github.com/mymmsc/gox@v1.3.33/util/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 util 6 7 // IteratorWithIndex is stateful iterator for ordered containers whose values can be fetched by an index. 8 type IteratorWithIndex interface { 9 // Next moves the iterator to the next element and returns true if there was a next element in the container. 10 // If Next() returns true, then next element's index and value can be retrieved by Index() and Value(). 11 // If Next() was called for the first time, then it will point the iterator to the first element if it exists. 12 // Modifies the state of the iterator. 13 Next() bool 14 15 // Value returns the current element's value. 16 // Does not modify the state of the iterator. 17 Value() interface{} 18 19 // Index returns the current element's index. 20 // Does not modify the state of the iterator. 21 Index() int 22 23 // Begin resets the iterator to its initial state (one-before-first) 24 // Call Next() to fetch the first element if any. 25 Begin() 26 27 // First moves the iterator to the first element and returns true if there was a first element in the container. 28 // If First() returns true, then first element's index and value can be retrieved by Index() and Value(). 29 // Modifies the state of the iterator. 30 First() bool 31 } 32 33 // IteratorWithKey is a stateful iterator for ordered containers whose elements are key value pairs. 34 type IteratorWithKey interface { 35 // Next moves the iterator to the next element and returns true if there was a next element in the container. 36 // If Next() returns true, then next element's key and value can be retrieved by Key() and Value(). 37 // If Next() was called for the first time, then it will point the iterator to the first element if it exists. 38 // Modifies the state of the iterator. 39 Next() bool 40 41 // Value returns the current element's value. 42 // Does not modify the state of the iterator. 43 Value() interface{} 44 45 // Key returns the current element's key. 46 // Does not modify the state of the iterator. 47 Key() interface{} 48 49 // Begin resets the iterator to its initial state (one-before-first) 50 // Call Next() to fetch the first element if any. 51 Begin() 52 53 // First moves the iterator to the first element and returns true if there was a first element in the container. 54 // If First() returns true, then first element's key and value can be retrieved by Key() and Value(). 55 // Modifies the state of the iterator. 56 First() bool 57 } 58 59 // ReverseIteratorWithIndex is stateful iterator for ordered containers whose values can be fetched by an index. 60 // 61 // Essentially it is the same as IteratorWithIndex, but provides additional: 62 // 63 // Prev() function to enable traversal in reverse 64 // 65 // Last() function to move the iterator to the last element. 66 // 67 // End() function to move the iterator past the last element (one-past-the-end). 68 type ReverseIteratorWithIndex interface { 69 // Prev moves the iterator to the previous element and returns true if there was a previous element in the container. 70 // If Prev() returns true, then previous element's index and value can be retrieved by Index() and Value(). 71 // Modifies the state of the iterator. 72 Prev() bool 73 74 // End moves the iterator past the last element (one-past-the-end). 75 // Call Prev() to fetch the last element if any. 76 End() 77 78 // Last moves the iterator to the last element and returns true if there was a last element in the container. 79 // If Last() returns true, then last element's index and value can be retrieved by Index() and Value(). 80 // Modifies the state of the iterator. 81 Last() bool 82 83 IteratorWithIndex 84 } 85 86 // ReverseIteratorWithKey is a stateful iterator for ordered containers whose elements are key value pairs. 87 // 88 // Essentially it is the same as IteratorWithKey, but provides additional: 89 // 90 // Prev() function to enable traversal in reverse 91 // 92 // Last() function to move the iterator to the last element. 93 type ReverseIteratorWithKey interface { 94 // Prev moves the iterator to the previous element and returns true if there was a previous element in the container. 95 // If Prev() returns true, then previous element's key and value can be retrieved by Key() and Value(). 96 // Modifies the state of the iterator. 97 Prev() bool 98 99 // End moves the iterator past the last element (one-past-the-end). 100 // Call Prev() to fetch the last element if any. 101 End() 102 103 // Last moves the iterator to the last element and returns true if there was a last element in the container. 104 // If Last() returns true, then last element's key and value can be retrieved by Key() and Value(). 105 // Modifies the state of the iterator. 106 Last() bool 107 108 IteratorWithKey 109 }