From b6948f0107061bafce98cdcf1282529bb61433ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Tue, 14 Aug 2018 17:56:30 +0200
Subject: [PATCH 1/7] Added writer for manipulating non-semantic view.

---
 src/view/rawwriter.js | 244 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 244 insertions(+)
 create mode 100644 src/view/rawwriter.js

diff --git a/src/view/rawwriter.js b/src/view/rawwriter.js
new file mode 100644
index 000000000..de951d11d
--- /dev/null
+++ b/src/view/rawwriter.js
@@ -0,0 +1,244 @@
+/**
+ * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+/**
+ * @module module:engine/view/rawwriter
+ */
+
+import Element from './element';
+import { isPlainObject } from 'lodash-es';
+
+/**
+ * View raw writer class. Provides set of methods used to properly manipulate nodes attached to
+ * {@link module:engine/view/view~View view instance}. It should be only used to manipulate non-semantic view
+ * (view created from HTML string). For view which was downcasted from the {@link module:engine/model/model~Model model}
+ * see {@link module:engine/view/writer~Writer writer}.
+ */
+export default class RawWriter {
+	/**
+	 * Clones provided element.
+	 *
+	 * @see module:engine/view/element~Element#_clone
+	 * @param {module:engine/view/element~Element} element Element to be cloned.
+	 * @param {Boolean} [deep=false] If set to `true` clones element and all its children recursively. When set to `false`,
+	 * element will be cloned without any children.
+	 * @returns {module:engine/view/element~Element} Clone of this element.
+	 */
+	clone( element, deep = false ) {
+		return element._clone( deep );
+	}
+
+	/**
+	 * Appends a child node or a list of child nodes at the end of this node
+	 * and sets the parent of these nodes to this element.
+	 *
+	 * @see module:engine/view/element~Element#_appendChild
+	 * @param {module:engine/view/element~Element} element Element to which items will be appended.
+	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
+	 * @fires module:engine/view/node~Node#change
+	 * @returns {Number} Number of appended nodes.
+	 */
+	appendChild( element, items ) {
+		return element._appendChild( items );
+	}
+
+	/**
+	 * Inserts a child node or a list of child nodes on the given index and sets the parent of these nodes to
+	 * this element.
+	 *
+	 * @see module:engine/view/element~Element#_insertChild
+	 * @param {module:engine/view/element~Element} element Element to which items will be inserted.
+	 * @param {Number} index Position where nodes should be inserted.
+	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
+	 * @fires module:engine/view/node~Node#change
+	 * @returns {Number} Number of inserted nodes.
+	 */
+	insertChild( element, index, items ) {
+		return element._insertChild( element, index, items );
+	}
+
+	/**
+	 * Removes number of child nodes starting at the given index and set the parent of these nodes to `null`.
+	 *
+	 * @see module:engine/view/element~Element#_removeChildren
+	 * @param {module:engine/view/element~Element} element Element from which children will be removed.
+	 * @param {Number} index Number of the first node to remove.
+	 * @param {Number} [howMany=1] Number of nodes to remove.
+	 * @fires module:engine/view/node~Node#change
+	 * @returns {Array.<module:engine/view/node~Node>} The array of removed nodes.
+	 */
+	removeChildren( element, index, howMany = 1 ) {
+		return element._removeChildren( index, howMany );
+	}
+
+	/**
+	 * Removes given element from the view structure. Will not have effect on detached elements.
+	 *
+	 * @param {module:engine/view/element~Element} element Element which will be removed.
+	 * @returns {Array.<module:engine/view/node~Node>|null} The array of removed nodes or null if element was already detached.
+	 */
+	remove( element ) {
+		const parent = element.parent;
+		if ( parent ) {
+			return this.removeChildren( parent, parent.getChildIndex( element ) );
+		}
+
+		return null;
+	}
+
+	/**
+	 * Replaces given element with the new one in the view structure. Will not have effect on detached elements.
+	 *
+	 * @param {module:engine/view/element~Element} oldElement Element which will be replaced.
+	 * @param {module:engine/view/element~Element} newElement Element which will inserted in the place of the old element.
+	 * @returns {Boolean} Whether old element was successfully replaced.
+	 */
+	replace( oldElement, newElement ) {
+		const parent = oldElement.parent;
+
+		if ( parent ) {
+			const index = parent.getChildIndex( oldElement );
+
+			this.removeChildren( parent, index );
+			this.insertChild( parent, index, newElement );
+		}
+
+		return null;
+	}
+
+	/**
+	 * Renames element by creating a copy of renamed element but with changed name and then moving contents of the
+	 * old element to the new one.
+	 *
+	 * Since this function creates a new element and removes the given one, the new element is returned to keep reference.
+	 *
+	 * @param {module:engine/view/element~Element} element Element to be renamed.
+	 * @param {String} newName New name for element.
+	 * @returns {module:engine/view/element~Element} New element.
+	 */
+	rename( element, newName ) {
+		const newElement = new Element( newName, element.getAttributes(), element.getChildren() );
+
+		this.replace( element, newElement );
+
+		return newElement;
+	}
+
+	/**
+	 * Adds or overwrite element's attribute with a specified key and value.
+	 *
+	 *		writer.setAttribute( 'href', 'http://ckeditor.com', linkElement );
+	 *
+	 * @see module:engine/view/element~Element#_setAttribute
+	 * @param {module:engine/view/element~Element} element
+	 * @param {String} key Attribute key.
+	 * @param {String} value Attribute value.
+	 */
+	setAttribute( element, key, value ) {
+		element._setAttribute( key, value );
+	}
+
+	/**
+	 * Removes attribute from the element.
+	 *
+	 *		writer.removeAttribute( 'href', linkElement );
+	 *
+	 * @see module:engine/view/element~Element#_removeAttribute
+	 * @param {module:engine/view/element~Element} element
+	 * @param {String} key Attribute key.
+	 */
+	removeAttribute( element, key ) {
+		element._removeAttribute( key );
+	}
+
+	/**
+	 * Adds specified class to the element.
+	 *
+	 *		writer.addClass( 'foo', linkElement );
+	 *		writer.addClass( [ 'foo', 'bar' ], linkElement );
+	 *
+	 * @see module:engine/view/element~Element#_addClass
+	 * @param {module:engine/view/element~Element} element
+	 * @param {Array.<String>|String} className
+	 */
+	addClass( element, className ) {
+		element._addClass( className );
+	}
+
+	/**
+	 * Removes specified class from the element.
+	 *
+	 *		writer.removeClass( 'foo', linkElement );
+	 *		writer.removeClass( [ 'foo', 'bar' ], linkElement );
+	 *
+	 * @see module:engine/view/element~Element#_removeClass
+	 * @param {module:engine/view/element~Element} element
+	 * @param {Array.<String>|String} className
+	 */
+	removeClass( element, className ) {
+		element._removeClass( className );
+	}
+
+	/**
+	 * Adds style to the element.
+	 *
+	 *		writer.setStyle( 'color', 'red', element );
+	 *		writer.setStyle( {
+	 *			color: 'red',
+	 *			position: 'fixed'
+	 *		}, element );
+	 *
+	 * @see module:engine/view/element~Element#_setStyle
+	 * @param {module:engine/view/element~Element} element
+	 * @param {String|Object} property Property name or object with key - value pairs.
+	 * @param {String} [value] Value to set. This parameter is ignored if object is provided as the first parameter.
+	 */
+	setStyle( element, property, value ) {
+		if ( isPlainObject( property ) && element === undefined ) {
+			element = value;
+		}
+
+		element._setStyle( property, value );
+	}
+
+	/**
+	 * Removes specified style from the element.
+	 *
+	 *		writer.removeStyle( 'color', element );  // Removes 'color' style.
+	 *		writer.removeStyle( [ 'color', 'border-top' ], element ); // Removes both 'color' and 'border-top' styles.
+	 *
+	 * @see module:engine/view/element~Element#_removeStyle
+	 * @param {module:engine/view/element~Element} element
+	 * @param {Array.<String>|String} property
+	 */
+	removeStyle( element, property ) {
+		element._removeStyle( property );
+	}
+
+	/**
+	 * Sets a custom property on element. Unlike attributes, custom properties are not rendered to the DOM,
+	 * so they can be used to add special data to elements.
+	 *
+	 * @see module:engine/view/element~Element#_setCustomProperty
+	 * @param {module:engine/view/element~Element} element
+	 * @param {String|Symbol} key
+	 * @param {*} value
+	 */
+	setCustomProperty( element, key, value ) {
+		element._setCustomProperty( key, value );
+	}
+
+	/**
+	 * Removes a custom property stored under the given key.
+	 *
+	 * @see module:engine/view/element~Element#_removeCustomProperty
+	 * @param {module:engine/view/element~Element} element
+	 * @param {String|Symbol} key
+	 * @returns {Boolean} Returns true if property was removed.
+	 */
+	removeCustomProperty( element, key ) {
+		return element._removeCustomProperty( key );
+	}
+}

