69 lines
2.7 KiB
Swift
69 lines
2.7 KiB
Swift
import Foundation
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final class RDEPUBTextSearchEngine: RDEPUBSearchEngine {
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private let textBook: RDEPUBTextBook
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private let publication: RDEPUBPublication
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init(textBook: RDEPUBTextBook, publication: RDEPUBPublication) {
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self.textBook = textBook
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self.publication = publication
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}
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func search(keyword: String) -> [RDEPUBSearchMatch] {
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let normalizedKeyword = keyword.trimmingCharacters(in: .whitespacesAndNewlines)
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guard !normalizedKeyword.isEmpty else {
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return []
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}
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var matches: [RDEPUBSearchMatch] = []
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for chapter in textBook.chapters {
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let source = chapter.attributedContent.string as NSString
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let fullLength = source.length
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guard fullLength > 0 else {
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continue
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}
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let normalizedHref = publication.resourceResolver.normalizedHref(chapter.href) ?? chapter.href
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var localMatchIndex = 0
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var searchRange = NSRange(location: 0, length: fullLength)
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while searchRange.length > 0 {
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let foundRange = source.range(of: normalizedKeyword, options: [.caseInsensitive], range: searchRange)
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guard foundRange.location != NSNotFound else {
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break
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}
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let progressionDenominator = max(fullLength - 1, 1)
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let progression = Double(foundRange.location) / Double(progressionDenominator)
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matches.append(
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RDEPUBSearchMatch(
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href: normalizedHref,
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progression: progression,
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previewText: previewText(in: source, matchRange: foundRange),
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localMatchIndex: localMatchIndex,
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rangeLocation: foundRange.location,
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rangeLength: foundRange.length
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)
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)
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localMatchIndex += 1
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let nextLocation = foundRange.location + max(foundRange.length, 1)
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if nextLocation >= fullLength {
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break
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}
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searchRange = NSRange(location: nextLocation, length: fullLength - nextLocation)
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}
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}
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return matches
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}
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private func previewText(in text: NSString, matchRange: NSRange) -> String {
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let previewRadius = 12
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let start = max(matchRange.location - previewRadius, 0)
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let end = min(matchRange.location + matchRange.length + previewRadius, text.length)
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let range = NSRange(location: start, length: max(end - start, 0))
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return text.substring(with: range).trimmingCharacters(in: .whitespacesAndNewlines)
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}
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}
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