Attempt to simplify range/position abstractions with the Bounded prot…

…ocol

README.md

@@ -52,19 +52,7 @@ typealias TextDirection = UITextDirection
 typealias UserInterfaceLayoutDirection = UIUserInterfaceLayoutDirection
 ```
 
-There are a variety of range/position models within AppKit, UIKit, and even between TextKit 1 and 2. Some abstraction is, unfortunately, required to model this. The protocol `TextPositionSpace` provides a way of mapping positions into and out of ranges. Here's what the implemenation looks like for UITextRanges
-
-```swift
-extension UITextView : TextPositionSpace {
-    public func decomposeRange(_ range: TextRange) -> (TextPosition, TextPosition) {
-        (range.start, range.end)
-    }
-
-    public func composeRange(_ components: (TextPosition, TextPosition)) -> TextRange? {
-        textRange(from: components.0, to: components.1)
-    }
-}
-```
+There are a variety of range/position models within AppKit, UIKit, and even between TextKit 1 and 2. Some abstraction is, unfortunately, required to model this. This should be all automatically handled by the `TextTokenizer` protocol **if** you are using `NSRange` or `NSTextRange`. The cross-platform `TextRange` type cannot do this without additional work on your part, typically by involving the text view.
 
 ## Contributing and Collaboration
 

Sources/Ligature/Bounded.swift

@@ -0,0 +1,32 @@
+public protocol Bounded<Bound> {
+	associatedtype Bound
+
+	var lowerBound: Bound { get }
+	var upperBound: Bound { get }
+}
+
+#if os(macOS)
+import AppKit
+#elseif canImport(UIKit)
+import UIKit
+#endif
+
+@available(iOS 15.0, macOS 12.0, tvOS 15.0, macCatalyst 15.0, *)
+extension NSTextRange : Bounded {
+	public var lowerBound: NSTextLocation { location }
+	public var upperBound: NSTextLocation { endLocation }
+}
+
+extension TextRange : Bounded {
+	public nonisolated var lowerBound: TextPosition {
+		MainActor.assumeIsolated { start }
+	}
+
+	public nonisolated var upperBound: TextPosition {
+		MainActor.assumeIsolated { end }
+	}
+}
+
+extension NSRange : Bounded {}
+
+extension Range : Bounded {}

Sources/Ligature/Platform.swift

@@ -3,8 +3,8 @@ import AppKit
 
 public typealias UserInterfaceLayoutDirection = NSUserInterfaceLayoutDirection
 
+@MainActor
 open class TextPosition: NSObject {
-
 }
 
 final class UTF16TextPosition: TextPosition {

Sources/Ligature/SourceTokenizer.swift

@@ -1,6 +1,8 @@
 import Foundation
 
-public struct SourceTokenizer<Position, FallbackTokenzier: TextTokenizer> where FallbackTokenzier.Position == Position, FallbackTokenzier.TextRange == TextRange {
+public struct SourceTokenizer<FallbackTokenzier: TextTokenizer> {
+	public typealias Position = FallbackTokenzier.Position
+
 	private let fallbackTokenzier: FallbackTokenzier
 
 	init(fallbackTokenzier: FallbackTokenzier) {
@@ -13,7 +15,7 @@ extension SourceTokenizer : TextTokenizer {
 		return fallbackTokenzier.position(from: position, toBoundary: granularity, inDirection: direction)
 	}
 
-	public func rangeEnclosingPosition(_ position: Position, with granularity: TextGranularity, inDirection direction: TextDirection) -> Ligature.TextRange? {
+	public func rangeEnclosingPosition(_ position: Position, with granularity: TextGranularity, inDirection direction: TextDirection) -> FallbackTokenzier.TextRange? {
 		return fallbackTokenzier.rangeEnclosingPosition(position, with: granularity, inDirection: direction)
 	}
 

Sources/Ligature/TextTokenizer.swift

@@ -1,9 +1,15 @@
-import Foundation
+#if os(macOS)
+import AppKit
+#elseif canImport(UIKit)
+import UIKit
+#endif
 
 @MainActor
-public protocol TextTokenizer<Position, TextRange> {
-	associatedtype Position
-	associatedtype TextRange
+public protocol TextTokenizer<TextRange> {
+	associatedtype TextRange: Bounded
+
+	typealias Position = TextRange.Bound
+	typealias RangeBuilder = (Position, Position) -> TextRange?
 
 	func position(from position: Position, toBoundary granularity: TextGranularity, inDirection direction: TextDirection) -> Position?
 	func rangeEnclosingPosition(_ position: Position, with granularity: TextGranularity, inDirection direction: TextDirection) -> TextRange?
@@ -13,9 +19,44 @@ public protocol TextTokenizer<Position, TextRange> {
 }
 
 #if canImport(UIKit)
-import UIKit
+extension UITextInputStringTokenizer : TextTokenizer {}
+#endif
+
+extension TextTokenizer {
+	public func range(
+		from range: TextRange,
+		to granularity: TextGranularity,
+		in direction: TextDirection,
+		rangeBuilder: RangeBuilder
+	) -> TextRange? {
+		let components = (range.lowerBound, range.upperBound)
+
+		guard
+			let start = position(from: components.0, toBoundary: granularity, inDirection: direction),
+			let end = position(from: components.1, toBoundary: granularity, inDirection: direction)
+		else {
+			return nil
+		}
 
-extension UITextInputStringTokenizer : TextTokenizer {
+		return rangeBuilder(start, end)
+	}
 }
 
-#endif
+extension TextTokenizer where TextRange == NSRange {
+	public func range(from range: TextRange, to granularity: TextGranularity, in direction: TextDirection) -> TextRange? {
+		self.range(from: range, to: granularity, in: direction, rangeBuilder: { NSRange($0..<$1) })
+	}
+}
+
+extension TextTokenizer where TextRange == Range<Int> {
+	public func range(from range: TextRange, to granularity: TextGranularity, in direction: TextDirection) -> TextRange? {
+		self.range(from: range, to: granularity, in: direction, rangeBuilder: { $0..<$1 })
+	}
+}
+
+@available(iOS 15.0, macOS 12.0, tvOS 15.0, macCatalyst 15.0, *)
+extension TextTokenizer where TextRange == NSTextRange {
+	public func range(from range: TextRange, to granularity: TextGranularity, in direction: TextDirection) -> TextRange? {
+		self.range(from: range, to: granularity, in: direction, rangeBuilder: { NSTextRange(location: $0, end: $1) })
+	}
+}