From e098d3eb613d48f5393d43b3a80814536f4d8fd2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Tue, 14 Aug 2018 17:57:23 +0200
Subject: [PATCH 2/7] Tests: writer unit tests - WIP.

---
 tests/view/rawwriter.js | 97 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 tests/view/rawwriter.js

diff --git a/tests/view/rawwriter.js b/tests/view/rawwriter.js
new file mode 100644
index 000000000..89e595860
--- /dev/null
+++ b/tests/view/rawwriter.js
@@ -0,0 +1,97 @@
+/**
+ * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import Element from '../../src/view/element';
+import RawWriter from '../../src/view/rawwriter';
+import HtmlDataProcessor from '../../src/dataprocessor/htmldataprocessor';
+
+describe( 'RawWriter', () => {
+	let writer, view, dataprocessor;
+
+	before( () => {
+		writer = new RawWriter();
+		dataprocessor = new HtmlDataProcessor();
+	} );
+
+	beforeEach( () => {
+		const html = '' +
+			'<h1>Heading <strong>1</strong></h1>' +
+			'<p class="foo1 bar2" style="text-align:left;" data-attr="abc">Foo <i>Bar</i> <strong>Bold</strong></p>' +
+			'<p><u>Some underlined</u> text</p>' +
+			'<ul>' +
+			'<li>Item 1</li>' +
+			'<li><span>Item <s>1</s></span></li>' +
+			'<li><h2>Item 1</h2></li>' +
+			'</ul>';
+
+		view = dataprocessor.toView( html );
+	} );
+
+	describe( 'clone', () => {
+		it( 'should clone simple element', () => {
+			const el = view.getChild( 0 );
+			const clone = writer.clone( el );
+
+			expect( clone ).to.not.equal( el );
+			expect( clone.isSimilar( el ) ).to.true;
+			expect( clone.childCount ).to.equal( 0 );
+		} );
+
+		it( 'should clone element with all attributes', () => {
+			const el = view.getChild( 1 );
+			const clone = writer.clone( el );
+
+			expect( clone ).to.not.equal( el );
+			expect( clone.isSimilar( el ) ).to.true;
+			expect( clone.childCount ).to.equal( 0 );
+		} );
+
+		it( 'should deep clone element', () => {
+			const el = view.getChild( 0 );
+			const clone = writer.clone( el, true );
+
+			expect( clone ).to.not.equal( el );
+			expect( clone.isSimilar( el ) ).to.true;
+			expect( clone.childCount ).to.equal( el.childCount );
+		} );
+	} );
+
+	describe( 'appendChild', () => {
+		it( 'should append inline child to paragraph', () => {
+			const el = view.getChild( 2 );
+			const newChild = new Element( 'span' );
+
+			const appended = writer.appendChild( el, newChild );
+
+			expect( appended ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.childCount ).to.equal( 3 );
+		} );
+
+		it( 'should append block children to paragraph', () => {
+			const el = view.getChild( 2 );
+			const newChild1 = new Element( 'p' );
+			const newChild2 = new Element( 'h2' );
+
+			const appended = writer.appendChild( el, [ newChild1, newChild2 ] );
+
+			expect( appended ).to.equal( 2 );
+			expect( newChild1.parent ).to.equal( el );
+			expect( newChild2.parent ).to.equal( el );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should append list item to the list', () => {
+			const el = view.getChild( 3 );
+			const newChild = new Element( 'li' );
+
+			const appended = writer.appendChild( el, newChild );
+
+			expect( appended ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+	} );
+} );

