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// Copyright 2011 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview A wrapper for the HTML5 FileWriter object.
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 *
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 * When adding or modifying functionality in this namespace, be sure to update
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 * the mock counterparts in goog.testing.fs.
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 *
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 */
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goog.provide('goog.fs.FileWriter');
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goog.require('goog.fs.Error');
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goog.require('goog.fs.FileSaver');
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/**
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 * An object for monitoring the saving of files, as well as other fine-grained
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 * writing operations.
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 *
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 * This should not be instantiated directly. Instead, it should be accessed via
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 * {@link goog.fs.FileEntry#createWriter}.
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 *
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 * @param {!FileWriter} writer The underlying FileWriter object.
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 * @constructor
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 * @extends {goog.fs.FileSaver}
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 * @final
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 */
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goog.fs.FileWriter = function(writer) {
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  goog.fs.FileWriter.base(this, 'constructor', writer);
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  /**
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   * The underlying FileWriter object.
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   *
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   * @type {!FileWriter}
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   * @private
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   */
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  this.writer_ = writer;
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};
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goog.inherits(goog.fs.FileWriter, goog.fs.FileSaver);
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/**
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 * @return {number} The byte offset at which the next write will occur.
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 */
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goog.fs.FileWriter.prototype.getPosition = function() {
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  return this.writer_.position;
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};
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/**
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 * @return {number} The length of the file.
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 */
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goog.fs.FileWriter.prototype.getLength = function() {
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  return this.writer_.length;
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};
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/**
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 * Write data to the file.
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 *
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 * @param {!Blob} blob The data to write.
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 */
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goog.fs.FileWriter.prototype.write = function(blob) {
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  try {
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    this.writer_.write(blob);
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  } catch (e) {
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    throw new goog.fs.Error(e, 'writing file');
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  }
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};
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/**
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 * Set the file position at which the next write will occur.
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 *
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 * @param {number} offset An absolute byte offset into the file.
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 */
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goog.fs.FileWriter.prototype.seek = function(offset) {
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  try {
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    this.writer_.seek(offset);
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  } catch (e) {
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    throw new goog.fs.Error(e, 'seeking in file');
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  }
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};
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/**
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 * Changes the length of the file to that specified.
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 *
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 * @param {number} size The new size of the file, in bytes.
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 */
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goog.fs.FileWriter.prototype.truncate = function(size) {
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  try {
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    this.writer_.truncate(size);
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  } catch (e) {
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    throw new goog.fs.Error(e, 'truncating file');
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  }
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};
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