src/liblog/lib.rs - third_party/rust - Git at Google

 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 /*!

 Utilities for program-wide and customizable logging

 ## Example

 ```
 #![feature(phase)]
 #[phase(plugin, link)] extern crate log;

 fn main() {
     debug!("this is a debug {}", "message");
     error!("this is printed by default");

     if log_enabled!(log::INFO) {
         let x = 3i * 4i; // expensive computation
         info!("the answer was: {}", x);
     }
 }
 ```

 ## Logging Macros

 There are five macros that the logging subsystem uses:

 * `log!(level, ...)` - the generic logging macro, takes a level as a u32 and any
                        related `format!` arguments
 * `debug!(...)` - a macro hard-wired to the log level of `DEBUG`
 * `info!(...)` - a macro hard-wired to the log level of `INFO`
 * `warn!(...)` - a macro hard-wired to the log level of `WARN`
 * `error!(...)` - a macro hard-wired to the log level of `ERROR`

 All of these macros use the same style of syntax as the `format!` syntax
 extension. Details about the syntax can be found in the documentation of
 `std::fmt` along with the Rust tutorial/manual.

 If you want to check at runtime if a given logging level is enabled (e.g. if the
 information you would want to log is expensive to produce), you can use the
 following macro:

 * `log_enabled!(level)` - returns true if logging of the given level is enabled

 ## Enabling logging

 Log levels are controlled on a per-module basis, and by default all logging is
 disabled except for `error!` (a log level of 1). Logging is controlled via the
 `RUST_LOG` environment variable. The value of this environment variable is a
 comma-separated list of logging directives. A logging directive is of the form:

 ```text
 path::to::module=log_level
 ```

 The path to the module is rooted in the name of the crate it was compiled for,
 so if your program is contained in a file `hello.rs`, for example, to turn on
 logging for this file you would use a value of `RUST_LOG=hello`.
 Furthermore, this path is a prefix-search, so all modules nested in the
 specified module will also have logging enabled.

 The actual `log_level` is optional to specify. If omitted, all logging will be
 enabled. If specified, the it must be either a numeric in the range of 1-255, or
 it must be one of the strings `debug`, `error`, `info`, or `warn`. If a numeric
 is specified, then all logging less than or equal to that numeral is enabled.
 For example, if logging level 3 is active, error, warn, and info logs will be
 printed, but debug will be omitted.

 As the log level for a module is optional, the module to enable logging for is
 also optional. If only a `log_level` is provided, then the global log level for
 all modules is set to this value.

 Some examples of valid values of `RUST_LOG` are:

 ```text
 hello                // turns on all logging for the 'hello' module
 info                 // turns on all info logging
 hello=debug          // turns on debug logging for 'hello'
 hello=3              // turns on info logging for 'hello'
 hello,std::option    // turns on hello, and std's option logging
 error,hello=warn     // turn on global error logging and also warn for hello
 ```

 ## Performance and Side Effects

 Each of these macros will expand to code similar to:

 ```rust,ignore
 if log_level <= my_module_log_level() {
     ::log::log(log_level, format!(...));
 }
 ```

 What this means is that each of these macros are very cheap at runtime if
 they're turned off (just a load and an integer comparison). This also means that
 if logging is disabled, none of the components of the log will be executed.

 */

 #![crate_id = "log#0.11.0"]
 #![experimental]
 #![license = "MIT/ASL2"]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
        html_root_url = "http://doc.rust-lang.org/0.11.0/",
        html_playground_url = "http://play.rust-lang.org/")]

 #![feature(macro_rules)]
 #![deny(missing_doc)]

 use std::fmt;
 use std::io::LineBufferedWriter;
 use std::io;
 use std::mem;
 use std::os;
 use std::rt;
 use std::slice;
 use std::sync::{Once, ONCE_INIT};

 use directive::LOG_LEVEL_NAMES;

 pub mod macros;
 mod directive;

 /// Maximum logging level of a module that can be specified. Common logging
 /// levels are found in the DEBUG/INFO/WARN/ERROR constants.
 pub static MAX_LOG_LEVEL: u32 = 255;

 /// The default logging level of a crate if no other is specified.
 static DEFAULT_LOG_LEVEL: u32 = 1;

 /// An unsafe constant that is the maximum logging level of any module
 /// specified. This is the first line of defense to determining whether a
 /// logging statement should be run.
 static mut LOG_LEVEL: u32 = MAX_LOG_LEVEL;

 static mut DIRECTIVES: *Vec<directive::LogDirective> =
     0 as *Vec<directive::LogDirective>;

