src/model/position.js
/**
* @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 engine/model/position
*/
import TreeWalker from './treewalker';
import compareArrays from '@ckeditor/ckeditor5-utils/src/comparearrays';
import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
// To check if component is loaded more than once.
import '@ckeditor/ckeditor5-utils/src/version';
/**
* Represents a position in the model tree.
*
* A position is represented by its {@link module:engine/model/position~Position#root} and
* a {@link module:engine/model/position~Position#path} in that root.
*
* You can create position instances via its constructor or the `createPosition*()` factory methods of
* {@link module:engine/model/model~Model} and {@link module:engine/model/writer~Writer}.
*
* **Note:** Position is based on offsets, not indexes. This means that a position between two text nodes
* `foo` and `bar` has offset `3`, not `1`. See {@link module:engine/model/position~Position#path} for more information.
*
* Since a position in the model is represented by a {@link module:engine/model/position~Position#root position root} and
* {@link module:engine/model/position~Position#path position path} it is possible to create positions placed in non-existing places.
* This requirement is important for operational transformation algorithms.
*
* Also, {@link module:engine/model/operation/operation~Operation operations}
* kept in the {@link module:engine/model/document~Document#history document history}
* are storing positions (and ranges) which were correct when those operations were applied, but may not be correct
* after the document has changed.
*
* When changes are applied to the model, it may also happen that {@link module:engine/model/position~Position#parent position parent}
* will change even if position path has not changed. Keep in mind, that if a position leads to non-existing element,
* {@link module:engine/model/position~Position#parent} and some other properties and methods will throw errors.
*
* In most cases, position with wrong path is caused by an error in code, but it is sometimes needed, as described above.
*/
export default class Position {
/**
* Creates a position.
*
* @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} root Root of the position.
* @param {Array.<Number>} path Position path. See {@link module:engine/model/position~Position#path}.
* @param {module:engine/model/position~PositionStickiness} [stickiness='toNone'] Position stickiness.
* See {@link module:engine/model/position~PositionStickiness}.
*/
constructor( root, path, stickiness = 'toNone' ) {
if ( !root.is( 'element' ) && !root.is( 'documentFragment' ) ) {
/**
* Position root is invalid.
*
* Positions can only be anchored in elements or document fragments.
*
* @error model-position-root-invalid
*/
throw new CKEditorError(
'model-position-root-invalid: Position root invalid.',
root
);
}
if ( !( path instanceof Array ) || path.length === 0 ) {
/**
* Position path must be an array with at least one item.
*
* @error model-position-path-incorrect-format
* @param path
*/
throw new CKEditorError(
'model-position-path-incorrect-format: Position path must be an array with at least one item.',
root,
{ path }
);
}
// Normalize the root and path when element (not root) is passed.
if ( root.is( 'rootElement' ) ) {
path = path.slice();
} else {
path = [ ...root.getPath(), ...path ];
root = root.root;
}
/**
* Root of the position path.
*
* @readonly
* @member {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment}
* module:engine/model/position~Position#root
*/
this.root = root;
/**
* Position of the node in the tree. **Path contains offsets, not indexes.**
*
* Position can be placed before, after or in a {@link module:engine/model/node~Node node} if that node has
* {@link module:engine/model/node~Node#offsetSize} greater than `1`. Items in position path are
* {@link module:engine/model/node~Node#startOffset starting offsets} of position ancestors, starting from direct root children,
* down to the position offset in it's parent.
*
* ROOT
* |- P before: [ 0 ] after: [ 1 ]
* |- UL before: [ 1 ] after: [ 2 ]
* |- LI before: [ 1, 0 ] after: [ 1, 1 ]
* | |- foo before: [ 1, 0, 0 ] after: [ 1, 0, 3 ]
* |- LI before: [ 1, 1 ] after: [ 1, 2 ]
* |- bar before: [ 1, 1, 0 ] after: [ 1, 1, 3 ]
*
* `foo` and `bar` are representing {@link module:engine/model/text~Text text nodes}. Since text nodes has offset size
* greater than `1` you can place position offset between their start and end:
*
* ROOT
* |- P
* |- UL
* |- LI
* | |- f^o|o ^ has path: [ 1, 0, 1 ] | has path: [ 1, 0, 2 ]
* |- LI
* |- b^a|r ^ has path: [ 1, 1, 1 ] | has path: [ 1, 1, 2 ]
*
* @readonly
* @member {Array.<Number>} module:engine/model/position~Position#path
*/
this.path = path;
/**
* Position stickiness. See {@link module:engine/model/position~PositionStickiness}.
