ckeditor/ckeditor5-engine

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src/model/utils/insertcontent.js

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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 engine/model/utils/insertcontent
 */

import Position from '../position';
import LivePosition from '../liveposition';
import Element from '../element';
import Range from '../range';
import DocumentSelection from '../documentselection';
import Selection from '../selection';
import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';

/**
 * Inserts content into the editor (specified selection) as one would expect the paste
 * functionality to work.
 *
 * If an instance of {@link module:engine/model/selection~Selection} is passed as `selectable` it will be modified
 * to the insertion selection (equal to a range to be selected after insertion).
 *
 * If `selectable` is not passed, the content will be inserted using the current selection of the model document.
 *
 * **Note:** Use {@link module:engine/model/model~Model#insertContent} instead of this function.
 * This function is only exposed to be reusable in algorithms which change the {@link module:engine/model/model~Model#insertContent}
 * method's behavior.
 *
 * @param {module:engine/model/model~Model} model The model in context of which the insertion
 * should be performed.
 * @param {module:engine/model/documentfragment~DocumentFragment|module:engine/model/item~Item} content The content to insert.
 * @param {module:engine/model/selection~Selectable} [selectable=model.document.selection]
 * Selection into which the content should be inserted.
 * @param {Number|'before'|'end'|'after'|'on'|'in'} [placeOrOffset] Sets place or offset of the selection.
 * @returns {module:engine/model/range~Range} Range which contains all the performed changes. This is a range that, if removed,
 * would return the model to the state before the insertion. If no changes were preformed by `insertContent`, returns a range collapsed
 * at the insertion position.
 */
export default function insertContent( model, content, selectable, placeOrOffset ) {
    return model.change( writer => {
        let selection;

        if ( !selectable ) {
            selection = model.document.selection;
        } else if ( selectable instanceof Selection || selectable instanceof DocumentSelection ) {
            selection = selectable;
        } else {
            selection = writer.createSelection( selectable, placeOrOffset );
        }

        if ( !selection.isCollapsed ) {
            model.deleteContent( selection, { doNotAutoparagraph: true } );
        }

        const insertion = new Insertion( model, writer, selection.anchor );

        let nodesToInsert;

        if ( content.is( 'documentFragment' ) ) {
            nodesToInsert = content.getChildren();
        } else {
            nodesToInsert = [ content ];
        }

        insertion.handleNodes( nodesToInsert, {
            // The set of children being inserted is the only set in this context
            // so it's the first and last (it's a hack ;)).
            isFirst: true,
            isLast: true
        } );

        const newRange = insertion.getSelectionRange();

        /* istanbul ignore else */
        if ( newRange ) {
            if ( selection instanceof DocumentSelection ) {
                writer.setSelection( newRange );
            } else {
                selection.setTo( newRange );
            }
        } else {
            // We are not testing else because it's a safe check for unpredictable edge cases:
            // an insertion without proper range to select.
            //
            // @if CK_DEBUG // console.warn( 'Cannot determine a proper selection range after insertion.' );
        }

        const affectedRange = insertion.getAffectedRange() || model.createRange( selection.anchor );

        insertion.destroy();

        return affectedRange;
    } );
}

/**
 * Utility class for performing content insertion.
 *
 * @private
 */
class Insertion {
    constructor( model, writer, position ) {
        /**
         * The model in context of which the insertion should be performed.
         *
         * @member {module:engine/model~Model} #model
         */
        this.model = model;

        /**
         * Batch to which operations will be added.
         *
         * @member {module:engine/controller/writer~Batch} #writer
         */
        this.writer = writer;

        /**
         * The position at which (or near which) the next node will be inserted.
         *
         * @member {module:engine/model/position~Position} #position
         */
        this.position = position;

        /**
         * Elements with which the inserted elements can be merged.
         *
         *        <p>x^</p><p>y</p> + <p>z</p> (can merge to <p>x</p>)
         *        <p>x</p><p>^y</p> + <p>z</p> (can merge to <p>y</p>)
         *        <p>x^y</p> + <p>z</p> (can merge to <p>xy</p> which will be split during the action,
         *                                so both its pieces will be added to this set)
         *
         *
         * @member {Set} #canMergeWith
         */
        this.canMergeWith = new Set( [ this.position.parent ] );

        /**
         * Schema of the model.
         *
         * @member {module:engine/model/schema~Schema} #schema
         */
        this.schema = model.schema;

        this._filterAttributesOf = [];

