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Merge pull request #7 from iSapozhnik/feature/decouple-text-engine
Decouple TextDiff engine and add reusable diff results
2 parents 167064a + 0ae38e4 commit b5815ad

15 files changed

Lines changed: 724 additions & 97 deletions

‎README.md‎

Lines changed: 62 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -80,6 +80,66 @@ TextDiffView(
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- `.token` (default): token-level diff behavior.
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- `.character`: refines adjacent word replacements by character so shared parts remain unchanged text (for example `Add` -> `Added` shows unchanged `Add` and inserted `ed`).
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83+
## Engine-Only Results
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You can compute a reusable diff result without rendering a view:
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```swift
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import TextDiff
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let result = TextDiffEngine.result(
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original: "Track old values in storage.",
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updated: "Track new values in storage.",
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mode: .token
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)
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for change in result.changes {
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print(change.kind, change.text)
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}
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print(result.summary.insertedCharacters)
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print(result.summary.deletedCharacters)
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```
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`TextDiffResult.changes` preserves the computed diff order for the selected mode and uses UTF-16 offsets/lengths so it can be stored and replayed consistently later. Summaries are derived from those mode-specific change records.
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## Precomputed Rendering
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If you already computed a diff result for storage or analytics, you can render it later without recomputing:
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```swift
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import SwiftUI
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import TextDiff
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let result = TextDiffEngine.result(
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original: "Track old values in storage.",
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updated: "Track new values in storage.",
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mode: .token
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)
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struct StoredDiffView: View {
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var body: some View {
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TextDiffView(result: result)
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.padding()
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}
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}
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```
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AppKit has the same precomputed rendering path:
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```swift
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import AppKit
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import TextDiff
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let result = TextDiffEngine.result(
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original: "Track old values in storage.",
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updated: "Track new values in storage.",
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mode: .token
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)
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let diffView = NSTextDiffView(result: result)
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```
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## Custom Styling
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```swift
@@ -123,8 +183,10 @@ Change-specific colors and text treatment live under `additionsStyle` and `remov
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- Matching is exact (case-sensitive and punctuation-sensitive).
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- Replacements are rendered as adjacent delete then insert segments.
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- Character mode refines adjacent word replacements only; punctuation and whitespace keep token-level behavior.
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- `TextDiffResult.changes` and `TextDiffResult.summary` are mode-specific outputs; `.token` and `.character` results are not normalized to each other.
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- Whitespace changes preserve the `updated` layout and stay visually neutral (no chips).
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- Rendering is display-only (not selectable) to keep chip geometry deterministic.
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- Result-driven rendering (`TextDiffView(result:)`, `NSTextDiffView(result:)`) is display-only and does not enable revert actions.
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- `interChipSpacing` controls spacing between adjacent changed lexical chips (words or punctuation).
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- `lineSpacing` controls vertical spacing between wrapped lines.
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- Chip horizontal padding is preserved with a minimum effective floor of 3pt per side.

‎Sources/TextDiff/AppKit/DiffRevertActionResolver.swift‎

Lines changed: 2 additions & 81 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,6 @@
11
import CoreGraphics
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import Foundation
33

