Implement new writable stream

PR-URL: #9

lib/errors.js

@@ -0,0 +1,68 @@
+'use strict';
+
+class ERR_INVALID_ARG_TYPE extends TypeError {
+  constructor(name, expected, actual) {
+    super(`The "${name}" argument must be one of type ${expected}. ` +
+      `Received type ${typeof(actual)}`);
+    this.code = 'ERR_INVALID_ARG_TYPE';
+    this.name += ` [${this.code}]`;
+  }
+}
+
+class ERR_STREAM_NULL_VALUES extends TypeError {
+  constructor() {
+    super('May not write null values to stream');
+    this.code = 'ERR_STREAM_NULL_VALUES';
+    this.name += ` [${this.code}]`;
+  }
+}
+
+class ERR_METHODS_NOT_IMPLEMENTED extends Error {
+  constructor() {
+    super('_write() and _vritev() methods are not implemented');
+    this.code = 'ERR_METHOD_NOT_IMPLEMENTED';
+    this.name += ` [${this.code}]`;
+  }
+}
+
+class ERR_STREAM_DESTROYED extends Error {
+  constructor() {
+    super('Cannot call write after a stream was destroyed');
+    this.code = 'ERR_STREAM_DESTROYED';
+    this.name += ` [${this.code}]`;
+  }
+}
+
+class ERR_STREAM_WRITE_AFTER_END extends Error {
+  constructor() {
+    super('write after end');
+    this.code = 'ERR_STREAM_WRITE_AFTER_END';
+    this.name += ` [${this.code}]`;
+  }
+}
+
+class ERR_UNKNOWN_ENCODING extends TypeError {
+  constructor(encoding) {
+    super(`Unknown encoding ${encoding}`);
+    this.code = 'ERR_UNKNOWN_ENCODING';
+    this.name += ` [${this.code}]`;
+  }
+}
+
+class ERR_OUT_OF_RANGE extends RangeError {
+  constructor(name, range, actual) {
+    super(`The value of ${name} is out of range. It must be ${range}. ` +
+      `Received ${actual}`);
+    this.code = 'ERR_OUT_OF_RANGE';
+    this.name += ` [${this.code}]`;
+  }
+}
+module.exports = {
+  ERR_OUT_OF_RANGE,
+  ERR_INVALID_ARG_TYPE,
+  ERR_STREAM_DESTROYED,
+  ERR_UNKNOWN_ENCODING,
+  ERR_STREAM_NULL_VALUES,
+  ERR_METHODS_NOT_IMPLEMENTED,
+  ERR_STREAM_WRITE_AFTER_END,
+};

lib/fs-writable.js

@@ -0,0 +1,146 @@
+// Copyright Node.js contributors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+'use strict';
+
+const fs = require('fs');
+
+const { Writable } = require('./writable');
+
+const {
+  ERR_INVALID_ARG_TYPE,
+  ERR_OUT_OF_RANGE
+} = require('./errors');
+
+const openSymbol = Symbol('open');
+const errorSymbol = Symbol('error');
+const closeStreamSymbol = Symbol('closeStream');
+
+class WritableFileStream extends Writable {
+  constructor(path, {
+    fd = null,
+    start,
+    flags = 'w',
+    bufferSize,
+    mode = 0o666,
+    encoding = null,
+    autoClose = true,
+  } = {}) {
+    super({ bufferSize });
+
+    this.fd = fd;
+    this.path = path;
+
+    this.closed = false;
+    this.bytesWritten = 0;
+
+    this.autoClose = autoClose;
+
+    if (typeof path !== 'string') {
+      throw new ERR_INVALID_ARG_TYPE('path', 'string', path);
+    }
+
+    if (start !== undefined) {
+      if (typeof start !== 'number') {
+        throw new ERR_INVALID_ARG_TYPE('start', 'number', start);
+      }
+      if (start < 0) {
+        throw new ERR_OUT_OF_RANGE('start', '>= 0', `{start: ${start}}`);
+      }
+
+      this.pos = start;
+    }
+
+    if (encoding) this.setDefaultEncoding(encoding);
+
+    if (this.fd === null) this[openSymbol](flags, mode);
+  }
+
+  [errorSymbol](error, cb) {
+    if (cb) cb(error);
+    if (this.autoClose) {
+      this.destroy(error);
+    } else {
+      this.emit('error', error);
+      this.emit('close');
+    }
+  }
+
+  [openSymbol](flags, mode) {
+    fs.open(this.path, flags, mode, (error, fd) => {
+      if (error) {
+        this[errorSymbol](error);
+        return;
+      }
+
+      this.fd = fd;
+      this.emit('open', fd);
+    });
+  }
+
+  [closeStreamSymbol](cb, err) {
+    fs.close(this.fd, (er) => {
+      er = er || err;
+      cb(er);
+      this.closed = true;
+      this.emit('close');
+    });
+  }
+
+  _write(data, cb) {
+    if (!Buffer.isBuffer(data)) {
+      const err = new ERR_INVALID_ARG_TYPE('data', 'Buffer', data);
+      this.emit('error', err);
+      return;
+    }
+
+    if (this.fd === null) {
+      this.once('open', () => this._write(data, cb));
+      return;
+    }
+
+    fs.write(this.fd, data, 0, data.length, this.pos, (error, bytes) => {
+      if (error) {
+        this[errorSymbol](error, cb);
+        return;
+      }
+      this.bytesWritten += bytes;
+      cb();
+    });
+
+    if (this.pos !== undefined) this.pos += data.length;
+  }
+
+  _destroy(err, cb) {
+    if (this.fd === null) {
+      this.once('open', () => this[closeStreamSymbol](cb, err));
+      return;
+    }
+    this[closeStreamSymbol](cb, err);
+    this.fd = null;
+  }
+
+  _final(cb) {
+    if (this.autoClose) this.destroy();
+    cb();
+  }
+}
+
+module.exports = { WritableFileStream };