*
* @member {module:engine/model/position~PositionStickiness} module:engine/model/position~Position#stickiness
*/
this.stickiness = stickiness;
}
/**
* Offset at which this position is located in its {@link module:engine/model/position~Position#parent parent}. It is equal
* to the last item in position {@link module:engine/model/position~Position#path path}.
*
* @type {Number}
*/
get offset() {
return this.path[ this.path.length - 1 ];
}
/**
* @param {Number} newOffset
*/
set offset( newOffset ) {
this.path[ this.path.length - 1 ] = newOffset;
}
/**
* Parent element of this position.
*
* Keep in mind that `parent` value is calculated when the property is accessed.
* If {@link module:engine/model/position~Position#path position path}
* leads to a non-existing element, `parent` property will throw error.
*
* Also it is a good idea to cache `parent` property if it is used frequently in an algorithm (i.e. in a long loop).
*
* @readonly
* @type {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment}
*/
get parent() {
let parent = this.root;
for ( let i = 0; i < this.path.length - 1; i++ ) {
parent = parent.getChild( parent.offsetToIndex( this.path[ i ] ) );
if ( !parent ) {
throw new CKEditorError( 'model-position-path-incorrect: The position\'s path is incorrect.', this, { position: this } );
}
}
if ( parent.is( 'text' ) ) {
/**
* The position's path is incorrect. This means that a position does not point to
* a correct place in the tree and hence, some of its methods and getters cannot work correctly.
*
* **Note**: Unlike DOM and view positions, in the model, the
* {@link module:engine/model/position~Position#parent position's parent} is always an element or a document fragment.
* The last offset in the {@link module:engine/model/position~Position#path position's path} is the point in this element where
* this position points.
*
* Read more about model positions and offsets in
* the {@glink framework/guides/architecture/editing-engine#indexes-and-offsets Editing engine architecture guide}.
*
* @error position-incorrect-path
* @param {module:engine/model/position~Position} position The incorrect position.
*/
throw new CKEditorError( 'model-position-path-incorrect: The position\'s path is incorrect.', this, { position: this } );
}
return parent;
}
/**
* Position {@link module:engine/model/position~Position#offset offset} converted to an index in position's parent node. It is
* equal to the {@link module:engine/model/node~Node#index index} of a node after this position. If position is placed
* in text node, position index is equal to the index of that text node.
*
* @readonly
* @type {Number}
*/
get index() {
return this.parent.offsetToIndex( this.offset );
}
/**
* Returns {@link module:engine/model/text~Text text node} instance in which this position is placed or `null` if this
* position is not in a text node.
*
* @readonly
* @type {module:engine/model/text~Text|null}
*/
get textNode() {
return getTextNodeAtPosition( this, this.parent );
}
/**
* Node directly after this position or `null` if this position is in text node.
*
* @readonly
* @type {module:engine/model/node~Node|null}
*/
get nodeAfter() {
// Cache the parent and reuse for performance reasons. See #6579 and #6582.
const parent = this.parent;
return getNodeAfterPosition( this, parent, getTextNodeAtPosition( this, parent ) );
}
/**
* Node directly before this position or `null` if this position is in text node.
*
* @readonly
* @type {module:engine/model/node~Node|null}
*/
get nodeBefore() {
// Cache the parent and reuse for performance reasons. See #6579 and #6582.
const parent = this.parent;
return getNodeBeforePosition( this, parent, getTextNodeAtPosition( this, parent ) );
}
/**
* Is `true` if position is at the beginning of its {@link module:engine/model/position~Position#parent parent}, `false` otherwise.
*
* @readonly
* @type {Boolean}
*/
get isAtStart() {
return this.offset === 0;
}
/**
* Is `true` if position is at the end of its {@link module:engine/model/position~Position#parent parent}, `false` otherwise.
*
* @readonly
* @type {Boolean}
*/
get isAtEnd() {
return this.offset == this.parent.maxOffset;
}
/**
* Checks whether this position is before or after given position.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {module:engine/model/position~Position} otherPosition Position to compare with.
* @returns {module:engine/model/position~PositionRelation}
*/
compareWith( otherPosition ) {
if ( this.root != otherPosition.root ) {
return 'different';
}
const result = compareArrays( this.path, otherPosition.path );
switch ( result ) {
case 'same':
return 'same';
case 'prefix':
return 'before';
case 'extension':
return 'after';
default:
return this.path[ result ] < otherPosition.path[ result ] ? 'before' : 'after';
}
}
/**
* Gets the farthest position which matches the callback using
* {@link module:engine/model/treewalker~TreeWalker TreeWalker}.