From f75d8d64c26b3af25bf8deef53f7fe6da49b5a9d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Thu, 16 Aug 2018 17:17:32 +0200
Subject: [PATCH 3/7] Writer docs rewording and code adjustments.

---
 src/view/rawwriter.js | 53 +++++++++++++++++++++----------------------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/src/view/rawwriter.js b/src/view/rawwriter.js
index de951d11d..68b3f9383 100644
--- a/src/view/rawwriter.js
+++ b/src/view/rawwriter.js
@@ -8,7 +8,6 @@
  */
 
 import Element from './element';
-import { isPlainObject } from 'lodash-es';
 
 /**
  * View raw writer class. Provides set of methods used to properly manipulate nodes attached to
@@ -35,7 +34,8 @@ export default class RawWriter {
 	 * and sets the parent of these nodes to this element.
 	 *
 	 * @see module:engine/view/element~Element#_appendChild
-	 * @param {module:engine/view/element~Element} element Element to which items will be appended.
+	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
+	 * to which items will be appended.
 	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
 	 * @fires module:engine/view/node~Node#change
 	 * @returns {Number} Number of appended nodes.
@@ -49,21 +49,23 @@ export default class RawWriter {
 	 * this element.
 	 *
 	 * @see module:engine/view/element~Element#_insertChild
-	 * @param {module:engine/view/element~Element} element Element to which items will be inserted.
+	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
+	 * to which items will be inserted.
 	 * @param {Number} index Position where nodes should be inserted.
 	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
 	 * @fires module:engine/view/node~Node#change
 	 * @returns {Number} Number of inserted nodes.
 	 */
 	insertChild( element, index, items ) {
-		return element._insertChild( element, index, items );
+		return element._insertChild( index, items );
 	}
 
 	/**
 	 * Removes number of child nodes starting at the given index and set the parent of these nodes to `null`.
 	 *
 	 * @see module:engine/view/element~Element#_removeChildren
-	 * @param {module:engine/view/element~Element} element Element from which children will be removed.
+	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
+	 * from which children will be removed.
 	 * @param {Number} index Number of the first node to remove.
 	 * @param {Number} [howMany=1] Number of nodes to remove.
 	 * @fires module:engine/view/node~Node#change
@@ -77,7 +79,7 @@ export default class RawWriter {
 	 * Removes given element from the view structure. Will not have effect on detached elements.
 	 *
 	 * @param {module:engine/view/element~Element} element Element which will be removed.
-	 * @returns {Array.<module:engine/view/node~Node>|null} The array of removed nodes or null if element was already detached.
+	 * @returns {Array.<module:engine/view/node~Node>} The array of removed nodes.
 	 */
 	remove( element ) {
 		const parent = element.parent;
@@ -85,7 +87,7 @@ export default class RawWriter {
 			return this.removeChildren( parent, parent.getChildIndex( element ) );
 		}
 
-		return null;
+		return [];
 	}
 
 	/**
@@ -103,9 +105,11 @@ export default class RawWriter {
 
 			this.removeChildren( parent, index );
 			this.insertChild( parent, index, newElement );
+
+			return true;
 		}
 
-		return null;
+		return false;
 	}
 
 	/**
@@ -116,20 +120,19 @@ export default class RawWriter {
 	 *
 	 * @param {module:engine/view/element~Element} element Element to be renamed.
 	 * @param {String} newName New name for element.
-	 * @returns {module:engine/view/element~Element} New element.
+	 * @returns {module:engine/view/element~Element|null} New element or null if the old element
+	 * was not replaced (happens for detached elements).
 	 */
 	rename( element, newName ) {
 		const newElement = new Element( newName, element.getAttributes(), element.getChildren() );
 
-		this.replace( element, newElement );
-
-		return newElement;
+		return this.replace( element, newElement ) ? newElement : null;
 	}
 
