fix(error)!: Remove nom from ConfigError

Fixes #516

Author: epage

src/error.rs

@@ -46,7 +46,7 @@ pub enum ConfigError {
     NotFound(String),
 
     /// Configuration path could not be parsed.
-    PathParse(nom::error::ErrorKind),
+    PathParse { cause: Box<dyn Error + Send + Sync> },
 
     /// Configuration could not be parsed from file.
     FileParse {
@@ -187,7 +187,7 @@ impl fmt::Display for ConfigError {
         match *self {
             ConfigError::Frozen => write!(f, "configuration is frozen"),
 
-            ConfigError::PathParse(ref kind) => write!(f, "{}", kind.description()),
+            ConfigError::PathParse { ref cause } => write!(f, "{cause}"),
 
             ConfigError::Message(ref s) => write!(f, "{s}"),
 

src/path/mod.rs

@@ -17,10 +17,29 @@ impl FromStr for Expression {
     type Err = ConfigError;
 
     fn from_str(s: &str) -> Result<Self> {
-        parser::from_str(s).map_err(ConfigError::PathParse)
+        parser::from_str(s).map_err(|e| ConfigError::PathParse {
+            cause: Box::new(ParseError::new(e)),
+        })
     }
 }
 
+#[derive(Debug)]
+struct ParseError(String);
+
+impl ParseError {
+    fn new(inner: nom::error::ErrorKind) -> Self {
+        Self(inner.description().to_owned())
+    }
+}
+
+impl std::fmt::Display for ParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl std::error::Error for ParseError {}
+
 fn sindex_to_uindex(index: isize, len: usize) -> usize {
     if index >= 0 {
         index as usize