kaf/
lib.rs

1//! # Kaf
2//!
3//! `kaf` is a [`log`](https://docs.rs/log) implementation that enables the user to filter logs based on entry metadata.
4//! For example:
5//! ```
6//! kaf::with_filter(
7//!     Box::new(|target, _level| {
8//!         (target == "mycrate" || target.starts_with("mycrate::"))
9//!     }),
10//!     log::LevelFilter::Info,
11//! );
12//! ```
13
14use ansi_term::{ANSIGenericString, Color::*, Style};
15use log::{Level, LevelFilter};
16use std::{fmt::Display, io::Write};
17
18/// A filter. Called for every log entry that is equal or below the global log level.
19type Filter = Box<dyn Fn(String, Level) -> bool + Send + Sync>;
20
21/// The logger.
22pub struct Logger {
23    filter: Filter,
24}
25
26/// Initializes logging with a global max level of `LevelFilter::Info`.
27///
28/// # Examples
29/// ```
30/// kaf::init();
31/// ```
32pub fn init() {
33    with_level(LevelFilter::Info);
34}
35
36/// Initializes logging with a global max level.
37///
38/// # Examples
39/// ```
40/// kaf::with_level(log::LevelFilter::Info);
41/// ```
42pub fn with_level(level: LevelFilter) {
43    with_filter(Box::new(|_, _| true), level);
44}
45
46/// Initializes logging with a `Filter` implementation.
47///
48/// * `filter` - The filter to determine if an entry should be logged.
49/// * `max_level` - The global maximum log level, `filter` will not be called for levels that are higher.
50///
51/// # Examples
52/// ```
53/// kaf::with_filter(
54///    Box::new(|target, _level| target == "crate::module"),
55///        log::LevelFilter::Info,
56///    );
57/// ```
58pub fn with_filter(filter: Filter, max_level: LevelFilter) {
59    log::set_max_level(max_level);
60    log::set_boxed_logger(Box::new(Logger { filter })).expect("Could not set logger");
61}
62
63/// Initializes logging from a `&str`. Helpful with external configuration.
64///
65/// # Examples
66/// ```
67/// kaf::from_str("INFO");
68/// ```
69pub fn from_str(level: &str) {
70    use std::str::FromStr;
71    with_level(LevelFilter::from_str(level).unwrap());
72}
73
74impl log::Log for Logger {
75    fn enabled(&self, metadata: &log::Metadata) -> bool {
76        metadata.level() <= log::max_level()
77            && (*self.filter)(metadata.target().to_string(), metadata.level())
78    }
79
80    fn log(&self, record: &log::Record) {
81        if self.enabled(record.metadata()) {
82            let stdout = std::io::stdout();
83            let mut handle = stdout.lock();
84
85            let (pre, args): (ANSIGenericString<'_, str>, Box<dyn Display>) = match record.level() {
86                log::Level::Error => (
87                    Red.bold().paint(record.target()),
88                    Box::new(Style::new().bold().paint(record.args().to_string())),
89                ),
90                log::Level::Warn => (
91                    Yellow.bold().paint(record.target()),
92                    Box::new(record.args()),
93                ),
94                log::Level::Trace | log::Level::Debug => (
95                    Purple.bold().paint(record.target()),
96                    Box::new(record.args()),
97                ),
98                log::Level::Info => (Cyan.bold().paint(record.target()), Box::new(record.args())),
99            };
100
101            writeln!(handle, "{} {}", pre, args).unwrap();
102        }
103    }
104
105    fn flush(&self) {}
106}
kaf/lib.rs

kaf/
lib.rs
