Start RSS-in-JSON parser.

Frameworks/RSParser/Feeds/FeedParser.swift

@@ -8,19 +8,65 @@
 
 import Foundation
 
+// FeedParser knows about the various syndication feed types.
+// It might be a good idea to do a plugin-style architecture here instead —
+// but feed formats don’t appear all that often, so it’s probably not necessary.
+
 public struct FeedParser {
 
-	static func feedType(parserData: ParserData) -> FeedType {
+	static let minNumberOfBytesRequired = 128
 
+	public static func feedType(parserData: ParserData) -> FeedType {
+
+		// Can call with partial data — while still downloading, for instance.
 		// If there’s not enough data, return .unknown. Ask again when there’s more data.
 		// If it’s definitely not a feed, return .notAFeed.
 
-		return .unknown //stub
+		if parserData.data.count < minNumberOfBytesRequired {
+			return .unknown
+		}
+
+		if parserData.data.isProbablyJSONFeed() {
+			return .jsonFeed
+		}
+		if parserData.data.isProbablyRSSInJSON() {
+			return .rssInJSON
+		}
+
+		if parserData.data.isProbablyHTML() {
+			return .notAFeed
+		}
+
+		if parserData.data.isProbablyRSS() {
+			return .rss
+		}
+		if parserData.data.isProbablyAtom() {
+			return .atom
+		}
+
+		return .notAFeed
 	}
 
-	static func parseFeed(parserData: ParserData) throws -> ParsedFeed? {
+	public static func parseFeed(parserData: ParserData) -> ParsedFeed? {
 
+		let type = feedType(parserData)
 
-		return nil //stub
+		switch type {
+
+		case .jsonFeed:
+			return JSONFeedParser.parse(parserData)
+
+		case .rssInJSON:
+			return RSSInJSONFeedParser.parse(parserData)
+
+		case .rss:
+			return RSSParser.parse(parserData)
+
+		case .atom:
+			return AtomParser.parser(parserData)
+
+		case .unknown, .notAFeed:
+			return nil
+		}
 	}
 }

Frameworks/RSParser/Feeds/FeedParserError.swift

@@ -0,0 +1,26 @@
+//
+//  FeedParserError.swift
+//  RSParser
+//
+//  Created by Brent Simmons on 6/24/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+import Foundation
+
+public struct FeedParserError: Error {
+
+	public enum FeedParserErrorType {
+
+		case rssChannelNotFound
+		case rssItemsNotFound
+
+	}
+
+	public let errorType: FeedParserErrorType
+
+	public init(_ errorType: FeedParserErrorType) {
+
+		self.errorType = errorType
+	}
+}

Frameworks/RSParser/Feeds/JSON/JSONTypes.swift

@@ -0,0 +1,12 @@
+//
+//  JSONDictionary.swift
+//  RSParser
+//
+//  Created by Brent Simmons on 6/24/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+import Foundation
+
+typealias JSONDictionary = [String: Any]
+typealias JSONArray = [JSONDictionary]

