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iterator.go
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/
iterator.go
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// Copyright (c) 2015, Emir Pasic. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package util
// IteratorWithIndex is stateful iterator for ordered containers whose values can be fetched by an index.
type IteratorWithIndex interface {
// Next moves the iterator to the next element and returns true if there was a next element in the container.
// If Next() returns true, then next element's index and value can be retrieved by Index() and Value().
// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
// Modifies the state of the iterator.
Next() bool
// Value returns the current element's value.
// Does not modify the state of the iterator.
Value() interface{}
// