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#![deny(warnings)] #![deny(missing_docs)] //! A logger configured via an environment variable which writes to standard //! error with nice colored output for log levels. //! //! ## Example //! //! ``` //! extern crate pretty_env_logger; //! #[macro_use] extern crate log; //! //! fn main() { //! pretty_env_logger::init(); //! //! trace!("a trace example"); //! debug!("deboogging"); //! info!("such information"); //! warn!("o_O"); //! error!("boom"); //! } //! ``` extern crate ansi_term; extern crate env_logger; extern crate log; use std::fmt; use std::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT}; use ansi_term::{Color, Style}; use env_logger::Builder; use log::Level; struct ColorLevel(Level); impl fmt::Display for ColorLevel { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self.0 { Level::Trace => Color::Purple.paint("TRACE"), Level::Debug => Color::Blue.paint("DEBUG"), Level::Info => Color::Green.paint("INFO "), Level::Warn => Color::Yellow.paint("WARN "), Level::Error => Color::Red.paint("ERROR") }.fmt(f) } } static MAX_MODULE_WIDTH: AtomicUsize = ATOMIC_USIZE_INIT; /// Initializes the global logger with a pretty env logger. /// /// This should be called early in the execution of a Rust program, and the /// global logger may only be initialized once. Future initialization attempts /// will return an error. /// /// # Panics /// /// This function fails to set the global logger if one has already been set. #[inline] pub fn init() { try_init().unwrap(); } /// Initializes the global logger with a pretty env logger. /// /// This should be called early in the execution of a Rust program, and the /// global logger may only be initialized once. Future initialization attempts /// will return an error. /// /// # Errors /// /// This function fails to set the global logger if one has already been set. pub fn try_init() -> Result<(), log::SetLoggerError> { try_init_custom_env("RUST_LOG") } /// Initialized the global logger with a pretty env logger, with a custom variable name. /// /// This should be called early in the execution of a Rust program, and the /// global logger may only be initialized once. Future initialization attempts /// will return an error. /// /// # Panics /// /// This function fails to set the global logger if one has already been set. pub fn init_custom_env(environment_variable_name: &str) { try_init_custom_env(environment_variable_name).unwrap(); } /// Initialized the global logger with a pretty env logger, with a custom variable name. /// /// This should be called early in the execution of a Rust program, and the /// global logger may only be initialized once. Future initialization attempts /// will return an error. /// /// # Errors /// /// This function fails to set the global logger if one has already been set. pub fn try_init_custom_env(environment_variable_name: &str) -> Result<(), log::SetLoggerError> { let mut builder = formatted_builder()?; if let Ok(s) = ::std::env::var(environment_variable_name) { builder.parse(&s); } builder.try_init() } /// Returns a `env_logger::Builder` for further customization. /// /// This method will return a colored and formatted) `env_logger::Builder` /// for further customization. Tefer to env_logger::Build crate documentation /// for further details and usage. /// /// This should be called early in the execution of a Rust program, and the /// global logger may only be initialized once. Future initialization attempts /// will return an error. /// /// # Errors /// /// This function fails to set the global logger if one has already been set. pub fn formatted_builder() -> Result<Builder, log::SetLoggerError> { let mut builder = Builder::new(); builder.format(|f, record| { use std::io::Write; if let Some(module_path) = record.module_path() { let mut max_width = MAX_MODULE_WIDTH.load(Ordering::Relaxed); if max_width < module_path.len() { MAX_MODULE_WIDTH.store(module_path.len(), Ordering::Relaxed); max_width = module_path.len(); } writeln!(f, " {} {} > {}", ColorLevel(record.level()), Style::new().bold().paint(format!("{: <width$}", module_path, width=max_width)), record.args()) } else { writeln!(f, " {} > {}", ColorLevel(record.level()), record.args()) } }); Ok(builder) }