@jupyterlab/notebook/lib/celllist.js

// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.
import { CodeCellModel, MarkdownCellModel, RawCellModel } from '@jupyterlab/cells';
import { Signal } from '@lumino/signaling';
/**
 * A cell list object that supports undo/redo.
 */
export class CellList {
    /**
     * Construct the cell list.
     */
    constructor(model) {
        this.model = model;
        this._cellMap = new WeakMap();
        this._changed = new Signal(this);
        this._isDisposed = false;
        this._insertCells(0, this.model.cells);
        this.model.changed.connect(this._onSharedModelChanged, this);
    }
    /**
     * A signal emitted when the cell list has changed.
     */
    get changed() {
        return this._changed;
    }
    /**
     * Test whether the cell list has been disposed.
     */
    get isDisposed() {
        return this._isDisposed;
    }
    /**
     * Get the length of the cell list.
     *
     * @returns The number of cells in the cell list.
     */
    get length() {
        return this.model.cells.length;
    }
    /**
     * Create an iterator over the cells in the cell list.
     *
     * @returns A new iterator starting at the front of the cell list.
     */
    *[Symbol.iterator]() {
        for (const cell of this.model.cells) {
            yield this._cellMap.get(cell);
        }
    }
    /**
     * Dispose of the resources held by the cell list.
     */
    dispose() {
        var _a;
        if (this._isDisposed) {
            return;
        }
        this._isDisposed = true;
        // Clean up the cell map and cell order objects.
        for (const cell of this.model.cells) {
            (_a = this._cellMap.get(cell)) === null || _a === void 0 ? void 0 : _a.dispose();
        }
        Signal.clearData(this);
    }
    /**
     * Get the cell at the specified index.
     *
     * @param index - The positive integer index of interest.
     *
     * @returns The cell at the specified index.
     */
    get(index) {
        return this._cellMap.get(this.model.cells[index]);
    }
    _insertCells(index, cells) {
        cells.forEach(sharedModel => {
            let cellModel;
            switch (sharedModel.cell_type) {
                case 'code': {
                    cellModel = new CodeCellModel({
                        sharedModel: sharedModel
                    });
                    break;
                }
                case 'markdown': {
                    cellModel = new MarkdownCellModel({
                        sharedModel: sharedModel
                    });
                    break;
                }
                default: {
                    cellModel = new RawCellModel({
                        sharedModel: sharedModel
                    });
                }
            }
            this._cellMap.set(sharedModel, cellModel);
            sharedModel.disposed.connect(() => {
                cellModel.dispose();
                this._cellMap.delete(sharedModel);
            });
        });
        return this.length;
    }
    _onSharedModelChanged(self, change) {
        var _a;
        let currpos = 0;
        // We differ emitting the list changes to ensure cell model for all current shared cell have been created.
        const events = new Array();
        (_a = change.cellsChange) === null || _a === void 0 ? void 0 : _a.forEach(delta => {
            if (delta.insert != null) {
                this._insertCells(currpos, delta.insert);
                events.push({
                    type: 'add',
                    newIndex: currpos,
                    newValues: delta.insert.map(c => this._cellMap.get(c)),
                    oldIndex: -2,
                    oldValues: []
                });
                currpos += delta.insert.length;
            }
            else if (delta.delete != null) {
                events.push({
                    type: 'remove',
                    newIndex: -1,
                    newValues: [],
                    oldIndex: currpos,
                    // Cells have been disposed, so we don't know which one are gone.
                    oldValues: new Array(delta.delete).fill(undefined)
                });
            }
            else if (delta.retain != null) {
                currpos += delta.retain;
            }
        });
        events.forEach(msg => this._changed.emit(msg));
    }
}
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