ndjson-stream/dist/index.js

This library provides TransformStream for ndjson.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.LineBreakerStream = exports.JsonParserStream = exports.NdjsonStream = void 0;
class LineBreakerTransformer {
    constructor() {
        this.processing = "";
        this.processing = "";
    }
    start(controller) {
        this.processing = "";
    }
    transform(chunk, controller) {
        const [first, ...others] = chunk.split("\n");
        const firstLine = this.processing + first;
        switch (others.length) {
            case 0:
                this.processing = firstLine;
                break;
            case 1:
                controller.enqueue(firstLine);
                this.processing = others[0];
                break;
            default: {
                controller.enqueue(firstLine);
                const last = others.pop();
                for (const line of others) {
                    controller.enqueue(line);
                }
                this.processing = last;
                break;
            }
        }
    }
    flush(controller) {
        // TODO: Should raise an error?
        if (this.processing !== "") {
            controller.enqueue(this.processing);
        }
    }
}
class LineBreakerStream extends TransformStream {
    constructor() {
        super(new LineBreakerTransformer());
    }
}
exports.LineBreakerStream = LineBreakerStream;
class JsonParserTransformer {
    constructor(ignoreEmptyLine) {
        this.ignoreEmptyLine = ignoreEmptyLine;
    }
    transform(chunk, controller) {
        if (this.ignoreEmptyLine && (chunk === "" || chunk === "\r")) {
            return;
        }
        try {
            const value = JSON.parse(chunk);
            controller.enqueue(value);
        }
        catch (e) {
            controller.error(e);
        }
    }
}
class JsonParserStream extends TransformStream {
    constructor(ignoreEmptyLine = true) {
        super(new JsonParserTransformer(ignoreEmptyLine));
    }
}
exports.JsonParserStream = JsonParserStream;
class NdjsonStream {
    constructor(ignoreEmptyLine = true) {
        const root = new TextDecoderStream();
        const chained = root.readable.pipeThrough(new LineBreakerStream()).pipeThrough(new JsonParserStream(ignoreEmptyLine));
        this.readable = chained;
        this.writable = root.writable;
    }
}
exports.NdjsonStream = NdjsonStream;
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