 /// Debug log level
 pub static DEBUG: u32 = 4;
 /// Info log level
 pub static INFO: u32 = 3;
 /// Warn log level
 pub static WARN: u32 = 2;
 /// Error log level
 pub static ERROR: u32 = 1;

 local_data_key!(local_logger: Box<Logger + Send>)

 /// A trait used to represent an interface to a task-local logger. Each task
 /// can have its own custom logger which can respond to logging messages
 /// however it likes.
 pub trait Logger {
     /// Logs a single message described by the `record`.
     fn log(&mut self, record: &LogRecord);
 }

 struct DefaultLogger {
     handle: LineBufferedWriter<io::stdio::StdWriter>,
 }

 /// Wraps the log level with fmt implementations.
 #[deriving(PartialEq, PartialOrd)]
 pub struct LogLevel(pub u32);

 impl fmt::Show for LogLevel {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let LogLevel(level) = *self;
         match LOG_LEVEL_NAMES.get(level as uint - 1) {
             Some(name) => name.fmt(fmt),
             None => level.fmt(fmt)
         }
     }
 }

 impl fmt::Signed for LogLevel {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let LogLevel(level) = *self;
         write!(fmt, "{}", level)
     }
 }

 impl Logger for DefaultLogger {
     fn log(&mut self, record: &LogRecord) {
         match writeln!(&mut self.handle,
                        "{}:{}: {}",
                        record.level,
                        record.module_path,
                        record.args) {
             Err(e) => fail!("failed to log: {}", e),
             Ok(()) => {}
         }
     }
 }

 impl Drop for DefaultLogger {
     fn drop(&mut self) {
         // FIXME(#12628): is failure the right thing to do?
         match self.handle.flush() {
             Err(e) => fail!("failed to flush a logger: {}", e),
             Ok(()) => {}
         }
     }
 }

 /// This function is called directly by the compiler when using the logging
 /// macros. This function does not take into account whether the log level
 /// specified is active or not, it will always log something if this method is
 /// called.
 ///
 /// It is not recommended to call this function directly, rather it should be
 /// invoked through the logging family of macros.
 #[doc(hidden)]
 pub fn log(level: u32, loc: &'static LogLocation, args: &fmt::Arguments) {
     // Completely remove the local logger from TLS in case anyone attempts to
     // frob the slot while we're doing the logging. This will destroy any logger
     // set during logging.
     let mut logger = local_logger.replace(None).unwrap_or_else(|| {
         box DefaultLogger { handle: io::stderr() } as Box<Logger + Send>
     });
     logger.log(&LogRecord {
         level: LogLevel(level),
         args: args,
         file: loc.file,
         module_path: loc.module_path,
         line: loc.line,
     });
     local_logger.replace(Some(logger));
 }

 /// Getter for the global log level. This is a function so that it can be called
 /// safely
 #[doc(hidden)]
 #[inline(always)]
 pub fn log_level() -> u32 { unsafe { LOG_LEVEL } }

 /// Replaces the task-local logger with the specified logger, returning the old
 /// logger.
 pub fn set_logger(logger: Box<Logger + Send>) -> Option<Box<Logger + Send>> {
     local_logger.replace(Some(logger))
 }

 /// A LogRecord is created by the logging macros, and passed as the only
 /// argument to Loggers.
 #[deriving(Show)]
 pub struct LogRecord<'a> {

     /// The module path of where the LogRecord originated.
     pub module_path: &'a str,

     /// The LogLevel of this record.
     pub level: LogLevel,

     /// The arguments from the log line.
     pub args: &'a fmt::Arguments<'a>,

     /// The file of where the LogRecord originated.
     pub file: &'a str,

     /// The line number of where the LogRecord originated.
     pub line: uint,
 }

 #[doc(hidden)]
 pub struct LogLocation {
     pub module_path: &'static str,
     pub file: &'static str,
     pub line: uint,
 }

 /// Tests whether a given module's name is enabled for a particular level of
 /// logging. This is the second layer of defense about determining whether a
 /// module's log statement should be emitted or not.
 #[doc(hidden)]
 pub fn mod_enabled(level: u32, module: &str) -> bool {
     static mut INIT: Once = ONCE_INIT;
     unsafe { INIT.doit(init); }

