Files
sst/Sources/SstData/CorrectionEngine.swift

80 lines
3.3 KiB
Swift

import Foundation
import SstCore
/// Whole-word, case-insensitive, single-pass replacement. Longest match wins, replaced text is never rescanned.
public struct CorrectionEngine: TextCorrecting {
private struct Rule {
let source: String
let wrote: String
}
private let rules: [Rule]
private let regex: NSRegularExpression?
public init(entries: [DictionaryEntry], knowledge: WordKnowledge) {
var seen = Set<String>()
var built: [(rule: Rule, order: Int)] = []
for (order, entry) in entries.enumerated() {
let source = entry.source.trimmingCharacters(in: .whitespacesAndNewlines)
let key = EntryKey.key(source)
guard !key.isEmpty, !seen.contains(key) else { continue }
// A single-word term that is also a real word only biases the model; capitalising it everywhere would corrupt normal text.
if case .term(let term) = entry.kind, EntryKey.parts(term).count == 1, knowledge.isWord(term) { continue }
seen.insert(key)
built.append((Rule(source: source, wrote: entry.wrote), order))
}
let ordered = built.sorted { a, b in
let la = a.rule.source.filter(\.isLetter).count
let lb = b.rule.source.filter(\.isLetter).count
return la != lb ? la > lb : a.order < b.order
}.map(\.rule)
rules = ordered
if ordered.isEmpty {
regex = nil
} else {
let alternatives = ordered.map { "(\(Self.pattern($0.source)))" }.joined(separator: "|")
regex = try? NSRegularExpression(
pattern: "(?<![\\p{L}\\p{N}])(?:\(alternatives))(?![\\p{L}\\p{N}])",
options: [.caseInsensitive]
)
}
}
/// Parts joined by "zero or more spaces/hyphens", so "cloud code" also finds "cloudcode" and "Cloud-Code".
private static func pattern(_ source: String) -> String {
EntryKey.parts(source)
.map { NSRegularExpression.escapedPattern(for: $0) }
.joined(separator: "[\\s\\-‐‑–]*")
}
public func correct(_ text: String) -> CorrectionResult {
guard let regex, !text.isEmpty else { return CorrectionResult(text: text, corrections: []) }
let ns = text as NSString
var output = ""
var outputLength = 0
var last = 0
var applied: [AppliedCorrection] = []
for match in regex.matches(in: text, range: NSRange(location: 0, length: ns.length)) {
let gap = ns.substring(with: NSRange(location: last, length: match.range.location - last))
output += gap
outputLength += gap.utf16.count
let heard = ns.substring(with: match.range)
let group = (1..<match.numberOfRanges).first { match.range(at: $0).location != NSNotFound } ?? 1
let rule = rules[group - 1]
output += rule.wrote
if heard != rule.wrote {
applied.append(AppliedCorrection(
heard: heard, wrote: rule.wrote, rule: rule.source,
start: outputLength, length: rule.wrote.utf16.count))
}
outputLength += rule.wrote.utf16.count
last = match.range.location + match.range.length
}
output += ns.substring(from: last)
return CorrectionResult(text: output, corrections: applied)
}
}