1 files changed, 465 insertions, 0 deletions
diff --git a/net/bufio.ts b/net/bufio.ts
new file mode 100644
index 000000000..b412cbce8
--- /dev/null
+++ b/net/bufio.ts
@@ -0,0 +1,465 @@
+// Based on https://github.com/golang/go/blob/891682/src/bufio/bufio.go
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import { Reader, ReadResult, Writer } from "deno";
+import { assert, charCode, copyBytes } from "./util.ts";
+
+const DEFAULT_BUF_SIZE = 4096;
+const MIN_BUF_SIZE = 16;
+const MAX_CONSECUTIVE_EMPTY_READS = 100;
+const CR = charCode("\r");
+const LF = charCode("\n");
+
+export type BufState =
+  | null
+  | "EOF"
+  | "BufferFull"
+  | "ShortWrite"
+  | "NoProgress"
+  | Error;
+
+/** BufReader implements buffering for a Reader object. */
+export class BufReader implements Reader {
+  private buf: Uint8Array;
+  private rd: Reader; // Reader provided by caller.
+  private r = 0; // buf read position.
+  private w = 0; // buf write position.
+  private lastByte: number;
+  private lastCharSize: number;
+  private err: BufState;
+
+  constructor(rd: Reader, size = DEFAULT_BUF_SIZE) {
+    if (size < MIN_BUF_SIZE) {
+      size = MIN_BUF_SIZE;
+    }
+    this._reset(new Uint8Array(size), rd);
+  }
+
+  /** Returns the size of the underlying buffer in bytes. */
+  size(): number {
+    return this.buf.byteLength;
+  }
+
+  buffered(): number {
+    return this.w - this.r;
+  }
+
+  private _readErr(): BufState {
+    const err = this.err;
+    this.err = null;
+    return err;
+  }
+
+  // Reads a new chunk into the buffer.
+  private async _fill(): Promise<void> {
+    // Slide existing data to beginning.
+    if (this.r > 0) {
+      this.buf.copyWithin(0, this.r, this.w);
+      this.w -= this.r;
+      this.r = 0;
+    }
+
+    if (this.w >= this.buf.byteLength) {
+      throw Error("bufio: tried to fill full buffer");
+    }
+
+    // Read new data: try a limited number of times.
+    for (let i = MAX_CONSECUTIVE_EMPTY_READS; i > 0; i--) {
+      let rr: ReadResult;
+      try {
+        rr = await this.rd.read(this.buf.subarray(this.w));
+      } catch (e) {
+        this.err = e;
+        return;
+      }
+      assert(rr.nread >= 0, "negative read");
+      this.w += rr.nread;
+      if (rr.eof) {
+        this.err = "EOF";
+        return;
+      }
+      if (rr.nread > 0) {
+        return;
+      }
+    }
+    this.err = "NoProgress";
+  }
+
+  /** Discards any buffered data, resets all state, and switches
+   * the buffered reader to read from r.
+   */
+  reset(r: Reader): void {
+    this._reset(this.buf, r);
+  }
+
+  private _reset(buf: Uint8Array, rd: Reader): void {
+    this.buf = buf;
+    this.rd = rd;
+    this.lastByte = -1;
+    // this.lastRuneSize = -1;
+  }
+
+  /** reads data into p.
+   * It returns the number of bytes read into p.
+   * The bytes are taken from at most one Read on the underlying Reader,
+   * hence n may be less than len(p).
+   * At EOF, the count will be zero and err will be io.EOF.
+   * To read exactly len(p) bytes, use io.ReadFull(b, p).
+   */
+  async read(p: Uint8Array): Promise<ReadResult> {
+    let rr: ReadResult = { nread: p.byteLength, eof: false };
+    if (rr.nread === 0) {
+      if (this.err) {
+        throw this._readErr();
+      }
+      return rr;
+    }
+
+    if (this.r === this.w) {
+      if (this.err) {
+        throw this._readErr();
+      }
+      if (p.byteLength >= this.buf.byteLength) {
+        // Large read, empty buffer.
+        // Read directly into p to avoid copy.
+        rr = await this.rd.read(p);
+        assert(rr.nread >= 0, "negative read");
+        if (rr.nread > 0) {
+          this.lastByte = p[rr.nread - 1];
+          // this.lastRuneSize = -1;
+        }
+        if (this.err) {
+          throw this._readErr();
+        }
+        return rr;
+      }
+      // One read.
+      // Do not use this.fill, which will loop.
+      this.r = 0;
+      this.w = 0;
+      try {
+        rr = await this.rd.read(this.buf);
+      } catch (e) {
+        this.err = e;
+      }
+      assert(rr.nread >= 0, "negative read");
+      if (rr.nread === 0) {
+        if (this.err) {
+          throw this._readErr();
+        }
+        return rr;
+      }
+      this.w += rr.nread;
+    }
+
+    // copy as much as we can
+    rr.nread = copyBytes(p as Uint8Array, this.buf.subarray(this.r, this.w), 0);
+    this.r += rr.nread;
+    this.lastByte = this.buf[this.r - 1];
+    // this.lastRuneSize = -1;
+    return rr;
+  }
+
+  /** reads exactly len(p) bytes into p.
