Unify the behavior around backspacing iOS lists and quotes (#194)

Previous PRs brought a bit of mayhem to lists and quotes on iOS in terms
of their behavior consistency;
- the added utils that removed styles when all characters of a line were
removed messed with the fact that lists and quotes shouldn't do that. A
zero width space should appear there. Added a check in these utils for
these styles.
- after fixing the above, zero width spaces still didn't appear in the
first line because empty input "reset attributes" check was running
first. Changed their order.
- cleaned up and fixed the logic for handling backspaces within lists.
Now backspace that is visibly done on the list/quote marker only removes
style, keeping the whole line intact
- also fixed one edge case to the above behavior, which resulted in the
style being removed because the attributes magically weren't preserved

Author: szydlovsky

ios/EnrichedTextInputView.mm

@@ -980,8 +980,8 @@ - (void)manageSelectionBasedChanges {
   }
 
   // typing attributes for empty lines selection reset
-  NSString *currentString = [[textView.textStorage.string copy] stringByReplacingOccurrencesOfString:@"\u200B" withString:@""];
-  if(textView.selectedRange.length == 0 && [_recentlyEmittedString isEqualToString: currentString] ) {
+  NSString *currentString = [textView.textStorage.string copy];
+  if(textView.selectedRange.length == 0 && [_recentlyEmittedString isEqualToString:currentString]) {
     // no string change means only a selection changed with no character changes
     NSRange paragraphRange = [textView.textStorage.string paragraphRangeForRange:textView.selectedRange];
     if(
@@ -1012,15 +1012,15 @@ - (void)anyTextMayHaveBeenModified {
     return;
   }
 
+  // zero width space adding or removal
+  [ZeroWidthSpaceUtils handleZeroWidthSpacesInInput:self];
+  
   // emptying input typing attributes management
   if(textView.textStorage.string.length == 0 && _recentlyEmittedString.length > 0) {
     // reset typing attribtues
     textView.typingAttributes = defaultTypingAttributes;
   }
 
-  // zero width space removal
-  [ZeroWidthSpaceUtils handleZeroWidthSpacesInInput:self];
-  
   // inline code on newlines fix
   InlineCodeStyle *codeStyle = stylesDict[@([InlineCodeStyle getStyleType])];
   if(codeStyle != nullptr) {

ios/styles/BlockQuoteStyle.mm

@@ -119,30 +119,19 @@ - (void)removeTypingAttributes {
 }
 
 - (BOOL)handleBackspaceInRange:(NSRange)range replacementText:(NSString *)text {
-  if(
-    [self detectStyle:_input->textView.selectedRange] &&
-    NSEqualRanges(_input->textView.selectedRange, NSMakeRange(0, 0)) &&
-    [text isEqualToString:@""]
-  ) {
-    // removing first quote line by backspacing doesn't remove typing attributes because it doesn't run textViewDidChange
-    // so we try guessing that a line should be deleted here
+  if([self detectStyle:_input->textView.selectedRange] && text.length == 0) {
+    // backspace while the style is active
+    
     NSRange paragraphRange = [_input->textView.textStorage.string paragraphRangeForRange:_input->textView.selectedRange];
-    [self removeAttributes:paragraphRange];
-    return YES;
-  } else if(
-    [self detectStyle:_input->textView.selectedRange] &&
-    [text isEqualToString:@""]
-  ) {
-    // other case; make sure removing all the (non newline) text from a quto line also removes the line itself
-    NSRange paragraphRange = [_input->textView.textStorage.string paragraphRangeForRange:range];
-    NSValue *nonNewlineVal = [ParagraphsUtils getNonNewlineRangesIn:_input->textView range:paragraphRange].firstObject;
-    if(nonNewlineVal == nullptr) {
-      return NO;
-    }
-    NSRange nonNewlineRange = [nonNewlineVal rangeValue];
-    if(NSEqualRanges(range, nonNewlineRange)) {
-      [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:_input withSelection:YES];
-      [self removeAttributes:NSMakeRange(range.location, 0)];
+    
+    if(NSEqualRanges(_input->textView.selectedRange, NSMakeRange(0, 0))) {
+      // a backspace on the very first input's line quote
+      // it doesn't run textVieDidChange so we need to manually remove attributes
+      [self removeAttributes:paragraphRange];
+      return YES;
+    } else if(range.location == paragraphRange.location - 1) {
+      // same case in other lines; here, the removed range location will be exactly 1 less than paragraph range location
+      [self removeAttributes:paragraphRange];
       return YES;
     }
   }