*
* For example:
*
* getLastMatchingPosition( value => value.type == 'text' );
* // <paragraph>[]foo</paragraph> -> <paragraph>foo[]</paragraph>
*
* getLastMatchingPosition( value => value.type == 'text', { direction: 'backward' } );
* // <paragraph>foo[]</paragraph> -> <paragraph>[]foo</paragraph>
*
* getLastMatchingPosition( value => false );
* // Do not move the position.
*
* @param {Function} skip Callback function. Gets {@link module:engine/model/treewalker~TreeWalkerValue} and should
* return `true` if the value should be skipped or `false` if not.
* @param {Object} options Object with configuration options. See {@link module:engine/model/treewalker~TreeWalker}.
*
* @returns {module:engine/model/position~Position} The position after the last item which matches the `skip` callback test.
*/
getLastMatchingPosition( skip, options = {} ) {
options.startPosition = this;
const treeWalker = new TreeWalker( options );
treeWalker.skip( skip );
return treeWalker.position;
}
/**
* Returns a path to this position's parent. Parent path is equal to position {@link module:engine/model/position~Position#path path}
* but without the last item.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @returns {Array.<Number>} Path to the parent.
*/
getParentPath() {
return this.path.slice( 0, -1 );
}
/**
* Returns ancestors array of this position, that is this position's parent and its ancestors.
*
* @returns {Array.<module:engine/model/item~Item>} Array with ancestors.
*/
getAncestors() {
const parent = this.parent;
if ( parent.is( 'documentFragment' ) ) {
return [ parent ];
} else {
return parent.getAncestors( { includeSelf: true } );
}
}
/**
* Returns the slice of two position {@link #path paths} which is identical. The {@link #root roots}
* of these two paths must be identical.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {module:engine/model/position~Position} position The second position.
* @returns {Array.<Number>} The common path.
*/
getCommonPath( position ) {
if ( this.root != position.root ) {
return [];
}
// We find on which tree-level start and end have the lowest common ancestor
const cmp = compareArrays( this.path, position.path );
// If comparison returned string it means that arrays are same.
const diffAt = ( typeof cmp == 'string' ) ? Math.min( this.path.length, position.path.length ) : cmp;
return this.path.slice( 0, diffAt );
}
/**
* Returns an {@link module:engine/model/element~Element} or {@link module:engine/model/documentfragment~DocumentFragment}
* which is a common ancestor of both positions. The {@link #root roots} of these two positions must be identical.
*
* @param {module:engine/model/position~Position} position The second position.
* @returns {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment|null}
*/
getCommonAncestor( position ) {
const ancestorsA = this.getAncestors();
const ancestorsB = position.getAncestors();
let i = 0;
while ( ancestorsA[ i ] == ancestorsB[ i ] && ancestorsA[ i ] ) {
i++;
}
return i === 0 ? null : ancestorsA[ i - 1 ];
}
/**
* Returns a new instance of `Position`, that has same {@link #parent parent} but it's offset
* is shifted by `shift` value (can be a negative value).
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {Number} shift Offset shift. Can be a negative value.
* @returns {module:engine/model/position~Position} Shifted position.
*/
getShiftedBy( shift ) {
const shifted = this.clone();
const offset = shifted.offset + shift;
shifted.offset = offset < 0 ? 0 : offset;
return shifted;
}
/**
* Checks whether this position is after given position.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @see module:engine/model/position~Position#isBefore
* @param {module:engine/model/position~Position} otherPosition Position to compare with.
* @returns {Boolean} True if this position is after given position.
*/
isAfter( otherPosition ) {
return this.compareWith( otherPosition ) == 'after';
}
/**
* Checks whether this position is before given position.
*
* **Note:** watch out when using negation of the value returned by this method, because the negation will also
* be `true` if positions are in different roots and you might not expect this. You should probably use
* `a.isAfter( b ) || a.isEqual( b )` or `!a.isBefore( p ) && a.root == b.root` in most scenarios. If your
* condition uses multiple `isAfter` and `isBefore` checks, build them so they do not use negated values, i.e.:
*
* if ( a.isBefore( b ) && c.isAfter( d ) ) {
* // do A.
* } else {
* // do B.
* }
*
* or, if you have only one if-branch:
*
* if ( !( a.isBefore( b ) && c.isAfter( d ) ) {
* // do B.
* }
*
* rather than:
*
* if ( !a.isBefore( b ) || && !c.isAfter( d ) ) {
* // do B.
* } else {
* // do A.
