Add logging module (denoland/deno_std#33)

Original: 25b88bcf8c

README.md

@@ -7,11 +7,11 @@ for Deno.
 
 | Collection                   | Description                                                     |
 | ---------------------------- | --------------------------------------------------------------- |
-| [colors](./colors/README.md) | Modules that generate ANSI color codes for the console.         |
+| [colors](./colors/)          | Modules that generate ANSI color codes for the console.         |
-| [net](./net/README.md)       | A framework for creating HTTP/HTTPS servers inspired by GoLang. |
+| [net](./net/)                | A framework for creating HTTP/HTTPS servers inspired by GoLang. |
-| [path](./path/README.md)     | A path manipulation library.                                    |
+| [path](./path/)              | File path manipulation.                                         |
-| [flags](./flags/README.md)   | Command line arguments parser based on minimist.                |
+| [flags](./flags/)            | Command line arguments parser.                                  |
-
+| [logging](./logging/)        | Command line logging                                            |
 ---
 
 Copyright 2018 the Deno authors. All rights reserved. MIT license.

logging/README.md

@@ -0,0 +1,12 @@
+# Logging module for Deno
+
+Very much work in progress. Contributions welcome.
+
+This library is heavily inspired by Python's [logging](https://docs.python.org/3/library/logging.html#logging.Logger.log) module, altough
+it's not planned to be a direct port. Having separate loggers, handlers, formatters and filters gives developer very granular control over logging
+which is most desirable for server side software.
+
+Todo:
+- [ ] implement formatters
+- [ ] implement `FileHandler`
+- [ ] tests

logging/handler.ts

@@ -0,0 +1,18 @@
+import { getLevelByName } from "./levels";
+
+export class BaseHandler {
+  level: number;
+  levelName: string;
+
+  constructor(levelName) {
+    this.level = getLevelByName(levelName);
+    this.levelName = levelName;
+  }
+
+  handle(level, ...args) {
+    if (this.level > level) return;
+    return this._log(level, ...args);
+  }
+
+  _log(level, ...args) {}
+}

logging/handlers/console.ts

@@ -0,0 +1,26 @@
+import { BaseHandler } from '../handler.ts';
+import { LogLevel } from '../levels.ts';
+
+export class ConsoleHandler extends BaseHandler {
+    _log(level, ...args) {
+        switch (level) {
+            case LogLevel.DEBUG:
+                console.log(...args);
+                return;
+            case LogLevel.INFO:
+                console.info(...args);
+                return;
+            case LogLevel.WARNING:
+                console.warn(...args);
+                return;
+            case LogLevel.ERROR:
+                console.error(...args);
+                return;
+            case LogLevel.CRITICAL:
+                console.error(...args);
+                return;
+            default:
+                return;
+        }
+    }
+}

logging/index.ts

@@ -0,0 +1,101 @@
+import { Logger } from "./logger.ts";
+import { BaseHandler } from "./handler.ts";
+import { ConsoleHandler } from "./handlers/console.ts";
+
+export interface HandlerConfig {
+  // TODO: replace with type describing class derived from BaseHandler
+  class: typeof BaseHandler;
+  level?: string;
+}
+
+export class LoggerConfig {
+  level?: string;
+  handlers?: string[];
+}
+
+export interface LoggingConfig {
+  handlers?: {
+    [name: string]: HandlerConfig;
+  };
+  loggers?: {
+    [name: string]: LoggerConfig;
+  };
+}
+
+const DEFAULT_LEVEL = "INFO";
+const DEFAULT_NAME = "";
+const DEFAULT_CONFIG: LoggingConfig = {
+  handlers: {
+    [DEFAULT_NAME]: {
+      level: DEFAULT_LEVEL,
+      class: ConsoleHandler
+    }
+  },
+
+  loggers: {
+    [DEFAULT_NAME]: {
+      level: DEFAULT_LEVEL,
+      handlers: [DEFAULT_NAME]
+    }
+  }
+};
+
+const state = {
+  loggers: new Map(),
+  config: DEFAULT_CONFIG
+};
+
+function createNewHandler(name: string) {
+  let handlerConfig = state.config.handlers[name];
+
+  if (!handlerConfig) {
+    handlerConfig = state.config.handlers[DEFAULT_NAME];
+  }
+
+  const constructor = handlerConfig.class;
+  console.log(constructor);
+  const handler = new constructor(handlerConfig.level);
+  return handler;
+}
+
+function createNewLogger(name: string) {
+  let loggerConfig = state.config.loggers[name];
+
+  if (!loggerConfig) {
+    loggerConfig = state.config.loggers[DEFAULT_NAME];
+  }
+
+  const handlers = (loggerConfig.handlers || []).map(createNewHandler);
+  const levelName = loggerConfig.level || DEFAULT_LEVEL;
+  return new Logger(levelName, handlers);
+}
+
+export const handlers = {
+  BaseHandler: BaseHandler,
+  ConsoleHandler: ConsoleHandler
+};
+
+export function getLogger(name?: string) {
+  if (!name) {
+    name = DEFAULT_NAME;
+  }
+
+  if (!state.loggers.has(name)) {
+    return createNewLogger(name);
+  }
+
+  return state.loggers.get(name);
+}
+
+export function setup(config: LoggingConfig) {
+  state.config = {
+    handlers: {
+      ...DEFAULT_CONFIG.handlers,
+      ...config.handlers!
+    },
+    loggers: {
+      ...DEFAULT_CONFIG.loggers,
+      ...config.loggers!
+    }
+  };
+}

