Support a shift interface for state adjustment for non-mutations

mattmassicotte · mattmassicotte · commit 2dda10f8c206 · 2025-12-14T14:44:43.000-05:00
diff --git a/Sources/TextFormation/ClosePairFilter.swift b/Sources/TextFormation/ClosePairFilter.swift
@@ -6,7 +6,6 @@ import Rearrange
 ///
 /// The logic of this operation is *extremely* complicated.
 public struct ClosePairFilter<Interface: TextSystemInterface> {
-	private var locationAfterSkippedClose: Int?
 	private let processAfterTrigger: Bool
 	private var recognizer: ConsecutiveCharacterRecognizer<Interface>
 	private var triggerPosition: Interface.Position?
@@ -161,7 +160,15 @@ extension ClosePairFilter: Filter {
 			self.triggerPosition = mutation.postApplyRange?.upperBound
 		}
 	}
-	
+
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+		try recognizer.processShift(by: offset, interface: interface)
+
+		if let pos = triggerPosition {
+			self.triggerPosition = interface.position(from: pos, offset: offset)
+		}
+	}
+
 	public mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		guard let pos = triggeringPosition(with: mutation) else {
 			try recognizerCheck(mutation)
diff --git a/Sources/TextFormation/CompositeFilter.swift b/Sources/TextFormation/CompositeFilter.swift
@@ -14,6 +14,12 @@ public struct CompositeFilter<Interface: TextSystemInterface> {
 
 @available(macOS 13, iOS 16, tvOS 16, watchOS 9, *)
 extension CompositeFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+		for index in filters.indices {
+			try filters[index].processShift(by: offset, interface: interface)
+		}
+	}
+
 	public mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		for index in filters.indices {
 			if let output = try filters[index].processMutation(mutation) {
diff --git a/Sources/TextFormation/ConsecutiveCharacterRecognizer.swift b/Sources/TextFormation/ConsecutiveCharacterRecognizer.swift
@@ -80,10 +80,27 @@ public struct ConsecutiveCharacterRecognizer<Interface: TextSystemInterface> {
 		}
 	}
 
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+		switch state {
+		case .idle:
+			break
+		case .tracking(let position, let int):
+			guard let newPos = interface.position(from: position, offset: offset) else {
+				self.state = .idle
+				break
+			}
+
+			self.state = .tracking(newPos, int)
+		case .triggered:
+			break
+		}
+	}
+	
 	@discardableResult
 	public mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Bool {
 		try updateState(mutation)
 
+		print(state)
 		switch state {
 		case .triggered:
 			return true
diff --git a/Sources/TextFormation/DeleteCloseFilter.swift b/Sources/TextFormation/DeleteCloseFilter.swift
@@ -19,6 +19,9 @@ public struct DeleteCloseFilter<Interface: TextSystemInterface> {
 }
 
 extension DeleteCloseFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+	}
+	
 	public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		let interface = mutation.interface
 		let range = mutation.range
diff --git a/Sources/TextFormation/Filter.swift b/Sources/TextFormation/Filter.swift
@@ -25,6 +25,7 @@ public protocol Filter<Interface> {
 	associatedtype Interface: TextSystemInterface
 	typealias Mutation = TextMutation<Interface>
 
+	mutating func processShift(by offset: Int, interface: Interface) throws
 	mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output?
 }
 
diff --git a/Sources/TextFormation/LineLeadingWhitespaceFilter.swift b/Sources/TextFormation/LineLeadingWhitespaceFilter.swift
@@ -43,7 +43,11 @@ extension LineLeadingWhitespaceFilter: Filter {
 			delta: mutationOuput.delta + whitespaceOutput.delta
 		)
 	}
-	
+
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+		try recognizer.processShift(by: offset, interface: interface)
+	}
+
 	public mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		if try recognizer.processMutation(mutation) {
 			if let value = try matchHandler(mutation) {
diff --git a/Sources/TextFormation/NewlineProcessingFilter.swift b/Sources/TextFormation/NewlineProcessingFilter.swift
@@ -9,6 +9,9 @@ public struct NewlineProcessingFilter<Interface: TextSystemInterface> {
 }
 
