32 {
-    fn encode(&self, mut encoder: ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
+    fn encode(&self, encoder: &mut ExemplarValueEncoder) -> Result<(), std::fmt::Error> {
         encoder.encode(*self as f64)
     }
 }

src/encoding/protobuf.rs

@@ -294,9 +294,8 @@ impl<S: EncodeLabelSet, V: EncodeExemplarValue> TryFrom<&Exemplar<S, V>>
 
     fn try_from(exemplar: &Exemplar<S, V>) -> Result<Self, Self::Error> {
         let mut value = f64::default();
-        exemplar
-            .value
-            .encode(ExemplarValueEncoder { value: &mut value }.into())?;
+        let mut encoder = ExemplarValueEncoder { value: &mut value }.into();
+        exemplar.value.encode(&mut encoder)?;
 
         let mut labels = vec![];
         let mut encoder = LabelSetEncoder {

src/encoding/text.rs

@@ -455,7 +455,7 @@ impl<'a> MetricEncoder<'a> {
             .encode(&mut LabelSetEncoder::new(self.writer).into())?;
         self.writer.write_str("} ")?;
         exemplar.value.encode(
-            ExemplarValueEncoder {
+            &mut ExemplarValueEncoder {
                 writer: self.writer,
             }
             .into(),