 	/**
 	 * Adds or overwrite element's attribute with a specified key and value.
 	 *
-	 *		writer.setAttribute( 'href', 'http://ckeditor.com', linkElement );
+	 *		writer.setAttribute( linkElement, 'href', 'http://ckeditor.com' );
 	 *
 	 * @see module:engine/view/element~Element#_setAttribute
 	 * @param {module:engine/view/element~Element} element
@@ -143,7 +146,7 @@ export default class RawWriter {
 	/**
 	 * Removes attribute from the element.
 	 *
-	 *		writer.removeAttribute( 'href', linkElement );
+	 *		writer.removeAttribute( linkElement, 'href' );
 	 *
 	 * @see module:engine/view/element~Element#_removeAttribute
 	 * @param {module:engine/view/element~Element} element
@@ -156,8 +159,8 @@ export default class RawWriter {
 	/**
 	 * Adds specified class to the element.
 	 *
-	 *		writer.addClass( 'foo', linkElement );
-	 *		writer.addClass( [ 'foo', 'bar' ], linkElement );
+	 *		writer.addClass( linkElement, 'foo' );
+	 *		writer.addClass( linkElement, [ 'foo', 'bar' ] );
 	 *
 	 * @see module:engine/view/element~Element#_addClass
 	 * @param {module:engine/view/element~Element} element
@@ -170,8 +173,8 @@ export default class RawWriter {
 	/**
 	 * Removes specified class from the element.
 	 *
-	 *		writer.removeClass( 'foo', linkElement );
-	 *		writer.removeClass( [ 'foo', 'bar' ], linkElement );
+	 *		writer.removeClass( linkElement, 'foo' );
+	 *		writer.removeClass( linkElement, [ 'foo', 'bar' ] );
 	 *
 	 * @see module:engine/view/element~Element#_removeClass
 	 * @param {module:engine/view/element~Element} element
@@ -184,11 +187,11 @@ export default class RawWriter {
 	/**
 	 * Adds style to the element.
 	 *
-	 *		writer.setStyle( 'color', 'red', element );
-	 *		writer.setStyle( {
+	 *		writer.setStyle( element, 'color', 'red' );
+	 *		writer.setStyle( element, {
 	 *			color: 'red',
 	 *			position: 'fixed'
-	 *		}, element );
+	 *		} );
 	 *
 	 * @see module:engine/view/element~Element#_setStyle
 	 * @param {module:engine/view/element~Element} element
@@ -196,18 +199,14 @@ export default class RawWriter {
 	 * @param {String} [value] Value to set. This parameter is ignored if object is provided as the first parameter.
 	 */
 	setStyle( element, property, value ) {
-		if ( isPlainObject( property ) && element === undefined ) {
-			element = value;
-		}
-
 		element._setStyle( property, value );
 	}
 
 	/**
 	 * Removes specified style from the element.
 	 *
-	 *		writer.removeStyle( 'color', element );  // Removes 'color' style.
-	 *		writer.removeStyle( [ 'color', 'border-top' ], element ); // Removes both 'color' and 'border-top' styles.
+	 *		writer.removeStyle( element, 'color' );  // Removes 'color' style.
+	 *		writer.removeStyle( element, [ 'color', 'border-top' ] ); // Removes both 'color' and 'border-top' styles.
 	 *
 	 * @see module:engine/view/element~Element#_removeStyle
 	 * @param {module:engine/view/element~Element} element

From 1cfe049bf81d2bb1e6abca3f0b63f679aa028a69 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Thu, 16 Aug 2018 17:23:30 +0200
Subject: [PATCH 4/7] Tests: writer unit tests - 100% cc.

---
 tests/view/rawwriter.js | 388 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 386 insertions(+), 2 deletions(-)

diff --git a/tests/view/rawwriter.js b/tests/view/rawwriter.js
index 89e595860..f6c7eb319 100644
--- a/tests/view/rawwriter.js
+++ b/tests/view/rawwriter.js
@@ -17,11 +17,11 @@ describe( 'RawWriter', () => {
 
