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// Copyright Node.js contributors. All rights reserved. MIT License.import { Buffer } from "../buffer.ts";
type BufferListItem = {  data: Buffer | string | Uint8Array;  next: BufferListItem | null;};
export default class BufferList {  head: BufferListItem | null = null;  tail: BufferListItem | null = null;  length: number;
  constructor() {    this.head = null;    this.tail = null;    this.length = 0;  }
  push(v: Buffer | string | Uint8Array) {    const entry = { data: v, next: null };    if (this.length > 0) {      (this.tail as BufferListItem).next = entry;    } else {      this.head = entry;    }    this.tail = entry;    ++this.length;  }
  unshift(v: Buffer | string | Uint8Array) {    const entry = { data: v, next: this.head };    if (this.length === 0) {      this.tail = entry;    }    this.head = entry;    ++this.length;  }
  shift() {    if (this.length === 0) {      return;    }    const ret = (this.head as BufferListItem).data;    if (this.length === 1) {      this.head = this.tail = null;    } else {      this.head = (this.head as BufferListItem).next;    }    --this.length;    return ret;  }
  clear() {    this.head = this.tail = null;    this.length = 0;  }
  join(s: string) {    if (this.length === 0) {      return "";    }    let p: BufferListItem | null = (this.head as BufferListItem);    let ret = "" + p.data;    p = p.next;    while (p) {      ret += s + p.data;      p = p.next;    }    return ret;  }
  concat(n: number) {    if (this.length === 0) {      return Buffer.alloc(0);    }    const ret = Buffer.allocUnsafe(n >>> 0);    let p = this.head;    let i = 0;    while (p) {      ret.set(p.data as Buffer, i);      i += p.data.length;      p = p.next;    }    return ret;  }
  // Consumes a specified amount of bytes or characters from the buffered data.  consume(n: number, hasStrings: boolean) {    const data = (this.head as BufferListItem).data;    if (n < data.length) {      // `slice` is the same for buffers and strings.      const slice = data.slice(0, n);      (this.head as BufferListItem).data = data.slice(n);      return slice;    }    if (n === data.length) {      // First chunk is a perfect match.      return this.shift();    }    // Result spans more than one buffer.    return hasStrings ? this._getString(n) : this._getBuffer(n);  }
  first() {    return (this.head as BufferListItem).data;  }
  *[Symbol.iterator]() {    for (let p = this.head; p; p = p.next) {      yield p.data;    }  }
  // Consumes a specified amount of characters from the buffered data.  _getString(n: number) {    let ret = "";    let p: BufferListItem | null = (this.head as BufferListItem);    let c = 0;    p = p.next as BufferListItem;    do {      const str = p.data;      if (n > str.length) {        ret += str;        n -= str.length;      } else {        if (n === str.length) {          ret += str;          ++c;          if (p.next) {            this.head = p.next;          } else {            this.head = this.tail = null;          }        } else {          ret += str.slice(0, n);          this.head = p;          p.data = str.slice(n);        }        break;      }      ++c;      p = p.next;    } while (p);    this.length -= c;    return ret;  }
  // Consumes a specified amount of bytes from the buffered data.  _getBuffer(n: number) {    const ret = Buffer.allocUnsafe(n);    const retLen = n;    let p: BufferListItem | null = (this.head as BufferListItem);    let c = 0;    p = p.next as BufferListItem;    do {      const buf = p.data as Buffer;      if (n > buf.length) {        ret.set(buf, retLen - n);        n -= buf.length;      } else {        if (n === buf.length) {          ret.set(buf, retLen - n);          ++c;          if (p.next) {            this.head = p.next;          } else {            this.head = this.tail = null;          }        } else {          ret.set(new Uint8Array(buf.buffer, buf.byteOffset, n), retLen - n);          this.head = p;          p.data = buf.slice(n);        }        break;      }      ++c;      p = p.next;    } while (p);    this.length -= c;    return ret;  }}