* }
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {module:engine/model/position~Position} otherPosition Position to compare with.
* @returns {Boolean} True if this position is before given position.
*/
isBefore( otherPosition ) {
return this.compareWith( otherPosition ) == 'before';
}
/**
* Checks whether this position is equal to given position.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {module:engine/model/position~Position} otherPosition Position to compare with.
* @returns {Boolean} True if positions are same.
*/
isEqual( otherPosition ) {
return this.compareWith( otherPosition ) == 'same';
}
/**
* Checks whether this position is touching given position. Positions touch when there are no text nodes
* or empty nodes in a range between them. Technically, those positions are not equal but in many cases
* they are very similar or even indistinguishable.
*
* @param {module:engine/model/position~Position} otherPosition Position to compare with.
* @returns {Boolean} True if positions touch.
*/
isTouching( otherPosition ) {
let left = null;
let right = null;
const compare = this.compareWith( otherPosition );
switch ( compare ) {
case 'same':
return true;
case 'before':
left = Position._createAt( this );
right = Position._createAt( otherPosition );
break;
case 'after':
left = Position._createAt( otherPosition );
right = Position._createAt( this );
break;
default:
return false;
}
// Cached for optimization purposes.
let leftParent = left.parent;
while ( left.path.length + right.path.length ) {
if ( left.isEqual( right ) ) {
return true;
}
if ( left.path.length > right.path.length ) {
if ( left.offset !== leftParent.maxOffset ) {
return false;
}
left.path = left.path.slice( 0, -1 );
leftParent = leftParent.parent;
left.offset++;
} else {
if ( right.offset !== 0 ) {
return false;
}
right.path = right.path.slice( 0, -1 );
}
}
}
/**
* Checks whether this object is of the given.
*
* position.is( 'position' ); // -> true
* position.is( 'model:position' ); // -> true
*
* position.is( 'view:position' ); // -> false
* position.is( 'documentSelection' ); // -> false
*
* {@link module:engine/model/node~Node#is Check the entire list of model objects} which implement the `is()` method.
*
* @param {String} type
* @returns {Boolean}
*/
is( type ) {
return type === 'position' || type === 'model:position';
}
/**
* Checks if two positions are in the same parent.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {module:engine/model/position~Position} position Position to compare with.
* @returns {Boolean} `true` if positions have the same parent, `false` otherwise.
*/
hasSameParentAs( position ) {
if ( this.root !== position.root ) {
return false;
}
const thisParentPath = this.getParentPath();
const posParentPath = position.getParentPath();
return compareArrays( thisParentPath, posParentPath ) == 'same';
}
/**
* Returns a copy of this position that is transformed by given `operation`.
*
* The new position's parameters are updated accordingly to the effect of the `operation`.
*
* For example, if `n` nodes are inserted before the position, the returned position {@link ~Position#offset} will be
* increased by `n`. If the position was in a merged element, it will be accordingly moved to the new element, etc.
*
* This method is safe to use it on non-existing positions (for example during operational transformation).
*
* @param {module:engine/model/operation/operation~Operation} operation Operation to transform by.
* @returns {module:engine/model/position~Position} Transformed position.
*/
getTransformedByOperation( operation ) {
let result;
switch ( operation.type ) {
case 'insert':
result = this._getTransformedByInsertOperation( operation );
break;
case 'move':
case 'remove':
case 'reinsert':
result = this._getTransformedByMoveOperation( operation );
break;
case 'split':
result = this._getTransformedBySplitOperation( operation );
break;
case 'merge':
result = this._getTransformedByMergeOperation( operation );
break;
default:
result = Position._createAt( this );
break;
}
return result;
}
/**
* Returns a copy of this position transformed by an insert operation.
*
* @protected
* @param {module:engine/model/operation/insertoperation~InsertOperation} operation
* @returns {module:engine/model/position~Position}
*/
_getTransformedByInsertOperation( operation ) {
return this._getTransformedByInsertion( operation.position, operation.howMany );
}
/**
* Returns a copy of this position transformed by a move operation.
*
* @protected
* @param {module:engine/model/operation/moveoperation~MoveOperation} operation
* @returns {module:engine/model/position~Position}
*/
_getTransformedByMoveOperation( operation ) {
return this._getTransformedByMove( operation.sourcePosition, operation.targetPosition, operation.howMany );
}
/**
* Returns a copy of this position transformed by a split operation.