 	beforeEach( () => {
 		const html = '' +
-			'<h1>Heading <strong>1</strong></h1>' +
+			'<h1 style="color:blue;position:fixed;">Heading <strong>1</strong></h1>' +
 			'<p class="foo1 bar2" style="text-align:left;" data-attr="abc">Foo <i>Bar</i> <strong>Bold</strong></p>' +
 			'<p><u>Some underlined</u> text</p>' +
 			'<ul>' +
-			'<li>Item 1</li>' +
+			'<li class="single">Item 1</li>' +
 			'<li><span>Item <s>1</s></span></li>' +
 			'<li><h2>Item 1</h2></li>' +
 			'</ul>';
@@ -93,5 +93,389 @@ describe( 'RawWriter', () => {
 			expect( newChild.parent ).to.equal( el );
 			expect( el.childCount ).to.equal( 4 );
 		} );
+
+		it( 'should append element to DocumentFragment element', () => {
+			const newChild = new Element( 'p' );
+
+			const appended = writer.appendChild( view, newChild );
+
+			expect( appended ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( view );
+			expect( view.childCount ).to.equal( 5 );
+		} );
+	} );
+
+	describe( 'insertChild', () => {
+		it( 'should insert inline child into the paragraph on the first position', () => {
+			const el = view.getChild( 2 );
+			const newChild = new Element( 'span' );
+
+			const inserted = writer.insertChild( el, 0, newChild );
+
+			expect( inserted ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.getChild( 0 ) ).to.equal( newChild );
+			expect( el.childCount ).to.equal( 3 );
+		} );
+
+		it( 'should insert block children into the paragraph on the last position', () => {
+			const el = view.getChild( 2 );
+			const newChild1 = new Element( 'blockquote' );
+			const newChild2 = new Element( 'h2' );
+
+			const inserted = writer.insertChild( el, 2, [ newChild1, newChild2 ] );
+
+			expect( inserted ).to.equal( 2 );
+			expect( newChild1.parent ).to.equal( el );
+			expect( newChild2.parent ).to.equal( el );
+			expect( el.getChild( 2 ) ).to.equal( newChild1 );
+			expect( el.getChild( 3 ) ).to.equal( newChild2 );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should insert list item into the list element', () => {
+			const el = view.getChild( 3 );
+			const newChild = new Element( 'li' );
+
+			const inserted = writer.insertChild( el, 1, newChild );
+
+			expect( inserted ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.getChild( 1 ) ).to.equal( newChild );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should insert element to DocumentFragment element', () => {
+			const newChild = new Element( 'p' );
+
+			const inserted = writer.insertChild( view, 4, newChild );
+
+			expect( inserted ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( view );
+			expect( view.getChild( 4 ) ).to.equal( newChild );
+			expect( view.childCount ).to.equal( 5 );
+		} );
+	} );
+
+	describe( 'removeChildren', () => {
+		it( 'should remove child from the beginning of the paragraph', () => {
+			const el = view.getChild( 1 );
+			const toRemove = el.getChild( 0 );
+
+			const removed = writer.removeChildren( el, 0 );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( el.childCount ).to.equal( 3 );
+		} );
+
+		it( 'should remove two last list items from the list element', () => {
+			const el = view.getChild( 3 );
+			const toRemove1 = el.getChild( 1 );
+			const toRemove2 = el.getChild( 2 );
+
+			const removed = writer.removeChildren( el, 1, 2 );
+
+			expect( removed.length ).to.equal( 2 );
+			expect( removed[ 0 ] ).to.equal( toRemove1 );
+			expect( removed[ 1 ] ).to.equal( toRemove2 );
+			expect( el.childCount ).to.equal( 1 );
+		} );
+
+		it( 'should remove child from DocumentFragment element', () => {
+			const toRemove = view.getChild( 2 );
+
+			const removed = writer.removeChildren( view, 2 );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( view.childCount ).to.equal( 3 );
+		} );
+	} );
+
+	describe( 'remove', () => {
+		it( 'should remove list item from the list element', () => {
+			const toRemove = view.getChild( 3 ).getChild( 1 );
+
+			const removed = writer.remove( toRemove );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( view.getChild( 3 ).childCount ).to.equal( 2 );
+		} );
+
+		it( 'should have no effect on detached elements', () => {
+			const newChild = new Element( 'h2' );
+
+			const removed = writer.remove( newChild );
+
+			expect( removed.length ).to.equal( 0 );
+			expect( view.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should remove direct root (DocumentFragment) child', () => {
+			const toRemove = view.getChild( 3 );
+
+			const removed = writer.remove( toRemove );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( view.childCount ).to.equal( 3 );
+		} );
+	} );
+
+	describe( 'replace', () => {
+		it( 'should replace single element', () => {
+			const el = view.getChild( 0 ).getChild( 1 );
+			const newChild = new Element( 'span' );
+
+			const replacement = writer.replace( el, newChild );
+
+			expect( replacement ).to.true;
+			expect( view.getChild( 0 ).getChild( 1 ) ).to.equal( newChild );
+			expect( view.getChild( 0 ).childCount ).to.equal( 2 );
+		} );
+
+		it( 'should replace element with children', () => {
+			const el = view.getChild( 3 );
+			const newChild = new Element( 'ol' );
+
+			const replacement = writer.replace( el, newChild );
+
+			expect( replacement ).to.true;
+			expect( view.getChild( 3 ) ).to.equal( newChild );
+			expect( view.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should have no effect on detached elements', () => {
+			const oldChild = new Element( 'h2' );
+			const newChild = new Element( 'h2' );
+
+			const replacement = writer.replace( oldChild, newChild );
+
+			expect( replacement ).to.false;
+			expect( view.childCount ).to.equal( 4 );
+		} );
+	} );
+
+	describe( 'rename', () => {
+		it( 'should rename simple element', () => {
+			const el = view.getChild( 0 ).getChild( 1 );
+
+			const renamed = writer.rename( el, 'i' );
+
+			expect( renamed ).to.not.equal( el );
+			expect( renamed ).to.equal( view.getChild( 0 ).getChild( 1 ) );
+			expect( renamed.name ).to.equal( 'i' );
+			expect( view.getChild( 0 ).childCount ).to.equal( 2 );
+		} );
+
+		it( 'should rename direct root (DocumentFragment) child element', () => {
+			const el = view.getChild( 1 );
+
+			const renamed = writer.rename( el, 'h3' );
+
+			expect( renamed ).to.not.equal( el );
+			expect( renamed ).to.equal( view.getChild( 1 ) );
+			expect( renamed.name ).to.equal( 'h3' );
+			expect( view.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should have no effect on detached element', () => {
+			const element = new Element( 'h2' );
+
+			const renamed = writer.rename( element, 'h3' );
+
+			expect( renamed ).to.null;
+			expect( view.childCount ).to.equal( 4 );
+		} );
+	} );
+
+	describe( 'setAttribute', () => {
+		it( 'should add new attribute', () => {
+			const el = view.getChild( 0 );
+
+			writer.setAttribute( el, 'testAttr', 'testVal' );
+
+			expect( el.getAttribute( 'testAttr' ) ).to.equal( 'testVal' );
+		} );
+
+		it( 'should update existing attribute', () => {
+			const el = view.getChild( 1 );
+
+			writer.setAttribute( el, 'data-attr', 'foo' );
+
+			expect( el.getAttribute( 'data-attr' ) ).to.equal( 'foo' );
+		} );
+	} );
+
+	describe( 'removeAttribute', () => {
+		it( 'should remove existing attribute', () => {
+			const el = view.getChild( 1 );
+
+			writer.removeAttribute( el, 'data-attr' );
+
+			expect( el.hasAttribute( 'data-attr' ) ).to.false;
+		} );
+
+		it( 'should have no effect if attribute does not exists', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeAttribute( el, 'non-existent' );
+
+			expect( el.hasAttribute( 'non-existent' ) ).to.false;
+		} );
+	} );
+
+	describe( 'addClass', () => {
+		it( 'should add new classes if no classes', () => {
+			const el = view.getChild( 2 );
+
+			writer.addClass( el, [ 'foo', 'bar' ] );
+
+			expect( el.hasClass( 'foo' ) ).to.true;
+			expect( el.hasClass( 'bar' ) ).to.true;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 2 );
+		} );
+
+		it( 'should add new class to existing classes', () => {
+			const el = view.getChild( 1 );
+
+			writer.addClass( el, 'newClass' );
+
+			expect( el.hasClass( 'newClass' ) ).to.true;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 3 );
+		} );
+	} );
+
+	describe( 'removeClass', () => {
+		it( 'should remove existing class', () => {
+			const el = view.getChild( 3 ).getChild( 0 );
+
+			writer.removeClass( el, 'single' );
+
+			expect( el.hasClass( 'single' ) ).to.false;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 0 );
+		} );
+
+		it( 'should remove existing class from many classes', () => {
+			const el = view.getChild( 1 );
+
+			writer.removeClass( el, 'foo1' );
+
+			expect( el.hasClass( 'foo1' ) ).to.false;
+			expect( el.hasClass( 'bar2' ) ).to.true;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 1 );
+		} );
+
+		it( 'should have no effect if there are no classes', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeClass( el, 'non-existent' );
+
+			expect( el.hasClass( 'non-existent' ) ).to.false;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 0 );
+		} );
+	} );
+
+	describe( 'setStyle', () => {
+		it( 'should add new style', () => {
+			const el = view.getChild( 2 );
+
+			writer.setStyle( el, {
+				color: 'red',
+				position: 'fixed'
+			} );
+
+			expect( el.getStyle( 'color' ) ).to.equal( 'red' );
+			expect( el.getStyle( 'position' ) ).to.equal( 'fixed' );
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 2 );
+		} );
+
+		it( 'should update existing styles', () => {
+			const el = view.getChild( 1 );
+
+			writer.setStyle( el, 'text-align', 'center' );
+
+			expect( el.getStyle( 'text-align' ) ).to.equal( 'center' );
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 1 );
+		} );
+	} );
+
+	describe( 'removeStyle', () => {
+		it( 'should remove existing style', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeStyle( el, [ 'color', 'position' ] );
+
+			expect( el.hasStyle( 'color' ) ).to.false;
+			expect( el.hasStyle( 'position' ) ).to.false;
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 0 );
+		} );
+
+		it( 'should remove value from existing styles', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeStyle( el, 'position' );
+
+			expect( el.hasStyle( 'color' ) ).to.true;
+			expect( el.hasStyle( 'position' ) ).to.false;
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 1 );
+		} );
+
+		it( 'should have no effect if styles does not exists', () => {
+			const el = view.getChild( 2 );
+
+			writer.removeStyle( el, [ 'color', 'position' ] );
+
+			expect( el.hasStyle( 'color' ) ).to.false;
+			expect( el.hasStyle( 'position' ) ).to.false;
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 0 );
+		} );
+	} );
+
+	describe( 'setCustomProperty', () => {
+		it( 'should add or update custom property', () => {
+			const el = new Element( 'span' );
+
+			writer.setCustomProperty( el, 'prop1', 'foo' );
+			writer.setCustomProperty( el, 'prop2', 'bar' );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.equal( 'foo' );
+			expect( el.getCustomProperty( 'prop2' ) ).to.equal( 'bar' );
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 2 );
+
+			const objectProperty = { foo: 'bar' };
+			writer.setCustomProperty( el, 'prop2', objectProperty );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.equal( 'foo' );
+			expect( el.getCustomProperty( 'prop2' ) ).to.equal( objectProperty );
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 2 );
+		} );
+	} );
+
+	describe( 'removeCustomProperty', () => {
+		it( 'should remove existing custom property', () => {
+			const el = new Element( 'p' );
+
+			writer.setCustomProperty( el, 'prop1', 'foo' );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.equal( 'foo' );
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 1 );
+
+			writer.removeCustomProperty( el, 'prop1' );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.undefined;
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 0 );
+		} );
+
+		it( 'should have no effect if custom property does not exists', () => {
+			const el = new Element( 'h1' );
+
+			writer.removeCustomProperty( el, 'prop1' );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.undefined;
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 0 );
+		} );
 	} );
 } );

