defmt-decoder: impl TryFrom<Option<String>> for Encoding

decoder/src/elf2table/mod.rs

@@ -98,14 +98,7 @@ pub fn parse_impl(elf: &[u8], check_version: bool) -> Result<Option<Table>, anyh
         self::check_version(&version).map_err(anyhow::Error::msg)?;
     }
 
-    let encoding = match encoding {
-        Some(e) => match &e[..] {
-            "raw" => Encoding::Raw,
-            "rzcobs" => Encoding::Rzcobs,
-            _ => bail!("Unknown defmt encoding '{}' specified. This is a bug.", e),
-        },
-        None => bail!("No defmt encoding specified. This is a bug."),
-    };
+    let encoding = encoding.try_into()?;
 
     // second pass to demangle symbols
     let mut map = BTreeMap::new();

decoder/src/lib.rs

@@ -20,6 +20,7 @@ mod stream;
 
 use std::{
     collections::{BTreeMap, HashMap},
+    convert::TryFrom,
     error::Error,
     fmt, io,
 };
@@ -121,6 +122,21 @@ enum Encoding {
     Rzcobs,
 }
 
+impl TryFrom<Option<String>> for Encoding {
+    type Error = anyhow::Error;
+
+    fn try_from(value: Option<String>) -> Result<Self, Self::Error> {
+        match value {
+            Some(e) => match &*e {
+                "raw" => Ok(Encoding::Raw),
+                "rzcobs" => Ok(Encoding::Rzcobs),
+                _ => anyhow::bail!("Unknown defmt encoding '{}' specified. This is a bug.", e),
+            },
+            None => anyhow::bail!("No defmt encoding specified. This is a bug."),
+        }
+    }
+}
+
 /// Internal table that holds log levels and maps format strings to indices
 #[derive(Debug, PartialEq)]
 pub struct Table {