 extension NewlineProcessingFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+	}
+
 	public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		if mutation.string != lineEndingSequence {
 			return nil
diff --git a/Sources/TextFormation/NewlineWithinPairFilter.swift b/Sources/TextFormation/NewlineWithinPairFilter.swift
@@ -13,6 +13,9 @@ public struct NewlineWithinPairFilter<Interface: TextSystemInterface> {
 }
 
 extension NewlineWithinPairFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+	}
+	
 	public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		let interface = mutation.interface
 		let pos = mutation.range.lowerBound
diff --git a/Sources/TextFormation/OpenPairReplacementFilter.swift b/Sources/TextFormation/OpenPairReplacementFilter.swift
@@ -11,6 +11,9 @@ public struct OpenPairReplacementFilter<Interface: TextSystemInterface> {
 }
 
 extension OpenPairReplacementFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+	}
+
 	public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		let interface = mutation.interface
 		let start = mutation.range.lowerBound
diff --git a/Sources/TextFormation/SkipFilter.swift b/Sources/TextFormation/SkipFilter.swift
@@ -9,6 +9,9 @@ public struct SkipFilter<Interface: TextSystemInterface> {
 }
 
 extension SkipFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+	}
+
 	public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		let string = mutation.string
 		let interface = mutation.interface
diff --git a/Sources/TextFormation/StandardOpenPairFilter.swift b/Sources/TextFormation/StandardOpenPairFilter.swift
@@ -35,6 +35,11 @@ public struct StandardOpenPairFilter<Interface: TextSystemInterface> {
 }
 
 extension StandardOpenPairFilter: Filter {
+	public mutating func processShift(by offset: Int, interface: Interface) throws {
+		try closeWhitespace?.processShift(by: offset, interface: interface)
+		try closePair.processShift(by: offset, interface: interface)
+	}
+
 	public mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {
 		if let output = try skip.processMutation(mutation) {
 			return output
diff --git a/Sources/TextFormation/TextMutation.swift b/Sources/TextFormation/TextMutation.swift
@@ -14,7 +14,7 @@ public struct TextMutation<Interface: TextSystemInterface> {
 	public let range: Interface.TextRange
 	public let interface: Interface
 	public let string: String
-	
+
 	public init(range: Interface.TextRange, interface: Interface, string: String) {
 		self.range = range
 		self.interface = interface
diff --git a/Tests/TextFormationTests/ClosePairFilterTests.swift b/Tests/TextFormationTests/ClosePairFilterTests.swift
@@ -262,4 +262,23 @@ struct ClosePairFilterTests {
 		#expect(output == MutationOutput(selection: NSRange(5..<5), delta: 6))
 		#expect(system.string == "abct\n\ndef")
 	}
+
+	@Test func processingShift() throws {
+		let system = MockSystem(string: "")
+		var filter = ClosePairFilter<MockSystem>(open: "(", close: ")")
+
+		let openOutput = try #require(try system.runFilter(&filter, 0..<0, "("))
+		#expect(openOutput == MutationOutput(selection: NSRange(1..<1), delta: 1))
+		#expect(system.string == "(")
+
+		// simulate inserting 2 characters before the paren
+		_ = try system.applyMutation(NSRange(0..<0), string: "  ")
+		try filter.processShift(by: 2, interface: system)
+
+		let output = try #require(try filter.processMutation(3..<3, "a", system))
+
+		#expect(output == MutationOutput(selection: NSRange(4..<4), delta: 2))
+		#expect(output == MutationOutput(selection: NSRange(4..<4), delta: 2))
+		#expect(system.string == "  (a)")
+	}
 }

