v8/tools/consarray.js
yangguo@chromium.org aa3518a0f3 Make sure files end with exactly one new line and police this in presubmit.
The changes are (excluding presubmit.py) mechanical. I added the following
lines after the check and iterated the presubmit script until all errors
went away:

f = open(name, "w");
if contents.endswith('\n\n'):
  f.write(contents[0:-1])
else:
  f.write(contents + '\n')

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/82803005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18017 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2013-11-22 13:50:39 +00:00

93 lines
3.1 KiB
JavaScript

// Copyright 2009 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/**
* Constructs a ConsArray object. It is used mainly for tree traversal.
* In this use case we have lots of arrays that we need to iterate
* sequentally. The internal Array implementation is horribly slow
* when concatenating on large (10K items) arrays due to memory copying.
* That's why we avoid copying memory and insead build a linked list
* of arrays to iterate through.
*
* @constructor
*/
function ConsArray() {
this.tail_ = new ConsArray.Cell(null, null);
this.currCell_ = this.tail_;
this.currCellPos_ = 0;
};
/**
* Concatenates another array for iterating. Empty arrays are ignored.
* This operation can be safely performed during ongoing ConsArray
* iteration.
*
* @param {Array} arr Array to concatenate.
*/
ConsArray.prototype.concat = function(arr) {
if (arr.length > 0) {
this.tail_.data = arr;
this.tail_ = this.tail_.next = new ConsArray.Cell(null, null);
}
};
/**
* Whether the end of iteration is reached.
*/
ConsArray.prototype.atEnd = function() {
return this.currCell_ === null ||
this.currCell_.data === null ||
this.currCellPos_ >= this.currCell_.data.length;
};
/**
* Returns the current item, moves to the next one.
*/
ConsArray.prototype.next = function() {
var result = this.currCell_.data[this.currCellPos_++];
if (this.currCellPos_ >= this.currCell_.data.length) {
this.currCell_ = this.currCell_.next;
this.currCellPos_ = 0;
}
return result;
};
/**
* A cell object used for constructing a list in ConsArray.
*
* @constructor
*/
ConsArray.Cell = function(data, next) {
this.data = data;
this.next = next;
};