Frameworks/RSParser/Feeds/JSON/RSSInJSONParser.swift

@@ -0,0 +1,158 @@
+//
+//  RSSInJSONParser.swift
+//  RSParser
+//
+//  Created by Brent Simmons on 6/24/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+import Foundation
+
+// See https://github.com/scripting/Scripting-News/blob/master/rss-in-json/README.md
+// Also: http://cyber.harvard.edu/rss/rss.html
+
+public struct RSSInJSONParser {
+
+	public static func parse(parserData: ParserData) throws -> ParsedFeed? {
+
+		do {
+			let parsedObject = try JSONSerialization.jsonObject(with: parserData.data)
+
+			guard let channelObject = parsedObject["channel"] as? JSONDictionary else {
+				throw FeedParserError(.rssChannelNotFound)
+			}
+
+			// I’d bet money that in practice the items array won’t always appear correctly inside the channel object.
+			// I’d also bet that sometimes it gets called "items" instead of "item".
+			var itemsObject = channelObject["item"] as? JSONArray
+			if itemsObject == nil {
+				itemsObject = parsedObject["item"] as? JSONArray
+			}
+			if itemsObject == nil {
+				itemsObject = channelObject["items"] as? JSONArray
+			}
+			if itemsObject == nil {
+				itemsObject == parsedObject["items"] as? JSONArray
+			}
+			if itemsObject == nil {
+				throw FeedParserError(.rssItemsNotFound)
+			}
+
+			let title = channelObject["title"] as? String
+			let homePageURL = channelObject["link"] as? String
+			let feedURL = parserData.url
+			let feedDescription = channelObject["description"] as? String
+
+			let items = parseItems(itemsObject)
+
+			return ParsedFeed(type: .rssInJSON, title: title, homePageURL: homePageURL, feedURL: feedURL, feedDescription: feedDescription, nextURL: nil, iconURL: nil, faviconURL: nil, authors: nil, expired: false, hubs: nil, items: items)
+
+		}
+		catch { throw error }
+	}
+
+}
+
+private extension RSSInJSONParser {
+
+	static func parseItems(_ itemsObject: JSONArray) -> [ParsedItem] {
+
+		return itemsObject.flatMap{ (oneItemDictionary) -> ParsedItem in
+
+			return parsedItemWithDictionary(oneItemDictionary)
+		}
+	}
+
+	static func parsedItemWithDictionary(_ JSONDictionary: itemDictionary) -> ParsedItem? {
+
+		let externalURL = itemDictionary["link"] as? String
+		let title = itemDictionary["title"] as? String
+
+		var contentHTML = itemDictionary["description"] as? String
+		var contentText = nil
+		if contentHTML != nil && !(contentHTML!.contains("<")) {
+			contentText = contentHTML
+			contentHTML = nil
+		}
+		if contentHTML == nil && contentText == nil && title == nil {
+			return nil
+		}
+
+		var datePublished: Date = nil
+		if let datePublishedString = itemDictionary["pubDate"] as? String {
+			datePublished = RSDateWithString(datePublishedString as NSString)
+		}
+
+		let authorEmailAddress = itemDictionary["author"] as? String
+		var authors: [ParsedAuthor] = nil
+		if authorEmailAddress != nil {
+			let parsedAuthor = ParsedAuthor(name: nil, url: nil, avatarURL: nil, emailAddress: authorEmailAddress)
+			authors = [parsedAuthor]
+		}
+
+		var tags: [String]? = nil
+		if let categoryObject = itemDictionary["category"] as? JSONDictionary {
+			if let oneTag = categoryObject["#value"] {
+				tags = [oneTag]
+			}
+		}
+		else if let categoryArray = itemDictionary["category"] as? JSONArray {
+			tags = categoryArray.flatMap{ (oneCategoryDictionary) in
+				return oneCategoryDictionary["#value"]
+			}
+		}
+
+		var attachments: [ParsedAttachment]? = nil
+		if let enclosureObject = itemDictionary["enclosure"] as? JSONDictionary {
+			if let attachmentURL = enclosureObject["url"] as? String {
+				var attachmentSize = enclosureObject["length"] as? Int
+				if attachmentSize == nil {
+					if let attachmentSizeString = enclosureObject["length"] as? String {
+						attachmentSize = (attachmentSizeString as NSString).integerValue
+					}
+				}
+				let type = enclosureObject["type"] as? String
+				let oneAttachment = ParsedAttachment(url: attachmentURL, mimeType: type, title: nil, sizeInBytes: attachmentSize, durationInSeconds: nil)
+				attachments = [oneAttachment]
+			}
+		}
+
+		var uniqueID: String? = itemDictionary["guid"] as? String
+		if uniqueID == nil {
+
+			// Calculate a uniqueID based on a combination of non-empty elements. Then hash the result.
+			// Items should have guids. When they don't, re-runs are very likely
+			// because there's no other 100% reliable way to determine identity.
+			// This calculated uniqueID is valid only for this particular feed. (Just like ids in JSON Feed.)
+
+			var s = ""
+			if let datePublished = datePublished {
+				s += "\(datePublished.timeIntervalSince1970)"
+			}
+			if let title = title {
+				s += title
+			}
+			if let externalURL = externalURL {
+				s += externalURL
+			}
+			if let authorEmailAddress = authorEmailAddress {
+				s += authorEmailAddress
+			}
+			if let oneAttachmentURL = attachments?.first?.url {
+				s += oneAttachmentURL
+			}
+			if s.isEmpty {
+				// Sheesh. Tough case.
+				if contentHTML != nil {
+					s = contentHTML
+				}
+				if contentText != nil {
+					s = contentText
+				}
+			}
+			uniqueID = (s as NSString).rsxml_md5HashString()
+		}
+
+		return ParsedItem(uniqueID: uniqueID, url: nil, externalURL: externalURL, title: title, contentHTML: contentHTML, contentText: contentText, summary: nil, imageURL: nil, bannerImageURL: nil, datePublished: datePublished, dateModified: nil, authors: authors, tags: tags, attachments: attachments)
+	}
+}