     // It's possible for many threads are in this function, only one of them
     // will peform the global initialization, but all of them will need to check
     // again to whether they should really be here or not. Hence, despite this
     // check being expanded manually in the logging macro, this function checks
     // the log level again.
     if level > unsafe { LOG_LEVEL } { return false }

     // This assertion should never get tripped unless we're in an at_exit
     // handler after logging has been torn down and a logging attempt was made.
     assert!(unsafe { !DIRECTIVES.is_null() });

     enabled(level, module, unsafe { (*DIRECTIVES).iter() })
 }

 fn enabled(level: u32,
            module: &str,
            iter: slice::Items<directive::LogDirective>)
            -> bool {
     // Search for the longest match, the vector is assumed to be pre-sorted.
     for directive in iter.rev() {
         match directive.name {
             Some(ref name) if !module.starts_with(name.as_slice()) => {},
             Some(..) | None => {
                 return level <= directive.level
             }
         }
     }
     level <= DEFAULT_LOG_LEVEL
 }

 /// Initialize logging for the current process.
 ///
 /// This is not threadsafe at all, so initialization os performed through a
 /// `Once` primitive (and this function is called from that primitive).
 fn init() {
     let mut directives = match os::getenv("RUST_LOG") {
         Some(spec) => directive::parse_logging_spec(spec.as_slice()),
         None => Vec::new(),
     };

     // Sort the provided directives by length of their name, this allows a
     // little more efficient lookup at runtime.
     directives.sort_by(|a, b| {
         let alen = a.name.as_ref().map(|a| a.len()).unwrap_or(0);
         let blen = b.name.as_ref().map(|b| b.len()).unwrap_or(0);
         alen.cmp(&blen)
     });

     let max_level = {
         let max = directives.iter().max_by(|d| d.level);
         max.map(|d| d.level).unwrap_or(DEFAULT_LOG_LEVEL)
     };

     unsafe {
         LOG_LEVEL = max_level;

         assert!(DIRECTIVES.is_null());
         DIRECTIVES = mem::transmute(box directives);

         // Schedule the cleanup for this global for when the runtime exits.
         rt::at_exit(proc() {
             assert!(!DIRECTIVES.is_null());
             let _directives: Box<Vec<directive::LogDirective>> =
                 mem::transmute(DIRECTIVES);
             DIRECTIVES = 0 as *Vec<directive::LogDirective>;
         });
     }
 }

 #[cfg(test)]
 mod tests {
     use super::enabled;
     use directive::LogDirective;

     #[test]
     fn match_full_path() {
         let dirs = [
             LogDirective {
                 name: Some("crate2".to_string()),
                 level: 3
             },
             LogDirective {
                 name: Some("crate1::mod1".to_string()),
                 level: 2
             }
         ];
         assert!(enabled(2, "crate1::mod1", dirs.iter()));
         assert!(!enabled(3, "crate1::mod1", dirs.iter()));
         assert!(enabled(3, "crate2", dirs.iter()));
         assert!(!enabled(4, "crate2", dirs.iter()));
     }

     #[test]
     fn no_match() {
         let dirs = [
             LogDirective { name: Some("crate2".to_string()), level: 3 },
             LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
         ];
         assert!(!enabled(2, "crate3", dirs.iter()));
     }

     #[test]
     fn match_beginning() {
         let dirs = [
             LogDirective { name: Some("crate2".to_string()), level: 3 },
             LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
         ];
         assert!(enabled(3, "crate2::mod1", dirs.iter()));
     }

     #[test]
     fn match_beginning_longest_match() {
         let dirs = [
             LogDirective { name: Some("crate2".to_string()), level: 3 },
             LogDirective { name: Some("crate2::mod".to_string()), level: 4 },
             LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
         ];
         assert!(enabled(4, "crate2::mod1", dirs.iter()));
         assert!(!enabled(4, "crate2", dirs.iter()));
     }

     #[test]
     fn match_default() {
         let dirs = [
             LogDirective { name: None, level: 3 },
             LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
         ];
         assert!(enabled(2, "crate1::mod1", dirs.iter()));
         assert!(enabled(3, "crate2::mod2", dirs.iter()));
     }

     #[test]
     fn zero_level() {
         let dirs = [
             LogDirective { name: None, level: 3 },
             LogDirective { name: Some("crate1::mod1".to_string()), level: 0 }
         ];
         assert!(!enabled(1, "crate1::mod1", dirs.iter()));
         assert!(enabled(3, "crate2::mod2", dirs.iter()));
     }
 }
	// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	/*!