4-
struct IndexedSegment {
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let segmentIndex: Int
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let segment: DiffSegment
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let originalCursor: Int
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let updatedCursor: Int
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let originalRange: NSRange
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let updatedRange: NSRange
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}
12-
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enum DiffRevertCandidateKind: Equatable {
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case singleInsertion
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case singleDeletion
@@ -35,67 +26,6 @@ struct DiffRevertInteractionContext {
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}
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enum DiffRevertActionResolver {
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static func indexedSegments(
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from segments: [DiffSegment],
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original: String,
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updated: String
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) -> [IndexedSegment] {
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var output: [IndexedSegment] = []
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output.reserveCapacity(segments.count)
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let originalNSString = original as NSString
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let updatedNSString = updated as NSString
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var originalCursor = 0
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var updatedCursor = 0
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for (index, segment) in segments.enumerated() {
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let textLength = segment.text.utf16.count
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let originalRange: NSRange
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let updatedRange: NSRange
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56-
switch segment.kind {
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case .equal:
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originalRange = NSRange(location: originalCursor, length: textLength)
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updatedRange = NSRange(location: updatedCursor, length: textLength)
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let originalMatches = textMatches(segment.text, source: originalNSString, at: originalCursor)
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let updatedMatches = textMatches(segment.text, source: updatedNSString, at: updatedCursor)
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#if !TESTING
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assert(
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originalMatches,
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"Equal segment text mismatch in original at \(originalCursor) for segment \(index): \(segment.text)"
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)
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assert(
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updatedMatches,
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"Equal segment text mismatch in updated at \(updatedCursor) for segment \(index): \(segment.text)"
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)
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#endif
72-
originalCursor += textLength
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updatedCursor += textLength
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case .delete:
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originalRange = NSRange(location: originalCursor, length: textLength)
76-
updatedRange = NSRange(location: updatedCursor, length: 0)
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originalCursor += textLength
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case .insert:
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originalRange = NSRange(location: originalCursor, length: 0)
80-
updatedRange = NSRange(location: updatedCursor, length: textLength)
81-
updatedCursor += textLength
82-
}
83-
84-
output.append(
85-
IndexedSegment(
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segmentIndex: index,
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segment: segment,
88-
originalCursor: originalRange.location,
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updatedCursor: updatedRange.location,
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originalRange: originalRange,
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updatedRange: updatedRange
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)
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)
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}
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return output
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}
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static func candidates(
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from segments: [DiffSegment],
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mode: TextDiffComparisonMode
@@ -121,7 +51,7 @@ enum DiffRevertActionResolver {
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return []
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}
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let indexed = indexedSegments(from: segments, original: original, updated: updated)
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let indexed = DiffSegmentIndexer.indexedSegments(from: segments, original: original, updated: updated)
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guard !indexed.isEmpty else {
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return []
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}
@@ -181,7 +111,7 @@ enum DiffRevertActionResolver {
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kind: .singleDeletion,
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tokenKind: current.segment.tokenKind,
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segmentIndices: [current.segmentIndex],
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updatedRange: NSRange(location: current.updatedCursor, length: 0),
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updatedRange: NSRange(location: current.updatedRange.location, length: 0),
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replacementText: current.segment.text,
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originalTextFragment: current.segment.text,
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updatedTextFragment: nil
@@ -331,15 +261,6 @@ enum DiffRevertActionResolver {
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return false
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}
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private static func textMatches(_ text: String, source: NSString, at location: Int) -> Bool {
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let length = text.utf16.count
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guard location >= 0, location + length <= source.length else {
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return false
339-
}
340-
return source.substring(with: NSRange(location: location, length: length)) == text
341-
}
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private static func adjustedStandaloneWordDeletionReplacement(
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_ replacement: String,
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insertionLocation: Int,

‎Sources/TextDiff/AppKit/DiffTextViewRepresentable.swift‎

Lines changed: 24 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,7 @@ import AppKit
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import SwiftUI
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44
struct DiffTextViewRepresentable: NSViewRepresentable {
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let result: TextDiffResult?
56
let original: String
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let updated: String
78
let updatedBinding: Binding<String>?
@@ -16,20 +17,25 @@ struct DiffTextViewRepresentable: NSViewRepresentable {
1617
}
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1819
func makeNSView(context: Context) -> NSTextDiffView {
19-
let view = NSTextDiffView(
20-
original: original,
21-
updated: updated,
22-
style: style,
23-
mode: mode
24-
)
20+
let view: NSTextDiffView
21+
if let result {
22+
view = NSTextDiffView(result: result, style: style)
23+
} else {
24+
view = NSTextDiffView(
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original: original,
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updated: updated,
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style: style,
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mode: mode
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)
30+
}
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view.setContentCompressionResistancePriority(.required, for: .vertical)
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view.setContentHuggingPriority(.required, for: .vertical)
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context.coordinator.update(
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updatedBinding: updatedBinding,
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onRevertAction: onRevertAction
3036
)
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view.showsInvisibleCharacters = showsInvisibleCharacters
32-
view.isRevertActionsEnabled = isRevertActionsEnabled
38+
view.isRevertActionsEnabled = result == nil ? isRevertActionsEnabled : false
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view.onRevertAction = { [coordinator = context.coordinator] action in
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coordinator.handle(action)
3541
}
@@ -45,13 +51,17 @@ struct DiffTextViewRepresentable: NSViewRepresentable {
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coordinator.handle(action)
4652
}
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view.showsInvisibleCharacters = showsInvisibleCharacters
48-
view.isRevertActionsEnabled = isRevertActionsEnabled
49-
view.setContent(
50-
original: original,
51-
updated: updated,
52-
style: style,
53-
mode: mode
54-
)
54+
view.isRevertActionsEnabled = result == nil ? isRevertActionsEnabled : false
55+
if let result {
56+
view.setContent(result: result, style: style)
57+
} else {
58+
view.setContent(
59+
original: original,
60+
updated: updated,
61+
style: style,
62+
mode: mode
63+
)
64+
}
5565
}
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final class Coordinator {

‎Sources/TextDiff/AppKit/NSTextDiffContentSource.swift‎

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Original file line numberDiff line numberDiff line change
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import Foundation
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enum NSTextDiffContentSource {
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case text
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case result(TextDiffResult)
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var isResultDriven: Bool {
8+
if case .result = self {
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return true
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}
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return false
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}
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}

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