*
* @protected
* @param {module:engine/model/operation/splitoperation~SplitOperation} operation
* @returns {module:engine/model/position~Position}
*/
_getTransformedBySplitOperation( operation ) {
const movedRange = operation.movedRange;
const isContained = movedRange.containsPosition( this ) ||
( movedRange.start.isEqual( this ) && this.stickiness == 'toNext' );
if ( isContained ) {
return this._getCombined( operation.splitPosition, operation.moveTargetPosition );
} else {
if ( operation.graveyardPosition ) {
return this._getTransformedByMove( operation.graveyardPosition, operation.insertionPosition, 1 );
} else {
return this._getTransformedByInsertion( operation.insertionPosition, 1 );
}
}
}
/**
* Returns a copy of this position transformed by merge operation.
*
* @protected
* @param {module:engine/model/operation/mergeoperation~MergeOperation} operation
* @returns {module:engine/model/position~Position}
*/
_getTransformedByMergeOperation( operation ) {
const movedRange = operation.movedRange;
const isContained = movedRange.containsPosition( this ) || movedRange.start.isEqual( this );
let pos;
if ( isContained ) {
pos = this._getCombined( operation.sourcePosition, operation.targetPosition );
if ( operation.sourcePosition.isBefore( operation.targetPosition ) ) {
// Above happens during OT when the merged element is moved before the merged-to element.
pos = pos._getTransformedByDeletion( operation.deletionPosition, 1 );
}
} else if ( this.isEqual( operation.deletionPosition ) ) {
pos = Position._createAt( operation.deletionPosition );
} else {
pos = this._getTransformedByMove( operation.deletionPosition, operation.graveyardPosition, 1 );
}
return pos;
}
/**
* Returns a copy of this position that is updated by removing `howMany` nodes starting from `deletePosition`.
* It may happen that this position is in a removed node. If that is the case, `null` is returned instead.
*
* @protected
* @param {module:engine/model/position~Position} deletePosition Position before the first removed node.
* @param {Number} howMany How many nodes are removed.
* @returns {module:engine/model/position~Position|null} Transformed position or `null`.
*/
_getTransformedByDeletion( deletePosition, howMany ) {
const transformed = Position._createAt( this );
// This position can't be affected if deletion was in a different root.
if ( this.root != deletePosition.root ) {
return transformed;
}
if ( compareArrays( deletePosition.getParentPath(), this.getParentPath() ) == 'same' ) {
// If nodes are removed from the node that is pointed by this position...
if ( deletePosition.offset < this.offset ) {
// And are removed from before an offset of that position...
if ( deletePosition.offset + howMany > this.offset ) {
// Position is in removed range, it's no longer in the tree.
return null;
} else {
// Decrement the offset accordingly.
transformed.offset -= howMany;
}
}
} else if ( compareArrays( deletePosition.getParentPath(), this.getParentPath() ) == 'prefix' ) {
// If nodes are removed from a node that is on a path to this position...
const i = deletePosition.path.length - 1;
if ( deletePosition.offset <= this.path[ i ] ) {
// And are removed from before next node of that path...
if ( deletePosition.offset + howMany > this.path[ i ] ) {
// If the next node of that path is removed return null
// because the node containing this position got removed.
return null;
} else {
// Otherwise, decrement index on that path.
transformed.path[ i ] -= howMany;
}
}
}
return transformed;
}
/**
* Returns a copy of this position that is updated by inserting `howMany` nodes at `insertPosition`.
*
* @protected
* @param {module:engine/model/position~Position} insertPosition Position where nodes are inserted.
* @param {Number} howMany How many nodes are inserted.
* @returns {module:engine/model/position~Position} Transformed position.
*/
_getTransformedByInsertion( insertPosition, howMany ) {
const transformed = Position._createAt( this );
// This position can't be affected if insertion was in a different root.
if ( this.root != insertPosition.root ) {
return transformed;
}
if ( compareArrays( insertPosition.getParentPath(), this.getParentPath() ) == 'same' ) {
// If nodes are inserted in the node that is pointed by this position...
if ( insertPosition.offset < this.offset || ( insertPosition.offset == this.offset && this.stickiness != 'toPrevious' ) ) {
// And are inserted before an offset of that position...
// "Push" this positions offset.
transformed.offset += howMany;
}
} else if ( compareArrays( insertPosition.getParentPath(), this.getParentPath() ) == 'prefix' ) {
// If nodes are inserted in a node that is on a path to this position...
const i = insertPosition.path.length - 1;
if ( insertPosition.offset <= this.path[ i ] ) {
// And are inserted before next node of that path...
// "Push" the index on that path.
transformed.path[ i ] += howMany;
}
}
return transformed;
}
/**
* Returns a copy of this position that is updated by moving `howMany` nodes from `sourcePosition` to `targetPosition`.