        /**
         * Beginning of the affected range. See {@link module:engine/model/utils/insertcontent~Insertion#getAffectedRange}.
         *
         * @private
         * @member {module:engine/model/liveposition~LivePosition|null} #_affectedStart
         */
        this._affectedStart = null;

        /**
         * End of the affected range. See {@link module:engine/model/utils/insertcontent~Insertion#getAffectedRange}.
         *
         * @private
         * @member {module:engine/model/liveposition~LivePosition|null} #_affectedEnd
         */
        this._affectedEnd = null;
    }

    /**
     * Handles insertion of a set of nodes.
     *
     * @param {Iterable.<module:engine/model/node~Node>} nodes Nodes to insert.
     * @param {Object} parentContext Context in which parent of these nodes was supposed to be inserted.
     * If the parent context is passed it means that the parent element was stripped (was not allowed).
     */
    handleNodes( nodes, parentContext ) {
        nodes = Array.from( nodes );

        for ( let i = 0; i < nodes.length; i++ ) {
            const node = nodes[ i ];

            this._handleNode( node, {
                isFirst: i === 0 && parentContext.isFirst,
                isLast: ( i === ( nodes.length - 1 ) ) && parentContext.isLast
            } );
        }

        // TMP this will become a post-fixer.
        this.schema.removeDisallowedAttributes( this._filterAttributesOf, this.writer );
        this._filterAttributesOf = [];
    }

    /**
     * Returns range to be selected after insertion.
     * Returns `null` if there is no valid range to select after insertion.
     *
     * @returns {module:engine/model/range~Range|null}
     */
    getSelectionRange() {
        if ( this.nodeToSelect ) {
            return Range._createOn( this.nodeToSelect );
        }

        return this.model.schema.getNearestSelectionRange( this.position );
    }

    /**
     * Returns a range which contains all the performed changes. This is a range that, if removed, would return the model to the state
     * before the insertion. Returns `null` if no changes were done.
     *
     * @returns {module:engine/model/range~Range|null}
     */
    getAffectedRange() {
        if ( !this._affectedStart ) {
            return null;
        }

        return new Range( this._affectedStart, this._affectedEnd );
    }

    /**
     * Destroys `Insertion` instance.
     */
    destroy() {
        if ( this._affectedStart ) {
            this._affectedStart.detach();
        }

        if ( this._affectedEnd ) {
            this._affectedEnd.detach();
        }
    }

    /**
     * Handles insertion of a single node.
     *
     * @private
     * @param {module:engine/model/node~Node} node
     * @param {Object} context
     * @param {Boolean} context.isFirst Whether the given node is the first one in the content to be inserted.
     * @param {Boolean} context.isLast Whether the given node is the last one in the content to be inserted.
     */
    _handleNode( node, context ) {
        // Let's handle object in a special way.
        // * They should never be merged with other elements.
        // * If they are not allowed in any of the selection ancestors, they could be either autoparagraphed or totally removed.
        if ( this.schema.isObject( node ) ) {
            this._handleObject( node, context );

            return;
        }

        // Try to find a place for the given node.
        // Split the position.parent's branch up to a point where the node can be inserted.
        // If it isn't allowed in the whole branch, then of course don't split anything.
        const isAllowed = this._checkAndSplitToAllowedPosition( node, context );

        if ( !isAllowed ) {
            this._handleDisallowedNode( node, context );

            return;
        }

        this._insert( node );

        // After the node was inserted we may try to merge it with its siblings.
        // This should happen only if it was the first and/or last of the nodes (so only with boundary nodes)
        // and only if the selection was in those elements initially.
        //
        // E.g.:
        // <p>x^</p> + <p>y</p> => <p>x</p><p>y</p> => <p>xy[]</p>
        // and:
        // <p>x^y</p> + <p>z</p> => <p>x</p>^<p>y</p> + <p>z</p> => <p>x</p><p>z</p><p>y</p> => <p>xz[]y</p>
        // but:
        // <p>x</p><p>^</p><p>z</p> + <p>y</p> => <p>x</p><p>y</p><p>z</p> (no merging)
        // <p>x</p>[<img>]<p>z</p> + <p>y</p> => <p>x</p><p>y</p><p>z</p> (no merging, note: after running deleteContents
        //                                                                     it's exactly the same case as above)
        this._mergeSiblingsOf( node, context );
    }