From d0ea328a1d7e9ed14a51b00de00839ea76b3aefd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Mon, 27 Aug 2018 11:09:04 +0200
Subject: [PATCH 5/7] Renamed 'RawWriter' to 'UpcastWriter'.

---
 src/view/{rawwriter.js => upcastwriter.js}   | 6 +++---
 tests/view/{rawwriter.js => upcastwriter.js} | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)
 rename src/view/{rawwriter.js => upcastwriter.js} (97%)
 rename tests/view/{rawwriter.js => upcastwriter.js} (99%)

diff --git a/src/view/rawwriter.js b/src/view/upcastwriter.js
similarity index 97%
rename from src/view/rawwriter.js
rename to src/view/upcastwriter.js
index 68b3f9383..a8ad45bd0 100644
--- a/src/view/rawwriter.js
+++ b/src/view/upcastwriter.js
@@ -4,18 +4,18 @@
  */
 
 /**
- * @module module:engine/view/rawwriter
+ * @module module:engine/view/upcastwriter
  */
 
 import Element from './element';
 
 /**
- * View raw writer class. Provides set of methods used to properly manipulate nodes attached to
+ * View upcast writer class. Provides set of methods used to properly manipulate nodes attached to
  * {@link module:engine/view/view~View view instance}. It should be only used to manipulate non-semantic view
  * (view created from HTML string). For view which was downcasted from the {@link module:engine/model/model~Model model}
  * see {@link module:engine/view/writer~Writer writer}.
  */
-export default class RawWriter {
+export default class UpcastWriter {
 	/**
 	 * Clones provided element.
 	 *
diff --git a/tests/view/rawwriter.js b/tests/view/upcastwriter.js
similarity index 99%
rename from tests/view/rawwriter.js
rename to tests/view/upcastwriter.js
index f6c7eb319..33c9e4f9b 100644
--- a/tests/view/rawwriter.js
+++ b/tests/view/upcastwriter.js
@@ -4,14 +4,14 @@
  */
 
 import Element from '../../src/view/element';
-import RawWriter from '../../src/view/rawwriter';
+import UpcastWriter from '../../src/view/upcastwriter';
 import HtmlDataProcessor from '../../src/dataprocessor/htmldataprocessor';
 
-describe( 'RawWriter', () => {
+describe( 'UpcastWriter', () => {
 	let writer, view, dataprocessor;
 
 	before( () => {
-		writer = new RawWriter();
+		writer = new UpcastWriter();
 		dataprocessor = new HtmlDataProcessor();
 	} );
 

From 9cc372950dc114479bfda8e0f813d69054e1ebe4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Mon, 27 Aug 2018 15:47:06 +0200
Subject: [PATCH 6/7] Docs rewording.