ios/styles/OrderedListStyle.mm

@@ -131,30 +131,19 @@ - (void)removeTypingAttributes {
 }
 
 - (BOOL)handleBackspaceInRange:(NSRange)range replacementText:(NSString *)text {
-  if(
-    [self detectStyle:_input->textView.selectedRange] &&
-    NSEqualRanges(_input->textView.selectedRange, NSMakeRange(0, 0)) &&
-    [text isEqualToString:@""]
-  ) {
-    // removing first list point by backspacing doesn't remove typing attributes because it doesn't run textViewDidChange
-    // so we try guessing that a point should be deleted here
+  if([self detectStyle:_input->textView.selectedRange] && text.length == 0) {
+    // backspace while the style is active
+    
     NSRange paragraphRange = [_input->textView.textStorage.string paragraphRangeForRange:_input->textView.selectedRange];
-    [self removeAttributes:paragraphRange];
-    return YES;
-  } else if(
-    [self detectStyle:_input->textView.selectedRange] &&
-    [text isEqualToString:@""]
-  ) {
-    // other case; make sure removing all the (non newline) text from a list item also removes the item itself
-    NSRange paragraphRange = [_input->textView.textStorage.string paragraphRangeForRange:range];
-    NSValue *nonNewlineVal = [ParagraphsUtils getNonNewlineRangesIn:_input->textView range:paragraphRange].firstObject;
-    if(nonNewlineVal == nullptr) {
-      return NO;
-    }
-    NSRange nonNewlineRange = [nonNewlineVal rangeValue];
-    if(NSEqualRanges(range, nonNewlineRange)) {
-      [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:_input withSelection:YES];
-      [self removeAttributes:NSMakeRange(range.location, 0)];
+    
+    if(NSEqualRanges(_input->textView.selectedRange, NSMakeRange(0, 0))) {
+      // a backspace on the very first input's line list point
+      // it doesn't run textVieDidChange so we need to manually remove attributes
+      [self removeAttributes:paragraphRange];
+      return YES;
+    } else if(range.location == paragraphRange.location - 1) {
+      // same case in other lines; here, the removed range location will be exactly 1 less than paragraph range location
+      [self removeAttributes:paragraphRange];
       return YES;
     }
   }

ios/styles/UnorderedListStyle.mm

@@ -131,30 +131,19 @@ - (void)removeTypingAttributes {
 }
 
 - (BOOL)handleBackspaceInRange:(NSRange)range replacementText:(NSString *)text {
-  if(
-    [self detectStyle:_input->textView.selectedRange] &&
-    NSEqualRanges(_input->textView.selectedRange, NSMakeRange(0, 0)) &&
-    [text isEqualToString:@""]
-  ) {
-    // removing first list point by backspacing doesn't remove typing attributes because it doesn't run textViewDidChange
-    // so we try guessing that a point should be deleted here
+  if([self detectStyle:_input->textView.selectedRange] && text.length == 0) {
+    // backspace while the style is active
+    
     NSRange paragraphRange = [_input->textView.textStorage.string paragraphRangeForRange:_input->textView.selectedRange];
-    [self removeAttributes:paragraphRange];
-    return YES;
-  } else if(
-    [self detectStyle:_input->textView.selectedRange] &&
-    [text isEqualToString:@""]
-  ) {
-    // other case; make sure removing all the (non newline) text from a list item also removes the item itself
-    NSRange paragraphRange = [_input->textView.textStorage.string paragraphRangeForRange:range];
-    NSValue *nonNewlineVal = [ParagraphsUtils getNonNewlineRangesIn:_input->textView range:paragraphRange].firstObject;
-    if(nonNewlineVal == nullptr) {
-      return NO;
-    }
-    NSRange nonNewlineRange = [nonNewlineVal rangeValue];
-    if(NSEqualRanges(range, nonNewlineRange)) {
-      [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:_input withSelection:YES];
-      [self removeAttributes:NSMakeRange(range.location, 0)];
+    
+    if(NSEqualRanges(_input->textView.selectedRange, NSMakeRange(0, 0))) {
+      // a backspace on the very first input's line list point
+      // it doesn't run textVieDidChange so we need to manually remove attributes
+      [self removeAttributes:paragraphRange];
+      return YES;
+    } else if(range.location == paragraphRange.location - 1) {
+      // same case in other lines; here, the removed range location will be exactly 1 less than paragraph range location
+      [self removeAttributes:paragraphRange];
       return YES;
     }
   }

