Fixed bug when delegate wasn't notified of edited paragraphs or some part of a paragraph if users pasted a string over selected text which has the same length as the inserted string

Author: CineDev

Sources/ParagraphTextKit/ParagraphTextStorage.swift

@@ -48,9 +48,15 @@ open class ParagraphTextStorage: NSTextStorage {
 	/// Helper var indicating that after the editing the resulting range of the next paragraph will be equal to the first edited paragraph
 	/// and that might confuse the diff algorhythm.
 	///
-	/// Confusing results in the case when the diff algorhythm will not notify the delegate that the next paragraph was edited,
+	/// That confusing results in the case when the diff algorhythm will not notify the delegate that the next paragraph was edited,
 	/// because the algorhythm will consider that if the range is the same, then there was no change at all
 	private var nextEditedParagraphWillHaveRangeEqualWithFirst = false
+	
+	/// Helper var for the case when a user pastes some text and that text length is equal to the selected text within the text view.
+	///
+	/// It is important, because if the edit with the same length of the selected text , the diff algrothythm
+	/// won't recognize it as a change, since the result text storage will have the same paragraph lengths
+	private var editHasSameLength = false
 
 	/// Subscriber to the NSTextStorage.willProcessEditingNotification
 	private var processingSubscriber: AnyCancellable?
@@ -93,6 +99,12 @@ open class ParagraphTextStorage: NSTextStorage {
 
 		indexesBeforeEditing = paragraphIndexes(in: range)
 
+		if delta == 0 && str.length > 0 {
+			editHasSameLength = true
+		} else {
+			editHasSameLength = false
+		}
+		
 		if indexesBeforeEditing.count > 1 && delta < 0 {
 			let firstRange = paragraphRanges[indexesBeforeEditing[0]]
 
@@ -158,6 +170,22 @@ open class ParagraphTextStorage: NSTextStorage {
 												baseParagraphRange: paragraphsBefore.first!,
 												insertionLocation: editedRange.location)
 
+		// if delta of edits is zero (user could just paste the same-length text over the same-length selected text)
+		// make sure that the delegate will be notified of those changes, since the diff algorhythm won't recognize
+		// any changes in that case
+		guard changes.count != 0 && !editHasSameLength else {
+			indexesBeforeEditing.forEach{
+				changes.append(ParagraphRangeChange.editedParagraph(index: $0, range: paragraphRanges[$0]))
+			}
+			
+			if let existingDelegate = paragraphDelegate {
+				let descriptedChanges = ParagraphChange.from(rangeChanges: changes, textStorage: self)
+				existingDelegate.textStorage(self, didChangeParagraphs: descriptedChanges)
+			}
+			
+			return
+		}
+		
 		var hasEditedChange = false
 		changes.forEach{ change in
 			if case ParagraphRangeChange.editedParagraph(index: _, range: _) = change { hasEditedChange = true }
@@ -251,7 +279,10 @@ open class ParagraphTextStorage: NSTextStorage {
 		guard length > 0 else { return [0] }
 
 		// get paragraphs from the range
-		let paragraphs = attributedSubstring(from: range).string.paragraphs
+		var paragraphs = attributedSubstring(from: range).string.paragraphs
+		if paragraphs.last?.isEmpty == true && editHasSameLength {
+			paragraphs = paragraphs.dropLast()
+		}
 
 		// get start/end indexes for substring the existing paragraphs array..
 		// .. it's better than iterating through all the paragraphs, especially if text is huge

Tests/ParagraphTextKitTests/ParagraphTextStorageTests.swift

@@ -716,6 +716,77 @@ final class ParagraphTextStorageTests: XCTestCase {
 					   "ParagraphTextStorage paragraph ranges should match the delegate ranges")
 	}
 
+	func testParagraphTextStorage_EditParagraphWithSameLengthEdit() {
+		let string = "First paragraph\nSecond paragraph"
+		let editString = "additions"
+		
+		textStorage.beginEditing()
+		textStorage.replaceCharacters(in: NSRange(location: 0, length: 0), with: string)
+		textStorage.endEditing()
+		
+		textStorage.beginEditing()
+		textStorage.replaceCharacters(in: NSRange(location: 6, length: 9), with: editString)
+		textStorage.endEditing()
+		
+		XCTAssertTrue(delegate.insertions.count == 1 && delegate.editions.count == 2 && delegate.removals.count == 0,
+					  "ParagraphTextStorage paragraph delegate should be notified of exact changes")
+
+		XCTAssertTrue(delegate.insertions[0] == 1)
+		XCTAssertTrue(delegate.editions[0] == 0 && delegate.editions[1] == 0)
+
+		let endString = "First additions\nSecond paragraph"
+
+		XCTAssertTrue(textStorage.paragraphRanges.count == 2,
+					  "ParagraphTextStorage should now have 2 paragraphs")
+		
+		let firstRange = NSRange(location: 0, length: endString.paragraphs[0].length)
+		let secondRange = NSRange(location: NSMaxRange(firstRange), length: endString.paragraphs[1].length)
+		
+		XCTAssertTrue(textStorage.paragraphRanges[0] == firstRange &&
+			textStorage.paragraphRanges[1] == secondRange,
+					  "ParagraphTextStorage paragraph ranges should be correct")
+		
+		XCTAssertEqual(textStorage.paragraphRanges, delegate.ranges,
+					   "ParagraphTextStorage paragraph ranges should match the delegate ranges")
+	}
+	
+	func testParagraphTextStorage_EditMultipleParagraphWithSameLengthEdit() {
+		let string = "First paragraph\nSecond paragraph\nThird paragraph"
+		let editString = "First paragraph\nSecond paragraph\n"
+		
+		textStorage.beginEditing()
+		textStorage.replaceCharacters(in: NSRange(location: 0, length: 0), with: string)
+		textStorage.endEditing()
+		
+		textStorage.beginEditing()
+		textStorage.replaceCharacters(in: NSRange(location: 0, length: 33), with: editString)
+		textStorage.endEditing()
+		
+		XCTAssertTrue(delegate.insertions.count == 2 && delegate.editions.count == 4 && delegate.removals.count == 0,
+					  "ParagraphTextStorage paragraph delegate should be notified of exact changes")
+
+		XCTAssertTrue(delegate.insertions[0] == 1 && delegate.insertions[1] == 2)
+		XCTAssertTrue(delegate.editions[0] == 0 && delegate.editions[1] == 0 && delegate.editions[2] == 1 && delegate.editions[3] == 2)
+
+		let endString = "First paragraph\nSecond paragraph\nThird paragraph"
+
+		XCTAssertTrue(textStorage.paragraphRanges.count == 3,
+					  "ParagraphTextStorage should now have 3 paragraphs")
+		
+		let firstRange = NSRange(location: 0, length: endString.paragraphs[0].length)
+		let secondRange = NSRange(location: NSMaxRange(firstRange), length: endString.paragraphs[1].length)
+		let thirdRange = NSRange(location: NSMaxRange(secondRange), length: endString.paragraphs[2].length)
+
+		XCTAssertTrue(textStorage.paragraphRanges[0] == firstRange &&
+						textStorage.paragraphRanges[1] == secondRange &&
+						textStorage.paragraphRanges[2] == thirdRange,
+					  "ParagraphTextStorage paragraph ranges should be correct")
+		
+		XCTAssertEqual(textStorage.paragraphRanges, delegate.ranges,
+					   "ParagraphTextStorage paragraph ranges should match the delegate ranges")
+	}
+
+	
 	func testParagraphTextStorage_EditParagraphAtEnd() {
 		let string = "First paragraph\nSecond paragraph"
 		let editString = "addition"