86 lines
2.0 KiB
Swift
86 lines
2.0 KiB
Swift
//
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// FeedParser.swift
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// RSParser
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//
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// Created by Brent Simmons on 6/20/17.
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// Copyright © 2017 Ranchero Software, LLC. All rights reserved.
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//
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import Foundation
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// FeedParser handles the various syndication feed types.
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// It might be a good idea to do a plugin-style architecture here instead —
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// but feed formats don’t appear all that often, so it’s probably not necessary.
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public struct FeedParser {
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static let minNumberOfBytesRequired = 128
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public static func feedType(_ parserData: ParserData) -> FeedType {
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// Can call with partial data — while still downloading, for instance.
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// If there’s not enough data, return .unknown. Ask again when there’s more data.
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// If it’s definitely not a feed, return .notAFeed.
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//
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// This should be fast enough to call on the main thread.
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if parserData.data.count < minNumberOfBytesRequired {
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return .unknown
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}
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let nsdata = parserData.data as NSData
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if nsdata.isProbablyJSONFeed() {
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return .jsonFeed
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}
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if nsdata.isProbablyRSSInJSON() {
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return .rssInJSON
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}
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if nsdata.isProbablyHTML() {
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return .notAFeed
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}
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if nsdata.isProbablyRSS() {
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return .rss
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}
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if nsdata.isProbablyAtom() {
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return .atom
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}
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return .notAFeed
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}
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public static func parseFeed(_ parserData: ParserData) throws -> ParsedFeed? {
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// All the concrete parsers return a ParsedFeed struct.
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// Related: ParsedItem, ParsedAuthor, ParsedHub, ParsedAttachment.
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//
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// This is probably fast enough to call on the main thread —
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// but it’s probably a good idea to use a background queue if
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// you might be doing a lot of parsing. (Such as in a feed reader.)
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do {
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let type = feedType(parserData)
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switch type {
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case .jsonFeed:
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return try JSONFeedParser.parse(parserData)
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case .rssInJSON:
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return try RSSInJSONParser.parse(parserData)
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case .rss:
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return RSSParser.parse(parserData)
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case .atom:
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return AtomParser.parse(parserData)
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case .unknown, .notAFeed:
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return nil
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}
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}
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catch { throw error }
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}
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}
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