mirror of
https://github.com/emirpasic/gods
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107 lines
4.0 KiB
Go
107 lines
4.0 KiB
Go
/*
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Copyright (c) 2015, Emir Pasic
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package binaryheap
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import "github.com/emirpasic/gods/containers"
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func assertIteratorImplementation() {
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var _ containers.ReverseIteratorWithIndex = (*Iterator)(nil)
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}
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// Iterator returns a stateful iterator whose values can be fetched by an index.
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type Iterator struct {
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heap *Heap
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index int
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}
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// Iterator returns a stateful iterator whose values can be fetched by an index.
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func (heap *Heap) Iterator() Iterator {
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return Iterator{heap: heap, index: -1}
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}
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// Next moves the iterator to the next element and returns true if there was a next element in the container.
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// If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
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// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
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// Modifies the state of the iterator.
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func (iterator *Iterator) Next() bool {
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if iterator.index < iterator.heap.Size() {
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iterator.index++
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}
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return iterator.heap.withinRange(iterator.index)
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}
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// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
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// If Prev() returns true, then previous element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator) Prev() bool {
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if iterator.index >= 0 {
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iterator.index--
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}
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return iterator.heap.withinRange(iterator.index)
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}
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// Value returns the current element's value.
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// Does not modify the state of the iterator.
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func (iterator *Iterator) Value() interface{} {
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value, _ := iterator.heap.list.Get(iterator.index)
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return value
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}
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// Index returns the current element's index.
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// Does not modify the state of the iterator.
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func (iterator *Iterator) Index() int {
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return iterator.index
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}
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// Begin resets the iterator to its initial state (one-before-first)
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// Call Next() to fetch the first element if any.
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func (iterator *Iterator) Begin() {
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iterator.index = -1
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}
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// End moves the iterator past the last element (one-past-the-end).
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// Call Prev() to fetch the last element if any.
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func (iterator *Iterator) End() {
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iterator.index = iterator.heap.Size()
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}
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// First moves the iterator to the first element and returns true if there was a first element in the container.
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// If First() returns true, then first element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator) First() bool {
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iterator.Begin()
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return iterator.Next()
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}
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// Last moves the iterator to the last element and returns true if there was a last element in the container.
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// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
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// Modifies the state of the iterator.
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func (iterator *Iterator) Last() bool {
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iterator.End()
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return iterator.Prev()
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}
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