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//
// Copyright (c) 2019 Open Whisper Systems. All rights reserved.
//
import Foundation
// ObjC compatible searcher
@objc class AnySearcher: NSObject {
private let searcher: Searcher<AnyObject>
public init(indexer: @escaping (AnyObject) -> String ) {
searcher = Searcher(indexer: indexer)
super.init()
}
@objc(item:doesMatchQuery:)
public func matches(item: AnyObject, query: String) -> Bool {
return searcher.matches(item: item, query: query)
}
}
// A generic searching class, configurable with an indexing block
public class Searcher<T> {
private let indexer: (T) -> String
public init(indexer: @escaping (T) -> String) {
self.indexer = indexer
}
public func matches(item: T, query: String) -> Bool {
let itemString = normalize(string: indexer(item))
return stem(string: query).map { queryStem in
return itemString.contains(queryStem)
}.reduce(true) { $0 && $1 }
}
private func stem(string: String) -> [String] {
var normalized = normalize(string: string)
// Remove any phone number formatting from the search terms
let nonformattingScalars = normalized.unicodeScalars.lazy.filter {
!CharacterSet.punctuationCharacters.contains($0)
}
normalized = String(String.UnicodeScalarView(nonformattingScalars))
return normalized.components(separatedBy: .whitespacesAndNewlines)
}
private func normalize(string: String) -> String {
return string.lowercased().trimmingCharacters(in: .whitespacesAndNewlines)
}
}