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- /**
- * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
- * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
- */
- /**
- * @module utils/difftochanges
- */
- /**
- * Creates a set of changes which need to be applied to the input in order to transform
- * it into the output. This function can be used with strings or arrays.
- *
- * const input = Array.from( 'abc' );
- * const output = Array.from( 'xaby' );
- * const changes = diffToChanges( diff( input, output ), output );
- *
- * changes.forEach( change => {
- * if ( change.type == 'insert' ) {
- * input.splice( change.index, 0, ...change.values );
- * } else if ( change.type == 'delete' ) {
- * input.splice( change.index, change.howMany );
- * }
- * } );
- *
- * input.join( '' ) == output.join( '' ); // -> true
- *
- * @param {Array.<'equal'|'insert'|'delete'>} diff Result of {@link module:utils/diff~diff}.
- * @param {String|Array} output The string or array which was passed as diff's output.
- * @returns {Array.<Object>} Set of changes (insert or delete) which need to be applied to the input
- * in order to transform it into the output.
- */
- export default function diffToChanges( diff, output ) {
- const changes = [];
- let index = 0;
- let lastOperation;
- diff.forEach( change => {
- if ( change == 'equal' ) {
- pushLast();
- index++;
- } else if ( change == 'insert' ) {
- if ( isContinuationOf( 'insert' ) ) {
- lastOperation.values.push( output[ index ] );
- } else {
- pushLast();
- lastOperation = {
- type: 'insert',
- index,
- values: [ output[ index ] ]
- };
- }
- index++;
- } else /* if ( change == 'delete' ) */ {
- if ( isContinuationOf( 'delete' ) ) {
- lastOperation.howMany++;
- } else {
- pushLast();
- lastOperation = {
- type: 'delete',
- index,
- howMany: 1
- };
- }
- }
- } );
- pushLast();
- return changes;
- function pushLast() {
- if ( lastOperation ) {
- changes.push( lastOperation );
- lastOperation = null;
- }
- }
- function isContinuationOf( expected ) {
- return lastOperation && lastOperation.type == expected;
- }
- }
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