Class LineDecoder

packages/baseai/src/dev/utils/stream/stream.ts:372–477

* A re-implementation of httpx's `LineDecoder` in Python that handles incrementally * reading lines from text. * * https://github.com/encode/httpx/blob/920333ea98118e9cf617f246905d7b202510941c/httpx/_decoders.py#L258

 * https://github.com/encode/httpx/blob/920333ea98118e9cf617f246905d7b202510941c/httpx/_decoders.py#L258
 */
class LineDecoder {
	// prettier-ignore
	static NEWLINE_CHARS = new Set(['\n', '\r']);
	static NEWLINE_REGEXP = /\r\n|[\n\r]/g;

	buffer: string[];
	trailingCR: boolean;
	textDecoder: any; // TextDecoder found in browsers; not typed to avoid pulling in either "dom" or "node" types.

	constructor() {
		this.buffer = [];
		this.trailingCR = false;
	}

	decode(chunk: Bytes): string[] {
		let text = this.decodeText(chunk);

		if (this.trailingCR) {
			text = '\r' + text;
			this.trailingCR = false;
		}
		if (text.endsWith('\r')) {
			this.trailingCR = true;
			text = text.slice(0, -1);
		}

		if (!text) {
			return [];
		}

		const trailingNewline = LineDecoder.NEWLINE_CHARS.has(
			text[text.length - 1] || ''
		);
		let lines = text.split(LineDecoder.NEWLINE_REGEXP);

		// if there is a trailing new line then the last entry will be an empty
		// string which we don't care about
		if (trailingNewline) {
			lines.pop();
		}

		if (lines.length === 1 && !trailingNewline) {
			this.buffer.push(lines[0]!);
			return [];
		}

		if (this.buffer.length > 0) {
			lines = [this.buffer.join('') + lines[0], ...lines.slice(1)];
			this.buffer = [];
		}

		if (!trailingNewline) {
			this.buffer = [lines.pop() || ''];
		}

		return lines;
	}