	Utilities for program-wide and customizable logging

	## Example

	```
	#![feature(phase)]
	#[phase(plugin, link)] extern crate log;

	fn main() {
	debug!("this is a debug {}", "message");
	error!("this is printed by default");

	if log_enabled!(log::INFO) {
	let x = 3i * 4i; // expensive computation
	info!("the answer was: {}", x);
	}
	}
	```

	## Logging Macros

	There are five macros that the logging subsystem uses:

	* `log!(level, ...)` - the generic logging macro, takes a level as a u32 and any
	related `format!` arguments
	* `debug!(...)` - a macro hard-wired to the log level of `DEBUG`
	* `info!(...)` - a macro hard-wired to the log level of `INFO`
	* `warn!(...)` - a macro hard-wired to the log level of `WARN`
	* `error!(...)` - a macro hard-wired to the log level of `ERROR`

	All of these macros use the same style of syntax as the `format!` syntax
	extension. Details about the syntax can be found in the documentation of
	`std::fmt` along with the Rust tutorial/manual.

	If you want to check at runtime if a given logging level is enabled (e.g. if the
	information you would want to log is expensive to produce), you can use the
	following macro:

	* `log_enabled!(level)` - returns true if logging of the given level is enabled

	## Enabling logging

	Log levels are controlled on a per-module basis, and by default all logging is
	disabled except for `error!` (a log level of 1). Logging is controlled via the
	`RUST_LOG` environment variable. The value of this environment variable is a
	comma-separated list of logging directives. A logging directive is of the form:

	```text
	path::to::module=log_level
	```

	The path to the module is rooted in the name of the crate it was compiled for,
	so if your program is contained in a file `hello.rs`, for example, to turn on
	logging for this file you would use a value of `RUST_LOG=hello`.
	Furthermore, this path is a prefix-search, so all modules nested in the
	specified module will also have logging enabled.

	The actual `log_level` is optional to specify. If omitted, all logging will be
	enabled. If specified, the it must be either a numeric in the range of 1-255, or
	it must be one of the strings `debug`, `error`, `info`, or `warn`. If a numeric
	is specified, then all logging less than or equal to that numeral is enabled.
	For example, if logging level 3 is active, error, warn, and info logs will be
	printed, but debug will be omitted.

	As the log level for a module is optional, the module to enable logging for is
	also optional. If only a `log_level` is provided, then the global log level for
	all modules is set to this value.

	Some examples of valid values of `RUST_LOG` are:

	```text
	hello // turns on all logging for the 'hello' module
	info // turns on all info logging
	hello=debug // turns on debug logging for 'hello'
	hello=3 // turns on info logging for 'hello'
	hello,std::option // turns on hello, and std's option logging
	error,hello=warn // turn on global error logging and also warn for hello
	```

	## Performance and Side Effects

	Each of these macros will expand to code similar to:

	```rust,ignore
	if log_level <= my_module_log_level() {
	::log::log(log_level, format!(...));
	}
	```

	What this means is that each of these macros are very cheap at runtime if
	they're turned off (just a load and an integer comparison). This also means that
	if logging is disabled, none of the components of the log will be executed.

	*/

	#![crate_id = "log#0.11.0"]
	#![experimental]
	#![license = "MIT/ASL2"]
	#![crate_type = "rlib"]
	#![crate_type = "dylib"]
	#![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
	html_favicon_url = "http://www.rust-lang.org/favicon.ico",
	html_root_url = "http://doc.rust-lang.org/0.11.0/",
	html_playground_url = "http://play.rust-lang.org/")]

	#![feature(macro_rules)]
	#![deny(missing_doc)]

	use std::fmt;
	use std::io::LineBufferedWriter;
	use std::io;
	use std::mem;
	use std::os;
	use std::rt;
	use std::slice;
	use std::sync::{Once, ONCE_INIT};

	use directive::LOG_LEVEL_NAMES;

	pub mod macros;
	mod directive;

	/// Maximum logging level of a module that can be specified. Common logging
	/// levels are found in the DEBUG/INFO/WARN/ERROR constants.
	pub static MAX_LOG_LEVEL: u32 = 255;

	/// The default logging level of a crate if no other is specified.
	static DEFAULT_LOG_LEVEL: u32 = 1;

	/// An unsafe constant that is the maximum logging level of any module
	/// specified. This is the first line of defense to determining whether a
	/// logging statement should be run.
	static mut LOG_LEVEL: u32 = MAX_LOG_LEVEL;

	static mut DIRECTIVES: *Vec<directive::LogDirective> =
	0 as *Vec<directive::LogDirective>;

