feat: add target filter (#44)

Co-authored-by: tison <[email protected]>

src/filter/level.rs

@@ -17,7 +17,7 @@ use log::Metadata;
 use crate::filter::Filter;
 use crate::filter::FilterResult;
 
-/// A filter that checks if the log level is at most the specified level.
+/// A filter that checks if the log level is higher than the specified level.
 ///
 /// From least to most verbose, the levels are:
 ///
@@ -31,9 +31,13 @@ use crate::filter::FilterResult;
 ///
 /// If LevelFilter is set to `Off`, it will reject all logs.
 #[derive(Debug, Clone)]
-pub struct LevelFilter(pub log::LevelFilter);
+pub struct LevelFilter(log::LevelFilter);
 
 impl LevelFilter {
+    pub fn new(level: log::LevelFilter) -> Self {
+        LevelFilter(level)
+    }
+
     pub(crate) fn filter(&self, metadata: &Metadata) -> FilterResult {
         let level = metadata.level();
         if level <= self.0 {

src/filter/mod.rs

@@ -16,9 +16,11 @@
 
 pub use self::custom::CustomFilter;
 pub use self::level::LevelFilter;
+pub use self::target::TargetFilter;
 
 mod custom;
 mod level;
+mod target;
 
 /// The result of a filter may return.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -34,13 +36,15 @@ pub enum FilterResult {
 #[derive(Debug)]
 pub enum Filter {
     Level(LevelFilter),
+    Target(TargetFilter),
     Custom(CustomFilter),
 }
 
 impl Filter {
     pub(crate) fn filter(&self, metadata: &log::Metadata) -> FilterResult {
         match self {
             Filter::Level(filter) => filter.filter(metadata),
+            Filter::Target(filter) => filter.filter(metadata),
             Filter::Custom(filter) => filter.filter(metadata),
         }
     }

src/filter/target.rs

@@ -0,0 +1,59 @@
+// Copyright 2024 FastLabs Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::borrow::Cow;
+
+use log::Metadata;
+
+use crate::filter::Filter;
+use crate::filter::FilterResult;
+
+/// A filter that checks if the log level is higher than the specified level for a specific
+/// target.
+///
+/// Only if the target has a prefix that matches the target of the log record, the filter
+/// will be applied.
+#[derive(Debug, Clone)]
+pub struct TargetFilter {
+    target: Cow<'static, str>,
+    level: log::LevelFilter,
+}
+
+impl TargetFilter {
+    pub fn level_for(target: impl Into<Cow<'static, str>>, level: log::LevelFilter) -> Self {
+        TargetFilter {
+            target: target.into(),
+            level,
+        }
+    }
+
+    pub(crate) fn filter(&self, metadata: &Metadata) -> FilterResult {
+        if metadata.target().starts_with(self.target.as_ref()) {
+            let level = metadata.level();
+            if level <= self.level {
+                FilterResult::Neutral
+            } else {
+                FilterResult::Reject
+            }
+        } else {
+            FilterResult::Neutral
+        }
+    }
+}
+
+impl From<TargetFilter> for Filter {
+    fn from(filter: TargetFilter) -> Self {
+        Filter::Target(filter)
+    }
+}