Frameworks/RSParser/Feeds/ParsedAttachment.swift

@@ -15,4 +15,13 @@ public struct ParsedAttachment {
 	public let title: String?
 	public let sizeInBytes: Int?
 	public let durationInSeconds: Int?
+
+	init(url: String?, mimeType: String?, title: String?, sizeInBytes: Int?, durationInSeconds: Int?) {
+
+		self.url = url
+		self.mimeType = mimeType
+		self.title = title
+		self.sizeInBytes = sizeInBytes
+		self.durationInSeconds = durationInSeconds
+	}
 }

Frameworks/RSParser/Feeds/ParsedAuthor.swift

@@ -14,4 +14,12 @@ public struct ParsedAuthor {
 	public let url: String?
 	public let avatarURL: String?
 	public let emailAddress: String?
+
+	init(name: String?, url: String?, avatarURL: String?, emailAddress: String?) {
+
+		self.name = name
+		self.url = url
+		self.avatarURL = avatarURL
+		self.emailAddress = emailAddress
+	}
 }

Frameworks/RSParser/Feeds/ParsedFeed.swift

@@ -22,4 +22,21 @@ public struct ParsedFeed {
 	public let expired: Bool
 	public let hubs: [ParsedHub]?
 	public let items: [ParsedItem]
+
+	init(type: FeedType, title: String?, homePageURL: String?, feedURL: String?, feedDescription: String?, nextURL: String?, iconURL: String?, faviconURL: String?, authors: [ParsedAuthor]?, expired: Bool, hubs: [ParsedHub]?, items:[ParsedItem]) {
+
+		self.type = type
+		self.title = title
+		self.homePageURL = homePageURL
+		self.feedURL = feedURL
+		self.feedDescription = feedDescription
+		self.nextURL = nextURL
+		self.iconURL = iconURL
+		self.faviconURL = faviconURL
+		self.authors = authors
+		self.expired = expired
+		self.hubs = hubs
+		self.items = items
+	}
 }
+

Frameworks/RSParser/Feeds/ParsedItem.swift

@@ -24,4 +24,23 @@ public struct ParsedItem {
 	public let authors: [ParsedAuthor]?
 	public let tags: [String]?
 	public let attachments: [ParsedAttachment]?
+
+	init(uniqueID: String?, url: String?, externalURL: String?, title: String?, contentHTML: String?, contentText: String?, summary: String?, imageURL: String?, bannerImageURL: String?, datePublished: Date?, dateModified: Date?, authors: [ParsedAuthor]?, tags: [String]?, attachments: [ParsedAttachment]?) {
+
+		self.uniqueID = uniqueID
+		self.url = url
+		self.externalURL = externalURL
+		self.title = title
+		self.contentHTML = contentHTML
+		self.contentText = contentText
+		self.summary = summary
+		self.imageURL = imageURL
+		self.bannerImageURL = bannerImageURL
+		self.datePublished = datePublished
+		self.dateModified = dateModified
+		self.authors = authors
+		self.tags = tags
+		self.attachments = attachments
+	}
 }
+

Frameworks/RSParser/RSParser.h

@@ -8,6 +8,8 @@
 
 @import Foundation;
 