*
* @protected
* @param {module:engine/model/position~Position} sourcePosition Position before the first element to move.
* @param {module:engine/model/position~Position} targetPosition Position where moved elements will be inserted.
* @param {Number} howMany How many consecutive nodes to move, starting from `sourcePosition`.
* @returns {module:engine/model/position~Position} Transformed position.
*/
_getTransformedByMove( sourcePosition, targetPosition, howMany ) {
// Update target position, as it could be affected by nodes removal.
targetPosition = targetPosition._getTransformedByDeletion( sourcePosition, howMany );
if ( sourcePosition.isEqual( targetPosition ) ) {
// If `targetPosition` is equal to `sourcePosition` this isn't really any move. Just return position as it is.
return Position._createAt( this );
}
// Moving a range removes nodes from their original position. We acknowledge this by proper transformation.
const transformed = this._getTransformedByDeletion( sourcePosition, howMany );
const isMoved = transformed === null ||
( sourcePosition.isEqual( this ) && this.stickiness == 'toNext' ) ||
( sourcePosition.getShiftedBy( howMany ).isEqual( this ) && this.stickiness == 'toPrevious' );
if ( isMoved ) {
// This position is inside moved range (or sticks to it).
// In this case, we calculate a combination of this position, move source position and target position.
return this._getCombined( sourcePosition, targetPosition );
} else {
// This position is not inside a removed range.
//
// In next step, we simply reflect inserting `howMany` nodes, which might further affect the position.
return transformed._getTransformedByInsertion( targetPosition, howMany );
}
}
/**
* Returns a new position that is a combination of this position and given positions.
*
* The combined position is a copy of this position transformed by moving a range starting at `source` position
* to the `target` position. It is expected that this position is inside the moved range.
*
* Example:
*
* let original = model.createPositionFromPath( root, [ 2, 3, 1 ] );
* let source = model.createPositionFromPath( root, [ 2, 2 ] );
* let target = model.createPositionFromPath( otherRoot, [ 1, 1, 3 ] );
* original._getCombined( source, target ); // path is [ 1, 1, 4, 1 ], root is `otherRoot`
*
* Explanation:
*
* We have a position `[ 2, 3, 1 ]` and move some nodes from `[ 2, 2 ]` to `[ 1, 1, 3 ]`. The original position
* was inside moved nodes and now should point to the new place. The moved nodes will be after
* positions `[ 1, 1, 3 ]`, `[ 1, 1, 4 ]`, `[ 1, 1, 5 ]`. Since our position was in the second moved node,
* the transformed position will be in a sub-tree of a node at `[ 1, 1, 4 ]`. Looking at original path, we
* took care of `[ 2, 3 ]` part of it. Now we have to add the rest of the original path to the transformed path.
* Finally, the transformed position will point to `[ 1, 1, 4, 1 ]`.
*
* @protected
* @param {module:engine/model/position~Position} source Beginning of the moved range.
* @param {module:engine/model/position~Position} target Position where the range is moved.
* @returns {module:engine/model/position~Position} Combined position.
*/
_getCombined( source, target ) {
const i = source.path.length - 1;
// The first part of a path to combined position is a path to the place where nodes were moved.
const combined = Position._createAt( target );
combined.stickiness = this.stickiness;
// Then we have to update the rest of the path.
// Fix the offset because this position might be after `from` position and we have to reflect that.
combined.offset = combined.offset + this.path[ i ] - source.offset;
// Then, add the rest of the path.
// If this position is at the same level as `from` position nothing will get added.
combined.path = [ ...combined.path, ...this.path.slice( i + 1 ) ];
return combined;
}
/**
* @inheritDoc
*/
toJSON() {
return {
root: this.root.toJSON(),
path: Array.from( this.path ),
stickiness: this.stickiness
};
}
/**
* Returns a new position that is equal to current position.
*
* @returns {module:engine/model/position~Position}
*/
clone() {
return new this.constructor( this.root, this.path, this.stickiness );
}
/**
* Creates position at the given location. The location can be specified as:
*
* * a {@link module:engine/model/position~Position position},
* * parent element and offset (offset defaults to `0`),
* * parent element and `'end'` (sets position at the end of that element),
* * {@link module:engine/model/item~Item model item} and `'before'` or `'after'` (sets position before or after given model item).
*
* This method is a shortcut to other factory methods such as:
*
* * {@link module:engine/model/position~Position._createBefore},
* * {@link module:engine/model/position~Position._createAfter}.
