scroll/src/common/document.ts

import { chars } from './utils.ts';
import { getRuntime } from './runtime.ts';
import { TAB_SIZE } from './mod.ts';

export class Row {
	chars: string[] = [];
	render: string[] = [];

	constructor(s: string = '') {
		this.chars = chars(s);
		this.render = [];
	}

	public get size(): number {
		return this.chars.length;
	}

	public get rsize(): number {
		return this.render.length;
	}

	public rstring(offset: number = 0): string {
		return this.render.slice(offset).join('');
	}

	public cxToRx(cx: number): number {
		let rx = 0;
		let j = 0;
		for (; j < cx; j++) {
			if (this.chars[j] === '\t') {
				rx += (TAB_SIZE - 1) - (rx % TAB_SIZE);
			}
			rx++;
		}

		return rx;
	}

	public toString(): string {
		return this.chars.join('');
	}
}

export class Document {
	#rows: Row[];

	private constructor() {
		this.#rows = [];
	}

	get numRows(): number {
		return this.#rows.length;
	}

	public static empty(): Document {
		return new Document();
	}

	public isEmpty(): boolean {
		return this.#rows.length === 0;
	}

	public async open(filename: string): Promise<Document> {
		const { file } = await getRuntime();

		// Clear any existing rows
		if (!this.isEmpty()) {
			this.#rows = [];
		}

		const rawFile = await file.openFile(filename);
		rawFile.split(/\r?\n/)
			.forEach((row) => this.appendRow(row));

		return this;
	}

	public row(i: number): Row | null {
		return this.#rows[i] ?? null;
	}

	public appendRow(s: string): void {
		const at = this.numRows;
		this.#rows[at] = new Row(s);
		this.updateRow(this.#rows[at]);
	}

	private updateRow(r: Row): void {
		r.render = chars(r.toString().replace('\t', ' '.repeat(TAB_SIZE)));
	}
}

export default Document;