+#import <RSParser/NSData+RSParser.h>
+#import <RSParser/RSParser.h>
 
 //#import <RSXML/RSSAXParser.h>
 //#import <RSXML/RSXMLData.h>

Frameworks/RSParser/RSParser.xcodeproj/project.pbxproj

@@ -45,6 +45,11 @@
 		84469D2F1EFA3134004A6B28 /* RSRSSParser.h in Headers */ = {isa = PBXBuildFile; fileRef = 84469D251EFA3134004A6B28 /* RSRSSParser.h */; };
 		84469D301EFA3134004A6B28 /* RSRSSParser.m in Sources */ = {isa = PBXBuildFile; fileRef = 84469D261EFA3134004A6B28 /* RSRSSParser.m */; };
 		84469D321EFA31CF004A6B28 /* FeedParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84469D311EFA31CF004A6B28 /* FeedParser.swift */; };
+		84469D351EFF1190004A6B28 /* NSData+RSParser.h in Headers */ = {isa = PBXBuildFile; fileRef = 84469D331EFF1190004A6B28 /* NSData+RSParser.h */; };
+		84469D361EFF1190004A6B28 /* NSData+RSParser.m in Sources */ = {isa = PBXBuildFile; fileRef = 84469D341EFF1190004A6B28 /* NSData+RSParser.m */; };
+		84469D381EFF2645004A6B28 /* RSSInJSONParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84469D371EFF2645004A6B28 /* RSSInJSONParser.swift */; };
+		84469D401EFF29A9004A6B28 /* FeedParserError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84469D3F1EFF29A9004A6B28 /* FeedParserError.swift */; };
+		84469D421EFF2B2D004A6B28 /* JSONTypes.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84469D411EFF2B2D004A6B28 /* JSONTypes.swift */; };
 		84D81BDC1EFA28E700652332 /* RSParser.h in Headers */ = {isa = PBXBuildFile; fileRef = 84D81BDA1EFA28E700652332 /* RSParser.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		84D81BDE1EFA2B7D00652332 /* ParsedFeed.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84D81BDD1EFA2B7D00652332 /* ParsedFeed.swift */; };
 		84D81BE01EFA2BAE00652332 /* FeedType.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84D81BDF1EFA2BAE00652332 /* FeedType.swift */; };
@@ -105,6 +110,11 @@
 		84469D251EFA3134004A6B28 /* RSRSSParser.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RSRSSParser.h; sourceTree = "<group>"; };
 		84469D261EFA3134004A6B28 /* RSRSSParser.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RSRSSParser.m; sourceTree = "<group>"; };
 		84469D311EFA31CF004A6B28 /* FeedParser.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = FeedParser.swift; path = Feeds/FeedParser.swift; sourceTree = "<group>"; };
+		84469D331EFF1190004A6B28 /* NSData+RSParser.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSData+RSParser.h"; sourceTree = "<group>"; };
+		84469D341EFF1190004A6B28 /* NSData+RSParser.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "NSData+RSParser.m"; sourceTree = "<group>"; };
+		84469D371EFF2645004A6B28 /* RSSInJSONParser.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = RSSInJSONParser.swift; path = Feeds/JSON/RSSInJSONParser.swift; sourceTree = "<group>"; };
+		84469D3F1EFF29A9004A6B28 /* FeedParserError.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = FeedParserError.swift; path = Feeds/FeedParserError.swift; sourceTree = "<group>"; };
+		84469D411EFF2B2D004A6B28 /* JSONTypes.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = JSONTypes.swift; path = Feeds/JSON/JSONTypes.swift; sourceTree = "<group>"; };
 		84D81BD91EFA28E700652332 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		84D81BDA1EFA28E700652332 /* RSParser.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RSParser.h; sourceTree = "<group>"; };
