Method render

packages/core/src/prompts/prompt.ts:284–343

()

	}

	private render() {
		const frame = wrapAnsi(this._render(this) ?? '', process.stdout.columns, {
			hard: true,
			trim: false,
		});
		if (frame === this._prevFrame) return;

		if (this.state === 'initial') {
			this.output.write(cursor.hide);
		} else {
			const diff = diffLines(this._prevFrame, frame);
			const rows = getRows(this.output);
			this.restoreCursor();
			if (diff) {
				const diffOffsetAfter = Math.max(0, diff.numLinesAfter - rows);
				const diffOffsetBefore = Math.max(0, diff.numLinesBefore - rows);
				let diffLine = diff.lines.find((line) => line >= diffOffsetAfter);

				if (diffLine === undefined) {
					this._prevFrame = frame;
					return;
				}

				// If a single line has changed, only update that line
				if (diff.lines.length === 1) {
					this.output.write(cursor.move(0, diffLine - diffOffsetBefore));
					this.output.write(erase.lines(1));
					const lines = frame.split('\n');
					this.output.write(lines[diffLine]);
					this._prevFrame = frame;
					this.output.write(cursor.move(0, lines.length - diffLine - 1));
					return;
					// If many lines have changed, rerender everything past the first line
				} else if (diff.lines.length > 1) {
					if (diffOffsetAfter < diffOffsetBefore) {
						diffLine = diffOffsetAfter;
					} else {
						const adjustedDiffLine = diffLine - diffOffsetBefore;
						if (adjustedDiffLine > 0) {
							this.output.write(cursor.move(0, adjustedDiffLine));
						}
					}
					this.output.write(erase.down());
					const lines = frame.split('\n');
					const newLines = lines.slice(diffLine);
					this.output.write(newLines.join('\n'));
					this._prevFrame = frame;
					return;
				}
			}

			this.output.write(erase.down());
		}

		this.output.write(frame);
		if (this.state === 'initial') {
			this.state = 'active';
		}