---
 src/view/upcastwriter.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/view/upcastwriter.js b/src/view/upcastwriter.js
index a8ad45bd0..6dbf0c458 100644
--- a/src/view/upcastwriter.js
+++ b/src/view/upcastwriter.js
@@ -13,7 +13,7 @@ import Element from './element';
  * View upcast writer class. Provides set of methods used to properly manipulate nodes attached to
  * {@link module:engine/view/view~View view instance}. It should be only used to manipulate non-semantic view
  * (view created from HTML string). For view which was downcasted from the {@link module:engine/model/model~Model model}
- * see {@link module:engine/view/writer~Writer writer}.
+ * see {@link module:engine/view/downcastwriter~DowncastWriter downcast writer}.
  */
 export default class UpcastWriter {
 	/**

From ac4b0cb5469377ed7bcabab4c770cd8cd639f17a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krzysztof=20Krzto=C5=84?= <k.krzton@cksource.com>
Date: Fri, 31 Aug 2018 09:31:17 +0200
Subject: [PATCH 7/7] Params order refactoring.

---
 src/view/upcastwriter.js | 83 ++++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 41 deletions(-)

diff --git a/src/view/upcastwriter.js b/src/view/upcastwriter.js
index 6dbf0c458..2085c4b09 100644
--- a/src/view/upcastwriter.js
+++ b/src/view/upcastwriter.js
@@ -34,13 +34,13 @@ export default class UpcastWriter {
 	 * and sets the parent of these nodes to this element.
 	 *
 	 * @see module:engine/view/element~Element#_appendChild
+	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
 	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
 	 * to which items will be appended.
-	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
-	 * @fires module:engine/view/node~Node#change
+	 * @fires module:engine/view/node~Node#event:change
 	 * @returns {Number} Number of appended nodes.
 	 */
-	appendChild( element, items ) {
+	appendChild( items, element ) {
 		return element._appendChild( items );
 	}
 
@@ -49,14 +49,14 @@ export default class UpcastWriter {
 	 * this element.
 	 *
 	 * @see module:engine/view/element~Element#_insertChild
+	 * @param {Number} index Offset at which nodes should be inserted.
+	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
 	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
 	 * to which items will be inserted.
-	 * @param {Number} index Position where nodes should be inserted.
-	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
-	 * @fires module:engine/view/node~Node#change
+	 * @fires module:engine/view/node~Node#event:change
 	 * @returns {Number} Number of inserted nodes.
 	 */
-	insertChild( element, index, items ) {
+	insertChild( index, items, element ) {
 		return element._insertChild( index, items );
 	}
 
@@ -64,14 +64,14 @@ export default class UpcastWriter {
 	 * Removes number of child nodes starting at the given index and set the parent of these nodes to `null`.
 	 *
 	 * @see module:engine/view/element~Element#_removeChildren
+	 * @param {Number} index Offset from which nodes will be removed.
+	 * @param {Number} howMany Number of nodes to remove.
 	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
-	 * from which children will be removed.
-	 * @param {Number} index Number of the first node to remove.
-	 * @param {Number} [howMany=1] Number of nodes to remove.
-	 * @fires module:engine/view/node~Node#change
-	 * @returns {Array.<module:engine/view/node~Node>} The array of removed nodes.
+	 * which children will be removed.
+	 * @fires module:engine/view/node~Node#event:change
+	 * @returns {Array.<module:engine/view/node~Node>} The array containing removed nodes.
 	 */
-	removeChildren( element, index, howMany = 1 ) {
+	removeChildren( index, howMany, element ) {
 		return element._removeChildren( index, howMany );
 	}
 
@@ -79,10 +79,11 @@ export default class UpcastWriter {
 	 * Removes given element from the view structure. Will not have effect on detached elements.
 	 *
 	 * @param {module:engine/view/element~Element} element Element which will be removed.
-	 * @returns {Array.<module:engine/view/node~Node>} The array of removed nodes.
+	 * @returns {Array.<module:engine/view/node~Node>} The array containing removed nodes.
 	 */
 	remove( element ) {
 		const parent = element.parent;
+
 		if ( parent ) {
 			return this.removeChildren( parent, parent.getChildIndex( element ) );
 		}
@@ -94,7 +95,7 @@ export default class UpcastWriter {
 	 * Replaces given element with the new one in the view structure. Will not have effect on detached elements.
 	 *
 	 * @param {module:engine/view/element~Element} oldElement Element which will be replaced.
-	 * @param {module:engine/view/element~Element} newElement Element which will inserted in the place of the old element.
+	 * @param {module:engine/view/element~Element} newElement Element which will be inserted in the place of the old element.
 	 * @returns {Boolean} Whether old element was successfully replaced.
 	 */
 	replace( oldElement, newElement ) {
@@ -113,33 +114,33 @@ export default class UpcastWriter {
 	}
 
