🔥 Diff.swift.

prototype/Doubt.xcodeproj/project.pbxproj

@@ -31,7 +31,6 @@
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 		D4AAE50E1B5AE22E004E581F /* Doubt.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = D4AAE4FD1B5AE22E004E581F /* Doubt.framework */; };
 		D4AAE5401B5AE2D0004E581F /* Array.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE5351B5AE2D0004E581F /* Array.swift */; };
-		D4AAE5411B5AE2D0004E581F /* Diff.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE5361B5AE2D0004E581F /* Diff.swift */; };
 		D4AAE5421B5AE2D0004E581F /* Doc.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE5371B5AE2D0004E581F /* Doc.swift */; };
 		D4AAE5451B5AE2D0004E581F /* Operators.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53A1B5AE2D0004E581F /* Operators.swift */; };
 		D4AAE5461B5AE2D0004E581F /* Parse.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53B1B5AE2D0004E581F /* Parse.swift */; };
@@ -116,7 +115,6 @@
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 		D4AAE5351B5AE2D0004E581F /* Array.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Array.swift; sourceTree = "<group>"; };
-		D4AAE5361B5AE2D0004E581F /* Diff.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Diff.swift; sourceTree = "<group>"; };
 		D4AAE5371B5AE2D0004E581F /* Doc.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Doc.swift; sourceTree = "<group>"; };
 		D4AAE53A1B5AE2D0004E581F /* Operators.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Operators.swift; sourceTree = "<group>"; };
 		D4AAE53B1B5AE2D0004E581F /* Parse.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Parse.swift; sourceTree = "<group>"; };
@@ -197,7 +195,6 @@
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 			children = (
 				D4AAE5351B5AE2D0004E581F /* Array.swift */,
-				D4AAE5361B5AE2D0004E581F /* Diff.swift */,
 				D4AAE5371B5AE2D0004E581F /* Doc.swift */,
 				D4AAE53A1B5AE2D0004E581F /* Operators.swift */,
 				D4AAE53B1B5AE2D0004E581F /* Parse.swift */,
@@ -398,7 +395,6 @@
 				D4AAE5471B5AE2D0004E581F /* Prelude.swift in Sources */,
 				D4413FEF1BB06D4C00E3C3C1 /* Dictionary.swift in Sources */,
 				D4AAE5481B5AE2D0004E581F /* String.swift in Sources */,
-				D4AAE5411B5AE2D0004E581F /* Diff.swift in Sources */,
 				D4D7F3171BBB22E500AAB0C0 /* Hash.swift in Sources */,
 				D45A36C91BBC667D00BE3DDE /* Category.swift in Sources */,
 				D4AAE5401B5AE2D0004E581F /* Array.swift in Sources */,