    /**
     * @private
     * @param {module:engine/model/element~Element} node The object element.
     * @param {Object} context
     */
    _handleObject( node, context ) {
        // Try finding it a place in the tree.
        if ( this._checkAndSplitToAllowedPosition( node ) ) {
            this._insert( node );
        }
        // Try autoparagraphing.
        else {
            this._tryAutoparagraphing( node, context );
        }
    }

    /**
     * @private
     * @param {module:engine/model/node~Node} node The disallowed node which needs to be handled.
     * @param {Object} context
     */
    _handleDisallowedNode( node, context ) {
        // If the node is an element, try inserting its children (strip the parent).
        if ( node.is( 'element' ) ) {
            this.handleNodes( node.getChildren(), context );
        }
        // If text is not allowed, try autoparagraphing it.
        else {
            this._tryAutoparagraphing( node, context );
        }
    }

    /**
     * @private
     * @param {module:engine/model/node~Node} node The node to insert.
     */
    _insert( node ) {
        /* istanbul ignore if */
        if ( !this.schema.checkChild( this.position, node ) ) {
            // Algorithm's correctness check. We should never end up here but it's good to know that we did.
            // Note that it would often be a silent issue if we insert node in a place where it's not allowed.

            /**
             * Given node cannot be inserted on the given position.
             *
             * @error insertcontent-wrong-position
             * @param {module:engine/model/node~Node} node Node to insert.
             * @param {module:engine/model/position~Position} position Position to insert the node at.
             */
            throw new CKEditorError(
                'insertcontent-wrong-position: Given node cannot be inserted on the given position.',
                this,
                { node, position: this.position }
            );
        }

        const livePos = LivePosition.fromPosition( this.position, 'toNext' );

        this._setAffectedBoundaries( this.position );
        this.writer.insert( node, this.position );

        this.position = livePos.toPosition();
        livePos.detach();

        // The last inserted object should be selected because we can't put a collapsed selection after it.
        if ( this.schema.isObject( node ) && !this.schema.checkChild( this.position, '$text' ) ) {
            this.nodeToSelect = node;
        } else {
            this.nodeToSelect = null;
        }

        this._filterAttributesOf.push( node );
    }

    /**
     * Sets `_affectedStart` and `_affectedEnd` to the given `position`. Should be used before a change is done during insertion process to
     * mark the affected range.
     *
     * This method is used before inserting a node or splitting a parent node. `_affectedStart` and `_affectedEnd` are also changed
     * during merging, but the logic there is more complicated so it is left out of this function.
     *
     * @private
     * @param {module:engine/model/position~Position} position
     */
    _setAffectedBoundaries( position ) {
        // Set affected boundaries stickiness so that those position will "expand" when something is inserted in between them:
        // <paragraph>Foo][bar</paragraph> -> <paragraph>Foo]xx[bar</paragraph>
        // This is why it cannot be a range but two separate positions.
        if ( !this._affectedStart ) {
            this._affectedStart = LivePosition.fromPosition( position, 'toPrevious' );
        }

        // If `_affectedEnd` is before the new boundary position, expand `_affectedEnd`. This can happen if first inserted node was
        // inserted into the parent but the next node is moved-out of that parent:
        // (1) <paragraph>Foo][</paragraph> -> <paragraph>Foo]xx[</paragraph>
        // (2) <paragraph>Foo]xx[</paragraph> -> <paragraph>Foo]xx</paragraph><widget></widget>[
        if ( !this._affectedEnd || this._affectedEnd.isBefore( position ) ) {
            if ( this._affectedEnd ) {
                this._affectedEnd.detach();
            }

            this._affectedEnd = LivePosition.fromPosition( position, 'toNext' );
        }
    }

    /**
     * @private
     * @param {module:engine/model/node~Node} node The node which could potentially be merged.
     * @param {Object} context
     */
    _mergeSiblingsOf( node, context ) {
        if ( !( node instanceof Element ) ) {
            return;
        }

        const mergeLeft = this._canMergeLeft( node, context );
        const mergeRight = this._canMergeRight( node, context );
        const mergePosLeft = LivePosition._createBefore( node );
        mergePosLeft.stickiness = 'toNext';
        const mergePosRight = LivePosition._createAfter( node );
        mergePosRight.stickiness = 'toNext';

        if ( mergeLeft ) {
            const livePosition = LivePosition.fromPosition( this.position );
            livePosition.stickiness = 'toNext';