+   * Ported from https://golang.org/pkg/io/#ReadFull
+   * It returns the number of bytes copied and an error if fewer bytes were read.
+   * The error is EOF only if no bytes were read.
+   * If an EOF happens after reading some but not all the bytes,
+   * readFull returns ErrUnexpectedEOF. ("EOF" for current impl)
+   * On return, n == len(p) if and only if err == nil.
+   * If r returns an error having read at least len(buf) bytes,
+   * the error is dropped.
+   */
+  async readFull(p: Uint8Array): Promise<[number, BufState]> {
+    let rr = await this.read(p);
+    let nread = rr.nread;
+    if (rr.eof) {
+      return [nread, nread < p.length ? "EOF" : null];
+    }
+    while (!rr.eof && nread < p.length) {
+      rr = await this.read(p.subarray(nread));
+      nread += rr.nread;
+    }
+    return [nread, nread < p.length ? "EOF" : null];
+  }
+
+
+  /** Returns the next byte [0, 255] or -1 if EOF. */
+  async readByte(): Promise<number> {
+    while (this.r === this.w) {
+      await this._fill(); // buffer is empty.
+      if (this.err == "EOF") {
+        return -1;
+      }
+      if (this.err != null) {
+        throw this._readErr();
+      }
+    }
+    const c = this.buf[this.r];
+    this.r++;
+    this.lastByte = c;
+    return c;
+  }
+
+  /** readString() reads until the first occurrence of delim in the input,
+   * returning a string containing the data up to and including the delimiter.
+   * If ReadString encounters an error before finding a delimiter,
+   * it returns the data read before the error and the error itself (often io.EOF).
+   * ReadString returns err != nil if and only if the returned data does not end in
+   * delim.
+   * For simple uses, a Scanner may be more convenient.
+   */
+  async readString(delim: string): Promise<string> {
+    throw new Error("Not implemented");
+  }
+
+  /** readLine() is a low-level line-reading primitive. Most callers should use
+   * readBytes('\n') or readString('\n') instead or use a Scanner.
+   *
+   * readLine tries to return a single line, not including the end-of-line bytes.
+   * If the line was too long for the buffer then isPrefix is set and the
+   * beginning of the line is returned. The rest of the line will be returned
+   * from future calls. isPrefix will be false when returning the last fragment
+   * of the line. The returned buffer is only valid until the next call to
+   * ReadLine. ReadLine either returns a non-nil line or it returns an error,
+   * never both.
+   *
+   * The text returned from ReadLine does not include the line end ("\r\n" or "\n").
+   * No indication or error is given if the input ends without a final line end.
+   * Calling UnreadByte after ReadLine will always unread the last byte read
+   * (possibly a character belonging to the line end) even if that byte is not
+   * part of the line returned by ReadLine.
+   */
+  async readLine(): Promise<[Uint8Array, boolean, BufState]> {
+    let [line, err] = await this.readSlice(LF);
+
+    if (err === "BufferFull") {
+      // Handle the case where "\r\n" straddles the buffer.
+      if (line.byteLength > 0 && line[line.byteLength - 1] === CR) {
+        // Put the '\r' back on buf and drop it from line.
+        // Let the next call to ReadLine check for "\r\n".
+        assert(this.r > 0, "bufio: tried to rewind past start of buffer");
+        this.r--;
+        line = line.subarray(0, line.byteLength - 1);
+      }
+      return [line, true, null];
+    }
+
+    if (line.byteLength === 0) {
+      return [line, false, err];
+    }
+    err = null;
+
+    if (line[line.byteLength - 1] == LF) {
+      let drop = 1;
+      if (line.byteLength > 1 && line[line.byteLength - 2] === CR) {
+        drop = 2;
+      }
+      line = line.subarray(0, line.byteLength - drop);
+    }
+    return [line, false, err];
+  }
+
+  /** readSlice() reads until the first occurrence of delim in the input,
+   * returning a slice pointing at the bytes in the buffer. The bytes stop
+   * being valid at the next read. If readSlice() encounters an error before
+   * finding a delimiter, it returns all the data in the buffer and the error
+   * itself (often io.EOF).  readSlice() fails with error ErrBufferFull if the
+   * buffer fills without a delim. Because the data returned from readSlice()
+   * will be overwritten by the next I/O operation, most clients should use
+   * readBytes() or readString() instead. readSlice() returns err != nil if and
+   * only if line does not end in delim.
+   */
+  async readSlice(delim: number): Promise<[Uint8Array, BufState]> {
+    let s = 0; // search start index
+    let line: Uint8Array;
+    let err: BufState;
+    while (true) {
+      // Search buffer.
+      let i = this.buf.subarray(this.r + s, this.w).indexOf(delim);
+      if (i >= 0) {
+        i += s;
+        line = this.buf.subarray(this.r, this.r + i + 1);
+        this.r += i + 1;
+        break;
+      }
+
+      // Pending error?