*
* @param {module:engine/model/item~Item|module:engine/model/position~Position} itemOrPosition
* @param {Number|'end'|'before'|'after'} [offset] Offset or one of the flags. Used only when the
* first parameter is a {@link module:engine/model/item~Item model item}.
* @param {module:engine/model/position~PositionStickiness} [stickiness='toNone'] Position stickiness. Used only when the
* first parameter is a {@link module:engine/model/item~Item model item}.
* @protected
*/
static _createAt( itemOrPosition, offset, stickiness = 'toNone' ) {
if ( itemOrPosition instanceof Position ) {
return new Position( itemOrPosition.root, itemOrPosition.path, itemOrPosition.stickiness );
} else {
const node = itemOrPosition;
if ( offset == 'end' ) {
offset = node.maxOffset;
} else if ( offset == 'before' ) {
return this._createBefore( node, stickiness );
} else if ( offset == 'after' ) {
return this._createAfter( node, stickiness );
} else if ( offset !== 0 && !offset ) {
/**
* {@link module:engine/model/model~Model#createPositionAt `Model#createPositionAt()`}
* requires the offset to be specified when the first parameter is a model item.
*
* @error model-createPositionAt-offset-required
*/
throw new CKEditorError(
'model-createPositionAt-offset-required: ' +
'Model#createPositionAt() requires the offset when the first parameter is a model item.',
[ this, itemOrPosition ]
);
}
if ( !node.is( 'element' ) && !node.is( 'documentFragment' ) ) {
/**
* Position parent have to be a model element or model document fragment.
*
* @error model-position-parent-incorrect
*/
throw new CKEditorError(
'model-position-parent-incorrect: Position parent have to be a element or document fragment.',
[ this, itemOrPosition ]
);
}
const path = node.getPath();
path.push( offset );
return new this( node.root, path, stickiness );
}
}
/**
* Creates a new position, after given {@link module:engine/model/item~Item model item}.
*
* @param {module:engine/model/item~Item} item Item after which the position should be placed.
* @param {module:engine/model/position~PositionStickiness} [stickiness='toNone'] Position stickiness.
* @returns {module:engine/model/position~Position}
* @protected
*/
static _createAfter( item, stickiness ) {
if ( !item.parent ) {
/**
* You can not make a position after a root element.
*
* @error model-position-after-root
* @param {module:engine/model/item~Item} root
*/
throw new CKEditorError(
'model-position-after-root: You cannot make a position after root.',
[ this, item ],
{ root: item }
);
}
return this._createAt( item.parent, item.endOffset, stickiness );
}
/**
* Creates a new position, before the given {@link module:engine/model/item~Item model item}.
*
* @param {module:engine/model/item~Item} item Item before which the position should be placed.
* @param {module:engine/model/position~PositionStickiness} [stickiness='toNone'] Position stickiness.
* @returns {module:engine/model/position~Position}
* @protected
*/
static _createBefore( item, stickiness ) {
if ( !item.parent ) {
/**
* You can not make a position before a root element.
*
* @error model-position-before-root
* @param {module:engine/model/item~Item} root
*/
throw new CKEditorError(
'model-position-before-root: You cannot make a position before root.',
item,
{ root: item }
);
}
return this._createAt( item.parent, item.startOffset, stickiness );
}
/**
* Creates a `Position` instance from given plain object (i.e. parsed JSON string).
*
* @param {Object} json Plain object to be converted to `Position`.
* @param {module:engine/model/document~Document} doc Document object that will be position owner.
* @returns {module:engine/model/position~Position} `Position` instance created using given plain object.
*/
static fromJSON( json, doc ) {
if ( json.root === '$graveyard' ) {
const pos = new Position( doc.graveyard, json.path );
pos.stickiness = json.stickiness;
return pos;
}
if ( !doc.getRoot( json.root ) ) {
/**
* Cannot create position for document. Root with specified name does not exist.
*
* @error model-position-fromjson-no-root
* @param {String} rootName
*/
throw new CKEditorError(
'model-position-fromjson-no-root: Cannot create position for document. Root with specified name does not exist.',
doc,
{ rootName: json.root }
);
}
return new Position( doc.getRoot( json.root ), json.path, json.stickiness );
}
// @if CK_DEBUG_ENGINE // toString() {
// @if CK_DEBUG_ENGINE // return `${ this.root } [ ${ this.path.join( ', ' ) } ]`;
// @if CK_DEBUG_ENGINE // }
// @if CK_DEBUG_ENGINE // log() {
// @if CK_DEBUG_ENGINE // console.log( 'ModelPosition: ' + this );
// @if CK_DEBUG_ENGINE // }
}
/**
* A flag indicating whether this position is `'before'` or `'after'` or `'same'` as given position.