prototype/Doubt/Diff.swift

@@ -1,170 +0,0 @@
-/// A domain-specific language for diffing specific domain languages.
-public enum Diff: Comparable, CustomDebugStringConvertible, CustomDocConvertible, AlgebraicHashable {
-	/// Replace a term with another term.
-	case Patch(Term<Info>?, Term<Info>?)
-
-	/// Copy a syntax node, recursively diffing its branches.
-	///
-	/// This represents a node in the syntax which is unchanged, but whose child nodes (if any) may have been changed; thus, its children are themselves represented by `Syntax` instantiated to `Diff`, rather than `Term`.
-	indirect case Copy(Syntax<Diff, Info>)
-
-	/// Insert, remove, and patch terms by some assigned identity.
-	indirect case ByKey([String:Term<Info>], [String:Term<Info>])
-
-	/// Insert, remove, and patch terms by index. This computes the SES (or some approximation thereof).
-	indirect case ByIndex([Term<Info>], [Term<Info>])
-
-	public static func Insert(term: Term<Info>) -> Diff {
-		return .Patch(nil, term)
-	}
-
-	public static func Delete(term: Term<Info>) -> Diff {
-		return .Patch(term, nil)
-	}
-
-	public init(_ term: Term<Info>) {
-		switch term {
-		case let .Roll(s):
-			self = .Copy(s.map(Diff.init))
-		}
-	}
-
-	public var doc: Doc {
-		switch self {
-		case let .Patch(a, b):
-			return (a.map { Doc($0).bracket("{-", "-}") } ?? Doc.Empty)
-				<> (b.map { Doc($0).bracket("{+", "+}") } ?? Doc.Empty)
-		case let .Copy(a):
-			return a.doc
-		case let .ByKey(a, b):
-			return a.keys.sort().map { Doc($0) <> Doc(":") <+> Doc(a[$0]!) }.joinWithSeparator(",").bracket("{-", "-}")
-				<> b.keys.sort().map { Doc($0) <> Doc(":") <+> Doc(b[$0]!) }.joinWithSeparator(",").bracket("{+", "+}")
-		case let .ByIndex(a, b):
-			return a.map(Doc.init).joinWithSeparator(",").bracket("{-", "-}")
-				<> b.map(Doc.init).joinWithSeparator(",").bracket("{+", "+}")
-		}
-	}
-
-	public var debugDescription: String {
-		switch self {
-		case let .Patch(a, b):
-			return ".Patch(\(String(reflecting: a)), \(String(reflecting: b)))"
-		case let .Copy(a):
-			return ".Copy(\(String(reflecting: a)))"
-		case let .ByKey(a, b):
-			return ".ByKey(\(String(reflecting: a)), \(String(reflecting: b)))"
-		case let .ByIndex(a, b):
-			return ".ByIndex(\(String(reflecting: a)), \(String(reflecting: b)))"
-		}
-	}
-
-	public var hash: Hash {
-		switch self {
-		case let .Patch(a, b):
-			return Hash("Patch", a?.hash ?? Hash.Empty, b?.hash ?? Hash.Empty)
-		case let .Copy(syntax):
-			return Hash("Copy", syntax.hash)
-		case let .ByKey(a, b):
-			return Hash("ByKey", .Unordered(a.map { Hash($0, $1.hash) }), .Unordered(b.map { Hash($0, $1.hash) }))
-		case let .ByIndex(a, b):
-			return Hash("ByIndex", .Ordered(a.map { $0.hash }), .Ordered(b.map { $0.hash }))
-		}
-	}
-
-	/// The magnitude, or cost, of a diff. This is, roughly speaking, a count of all the patches involved.
-	///
-	/// This is used to compute an optimal path through the edit graph.
-	public var magnitude: Int {
-		func magnitude(syntax: Syntax<Diff, Info>) -> Int {
-			return syntax.map { $0.magnitude }.reduce(0, combine: +)
-		}
-		switch self {
-		case .Patch:
-			return 1
-		case let .Copy(s):
-			return magnitude(s)
-		case let .ByKey(a, b):
-			let deleted = Set(a.keys).subtract(b.keys)
-			let inserted = Set(b.keys).subtract(a.keys)
-			let diffed = Set(a.keys).intersect(b.keys).map {
-				Diff(a[$0]!, b[$0]!).magnitude
-			}
-			return deleted.count + inserted.count + diffed.reduce(0, combine: +)
-		case let .ByIndex(a, b):
-			// fixme: SES 😞
-			return 0
-		}
-	}
-
-	public init(_ a: Term<Info>, _ b: Term<Info>) {
-		if a == b {
-			self = Diff(b)
-			return
-		}
-		switch (a.syntax, b.syntax) {
-		case let (.Leaf(v1), .Leaf(v2)) where v1 == v2:
-			self = .Copy(.Leaf(v2))
-
-		case let (.Indexed(v1), .Indexed(v2)):
-			self = .Copy(.Indexed(Diff.diff(v1, v2)))
-
-		default:
-			self = .Patch(a, b)
-		}
-	}
-
-	public static func diff<C1: CollectionType, C2: CollectionType where C1.Index : RandomAccessIndexType, C1.Generator.Element == Term<Info>, C2.Index : RandomAccessIndexType, C2.Generator.Element == Term<Info>>(a: C1, _ b: C2) -> [Diff] {
-		func magnitude(diffs: Stream<(Diff, Int)>) -> Int {
-//			return diffs.first?.magnitude ?? 0
-			return diffs.map { $1 }.reduce(0, combine: +)
-		}
-
-		func min<A>(a: A, _ rest: A..., _ isLessThan: (A, A) -> Bool) -> A {
-			return rest.reduce(a, combine: {
-				isLessThan($0, $1) ? $0 : $1
-			})
-		}
-
-		func diff(a: Stream<Term<Info>>, _ b: Stream<Term<Info>>) -> Stream<(Diff, Int)> {
-			switch (a, b) {
-			case (.Nil, .Nil):
-				return .Nil
-			case (.Nil, .Cons):
-				return b.map { (Diff.Insert($0), 1) }
-			case (.Cons, .Nil):
-				return a.map { (Diff.Delete($0), 1) }
-			case let (.Cons(x, xs), .Cons(y, ys)):
-				let copy = Diff(x, y)
-				let here = Stream.Cons((copy, copy.magnitude), Memo { diff(xs.value, ys.value) })
-				let insert = Stream.Cons((Diff.Insert(y), 1), Memo { diff(a, ys.value) })
-				let delete = Stream.Cons((Diff.Delete(x), 1), Memo { diff(xs.value, b) })
-				return min(here, insert, delete) {
-					magnitude($0) < magnitude($1)
-				}
-			}
-		}
-
-		return Array(diff(Stream(sequence: a), Stream(sequence: b)).map { $0.0 })
-	}
-}
-
-
-public func == (left: Diff, right: Diff) -> Bool {
-	switch (left, right) {
-	case let (.Patch(a1, b1), .Patch(a2, b2)):
-		return a1 == a2 && b1 == b2
-	case let (.Copy(a), .Copy(b)):
-		return a == b
-	case let (.ByKey(a1, b1), .ByKey(a2, b2)):
-		return a1 == a2 && b1 == b2
-	case let (.ByIndex(a1, b1), .ByIndex(a2, b2)):
-		return a1 == a2 && b1 == b2
-	default:
-		return false
-	}
-}
-
-
-public func < (left: Diff, right: Diff) -> Bool {
-	return left.magnitude < right.magnitude
-}