feat(protocol): add Source impls for Cow and Arc

src/protocol.rs

@@ -112,7 +112,7 @@ If you can read it, you can source it,
 and it's not necessary to read the whole thing--meaning you should be able to
 support Sources which are gigabytes or larger in size.
 */
-pub trait Source: std::fmt::Debug + Send + Sync + 'static {
+pub trait Source: std::fmt::Debug + Send + Sync {
     /// Read the bytes for a specific span from this Source.
     fn read_span<'a>(
         &'a self,

src/source_impls.rs

@@ -1,6 +1,8 @@
 /*!
 Default trait implementations for [Source].
 */
+use std::{borrow::Cow, sync::Arc};
+
 use crate::{MietteError, MietteSpanContents, Source, SourceSpan, SpanContents};
 
 impl Source for String {
@@ -43,6 +45,24 @@ impl Source for String {
     }
 }
 
+impl<T: Source> Source for Arc<T> {
+    fn read_span<'a>(
+        &'a self,
+        span: &SourceSpan,
+    ) -> Result<Box<dyn SpanContents + 'a>, MietteError> {
+        self.as_ref().read_span(span)
+    }
+}
+
+impl<T: Source + Clone> Source for Cow<'_, T> {
+    fn read_span<'a>(
+        &'a self,
+        span: &SourceSpan,
+    ) -> Result<Box<dyn SpanContents + 'a>, MietteError> {
+        self.as_ref().read_span(span)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

tests/derive.rs

@@ -232,11 +232,11 @@ fn test_snippet_enum() {
         #[diagnostic(code(foo::a))]
         A {
             src: String,
-            #[snippet(src, "my_snippet.rs", "hi this is where the thing went wrong")]
+            #[snippet(src, "hi this is where the thing went wrong")]
             snip: SourceSpan,
-            #[highlight(snip, "var 1")]
+            #[highlight(snip)]
             var1: SourceSpan,
-            #[highlight(snip, "var 2")]
+            #[highlight(snip)]
             var2: SourceSpan,
             filename: String,
             second_message: String,
@@ -246,15 +246,15 @@ fn test_snippet_enum() {
         #[diagnostic(code(foo::b))]
         B(
             String,
-            #[snippet(0, "my_snippet.rs", "hi")] SourceSpan,
-            #[highlight(1, "var 1")] SourceSpan,
+            #[snippet(0, "hi")] SourceSpan,
+            #[highlight(1)] SourceSpan,
             #[highlight(1, "var 2")] SourceSpan,
             // referenced source name
             String,
             String,
             #[snippet(0, 4, 5)] SourceSpan,
-            #[highlight(6, "var 3")] SourceSpan,
-            #[highlight(6, "var 4")] SourceSpan,
+            #[highlight(6)] SourceSpan,
+            #[highlight(6)] SourceSpan,
         ),
     }
 }