make filters Debug

It's nice if you can print out the filter tree for debugging, so we're
requireing filters to be Debug now.

1 files changed, 20 insertions, 2 deletions

diff --git a/src/filters/mod.rs b/src/filters/mod.rs
index 62dc04b..525ff27 100644
--- a/src/filters/mod.rs
+++ b/src/filters/mod.rs
@@ -1,5 +1,5 @@
 #![allow(clippy::new_ret_no_self)]
-use std::ops;
+use std::{ops, fmt};
 
 use num_derive::FromPrimitive;
 use num_traits::FromPrimitive as _;
@@ -59,7 +59,7 @@ impl From<bool> for Inclusion {
 /// The main filter trait.
 ///
 /// Filters are usually handled as a `Box<dyn Filter>`.
-pub trait Filter<Early, Late>: Send + Sync {
+pub trait Filter<Early, Late>: Send + Sync + fmt::Debug {
     /// Determine early (before processing all events) whether the log stands a chance to be
     /// included.
     ///
@@ -118,6 +118,12 @@ impl<E: 'static, L: 'static> ops::BitAnd<Box<dyn Filter<E, L>>> for Box<dyn Filt
     }
 }
 
+impl<E, L> fmt::Debug for AndFilter<E, L> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "({:?}) and ({:?})", self.0, self.1)
+    }
+}
+
 struct OrFilter<E, L>(Box<dyn Filter<E, L>>, Box<dyn Filter<E, L>>);
 
 impl<E, L> Filter<E, L> for OrFilter<E, L> {
@@ -144,6 +150,12 @@ impl<E: 'static, L: 'static> ops::BitOr<Box<dyn Filter<E, L>>> for Box<dyn Filte
     }
 }
 
+impl<E, L> fmt::Debug for OrFilter<E, L> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "({:?}) or ({:?})", self.0, self.1)
+    }
+}
+
 struct NotFilter<E, L>(Box<dyn Filter<E, L>>);
 
 impl<E, L> Filter<E, L> for NotFilter<E, L> {
@@ -164,6 +176,12 @@ impl<E: 'static, L: 'static> ops::Not for Box<dyn Filter<E, L>> {
     }
 }
 
+impl<E, L> fmt::Debug for NotFilter<E, L> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "not ({:?})", self.0)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;