 	/**
-	 * Renames element by creating a copy of renamed element but with changed name and then moving contents of the
+	 * Renames element by creating a copy of a given element but with its name changed and then moving contents of the
 	 * old element to the new one.
 	 *
 	 * Since this function creates a new element and removes the given one, the new element is returned to keep reference.
 	 *
+	 * @param {String} newName New element name.
 	 * @param {module:engine/view/element~Element} element Element to be renamed.
-	 * @param {String} newName New name for element.
 	 * @returns {module:engine/view/element~Element|null} New element or null if the old element
 	 * was not replaced (happens for detached elements).
 	 */
-	rename( element, newName ) {
+	rename( newName, element ) {
 		const newElement = new Element( newName, element.getAttributes(), element.getChildren() );
 
 		return this.replace( element, newElement ) ? newElement : null;
 	}
 
 	/**
-	 * Adds or overwrite element's attribute with a specified key and value.
+	 * Adds or overwrites element's attribute with a specified key and value.
 	 *
 	 *		writer.setAttribute( linkElement, 'href', 'http://ckeditor.com' );
 	 *
 	 * @see module:engine/view/element~Element#_setAttribute
-	 * @param {module:engine/view/element~Element} element
 	 * @param {String} key Attribute key.
 	 * @param {String} value Attribute value.
+	 * @param {module:engine/view/element~Element} element Element for which attribute will be set.
 	 */
-	setAttribute( element, key, value ) {
+	setAttribute( key, value, element ) {
 		element._setAttribute( key, value );
 	}
 
@@ -149,10 +150,10 @@ export default class UpcastWriter {
 	 *		writer.removeAttribute( linkElement, 'href' );
 	 *
 	 * @see module:engine/view/element~Element#_removeAttribute
-	 * @param {module:engine/view/element~Element} element
 	 * @param {String} key Attribute key.
+	 * @param {module:engine/view/element~Element} element Element from which attribute will be removed.
 	 */
-	removeAttribute( element, key ) {
+	removeAttribute( key, element ) {
 		element._removeAttribute( key );
 	}
 
@@ -163,10 +164,10 @@ export default class UpcastWriter {
 	 *		writer.addClass( linkElement, [ 'foo', 'bar' ] );
 	 *
 	 * @see module:engine/view/element~Element#_addClass
-	 * @param {module:engine/view/element~Element} element
-	 * @param {Array.<String>|String} className
+	 * @param {Array.<String>|String} className Single class name or array of class names which will be added.
+	 * @param {module:engine/view/element~Element} element Element for which class will be added.
 	 */
-	addClass( element, className ) {
+	addClass( className, element ) {
 		element._addClass( className );
 	}
 
@@ -177,10 +178,10 @@ export default class UpcastWriter {
 	 *		writer.removeClass( linkElement, [ 'foo', 'bar' ] );
 	 *
 	 * @see module:engine/view/element~Element#_removeClass
-	 * @param {module:engine/view/element~Element} element
-	 * @param {Array.<String>|String} className
+	 * @param {Array.<String>|String} className Single class name or array of class names which will be removed.
+	 * @param {module:engine/view/element~Element} element Element from which class will be removed.
 	 */
-	removeClass( element, className ) {
+	removeClass( className, element ) {
 		element._removeClass( className );
 	}
 
@@ -194,11 +195,11 @@ export default class UpcastWriter {
 	 *		} );
 	 *
 	 * @see module:engine/view/element~Element#_setStyle
-	 * @param {module:engine/view/element~Element} element
 	 * @param {String|Object} property Property name or object with key - value pairs.
 	 * @param {String} [value] Value to set. This parameter is ignored if object is provided as the first parameter.
+	 * @param {module:engine/view/element~Element} element Element for which style will be added.
 	 */
-	setStyle( element, property, value ) {
+	setStyle( property, value, element ) {
 		element._setStyle( property, value );
 	}
 
@@ -209,10 +210,10 @@ export default class UpcastWriter {
 	 *		writer.removeStyle( element, [ 'color', 'border-top' ] ); // Removes both 'color' and 'border-top' styles.
 	 *
 	 * @see module:engine/view/element~Element#_removeStyle
-	 * @param {module:engine/view/element~Element} element
-	 * @param {Array.<String>|String} property
+	 * @param {Array.<String>|String} property Style property name or names to be removed.
+	 * @param {module:engine/view/element~Element} element Element from which style will be removed.
 	 */
-	removeStyle( element, property ) {
+	removeStyle( property, element ) {
 		element._removeStyle( property );
 	}
 
@@ -221,11 +222,11 @@ export default class UpcastWriter {
 	 * so they can be used to add special data to elements.
 	 *
 	 * @see module:engine/view/element~Element#_setCustomProperty
-	 * @param {module:engine/view/element~Element} element
-	 * @param {String|Symbol} key
-	 * @param {*} value
+	 * @param {String|Symbol} key Custom property name/key.
+	 * @param {*} value Custom property value to be stored.
+	 * @param {module:engine/view/element~Element} element Element for which custom property will be set.
 	 */
-	setCustomProperty( element, key, value ) {
+	setCustomProperty( key, value, element ) {
 		element._setCustomProperty( key, value );
 	}
 
@@ -233,11 +234,11 @@ export default class UpcastWriter {
 	 * Removes a custom property stored under the given key.
 	 *
 	 * @see module:engine/view/element~Element#_removeCustomProperty
-	 * @param {module:engine/view/element~Element} element
-	 * @param {String|Symbol} key
+	 * @param {String|Symbol} key Name/key of the custom property to be removed.
+	 * @param {module:engine/view/element~Element} element Element from which the custom property will be removed.
 	 * @returns {Boolean} Returns true if property was removed.
 	 */
-	removeCustomProperty( element, key ) {
+	removeCustomProperty( key, element ) {
 		return element._removeCustomProperty( key );
 	}
 }