+      if (this.err) {
+        line = this.buf.subarray(this.r, this.w);
+        this.r = this.w;
+        err = this._readErr();
+        break;
+      }
+
+      // Buffer full?
+      if (this.buffered() >= this.buf.byteLength) {
+        this.r = this.w;
+        line = this.buf;
+        err = "BufferFull";
+        break;
+      }
+
+      s = this.w - this.r; // do not rescan area we scanned before
+
+      await this._fill(); // buffer is not full
+    }
+
+    // Handle last byte, if any.
+    let i = line.byteLength - 1;
+    if (i >= 0) {
+      this.lastByte = line[i];
+      // this.lastRuneSize = -1
+    }
+
+    return [line, err];
+  }
+
+  /** Peek returns the next n bytes without advancing the reader. The bytes stop
+   * being valid at the next read call. If Peek returns fewer than n bytes, it
+   * also returns an error explaining why the read is short. The error is
+   * ErrBufferFull if n is larger than b's buffer size.
+   */
+  async peek(n: number): Promise<[Uint8Array, BufState]> {
+    if (n < 0) {
+      throw Error("negative count");
+    }
+
+    while (
+      this.w - this.r < n &&
+      this.w - this.r < this.buf.byteLength &&
+      this.err == null
+    ) {
+      await this._fill(); // this.w - this.r < len(this.buf) => buffer is not full
+    }
+
+    if (n > this.buf.byteLength) {
+      return [this.buf.subarray(this.r, this.w), "BufferFull"];
+    }
+
+    // 0 <= n <= len(this.buf)
+    let err: BufState;
+    let avail = this.w - this.r;
+    if (avail < n) {
+      // not enough data in buffer
+      n = avail;
+      err = this._readErr();
+      if (!err) {
+        err = "BufferFull";
+      }
+    }
+    return [this.buf.subarray(this.r, this.r + n), err];
+  }
+}
+
+/** BufWriter implements buffering for an deno.Writer object.
+ * If an error occurs writing to a Writer, no more data will be
+ * accepted and all subsequent writes, and flush(), will return the error.
+ * After all data has been written, the client should call the
+ * flush() method to guarantee all data has been forwarded to
+ * the underlying deno.Writer.
+ */
+export class BufWriter implements Writer {
+  buf: Uint8Array;
+  n: number = 0;
+  err: null | BufState = null;
+
+  constructor(private wr: Writer, size = DEFAULT_BUF_SIZE) {
+    if (size <= 0) {
+      size = DEFAULT_BUF_SIZE;
+    }
+    this.buf = new Uint8Array(size);
+  }
+
+  /** Size returns the size of the underlying buffer in bytes. */
+  size(): number {
+    return this.buf.byteLength;
+  }
+
+  /** Discards any unflushed buffered data, clears any error, and
+   * resets b to write its output to w.
+   */
+  reset(w: Writer): void {
+    this.err = null;
+    this.n = 0;
+    this.wr = w;
+  }
+
+  /** Flush writes any buffered data to the underlying io.Writer. */
+  async flush(): Promise<BufState> {
+    if (this.err != null) {
+      return this.err;
+    }
+    if (this.n == 0) {
+      return null;
+    }
+
+    let n: number;
+    let err: BufState = null;
+    try {
+      n = await this.wr.write(this.buf.subarray(0, this.n));
+    } catch (e) {
+      err = e;
+    }
+
+    if (n < this.n && err == null) {
+      err = "ShortWrite";
+    }
+
+    if (err != null) {
+      if (n > 0 && n < this.n) {
+        this.buf.copyWithin(0, n, this.n);
+      }
+      this.n -= n;
+      this.err = err;
+      return err;
+    }
+    this.n = 0;
+  }
+
+  /** Returns how many bytes are unused in the buffer. */
+  available(): number {
+    return this.buf.byteLength - this.n;
+  }
+
+  /** buffered returns the number of bytes that have been written into the
+   * current buffer.
+   */
+  buffered(): number {
+    return this.n;
+  }
+
+  /** Writes the contents of p into the buffer.
+   * Returns the number of bytes written.
+   */
+  async write(p: Uint8Array): Promise<number> {
+    let nn = 0;
+    let n: number;
+    while (p.byteLength > this.available() && !this.err) {
+      if (this.buffered() == 0) {
+        // Large write, empty buffer.
+        // Write directly from p to avoid copy.
+        try {
+          n = await this.wr.write(p);
+        } catch (e) {
+          this.err = e;
+        }
+      } else {
+        n = copyBytes(this.buf, p, this.n);
+        this.n += n;
+        await this.flush();
+      }
+      nn += n;
+      p = p.subarray(n);
+    }
+    if (this.err) {
+      throw this.err;
+    }
+    n = copyBytes(this.buf, p, this.n);
+    this.n += n;
+    nn += n;
+    return nn;
+  }
+}