gitee.com/quant1x/gox@v1.21.2/util/linkedhashmap/iterator.go (about)

     1  // Copyright (c) 2015, Emir Pasic. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package linkedhashmap
     6  
     7  import (
     8  	"gitee.com/quant1x/gox/util/doublylinkedlist"
     9  	"gitee.com/quant1x/gox/util/internal"
    10  )
    11  
    12  func assertIteratorImplementation() {
    13  	var _ internal.ReverseIteratorWithKey = (*Iterator)(nil)
    14  }
    15  
    16  // Iterator holding the iterator's state
    17  type Iterator struct {
    18  	iterator doublylinkedlist.Iterator
    19  	table    map[interface{}]interface{}
    20  }
    21  
    22  // Iterator returns a stateful iterator whose elements are key/value pairs.
    23  func (m *Map) Iterator() Iterator {
    24  	return Iterator{
    25  		iterator: m.ordering.Iterator(),
    26  		table:    m.table}
    27  }
    28  
    29  // Next moves the iterator to the next element and returns true if there was a next element in the container.
    30  // If Next() returns true, then next element's key and value can be retrieved by Key() and Value().
    31  // If Next() was called for the first time, then it will point the iterator to the first element if it exists.
    32  // Modifies the state of the iterator.
    33  func (iterator *Iterator) Next() bool {
    34  	return iterator.iterator.Next()
    35  }
    36  
    37  // Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
    38  // If Prev() returns true, then previous element's key and value can be retrieved by Key() and Value().
    39  // Modifies the state of the iterator.
    40  func (iterator *Iterator) Prev() bool {
    41  	return iterator.iterator.Prev()
    42  }
    43  
    44  // Value returns the current element's value.
    45  // Does not modify the state of the iterator.
    46  func (iterator *Iterator) Value() interface{} {
    47  	key := iterator.iterator.Value()
    48  	return iterator.table[key]
    49  }
    50  
    51  // Key returns the current element's key.
    52  // Does not modify the state of the iterator.
    53  func (iterator *Iterator) Key() interface{} {
    54  	return iterator.iterator.Value()
    55  }
    56  
    57  // Begin resets the iterator to its initial state (one-before-first)
    58  // Call Next() to fetch the first element if any.
    59  func (iterator *Iterator) Begin() {
    60  	iterator.iterator.Begin()
    61  }
    62  
    63  // End moves the iterator past the last element (one-past-the-end).
    64  // Call Prev() to fetch the last element if any.
    65  func (iterator *Iterator) End() {
    66  	iterator.iterator.End()
    67  }
    68  
    69  // First moves the iterator to the first element and returns true if there was a first element in the container.
    70  // If First() returns true, then first element's key and value can be retrieved by Key() and Value().
    71  // Modifies the state of the iterator
    72  func (iterator *Iterator) First() bool {
    73  	return iterator.iterator.First()
    74  }
    75  
    76  // Last moves the iterator to the last element and returns true if there was a last element in the container.
    77  // If Last() returns true, then last element's key and value can be retrieved by Key() and Value().
    78  // Modifies the state of the iterator.
    79  func (iterator *Iterator) Last() bool {
    80  	return iterator.iterator.Last()
    81  }