            // If `_affectedStart` is sames as merge position, it means that the element "marked" by `_affectedStart` is going to be
            // removed and its contents will be moved. This won't transform `LivePosition` so `_affectedStart` needs to be moved
            // by hand to properly reflect affected range. (Due to `_affectedStart` and `_affectedEnd` stickiness, the "range" is
            // shown as `][`).
            //
            // Example - insert `<paragraph>Abc</paragraph><paragraph>Xyz</paragraph>` at the end of `<paragraph>Foo^</paragraph>`:
            //
            // <paragraph>Foo</paragraph><paragraph>Bar</paragraph>   -->
            // <paragraph>Foo</paragraph>]<paragraph>Abc</paragraph><paragraph>Xyz</paragraph>[<paragraph>Bar</paragraph>   -->
            // <paragraph>Foo]Abc</paragraph><paragraph>Xyz</paragraph>[<paragraph>Bar</paragraph>
            //
            // Note, that if we are here then something must have been inserted, so `_affectedStart` and `_affectedEnd` have to be set.
            if ( this._affectedStart.isEqual( mergePosLeft ) ) {
                this._affectedStart.detach();
                this._affectedStart = LivePosition._createAt( mergePosLeft.nodeBefore, 'end', 'toPrevious' );
            }

            this.writer.merge( mergePosLeft );

            // If only one element (the merged one) is in the "affected range", also move the affected range end appropriately.
            //
            // Example - insert `<paragraph>Abc</paragraph>` at the of `<paragraph>Foo^</paragraph>`:
            //
            // <paragraph>Foo</paragraph><paragraph>Bar</paragraph>   -->
            // <paragraph>Foo</paragraph>]<paragraph>Abc</paragraph>[<paragraph>Bar</paragraph>   -->
            // <paragraph>Foo]Abc</paragraph>[<paragraph>Bar</paragraph>   -->
            // <paragraph>Foo]Abc[</paragraph><paragraph>Bar</paragraph>
            if ( mergePosLeft.isEqual( this._affectedEnd ) && context.isLast ) {
                this._affectedEnd.detach();
                this._affectedEnd = LivePosition._createAt( mergePosLeft.nodeBefore, 'end', 'toNext' );
            }

            this.position = livePosition.toPosition();
            livePosition.detach();
        }

        if ( mergeRight ) {
            /* istanbul ignore if */
            if ( !this.position.isEqual( mergePosRight ) ) {
                // Algorithm's correctness check. We should never end up here but it's good to know that we did.
                // At this point the insertion position should be after the node we'll merge. If it isn't,
                // it should need to be secured as in the left merge case.
                /**
                 * An internal error occured during merging insertion content with siblings.
                 * The insertion position should equal to the merge position.
                 *
                 * @error insertcontent-invalid-insertion-position
                 */
                throw new CKEditorError( 'insertcontent-invalid-insertion-position', this );
            }

            // Move the position to the previous node, so it isn't moved to the graveyard on merge.
            // <p>x</p>[]<p>y</p> => <p>x[]</p><p>y</p>
            this.position = Position._createAt( mergePosRight.nodeBefore, 'end' );

            // OK:  <p>xx[]</p> + <p>yy</p> => <p>xx[]yy</p> (when sticks to previous)
            // NOK: <p>xx[]</p> + <p>yy</p> => <p>xxyy[]</p> (when sticks to next)
            const livePosition = LivePosition.fromPosition( this.position, 'toPrevious' );

            // See comment above on moving `_affectedStart`.
            if ( this._affectedEnd.isEqual( mergePosRight ) ) {
                this._affectedEnd.detach();
                this._affectedEnd = LivePosition._createAt( mergePosRight.nodeBefore, 'end', 'toNext' );
            }

            this.writer.merge( mergePosRight );