	/// Debug log level
	pub static DEBUG: u32 = 4;
	/// Info log level
	pub static INFO: u32 = 3;
	/// Warn log level
	pub static WARN: u32 = 2;
	/// Error log level
	pub static ERROR: u32 = 1;

	local_data_key!(local_logger: Box<Logger + Send>)

	/// A trait used to represent an interface to a task-local logger. Each task
	/// can have its own custom logger which can respond to logging messages
	/// however it likes.
	pub trait Logger {
	/// Logs a single message described by the `record`.
	fn log(&mut self, record: &LogRecord);
	}

	struct DefaultLogger {
	handle: LineBufferedWriter<io::stdio::StdWriter>,
	}

	/// Wraps the log level with fmt implementations.
	#[deriving(PartialEq, PartialOrd)]
	pub struct LogLevel(pub u32);

	impl fmt::Show for LogLevel {
	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
	let LogLevel(level) = *self;
	match LOG_LEVEL_NAMES.get(level as uint - 1) {
	Some(name) => name.fmt(fmt),
	None => level.fmt(fmt)
	}
	}
	}

	impl fmt::Signed for LogLevel {
	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
	let LogLevel(level) = *self;
	write!(fmt, "{}", level)
	}
	}

	impl Logger for DefaultLogger {
	fn log(&mut self, record: &LogRecord) {
	match writeln!(&mut self.handle,
	"{}:{}: {}",
	record.level,
	record.module_path,
	record.args) {
	Err(e) => fail!("failed to log: {}", e),
	Ok(()) => {}
	}
	}
	}

	impl Drop for DefaultLogger {
	fn drop(&mut self) {
	// FIXME(#12628): is failure the right thing to do?
	match self.handle.flush() {
	Err(e) => fail!("failed to flush a logger: {}", e),
	Ok(()) => {}
	}
	}
	}

	/// This function is called directly by the compiler when using the logging
	/// macros. This function does not take into account whether the log level
	/// specified is active or not, it will always log something if this method is
	/// called.
	///
	/// It is not recommended to call this function directly, rather it should be
	/// invoked through the logging family of macros.
	#[doc(hidden)]
	pub fn log(level: u32, loc: &'static LogLocation, args: &fmt::Arguments) {
	// Completely remove the local logger from TLS in case anyone attempts to
	// frob the slot while we're doing the logging. This will destroy any logger
	// set during logging.
	let mut logger = local_logger.replace(None).unwrap_or_else(\|\| {
	box DefaultLogger { handle: io::stderr() } as Box<Logger + Send>
	});
	logger.log(&LogRecord {
	level: LogLevel(level),
	args: args,
	file: loc.file,
	module_path: loc.module_path,
	line: loc.line,
	});
	local_logger.replace(Some(logger));
	}

	/// Getter for the global log level. This is a function so that it can be called
	/// safely
	#[doc(hidden)]
	#[inline(always)]
	pub fn log_level() -> u32 { unsafe { LOG_LEVEL } }

	/// Replaces the task-local logger with the specified logger, returning the old
	/// logger.
	pub fn set_logger(logger: Box<Logger + Send>) -> Option<Box<Logger + Send>> {
	local_logger.replace(Some(logger))
	}

	/// A LogRecord is created by the logging macros, and passed as the only
	/// argument to Loggers.
	#[deriving(Show)]
	pub struct LogRecord<'a> {

	/// The module path of where the LogRecord originated.
	pub module_path: &'a str,

	/// The LogLevel of this record.
	pub level: LogLevel,

	/// The arguments from the log line.
	pub args: &'a fmt::Arguments<'a>,

	/// The file of where the LogRecord originated.
	pub file: &'a str,

	/// The line number of where the LogRecord originated.
	pub line: uint,
	}

	#[doc(hidden)]
	pub struct LogLocation {
	pub module_path: &'static str,
	pub file: &'static str,
	pub line: uint,
	}

	/// Tests whether a given module's name is enabled for a particular level of
	/// logging. This is the second layer of defense about determining whether a
	/// module's log statement should be emitted or not.
	#[doc(hidden)]
	pub fn mod_enabled(level: u32, module: &str) -> bool {
	static mut INIT: Once = ONCE_INIT;
	unsafe { INIT.doit(init); }

