Merge pull request #324 from Maximkaaa/try_parse

Add `Builder::try_parse()` method

crates/env_filter/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 <!-- next-header -->
 ## [Unreleased] - ReleaseDate
 
+### Features
+
+- Added `env_filter::Builder::try_parse(&self, &str)` method (failable version of `env_filter::Builder::parse()`)
+
 ## [0.1.0] - 2024-01-19
 
 <!-- next-url -->

crates/env_filter/Cargo.toml

@@ -33,5 +33,8 @@ regex = ["dep:regex"]
 log = { version = "0.4.8", features = ["std"] }
 regex = { version = "1.0.3", optional = true, default-features=false, features=["std", "perf"] }
 
+[dev-dependencies]
+snapbox = "0.6"
+
 [lints]
 workspace = true

crates/env_filter/src/filter.rs

@@ -6,8 +6,10 @@ use log::{LevelFilter, Metadata, Record};
 
 use crate::enabled;
 use crate::parse_spec;
+use crate::parser::ParseResult;
 use crate::Directive;
 use crate::FilterOp;
+use crate::ParseError;
 
 /// A builder for a log filter.
 ///
@@ -97,7 +99,17 @@ impl Builder {
     ///
     /// [Enabling Logging]: ../index.html#enabling-logging
     pub fn parse(&mut self, filters: &str) -> &mut Self {
-        let (directives, filter) = parse_spec(filters);
+        #![allow(clippy::print_stderr)] // compatibility
+
+        let ParseResult {
+            directives,
+            filter,
+            errors,
+        } = parse_spec(filters);
+
+        for error in errors {
+            eprintln!("warning: {error}, ignoring it");
+        }
 
         self.filter = filter;
 
@@ -107,6 +119,22 @@ impl Builder {
         self
     }
 
+    /// Parses the directive string, returning an error if the given directive string is invalid.
+    ///
+    /// See the [Enabling Logging] section for more details.
+    ///
+    /// [Enabling Logging]: ../index.html#enabling-logging
+    pub fn try_parse(&mut self, filters: &str) -> Result<&mut Self, ParseError> {
+        let (directives, filter) = parse_spec(filters).ok()?;
+
+        self.filter = filter;
+
+        for directive in directives {
+            self.insert_directive(directive);
+        }
+        Ok(self)
+    }
+
     /// Build a log filter.
     pub fn build(&mut self) -> Filter {
         assert!(!self.built, "attempt to re-use consumed builder");
@@ -230,6 +258,7 @@ impl fmt::Debug for Filter {
 #[cfg(test)]
 mod tests {
     use log::{Level, LevelFilter};
+    use snapbox::{assert_data_eq, str};
 
     use super::{enabled, Builder, Directive, Filter};
 
@@ -444,6 +473,25 @@ mod tests {
         }
     }
 
+    #[test]
+    fn try_parse_valid_filter() {
+        let logger = Builder::new()
+            .try_parse("info,crate1::mod1=warn")
+            .expect("valid filter returned error")
+            .build();
+        assert!(enabled(&logger.directives, Level::Warn, "crate1::mod1"));
+        assert!(enabled(&logger.directives, Level::Info, "crate2::mod2"));
+    }
+
+    #[test]
+    fn try_parse_invalid_filter() {
+        let error = Builder::new().try_parse("info,crate1=invalid").unwrap_err();
+        assert_data_eq!(
+            error,
+            str!["error parsing logger filter: invalid logging spec 'invalid'"]
+        );
+    }
+
     #[test]
     fn match_full_path() {
         let logger = make_logger_filter(vec![

crates/env_filter/src/lib.rs

@@ -56,3 +56,4 @@ use parser::parse_spec;
 pub use filter::Builder;
 pub use filter::Filter;
 pub use filtered_log::FilteredLog;
+pub use parser::ParseError;