 		84D81BDD1EFA2B7D00652332 /* ParsedFeed.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = ParsedFeed.swift; path = Feeds/ParsedFeed.swift; sourceTree = "<group>"; };
@@ -148,6 +158,8 @@
 				84D81BE31EFA2D3D00652332 /* ParsedItem.swift */,
 				84D81BE51EFA2DFB00652332 /* ParsedAttachment.swift */,
 				84D81BE71EFA2E6700652332 /* ParsedHub.swift */,
+				84469D3F1EFF29A9004A6B28 /* FeedParserError.swift */,
+				84469D391EFF2649004A6B28 /* JSON */,
 				84469D1C1EFA3134004A6B28 /* XML */,
 			);
 			name = Feeds;
@@ -197,6 +209,8 @@
 		84469D0F1EFA30A2004A6B28 /* Utilities */ = {
 			isa = PBXGroup;
 			children = (
+				84469D331EFF1190004A6B28 /* NSData+RSParser.h */,
+				84469D341EFF1190004A6B28 /* NSData+RSParser.m */,
 				84469D101EFA30A2004A6B28 /* NSString+RSXML.h */,
 				84469D111EFA30A2004A6B28 /* NSString+RSXML.m */,
 				84469D121EFA30A2004A6B28 /* RSDateParser.h */,
@@ -225,6 +239,15 @@
 			path = Feeds/XML;
 			sourceTree = "<group>";
 		};
+		84469D391EFF2649004A6B28 /* JSON */ = {
+			isa = PBXGroup;
+			children = (
+				84469D411EFF2B2D004A6B28 /* JSONTypes.swift */,
+				84469D371EFF2645004A6B28 /* RSSInJSONParser.swift */,
+			);
+			name = JSON;
+			sourceTree = "<group>";
+		};
 		84FF5F7A1EFA285800C15A01 = {
 			isa = PBXGroup;
 			children = (
@@ -273,6 +296,7 @@
 				84469D2D1EFA3134004A6B28 /* RSParsedFeed.h in Headers */,
 				84469D181EFA30A2004A6B28 /* RSDateParser.h in Headers */,
 				84469D1A1EFA30A2004A6B28 /* RSXMLInternal.h in Headers */,
+				84469D351EFF1190004A6B28 /* NSData+RSParser.h in Headers */,
 				84D81BDC1EFA28E700652332 /* RSParser.h in Headers */,
 				84469D0B1EFA307E004A6B28 /* RSHTMLMetadataParser.h in Headers */,
 				84469CFC1EFA3069004A6B28 /* RSSAXParser.h in Headers */,
@@ -392,6 +416,7 @@
 				84469D0E1EFA307E004A6B28 /* RSSAXHTMLParser.m in Sources */,
 				84469CF41EFA3000004A6B28 /* RSOPMLFeedSpecifier.m in Sources */,
 				84469CF01EFA3000004A6B28 /* RSOPMLAttributes.m in Sources */,
+				84469D381EFF2645004A6B28 /* RSSInJSONParser.swift in Sources */,
 				84469D301EFA3134004A6B28 /* RSRSSParser.m in Sources */,
 				84469D191EFA30A2004A6B28 /* RSDateParser.m in Sources */,
 				84469CFD1EFA3069004A6B28 /* RSSAXParser.m in Sources */,
@@ -400,14 +425,17 @@
 				84469CF61EFA3000004A6B28 /* RSOPMLItem.m in Sources */,
 				84469D2A1EFA3134004A6B28 /* RSFeedParser.m in Sources */,
 				84D81BE41EFA2D3D00652332 /* ParsedItem.swift in Sources */,
+				84469D421EFF2B2D004A6B28 /* JSONTypes.swift in Sources */,
 				84469D0C1EFA307E004A6B28 /* RSHTMLMetadataParser.m in Sources */,
 				84469D0A1EFA307E004A6B28 /* RSHTMLMetadata.m in Sources */,
 				84469D171EFA30A2004A6B28 /* NSString+RSXML.m in Sources */,
 				84469D2C1EFA3134004A6B28 /* RSParsedArticle.m in Sources */,
 				84469D2E1EFA3134004A6B28 /* RSParsedFeed.m in Sources */,
 				84469CF81EFA3000004A6B28 /* RSOPMLParser.m in Sources */,
+				84469D401EFF29A9004A6B28 /* FeedParserError.swift in Sources */,
 				84469D321EFA31CF004A6B28 /* FeedParser.swift in Sources */,
 				84469D281EFA3134004A6B28 /* RSAtomParser.m in Sources */,
+				84469D361EFF1190004A6B28 /* NSData+RSParser.m in Sources */,
 				84D81BE61EFA2DFB00652332 /* ParsedAttachment.swift in Sources */,
 				84D81BDE1EFA2B7D00652332 /* ParsedFeed.swift in Sources */,
 				84D81BE81EFA2E6700652332 /* ParsedHub.swift in Sources */,

