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OpenGraphParser.swift
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OpenGraphParser.swift
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import Foundation
public protocol OpenGraphParser {
func parse(htmlString: String) -> [OpenGraphMetadata: String]
}
extension OpenGraphParser {
func parse(htmlString: String) -> [OpenGraphMetadata: String] {
// extract meta tag
let metatagRegex = try! NSRegularExpression(
pattern: "<meta(?:\".*?\"|\'.*?\'|[^\'\"])*?>",
options: [.dotMatchesLineSeparators]
)
let metaTagMatches = metatagRegex.matches(in: htmlString,
options: [],
range: NSMakeRange(0, htmlString.count))
if metaTagMatches.isEmpty {
return [:]
}
// prepare regular expressions to extract og property and content.
let propertyRegexp = try! NSRegularExpression(
pattern: "\\sproperty=(?:\"|\')*og:([a-zA_Z:]+)(?:\"|\')*",
options: []
)
let contentRegexp = try! NSRegularExpression(
pattern: "\\scontent=\\\\*?\"(.*?)\\\\*?\"",
options: []
)
// create attribute dictionary
let nsString = htmlString as NSString
let attributes = metaTagMatches.reduce([OpenGraphMetadata: String]()) { (attributes, result) -> [OpenGraphMetadata: String] in
var copiedAttributes = attributes
let property = { () -> (name: String, content: String)? in
let metaTag = nsString.substring(with: result.range(at: 0))
let propertyMatches = propertyRegexp.matches(in: metaTag,
options: [],
range: NSMakeRange(0, metaTag.count))
guard let propertyResult = propertyMatches.first else { return nil }
var contentMatches = contentRegexp.matches(in: metaTag, options: [], range: NSMakeRange(0, metaTag.count))
if contentMatches.first == nil {
let contentRegexp = try! NSRegularExpression(
pattern: "\\scontent=\\\\*?'(.*?)\\\\*?'",
options: []
)
contentMatches = contentRegexp.matches(in: metaTag, options: [], range: NSMakeRange(0, metaTag.count))
}
guard let contentResult = contentMatches.first else { return nil }
let nsMetaTag = metaTag as NSString
let property = nsMetaTag.substring(with: propertyResult.range(at: 1))
let content = nsMetaTag.substring(with: contentResult.range(at: 1)).stringByDecodingHTMLEntities
return (name: property, content: content)
}()
if let property = property, let metadata = OpenGraphMetadata(rawValue: property.name) {
copiedAttributes[metadata] = property.content
}
return copiedAttributes
}
return attributes
}
}