logging/levels.ts

@@ -0,0 +1,31 @@
+export const LogLevel = {
+  DEBUG: 10,
+  INFO: 20,
+  WARNING: 30,
+  ERROR: 40,
+  CRITICAL: 50
+};
+
+const byName = {
+  DEBUG: LogLevel.DEBUG,
+  INFO: LogLevel.INFO,
+  WARNING: LogLevel.WARNING,
+  ERROR: LogLevel.ERROR,
+  CRITICAL: LogLevel.DEBUG
+};
+
+const byLevel = {
+  [LogLevel.DEBUG]: "DEBUG",
+  [LogLevel.INFO]: "INFO",
+  [LogLevel.WARNING]: "WARNING",
+  [LogLevel.ERROR]: "ERROR",
+  [LogLevel.CRITICAL]: "CRITICAL"
+};
+
+export function getLevelByName(name) {
+  return byName[name];
+}
+
+export function getLevelName(level) {
+  return byLevel[level];
+}

logging/logger.ts

@@ -0,0 +1,44 @@
+import { LogLevel, getLevelByName, getLevelName } from "./levels.ts";
+
+export class Logger {
+  level: number;
+  levelName: string;
+  handlers: any[];
+
+  constructor(levelName, handlers) {
+    this.level = getLevelByName(levelName);
+    this.levelName = levelName;
+    this.handlers = handlers;
+  }
+
+  _log(level, ...args) {
+    this.handlers.forEach(handler => {
+      handler.handle(level, ...args);
+    });
+  }
+
+  log(level, ...args) {
+    if (this.level > level) return;
+    return this._log(level, ...args);
+  }
+
+  debug(...args) {
+    return this.log(LogLevel.DEBUG, ...args);
+  }
+
+  info(...args) {
+    return this.log(LogLevel.INFO, ...args);
+  }
+
+  warning(...args) {
+    return this.log(LogLevel.WARNING, ...args);
+  }
+
+  error(...args) {
+    return this.log(LogLevel.ERROR, ...args);
+  }
+
+  critical(...args) {
+    return this.log(LogLevel.CRITICAL, ...args);
+  }
+}

logging/test.ts

@@ -0,0 +1,53 @@
+import { assertEqual, test } from "https://deno.land/x/testing/testing.ts";
+
+import * as logging from "index.ts";
+
+// TODO: establish something more sophisticated
+
+let testOutput = "";
+
+class TestHandler extends logging.handlers.BaseHandler {
+  _log(level, ...args) {
+    testOutput += `${level} ${args[0]}\n`;
+  }
+}
+
+logging.setup({
+  handlers: {
+    debug: {
+      level: "DEBUG",
+      class: TestHandler
+    },
+
+    info: {
+      level: "INFO",
+      class: TestHandler
+    }
+  },
+
+  loggers: {
+    default: {
+      level: "DEBUG",
+      handlers: ["debug"]
+    },
+
+    info: {
+      level: "INFO",
+      handlers: ["info"]
+    }
+  }
+});
+
+const logger = logging.getLogger("default");
+const unknownLogger = logging.getLogger("info");
+
+test(function basicTest() {
+  logger.debug("I should be printed.");
+  unknownLogger.debug("I should not be printed.");
+  unknownLogger.info("And I should be printed as well.");
+
+  const expectedOutput =
+    "10 I should be printed.\n20 And I should be printed as well.\n";
+
+  assertEqual(testOutput, expectedOutput);
+});

test.ts

@@ -13,6 +13,9 @@ import "net/http_test.ts";
 import "net/textproto_test.ts";
 import { runTests, completePromise } from "net/file_server_test.ts";
 
+// logging tests
+import "logging/test.ts";
+
 // file server test
 const fileServer = run({
   args: ["deno", "--allow-net", "net/file_server.ts", "."]