commit

node_modules/peek-readable/lib/StreamReader.js

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+import { EndOfStreamError } from './EndOfFileStream.js';
+import { Deferred } from './Deferred.js';
+export { EndOfStreamError } from './EndOfFileStream.js';
+const maxStreamReadSize = 1 * 1024 * 1024; // Maximum request length on read-stream operation
+export class StreamReader {
+    constructor(s) {
+        this.s = s;
+        /**
+         * Deferred used for postponed read request (as not data is yet available to read)
+         */
+        this.deferred = null;
+        this.endOfStream = false;
+        /**
+         * Store peeked data
+         * @type {Array}
+         */
+        this.peekQueue = [];
+        if (!s.read || !s.once) {
+            throw new Error('Expected an instance of stream.Readable');
+        }
+        this.s.once('end', () => this.reject(new EndOfStreamError()));
+        this.s.once('error', err => this.reject(err));
+        this.s.once('close', () => this.reject(new Error('Stream closed')));
+    }
+    /**
+     * Read ahead (peek) from stream. Subsequent read or peeks will return the same data
+     * @param uint8Array - Uint8Array (or Buffer) to store data read from stream in
+     * @param offset - Offset target
+     * @param length - Number of bytes to read
+     * @returns Number of bytes peeked
+     */
+    async peek(uint8Array, offset, length) {
+        const bytesRead = await this.read(uint8Array, offset, length);
+        this.peekQueue.push(uint8Array.subarray(offset, offset + bytesRead)); // Put read data back to peek buffer
+        return bytesRead;
+    }
+    /**
+     * Read chunk from stream
+     * @param buffer - Target Uint8Array (or Buffer) to store data read from stream in
+     * @param offset - Offset target
+     * @param length - Number of bytes to read
+     * @returns Number of bytes read
+     */
+    async read(buffer, offset, length) {
+        if (length === 0) {
+            return 0;
+        }
+        if (this.peekQueue.length === 0 && this.endOfStream) {
+            throw new EndOfStreamError();
+        }
+        let remaining = length;
+        let bytesRead = 0;
+        // consume peeked data first
+        while (this.peekQueue.length > 0 && remaining > 0) {
+            const peekData = this.peekQueue.pop(); // Front of queue
+            if (!peekData)
+                throw new Error('peekData should be defined');
+            const lenCopy = Math.min(peekData.length, remaining);
+            buffer.set(peekData.subarray(0, lenCopy), offset + bytesRead);
+            bytesRead += lenCopy;
+            remaining -= lenCopy;
+            if (lenCopy < peekData.length) {
+                // remainder back to queue
+                this.peekQueue.push(peekData.subarray(lenCopy));
+            }
+        }
+        // continue reading from stream if required
+        while (remaining > 0 && !this.endOfStream) {
+            const reqLen = Math.min(remaining, maxStreamReadSize);
+            const chunkLen = await this.readFromStream(buffer, offset + bytesRead, reqLen);
+            bytesRead += chunkLen;
+            if (chunkLen < reqLen)
+                break;
+            remaining -= chunkLen;
+        }
+        return bytesRead;
+    }
+    /**
+     * Read chunk from stream
+     * @param buffer Target Uint8Array (or Buffer) to store data read from stream in
+     * @param offset Offset target
+     * @param length Number of bytes to read
+     * @returns Number of bytes read
+     */
+    async readFromStream(buffer, offset, length) {
+        const readBuffer = this.s.read(length);
+        if (readBuffer) {
+            buffer.set(readBuffer, offset);
+            return readBuffer.length;
+        }
+        else {
+            const request = {
+                buffer,
+                offset,
+                length,
+                deferred: new Deferred()
+            };
+            this.deferred = request.deferred;
+            this.s.once('readable', () => {
+                this.readDeferred(request);
+            });
+            return request.deferred.promise;
+        }
+    }
+    /**
+     * Process deferred read request
+     * @param request Deferred read request
+     */
+    readDeferred(request) {
+        const readBuffer = this.s.read(request.length);
+        if (readBuffer) {
+            request.buffer.set(readBuffer, request.offset);
+            request.deferred.resolve(readBuffer.length);
+            this.deferred = null;
+        }
+        else {
+            this.s.once('readable', () => {
+                this.readDeferred(request);
+            });
+        }
+    }
+    reject(err) {
+        this.endOfStream = true;
+        if (this.deferred) {
+            this.deferred.reject(err);
+            this.deferred = null;
+        }
+    }
+}