Original file line number	Diff line number	Diff line change
`@@ -19,6 +19,9 @@ public struct DeleteCloseFilter<Interface: TextSystemInterface> {`
`19`	`19`	`}`
`20`	`20`
`21`	`21`	`extension DeleteCloseFilter: Filter {`
	`22`	`+ public mutating func processShift(by offset: Int, interface: Interface) throws {`
	`23`	`+ }`
	`24`	`+`
`22`	`25`	`public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {`
`23`	`26`	`let interface = mutation.interface`
`24`	`27`	`let range = mutation.range`
Original file line number	Diff line number	Diff line change
`@@ -25,6 +25,7 @@ public protocol Filter<Interface> {`
`25`	`25`	`associatedtype Interface: TextSystemInterface`
`26`	`26`	`typealias Mutation = TextMutation<Interface>`
`27`	`27`
	`28`	`+ mutating func processShift(by offset: Int, interface: Interface) throws`
`28`	`29`	`mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output?`
`29`	`30`	`}`
`30`	`31`
Original file line number	Diff line number	Diff line change
`@@ -43,7 +43,11 @@ extension LineLeadingWhitespaceFilter: Filter {`
`43`	`43`	`delta: mutationOuput.delta + whitespaceOutput.delta`
`44`	`44`	`)`
`45`	`45`	`}`
`46`		`-`
	`46`	`+`
	`47`	`+ public mutating func processShift(by offset: Int, interface: Interface) throws {`
	`48`	`+ try recognizer.processShift(by: offset, interface: interface)`
	`49`	`+ }`
	`50`	`+`
`47`	`51`	`public mutating func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {`
`48`	`52`	`if try recognizer.processMutation(mutation) {`
`49`	`53`	`if let value = try matchHandler(mutation) {`
Original file line number	Diff line number	Diff line change
`@@ -9,6 +9,9 @@ public struct NewlineProcessingFilter<Interface: TextSystemInterface> {`
`9`	`9`	`}`
`10`	`10`
`11`	`11`	`extension NewlineProcessingFilter: Filter {`
	`12`	`+ public mutating func processShift(by offset: Int, interface: Interface) throws {`
	`13`	`+ }`
	`14`	`+`
`12`	`15`	`public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {`
`13`	`16`	`if mutation.string != lineEndingSequence {`
`14`	`17`	`return nil`
Original file line number	Diff line number	Diff line change
`@@ -13,6 +13,9 @@ public struct NewlineWithinPairFilter<Interface: TextSystemInterface> {`
`13`	`13`	`}`
`14`	`14`
`15`	`15`	`extension NewlineWithinPairFilter: Filter {`
	`16`	`+ public mutating func processShift(by offset: Int, interface: Interface) throws {`
	`17`	`+ }`
	`18`	`+`
`16`	`19`	`public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {`
`17`	`20`	`let interface = mutation.interface`
`18`	`21`	`let pos = mutation.range.lowerBound`
Original file line number	Diff line number	Diff line change
`@@ -11,6 +11,9 @@ public struct OpenPairReplacementFilter<Interface: TextSystemInterface> {`
`11`	`11`	`}`
`12`	`12`
`13`	`13`	`extension OpenPairReplacementFilter: Filter {`
	`14`	`+ public mutating func processShift(by offset: Int, interface: Interface) throws {`
	`15`	`+ }`
	`16`	`+`
`14`	`17`	`public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {`
`15`	`18`	`let interface = mutation.interface`
`16`	`19`	`let start = mutation.range.lowerBound`
Original file line number	Diff line number	Diff line change
`@@ -9,6 +9,9 @@ public struct SkipFilter<Interface: TextSystemInterface> {`
`9`	`9`	`}`
`10`	`10`
`11`	`11`	`extension SkipFilter: Filter {`
	`12`	`+ public mutating func processShift(by offset: Int, interface: Interface) throws {`
	`13`	`+ }`
	`14`	`+`
`12`	`15`	`public func processMutation(_ mutation: TextMutation<Interface>) throws -> Interface.Output? {`
`13`	`16`	`let string = mutation.string`
`14`	`17`	`let interface = mutation.interface`