* If positions are in different roots `'different'` flag is returned.
*
* @typedef {String} module:engine/model/position~PositionRelation
*/
/**
* Represents how position is "sticking" with neighbour nodes. Used to define how position should be transformed (moved)
* in edge cases. Possible values: `'toNone'`, `'toNext'`, `'toPrevious'`.
*
* Examples:
*
* Insert. Position is at | and nodes are inserted at the same position, marked as ^:
*
* - sticks to none: <p>f^|oo</p> -> <p>fbar|oo</p>
* - sticks to next node: <p>f^|oo</p> -> <p>fbar|oo</p>
* - sticks to previous node: <p>f|^oo</p> -> <p>f|baroo</p>
*
*
* Move. Position is at | and range [oo] is moved to position ^:
*
* - sticks to none: <p>f|[oo]</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
* - sticks to none: <p>f[oo]|</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
*
* - sticks to next node: <p>f|[oo]</p><p>b^ar</p> -> <p>f</p><p>b|ooar</p>
* - sticks to next node: <p>f[oo]|</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
*
* - sticks to previous node: <p>f|[oo]</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
* - sticks to previous node: <p>f[oo]|</p><p>b^ar</p> -> <p>f</p><p>boo|ar</p>
*
* @typedef {String} module:engine/model/position~PositionStickiness
*/
/**
* Returns a text node at the given position.
*
* This is a helper function optimized to reuse the position parent instance for performance reasons.
*
* Normally, you should use {@link module:engine/model/position~Position#textNode `Position#textNode`}.
* If you start hitting performance issues with {@link module:engine/model/position~Position#parent `Position#parent`}
* check if your algorithm does not access it multiple times (which can happen directly or indirectly via other position properties).
*
* See https://github.com/ckeditor/ckeditor5/issues/6579.
*
* See also:
*
* * {@link module:engine/model/position~getNodeAfterPosition}
* * {@link module:engine/model/position~getNodeBeforePosition}
*
* @param {module:engine/model/position~Position} position
* @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} positionParent The parent of the
* given position.
* @returns {module:engine/model/text~Text|null}
*/
export function getTextNodeAtPosition( position, positionParent ) {
const node = positionParent.getChild( positionParent.offsetToIndex( position.offset ) );
if ( node && node.is( 'text' ) && node.startOffset < position.offset ) {
return node;
}
return null;
}
/**
* Returns the node after the given position.
*
* This is a helper function optimized to reuse the position parent instance and the calculation of the text node at the
* specific position for performance reasons.
*
* Normally, you should use {@link module:engine/model/position~Position#nodeAfter `Position#nodeAfter`}.
* If you start hitting performance issues with {@link module:engine/model/position~Position#parent `Position#parent`} and/or
* {@link module:engine/model/position~Position#textNode `Position#textNode`}
* check if your algorithm does not access those properties multiple times
* (which can happen directly or indirectly via other position properties).
*
* See https://github.com/ckeditor/ckeditor5/issues/6579 and https://github.com/ckeditor/ckeditor5/issues/6582.
*
* See also:
*
* * {@link module:engine/model/position~getTextNodeAtPosition}
* * {@link module:engine/model/position~getNodeBeforePosition}
*
* @param {module:engine/model/position~Position} position
* @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} positionParent The parent of the
* given position.
* @param {module:engine/model/text~Text|null} textNode Text node at the given position.
* @returns {module:engine/model/node~Node|null}
*/
export function getNodeAfterPosition( position, positionParent, textNode ) {
if ( textNode !== null ) {
return null;
}
return positionParent.getChild( positionParent.offsetToIndex( position.offset ) );
}
/**
* Returns the node before the given position.
*
* Refer to {@link module:engine/model/position~getNodeBeforePosition} for documentation on when to use this util method.
*
* See also:
*
* * {@link module:engine/model/position~getTextNodeAtPosition}
* * {@link module:engine/model/position~getNodeAfterPosition}
*
* @param {module:engine/model/position~Position} position
* @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} positionParent The parent of the
* given position.
* @param {module:engine/model/text~Text|null} textNode Text node at the given position.
* @returns {module:engine/model/node~Node|null}
*/
export function getNodeBeforePosition( position, positionParent, textNode ) {
if ( textNode !== null ) {
return null;
}
return positionParent.getChild( positionParent.offsetToIndex( position.offset ) - 1 );
}