Add explicit disallow feature (#36)

* add explicit disallow feature isExplictlyDisallowed()

Author: SimonC-Audigent

Diff for: README.md

@@ -6,7 +6,7 @@ The parser currently supports:
 
 -   User-agent:
 -   Allow:
--   Disallow:
+-   Disallow (with explicit mode support):
 -   Sitemap:
 -   Crawl-delay:
 -   Host:
@@ -41,6 +41,7 @@ var robots = robotsParser('http://www.example.com/robots.txt', [
 robots.isAllowed('http://www.example.com/test.html', 'Sams-Bot/1.0'); // true
 robots.isAllowed('http://www.example.com/dir/test.html', 'Sams-Bot/1.0'); // true
 robots.isDisallowed('http://www.example.com/dir/test2.html', 'Sams-Bot/1.0'); // true
+robots.isExplicitlyDisallowed('http://www.example.com/dir/test2.html', 'Sams-Bot/1.0'); // false
 robots.getCrawlDelay('Sams-Bot/1.0'); // 1
 robots.getSitemaps(); // ['http://example.com/sitemap.xml']
 robots.getPreferredHost(); // example.com
@@ -62,6 +63,13 @@ Returns true if crawling the specified URL is not allowed for the specified user
 
 This will return `undefined` if the URL isn't valid for this robots.txt.
 
+### isExplicitlyDisallowed(url, ua)
+
+**boolean or undefined**
+
+Returns trues if explicitly disallowed for the specified user agent (User Agent wildcards are discarded).
+
+This will return undefined if the URL is not valid for this robots.txt file.
 ### getMatchingLineNumber(url, [ua])
 
 **number or undefined**

Diff for: Robots.js

@@ -361,7 +361,7 @@ Robots.prototype.setPreferredHost = function (url) {
 	this._preferredHost = url;
 };
 
-Robots.prototype._getRule = function (url, ua) {
+Robots.prototype._getRule = function (url, ua, explicit) {
 	var parsedUrl = parseUrl(url) || {};
 	var userAgent = formatUserAgent(ua || '*');
 
@@ -374,7 +374,12 @@ Robots.prototype._getRule = function (url, ua) {
 		return;
 	}
 
-	var rules = this._rules[userAgent] || this._rules['*'] || [];
+	var rules = this._rules[userAgent];
+	if (!explicit) {
+		rules = rules || this._rules['*']
+	}
+	rules = rules || []
+
 	var path = urlEncodeToUpper(parsedUrl.pathname + parsedUrl.search);
 	var rule = findRule(path, rules);
 
@@ -392,7 +397,7 @@ Robots.prototype._getRule = function (url, ua) {
  * @return {boolean?}
  */
 Robots.prototype.isAllowed = function (url, ua) {
-	var rule = this._getRule(url, ua);
+	var rule = this._getRule(url, ua, false);
 
 	if (typeof rule === 'undefined') {
 		return;
@@ -416,7 +421,7 @@ Robots.prototype.isAllowed = function (url, ua) {
  * @return {number?}
  */
 Robots.prototype.getMatchingLineNumber = function (url, ua) {
-	var rule = this._getRule(url, ua);
+	var rule = this._getRule(url, ua, false);
 
 	return rule ? rule.lineNumber : -1;
 };
@@ -425,13 +430,30 @@ Robots.prototype.getMatchingLineNumber = function (url, ua) {
  * Returns the opposite of isAllowed()
  *
  * @param  {string}  url
- * @param  {string}  ua
+ * @param  {string?}  ua
  * @return {boolean}
  */
 Robots.prototype.isDisallowed = function (url, ua) {
 	return !this.isAllowed(url, ua);
 };
 
+/**
+ * Returns trues if explicitly disallowed 
+ * for the specified user agent (User Agent wildcards are discarded).
+ * 
+ * This will return undefined if the URL is not valid for this robots.txt file.
+ * @param  {string}  url
+ * @param  {string}  ua
+ * @return {boolean?}
+ */
+Robots.prototype.isExplicitlyDisallowed = function(url, ua) {	
+	var rule = this._getRule(url, ua, true);
+	if (typeof rule === 'undefined') {
+		return true;
+	}
+	return !(!rule || rule.allow);
+}
+
 /**
  * Gets the crawl delay if there is one.
  *

Diff for: index.d.ts

@@ -3,6 +3,7 @@ declare module 'robots-parser';
 interface Robot {
 	isAllowed(url: string, ua?: string): boolean | undefined;
 	isDisallowed(url: string, ua?: string): boolean | undefined;
+	isExplicitlyDisallowed(url: string, ua: string): boolean | undefined;
 	getMatchingLineNumber(url: string, ua?: string): number;
 	getCrawlDelay(ua?: string): number | undefined;
 	getSitemaps(): string[];

Diff for: test/Robots.js

@@ -861,4 +861,30 @@ describe('Robots', function () {
 
 		testRobots('https://www.example.com/robots.txt', contents, allowed, disallowed);
 	});
+
+	it('should not be disallowed when wildcard is used in explicit mode', function () {
+		var contents = [
+			'User-agent: *',
+			'Disallow: /',
+		].join('\n')
+
+		var url = 'https://www.example.com/hello'
+		var userAgent = 'SomeBot';
+		var robots = robotsParser(url, contents);
+
+		expect(robots.isExplicitlyDisallowed(url, userAgent)).to.equal(false)
+	})
+
+	it('should be disallowed when user agent equal robots rule in explicit mode', function () {
+		var contents = [
+			'User-agent: SomeBot',
+			'Disallow: /',
+		].join('\n')
+
+		var url = 'https://www.example.com/hello'
+		var userAgent = 'SomeBot';
+		var robots = robotsParser(url, contents);
+		
+		expect(robots.isExplicitlyDisallowed(url, userAgent)).to.equal(true)
+	})
 });