ios/utils/OccurenceUtils.mm

@@ -47,7 +47,7 @@ + (BOOL)detect
     NSRange attrRange = NSMakeRange(0, 0);
     attrValue = [input->textView.textStorage attribute:key atIndex:index effectiveRange:&attrRange];
   }
-  return condition(attrValue, NSMakeRange(index, 0));
+  return condition(attrValue, detectionRange);
 }
 
 + (BOOL)detectMultiple

ios/utils/ParagraphAttributesUtils.mm

@@ -1,5 +1,6 @@
 #import "ParagraphAttributesUtils.h"
 #import "EnrichedTextInputView.h"
+#import "StyleHeaders.h"
 #import "ParagraphsUtils.h"
 #import "TextInsertionUtils.h"
 
@@ -10,6 +11,10 @@ @implementation ParagraphAttributesUtils
 // hence the solution - reset typing attributes
 + (BOOL)handleBackspaceInRange:(NSRange)range replacementText:(NSString *)text input:(id)input {
   EnrichedTextInputView *typedInput = (EnrichedTextInputView *)input;
+  UnorderedListStyle *ulStyle = typedInput->stylesDict[@([UnorderedListStyle getStyleType])];
+  OrderedListStyle *olStyle = typedInput->stylesDict[@([OrderedListStyle getStyleType])];
+  BlockQuoteStyle *bqStyle = typedInput->stylesDict[@([BlockQuoteStyle getStyleType])];
+  
   if(typedInput == nullptr) {
     return NO;
   }
@@ -21,15 +26,34 @@ + (BOOL)handleBackspaceInRange:(NSRange)range replacementText:(NSString *)text i
 
   // find a non-newline range of the paragraph
   NSRange paragraphRange = [typedInput->textView.textStorage.string paragraphRangeForRange:range];
+  
   NSArray *paragraphs = [ParagraphsUtils getNonNewlineRangesIn:typedInput->textView range:paragraphRange];
   if(paragraphs.count == 0) {
     return NO;
   }
 
   NSRange nonNewlineRange = [(NSValue *)paragraphs.firstObject rangeValue];
 
-  // if the backspace removes the whole content of a paragraph - do the thing
-  if(NSEqualRanges(nonNewlineRange, range)) {
+  // if the backspace removes the whole content of a paragraph (possibly more but has to start where the paragraph starts), we remove the typing attributes
+  if(range.location == nonNewlineRange.location && range.length >= nonNewlineRange.length) {
+    // for lists and quotes we want to remove the characters but keep attribtues so that a zero width space appears here
+    // so we do the removing manually and reapply attributes
+    if([ulStyle detectStyle:nonNewlineRange]) {
+      [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:typedInput withSelection:YES];
+      [ulStyle addAttributes:NSMakeRange(range.location, 0)];
+      return YES;
+    }
+    if([olStyle detectStyle:nonNewlineRange]) {
+      [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:typedInput withSelection:YES];
+      [olStyle addAttributes:NSMakeRange(range.location, 0)];
+      return YES;
+    }
+    if([bqStyle detectStyle:nonNewlineRange]) {
+      [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:typedInput withSelection:YES];
+      [bqStyle addAttributes:NSMakeRange(range.location, 0)];
+      return YES;
+    }
+  
     // do the replacement manually
     [TextInsertionUtils replaceText:text at:range additionalAttributes:nullptr input:typedInput withSelection:YES];
     // reset typing attribtues