wasm_logger/
lib.rs

1//! A simple logger for front end wasm web app.
2//!
3//! Please see [README](https://gitlab.com/limira-rs/wasm-logger/blob/master/README.md) for documentation.
4#![deny(missing_docs)]
5use log::{Level, Log, Metadata, Record};
6use wasm_bindgen::prelude::*;
7use web_sys::console;
8
9/// Specify what to be logged
10pub struct Config {
11    level: Level,
12    module_prefix: Option<String>,
13    message_location: MessageLocation,
14}
15
16/// Specify where the message will be logged.
17pub enum MessageLocation {
18    /// The message will be on the same line as other info (level, path...)
19    SameLine,
20    /// The message will be on its own line, a new after other info.
21    NewLine,
22}
23
24impl Default for Config {
25    fn default() -> Self {
26        Self {
27            level: Level::Debug,
28            module_prefix: None,
29            message_location: MessageLocation::SameLine,
30        }
31    }
32}
33
34impl Config {
35    /// Specify the maximum level you want to log
36    pub fn new(level: Level) -> Self {
37        Self {
38            level,
39            module_prefix: None,
40            message_location: MessageLocation::SameLine,
41        }
42    }
43
44    /// Configure the `target` of the logger. If specified, the logger
45    /// only output for `log`s in module that its path starts with
46    /// `module_prefix`. wasm-logger only supports single prefix. Only
47    /// the last call to `module_prefix` has effect if you call it multiple times.
48    pub fn module_prefix(mut self, module_prefix: &str) -> Self {
49        self.module_prefix = Some(module_prefix.to_string());
50        self
51    }
52
53    /// Put the message on a new line, separated from other information
54    /// such as level, file path, line number.
55    pub fn message_on_new_line(mut self) -> Self {
56        self.message_location = MessageLocation::NewLine;
57        self
58    }
59}
60
61/// The log styles
62struct Style {
63    lvl_trace: String,
64    lvl_debug: String,
65    lvl_info: String,
66    lvl_warn: String,
67    lvl_error: String,
68    tgt: String,
69    args: String,
70}
71
72impl Style {
73    fn new() -> Style {
74        let base = String::from("color: white; padding: 0 3px; background:");
75        Style {
76            lvl_trace: format!("{} gray;", base),
77            lvl_debug: format!("{} blue;", base),
78            lvl_info: format!("{} green;", base),
79            lvl_warn: format!("{} orange;", base),
80            lvl_error: format!("{} darkred;", base),
81            tgt: String::from("font-weight: bold; color: inherit"),
82            args: String::from("background: inherit; color: inherit"),
83        }
84    }
85}
86
87/// The logger
88struct WasmLogger {
89    config: Config,
90    style: Style,
91}
92
93impl Log for WasmLogger {
94    fn enabled(&self, metadata: &Metadata<'_>) -> bool {
95        if let Some(ref prefix) = self.config.module_prefix {
96            metadata.target().starts_with(prefix)
97        } else {
98            true
99        }
100    }
101
102    fn log(&self, record: &Record<'_>) {
103        if self.enabled(record.metadata()) {
104            let style = &self.style;
105            let message_separator = match self.config.message_location {
106                MessageLocation::NewLine => "\n",
107                MessageLocation::SameLine => " ",
108            };
109            let s = format!(
110                "%c{}%c {}:{}%c{}{}",
111                record.level(),
112                record.file().unwrap_or_else(|| record.target()),
113                record
114                    .line()
115                    .map_or_else(|| "[Unknown]".to_string(), |line| line.to_string()),
116                message_separator,
117                record.args(),
118            );
119            let s = JsValue::from_str(&s);
120            let tgt_style = JsValue::from_str(&style.tgt);
121            let args_style = JsValue::from_str(&style.args);
122
123            match record.level() {
124                Level::Trace => console::debug_4(
125                    &s,
126                    &JsValue::from(&style.lvl_trace),
127                    &tgt_style,
128                    &args_style,
129                ),
130                Level::Debug => console::log_4(
131                    &s,
132                    &JsValue::from(&style.lvl_debug),
133                    &tgt_style,
134                    &args_style,
135                ),
136                Level::Info => {
137                    console::info_4(&s, &JsValue::from(&style.lvl_info), &tgt_style, &args_style)
138                }
139                Level::Warn => {
140                    console::warn_4(&s, &JsValue::from(&style.lvl_warn), &tgt_style, &args_style)
141                }
142                Level::Error => console::error_4(
143                    &s,
144                    &JsValue::from(&style.lvl_error),
145                    &tgt_style,
146                    &args_style,
147                ),
148            }
149        }
150    }
151
152    fn flush(&self) {}
153}
154
155/// Initialize the logger which the given config. If failed, it will log a message to the the browser console.
156///
157/// ## Examples
158/// ```rust
159/// wasm_logger::init(wasm_logger::Config::new(log::Level::Debug));
160/// ```
161/// or
162/// ```rust
163/// wasm_logger::init(wasm_logger::Config::with_prefix(log::Level::Debug, "some::module"));
164/// ```
165pub fn init(config: Config) {
166    let max_level = config.level;
167    let wl = WasmLogger {
168        config,
169        style: Style::new(),
170    };
171
172    match log::set_boxed_logger(Box::new(wl)) {
173        Ok(_) => log::set_max_level(max_level.to_level_filter()),
174        Err(e) => console::error_1(&JsValue::from(e.to_string())),
175    }
176}
wasm_logger/lib.rs

wasm_logger/
lib.rs
