Added: Support for "word" unit in modifyselection() helper.

src/model/utils/modifyselection.js

@@ -31,6 +31,7 @@ import DocumentSelection from '../documentselection';
  *  For example `𨭎` is represented in `String` by `\uD862\uDF4E`. Both `\uD862` and `\uDF4E` do not have any meaning
  *  outside the pair (are rendered as ? when alone). Position between them would be incorrect. In this case, selection
  *  extension will include whole "surrogate pair".
+ *  * `'word'` - moves selection by whole word.
  *
  * **Note:** if you extend a forward selection in a backward direction you will in fact shrink it.
  *
@@ -79,11 +80,13 @@ export default function modifySelection( model, selection, options = {} ) {
 }
 
 // Checks whether the selection can be extended to the the walker's next value (next position).
+// @param {{ walker, unit, isForward, schema }} data
+// @param {{ item, nextPosition, type}} value
 function tryExtendingTo( data, value ) {
 	// If found text, we can certainly put the focus in it. Let's just find a correct position
 	// based on the unit.
 	if ( value.type == 'text' ) {
-		return getCorrectPosition( data.walker, data.unit );
+		return getCorrectPosition( data.walker, data.unit, data.isForward );
 	}
 
 	// Entering an element.
@@ -117,17 +120,27 @@ function tryExtendingTo( data, value ) {
 
 // Finds a correct position by walking in a text node and checking whether selection can be extended to given position
 // or should be extended further.
-function getCorrectPosition( walker, unit ) {
+//
+// @param {} walker
+// @param {String} unit A boundary limit: character, codePoint, word.
+function getCorrectPosition( walker, unit, isForward ) {
 	const textNode = walker.position.textNode;
 
 	if ( textNode ) {
 		const data = textNode.data;
 		let offset = walker.position.offset - textNode.startOffset;
 
-		while ( isInsideSurrogatePair( data, offset ) || ( unit == 'character' && isInsideCombinedSymbol( data, offset ) ) ) {
+		let endOffset = isForward ? textNode.endOffset : 0;
+
+		while (
+			isInsideSurrogatePair( data, offset ) ||
+			( unit == 'character' && isInsideCombinedSymbol( data, offset ) ) ||
+			( unit == 'word' && !isAtWordEnd( data, offset, isForward ) && !( offset === endOffset ) )
+		) {
 			walker.next();
 
 			offset = walker.position.offset - textNode.startOffset;
+			endOffset = isForward ? textNode.endOffset : 0;
 		}
 	}
 
@@ -144,3 +157,9 @@ function getSearchRange( start, isForward ) {
 		return new Range( searchEnd, start );
 	}
 }
+
+function isAtWordEnd( data, offset, isForward ) {
+	const char = data.charAt( offset + ( isForward ? 0 : -1 ) );
+
+	return ' ,.-'.includes( char );
+}