Frameworks/RSParser/Utilities/NSData+RSParser.h

@@ -0,0 +1,21 @@
+//
+//  NSData+RSParser.h
+//  RSParser
+//
+//  Created by Brent Simmons on 6/24/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+@import Foundation;
+
+
+@interface NSData (RSParser)
+
+- (BOOL)isProbablyHTML;
+- (BOOL)isProbablyXML;
+- (BOOL)isProbablyJSON;
+
+@end
+
+
+

Frameworks/RSParser/Utilities/NSData+RSParser.m

@@ -0,0 +1,132 @@
+//
+//  NSData+RSParser.m
+//  RSParser
+//
+//  Created by Brent Simmons on 6/24/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+#import "NSData+RSParser.h"
+
+/* TODO: find real-world cases where the isProbably* cases fail when they should succeed, and add them to tests.*/
+
+static BOOL bytesAreProbablyHTML(const char *bytes, NSUInteger numberOfBytes);
+static BOOL bytesAreProbablyXML(const char *bytes, NSUInteger numberOfBytes);
+static BOOL bytesStartWithStringIgnoringWhitespace(const char *string, const char *bytes, NSUInteger numberOfBytes);
+
+@implementation NSData (RSParser)
+
+- (BOOL)isProbablyHTML {
+
+	return bytesAreProbablyHTML(self.bytes, self.length);
+}
+
+- (BOOL)isProbablyXML {
+
+	return bytesAreProbablyXML(self.bytes, self.length);
+}
+
+- (BOOL)isProbablyJSON {
+
+	return bytesStartWithStringIgnoringWhitespace("{", self.bytes, self.length);
+}
+
+- (BOOL)isProbablyJSONFeed {
+
+	if (![self isProbablyJSON]) {
+		return NO;
+	}
+	return didFindString("https://jsonfeed.org/version/", self.bytes, self.length);
+}
+
+- (BOOL)isProbablyRSSInJSONFeed {
+
+	if (![self isProbablyJSON]) {
+		return NO;
+	}
+	const char *bytes = self.bytes;
+	NSUInteger length = self.length;
+	return didFindString("rss", bytes, length) && didFindString("channel", bytes, length) && didFindString("item", bytes, length);
+}
+
+- (BOOL)isProbablyRSS {
+
+	if (![self isProbablyXML]) {
+		return NO;
+	}
+
+	return didFindString("<rss", bytes, length);
+}
+
+- (BOOL)isProbablyAtom {
+
+	if (![self isProbablyXML]) {
+		return NO;
+	}
+
+	return didFindString("<feed", bytes, length);
+}
+
+@end
+
+
+static BOOL didFindString(const char *string, const char *bytes, NSUInteger numberOfBytes) {
+
+	char *foundString = strnstr(bytes, string, numberOfBytes);
+	return foundString != NULL;
+}
+
+static BOOL bytesStartWithStringIgnoringWhitespace(const char *string, const char *bytes, NSUInteger numberOfBytes) {
+
+	NSUInteger i = 0;
+	for (i = 0; i < numberOfBytes; i++) {
+
+		const char *ch = bytes[i];
+		if (ch == ' ' || ch = '\r' || ch == '\n' || ch == '\t') {
+			continue;
+		}
+
+		if (ch == string[0]) {
+			return strnstr(bytes, string, numberOfBytes) == bytes + i;
+		}
+		break;
+	}
+	return NO;
+}
+
+static BOOL bytesAreProbablyHTML(const char *bytes, NSUInteger numberOfBytes) {
+
+	if (didFindString("<html", bytes, numberOfBytes)) {
+		return YES;
+	}
+	if (didFindString("<HTML", bytes, numberOfBytes)) {
+		return YES;
+	}
+
+	if (didFindString("<body", bytes, numberOfBytes)) {
+		return YES;
+	}
+	if (didFindString("<meta", bytes, numberOfBytes)) {
+		return YES;
+	}
+
+	if (didFindString("<", bytes, numberOfBytes) {
+		if (didFindString("doctype html", bytes, numberOfBytes)) {
+			return YES;
+		}
+		if (didFindString("DOCTYPE html", bytes, numberOfBytes)) {
+			return YES;
+		}
+		if (didFindString("DOCTYPE HTML", bytes, numberOfBytes)) {
+			return YES;
+		}
+	}
+
+	return NO;
+}
+
+static BOOL bytesAreProbablyXML(const char *bytes, NSUInteger numberOfBytes) {
+
+	return bytesStartWithStringIgnoringWhiteSpace("<?xml", bytes, numberOfBytes);
+}
+