Use facets to prioritize when resolving type conflicts

... plus a couple other misc things

.eslintrc.json

@@ -0,0 +1,46 @@
+{
+  "root": true,
+  "env": {
+    "browser": true,
+    "commonjs": true,
+    "node": true,
+    "mocha": true
+  },
+  "extends": ["eslint:recommended"],
+  "installedESLint": true,
+  "rules": {
+    "array-bracket-spacing": ["warn", "never"],
+    "arrow-body-style": ["warn", "as-needed"],
+    "arrow-parens": ["warn", "as-needed"],
+    "arrow-spacing": "warn",
+    "brace-style": "warn",
+    "camelcase": "warn",
+    "comma-spacing": ["warn", {"after": true}],
+    "dot-notation": "warn",
+    "indent": ["warn", 2, {
+      "SwitchCase": 1,
+      "FunctionDeclaration": {"parameters": 1},
+      "MemberExpression": 1,
+      "CallExpression": {"arguments": 1}
+    }],
+    "key-spacing": ["warn", {"beforeColon": false, "afterColon": true, "mode": "minimum"}],
+    "keyword-spacing": "warn",
+    "no-console": "off",
+    "no-empty": "off",
+    "no-multi-spaces": "warn",
+    "no-redeclare": "off",
+    "no-restricted-globals": ["warn", "Promise"],
+    "no-trailing-spaces": "warn",
+    "no-undef": "error",
+    "no-unused-vars": ["warn", {"args": "none"}],
+    "padded-blocks": ["warn", "never"],
+    "object-curly-spacing": ["warn", "never"],
+    "quotes": ["warn", "single"],
+    "react/prop-types": "off",
+    "react/jsx-no-bind": "off",
+    "semi": ["warn", "always"],
+    "space-before-blocks": ["warn", "always"],
+    "space-before-function-paren": ["warn", "never"],
+    "space-in-parens": ["warn", "never"]
+  }
+}

.gitignore

@@ -1,2 +1,4 @@
 node_modules
 npm-debug.log
+*.sw*           # VIM temp files
+.DS_Store       # Mac desktop services store

build/test.js

@@ -4,7 +4,6 @@
 
 var mime = require('../mime');
 var assert = require('assert');
-var path = require('path');
 
 //
 // Test mime lookups
@@ -21,6 +20,24 @@ assert.equal('text/plain', mime.lookup('\\txt'));        // Windows, extension-l
 assert.equal('application/octet-stream', mime.lookup('text.nope')); // unrecognized
 assert.equal('fallback', mime.lookup('text.fallback', 'fallback')); // alternate default
 
+//
+// Test types that are known to have conflicting definitions but different facet priorities
+//
+
+assert.equal('application/octet-stream', mime.lookup('dmg'));
+assert.equal('application/bdoc', mime.lookup('bdoc'));
+assert.equal('application/octet-stream', mime.lookup('deb'));
+assert.equal('application/octet-stream', mime.lookup('iso'));
+assert.equal('application/octet-stream', mime.lookup('exe'));
+assert.equal('application/octet-stream', mime.lookup('exe'));
+assert.equal('application/octet-stream', mime.lookup('dll'));
+assert.equal('application/octet-stream', mime.lookup('msi'));
+assert.equal('application/vnd.palm', mime.lookup('pdb'));
+assert.equal('audio/mp3', mime.lookup('mp3'));
+assert.equal('audio/mp4', mime.lookup('m4a'));
+assert.equal('font/opentype', mime.lookup('otf'));
+assert.equal('image/bmp', mime.lookup('bmp'));
+
 //
 // Test extensions
 //

mime.js

@@ -1,6 +1,11 @@
-var path = require('path');
 var fs = require('fs');
 
+// If two types claim the same extension, we resolve the conflict by checking
+// facet precedence. https://tools.ietf.org/html/rfc6838#section-3
+// Facets listed here are in order of decreasing precedence
+var FACETS = ['vnd.', 'x-', 'prs.'];
+var FACET_RE = new RegExp('/(' + FACETS.join('|') + ')');
+
 function Mime() {
   // Map of extension -> mime type
   this.types = Object.create(null);
@@ -18,16 +23,27 @@ function Mime() {
  *
  * @param map (Object) type definitions
  */
-Mime.prototype.define = function (map) {
+Mime.prototype.define = function(map) {
   for (var type in map) {
     var exts = map[type];
+
     for (var i = 0; i < exts.length; i++) {
-      if (process.env.DEBUG_MIME && this.types[exts[i]]) {
-        console.warn((this._loading || "define()").replace(/.*\//, ''), 'changes "' + exts[i] + '" extension type from ' +
-          this.types[exts[i]] + ' to ' + type);
+      var ext = exts[i];
+      var found = this.types[ext];
+
+      // If there's already a type for this extension ...
+      if (found) {
+        var pri0 = FACETS.indexOf(FACET_RE.test(found) && RegExp.$1);
+        var pri1 = FACETS.indexOf(FACET_RE.test(type) && RegExp.$1);
+
+        if (process.env.DEBUG_MIME) console.warn('Type conflict for .' + ext +
+          ' (' + found + ' pri=' + pri0 + ', ' + type + ' pri=' + pri1 + ')');
+
+        // Prioritize based on facet precedence
+        if (pri0 <= pri1) continue;
       }
 
-      this.types[exts[i]] = type;
+      this.types[ext] = type;
     }
 
     // Default extension is the first one we encounter
@@ -48,9 +64,9 @@ Mime.prototype.define = function (map) {
 Mime.prototype.load = function(file) {
   this._loading = file;
   // Read file and split into lines
-  var map = {},
-      content = fs.readFileSync(file, 'ascii'),
-      lines = content.split(/[\r\n]+/);
+  var map = {};
+  var content = fs.readFileSync(file, 'ascii');
+  var lines = content.split(/[\r\n]+/);
 
   lines.forEach(function(line) {
     // Clean up whitespace/comments, and split into fields
@@ -69,7 +85,7 @@ Mime.prototype.load = function(file) {
 Mime.prototype.lookup = function(path, fallback) {
   var ext = path.replace(/.*[\.\/\\]/, '').toLowerCase();
 
-  return this.types[ext] || fallback || this.default_type;
+  return this.types[ext] || fallback || this.default_type; // eslint-disable-line camelcase
 };
 
 /**
@@ -87,7 +103,7 @@ var mime = new Mime();
 mime.define(require('./types.json'));
 
 // Default type
-mime.default_type = mime.lookup('bin');
+mime.default_type = mime.lookup('bin'); // eslint-disable-line camelcase
 
 //
 // Additional API specific to the default instance

package.json

@@ -21,7 +21,7 @@
     "mime-db": "^1.22.0"
   },
   "scripts": {
-    "prepublish": "node build/build.js > types.json",
+    "prepare": "node build/build.js > types.json",
     "test": "node build/test.js"
   },
   "keywords": [