Sort search results by name and version

Sources/apk/Common/ApkVersionReader.swift

@@ -0,0 +1,200 @@
+/*
+ * darwin-apk © 2024 Gay Pizza Specifications
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+internal struct ApkVersionReader {
+  var string: Substring
+  private var seen: TokenFlag, last: TokenFlag
+
+  init(_ string: Substring) {
+    self.string = string
+    self.seen = []
+    self.last = []
+  }
+
+  mutating func next() throws(Invalid) -> TokenPart {
+    self.seen.formUnion(self.last)
+
+    switch string.first ?? "\0" {
+    case "a"..."z":  // Letter suffix
+      guard self.seen.contains(.initial),
+          self.last.isDisjoint(with: [ .letter, .suffix, .suffixNumber, .commitHash, .revision ]) else {
+        throw .invalid
+      }
+      self.last = .letter
+      return .letter(self.advance())
+    case ".":  // Version separator
+      guard self.seen.contains(.initial), self.last.contains(.digit) else {
+        throw .invalid
+      }
+      self.advance()
+      fallthrough
+    case "0"..."9":  // Numeric component
+      guard self.last.isSubset(of: [ .initial, .digit, .suffix ]),
+          let (number, numString) = self.readNumber() else {
+        throw .invalid
+      }
+      if self.last == .suffix {
+        self.last = .suffixNumber
+        return .suffixNumber(number)
+      } else {
+        self.last = .digit
+        if !self.seen.contains(.initial) {
+          self.last.insert(.initial)
+          return .digit(number, nil)
+        } else {
+          // Numeric digits that aren't initial might be compared as a string instead
+          return .digit(number, numString)
+        }
+      }
+    case "_":  // Suffix
+      guard self.seen.contains(.initial), self.seen.isDisjoint(with: [ .commitHash, .revision ]) else {
+        throw .invalid
+      }
+      self.advance()
+      guard let suffix = self.readVersionSuffix() else {
+        throw .invalid
+      }
+      self.last = .suffix
+      return .suffix(suffix)
+    case "~":  // Commit hash
+      guard self.seen.contains(.initial), self.seen.isDisjoint(with: [ .commitHash, .revision ]) else {
+        throw .invalid
+      }
+      self.advance()
+      let end = self.string.firstIndex(where: { !$0.isHexDigit }) ?? self.string.endIndex
+      let hex = self.advance(end)
+      guard self.string.isEmpty else {  // Commit hash should take the rest of string
+        throw .invalid
+      }
+      self.last = .commitHash
+      return .commitHash(hex)
+    case "-":  // Package revision
+      guard self.seen.contains(.initial), self.seen.isDisjoint(with: .revision),
+          self.advance(2) == "-r",
+          let (number, _) = self.readNumber() else {
+        throw .invalid
+      }
+      self .last = .revision
+      return .revision(number)
+    case "\0":  // End of version string
+      guard self.seen.contains(.initial) else {
+        throw .invalid
+      }
+      return .end
+    default:
+      throw .invalid
+    }
+  }
+
+  //MARK: - Private Implementation
+
+  private mutating func readNumber() -> (UInt, Substring)? {
+    // Hacky and awful but seems to be the fastest way to get numeric token length
+    let digits = self.string.withCString {
+      var i = 0
+      while 48...57 ~= $0[i] {  // isnumber(Int32($0[i])) != 0
+        i += 1
+      }
+      return i
+    }
+    let end = self.string.index(self.string.startIndex, offsetBy: digits)
+    let string = self.string[..<end]
+    self.string = self.string[end...]
+    guard !string.isEmpty, let result = UInt(string, radix: 10) else {
+      return nil
+    }
+    return (result, string)
+  }
+
+  private mutating func readVersionSuffix() -> VersionSuffix? {
+    let end = self.string.firstIndex(where: { !$0.isLowercase }) ?? self.string.endIndex
+    let suffix = self.advance(end)
+    return switch suffix.first {  // TODO: Should this matching be stricter?
+    case "a": .alpha
+    case "b": .beta
+    case "c": .cvs
+    case "g": .git
+    case "h": .hg
+    case "p": suffix.count == 1 ? .p : .pre
+    case "r": .rc
+    case "s": .svn
+    default: nil
+    }
+  }
+
+  @discardableResult
+  private mutating func advance(_ next: String.Index) -> Substring {
+    defer {
+      self.string = self.string[next...]
+    }
+    return self.string[..<next]
+  }
+
+  @discardableResult
+  private mutating func advance() -> Character {
+    defer {
+      self.string = string[string.index(after: string.startIndex)...]
+    }
+    return self.string[self.string.startIndex]
+  }
+
+  private mutating func advance(_ len: Int) -> Substring {
+    self.advance(self.string.index(self.string.startIndex, offsetBy: len))
+  }
+}
+
+extension ApkVersionReader {
+  private struct TokenFlag: OptionSet {
+    let rawValue: UInt8
+
+    static let initial      = Self(rawValue: 1 << 0)
+    static let digit        = Self(rawValue: 1 << 1)
+    static let letter       = Self(rawValue: 1 << 2)
+    static let suffix       = Self(rawValue: 1 << 3)
+    static let suffixNumber = Self(rawValue: 1 << 4)
+    static let commitHash   = Self(rawValue: 1 << 5)
+    static let revision     = Self(rawValue: 1 << 6)
+  }
+
+  enum TokenPart {
+    case digit(_ number: UInt, _ string: Substring?)
+    case letter(_ char: Character)
+    case suffix(_ suffix: VersionSuffix)
+    case suffixNumber(_ number: UInt)
+    case commitHash(_ hash: Substring)
+    case revision(_ number: UInt)
+    case end
+  }
+
+  enum VersionSuffix: Int {
+    case alpha = 0, beta = 1, cvs = 5, git = 7, hg = 8, pre = 2, p = 9, rc = 3, svn = 6
+  }
+
+  enum Invalid: Error {
+    case invalid
+  }
+}
+
+extension ApkVersionReader.TokenPart: Comparable {
+  @inlinable var order: Int {
+    switch self {
+    case .digit:        1
+    case .letter:       2
+    case .suffix:       3
+    case .suffixNumber: 4
+    case .commitHash:   5
+    case .revision:     6
+    case .end:          7
+    }
+  }
+
+  @inlinable static func == (lhs: Self, rhs: Self) -> Bool {
+    return lhs.order == rhs.order
+  }
+
+  @inlinable static func < (lhs: Self, rhs: Self) -> Bool {
+    return lhs.order < rhs.order
+  }
+}