	// It's possible for many threads are in this function, only one of them
	// will peform the global initialization, but all of them will need to check
	// again to whether they should really be here or not. Hence, despite this
	// check being expanded manually in the logging macro, this function checks
	// the log level again.
	if level > unsafe { LOG_LEVEL } { return false }

	// This assertion should never get tripped unless we're in an at_exit
	// handler after logging has been torn down and a logging attempt was made.
	assert!(unsafe { !DIRECTIVES.is_null() });

	enabled(level, module, unsafe { (*DIRECTIVES).iter() })
	}

	fn enabled(level: u32,
	module: &str,
	iter: slice::Items<directive::LogDirective>)
	-> bool {
	// Search for the longest match, the vector is assumed to be pre-sorted.
	for directive in iter.rev() {
	match directive.name {
	Some(ref name) if !module.starts_with(name.as_slice()) => {},
	Some(..) \| None => {
	return level <= directive.level
	}
	}
	}
	level <= DEFAULT_LOG_LEVEL
	}

	/// Initialize logging for the current process.
	///
	/// This is not threadsafe at all, so initialization os performed through a
	/// `Once` primitive (and this function is called from that primitive).
	fn init() {
	let mut directives = match os::getenv("RUST_LOG") {
	Some(spec) => directive::parse_logging_spec(spec.as_slice()),
	None => Vec::new(),
	};

	// Sort the provided directives by length of their name, this allows a
	// little more efficient lookup at runtime.
	directives.sort_by(\|a, b\| {
	let alen = a.name.as_ref().map(\|a\| a.len()).unwrap_or(0);
	let blen = b.name.as_ref().map(\|b\| b.len()).unwrap_or(0);
	alen.cmp(&blen)
	});

	let max_level = {
	let max = directives.iter().max_by(\|d\| d.level);
	max.map(\|d\| d.level).unwrap_or(DEFAULT_LOG_LEVEL)
	};

	unsafe {
	LOG_LEVEL = max_level;

	assert!(DIRECTIVES.is_null());
	DIRECTIVES = mem::transmute(box directives);

	// Schedule the cleanup for this global for when the runtime exits.
	rt::at_exit(proc() {
	assert!(!DIRECTIVES.is_null());
	let _directives: Box<Vec<directive::LogDirective>> =
	mem::transmute(DIRECTIVES);
	DIRECTIVES = 0 as *Vec<directive::LogDirective>;
	});
	}
	}

	#[cfg(test)]
	mod tests {
	use super::enabled;
	use directive::LogDirective;

	#[test]
	fn match_full_path() {
	let dirs = [
	LogDirective {
	name: Some("crate2".to_string()),
	level: 3
	},
	LogDirective {
	name: Some("crate1::mod1".to_string()),
	level: 2
	}
	];
	assert!(enabled(2, "crate1::mod1", dirs.iter()));
	assert!(!enabled(3, "crate1::mod1", dirs.iter()));
	assert!(enabled(3, "crate2", dirs.iter()));
	assert!(!enabled(4, "crate2", dirs.iter()));
	}

	#[test]
	fn no_match() {
	let dirs = [
	LogDirective { name: Some("crate2".to_string()), level: 3 },
	LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
	];
	assert!(!enabled(2, "crate3", dirs.iter()));
	}

	#[test]
	fn match_beginning() {
	let dirs = [
	LogDirective { name: Some("crate2".to_string()), level: 3 },
	LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
	];
	assert!(enabled(3, "crate2::mod1", dirs.iter()));
	}

	#[test]
	fn match_beginning_longest_match() {
	let dirs = [
	LogDirective { name: Some("crate2".to_string()), level: 3 },
	LogDirective { name: Some("crate2::mod".to_string()), level: 4 },
	LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
	];
	assert!(enabled(4, "crate2::mod1", dirs.iter()));
	assert!(!enabled(4, "crate2", dirs.iter()));
	}

	#[test]
	fn match_default() {
	let dirs = [
	LogDirective { name: None, level: 3 },
	LogDirective { name: Some("crate1::mod1".to_string()), level: 2 }
	];
	assert!(enabled(2, "crate1::mod1", dirs.iter()));
	assert!(enabled(3, "crate2::mod2", dirs.iter()));
	}

	#[test]
	fn zero_level() {
	let dirs = [
	LogDirective { name: None, level: 3 },
	LogDirective { name: Some("crate1::mod1".to_string()), level: 0 }
	];
	assert!(!enabled(1, "crate1::mod1", dirs.iter()));
	assert!(enabled(3, "crate2::mod2", dirs.iter()));
	}
	}