            // See comment above on moving `_affectedStart`.
            if ( mergePosRight.getShiftedBy( -1 ).isEqual( this._affectedStart ) && context.isFirst ) {
                this._affectedStart.detach();
                this._affectedStart = LivePosition._createAt( mergePosRight.nodeBefore, 0, 'toPrevious' );
            }

            this.position = livePosition.toPosition();
            livePosition.detach();
        }

        if ( mergeLeft || mergeRight ) {
            // After merge elements that were marked by _insert() to be filtered might be gone so
            // we need to mark the new container.
            this._filterAttributesOf.push( this.position.parent );
        }

        mergePosLeft.detach();
        mergePosRight.detach();
    }

    /**
     * Checks whether specified node can be merged with previous sibling element.
     *
     * @private
     * @param {module:engine/model/node~Node} node The node which could potentially be merged.
     * @param {Object} context
     * @returns {Boolean}
     */
    _canMergeLeft( node, context ) {
        const previousSibling = node.previousSibling;

        return context.isFirst &&
            ( previousSibling instanceof Element ) &&
            this.canMergeWith.has( previousSibling ) &&
            this.model.schema.checkMerge( previousSibling, node );
    }

    /**
     * Checks whether specified node can be merged with next sibling element.
     *
     * @private
     * @param {module:engine/model/node~Node} node The node which could potentially be merged.
     * @param {Object} context
     * @returns {Boolean}
     */
    _canMergeRight( node, context ) {
        const nextSibling = node.nextSibling;

        return context.isLast &&
            ( nextSibling instanceof Element ) &&
            this.canMergeWith.has( nextSibling ) &&
            this.model.schema.checkMerge( node, nextSibling );
    }

    /**
     * Tries wrapping the node in a new paragraph and inserting it this way.
     *
     * @private
     * @param {module:engine/model/node~Node} node The node which needs to be autoparagraphed.
     * @param {Object} context
     */
    _tryAutoparagraphing( node, context ) {
        const paragraph = this.writer.createElement( 'paragraph' );

        // Do not autoparagraph if the paragraph won't be allowed there,
        // cause that would lead to an infinite loop. The paragraph would be rejected in
        // the next _handleNode() call and we'd be here again.
        if ( this._getAllowedIn( paragraph, this.position.parent ) && this.schema.checkChild( paragraph, node ) ) {
            paragraph._appendChild( node );
            this._handleNode( paragraph, context );
        }
    }

    /**
     * @private
     * @param {module:engine/model/node~Node} node
     * @returns {Boolean} Whether an allowed position was found.
     * `false` is returned if the node isn't allowed at any position up in the tree, `true` if was.
     */
    _checkAndSplitToAllowedPosition( node ) {
        const allowedIn = this._getAllowedIn( node, this.position.parent );

        if ( !allowedIn ) {
            return false;
        }

        while ( allowedIn != this.position.parent ) {
            // If a parent which we'd need to leave is a limit element, break.
            if ( this.schema.isLimit( this.position.parent ) ) {
                return false;
            }

            if ( this.position.isAtStart ) {
                // If insertion position is at the beginning of the parent, move it out instead of splitting.
                // <p>^Foo</p> -> ^<p>Foo</p>
                const parent = this.position.parent;

                this.position = this.writer.createPositionBefore( parent );

                // Special case – parent is empty (<p>^</p>).
                //
                // 1. parent.isEmpty
                // We can remove the element after moving insertion position out of it.
                //
                // 2. parent.parent === allowedIn
                // However parent should remain in place when allowed element is above limit element in document tree.
                // For example there shouldn't be allowed to remove empty paragraph from tableCell, when is pasted
                // content allowed in $root.
                if ( parent.isEmpty && parent.parent === allowedIn ) {
                    this.writer.remove( parent );
                }
            } else if ( this.position.isAtEnd ) {
                // If insertion position is at the end of the parent, move it out instead of splitting.
                // <p>Foo^</p> -> <p>Foo</p>^
                this.position = this.writer.createPositionAfter( this.position.parent );
            } else {
                const tempPos = this.writer.createPositionAfter( this.position.parent );

                this._setAffectedBoundaries( this.position );
                this.writer.split( this.position );

                this.position = tempPos;

                this.canMergeWith.add( this.position.nodeAfter );
            }
        }

        return true;
    }

    /**
     * Gets the element in which the given node is allowed. It checks the passed element and all its ancestors.
     *
     * @private
     * @param {module:engine/model/node~Node} node The node to check.
     * @param {module:engine/model/element~Element} element The element in which the node's correctness should be checked.
     * @returns {module:engine/model/element~Element|null}
     */
    _getAllowedIn( node, element ) {
        if ( this.schema.checkChild( element, node ) ) {
            return element;
        }

        if ( element.parent ) {
            return this._getAllowedIn( node, element.parent );
        }

        return null;
    }
}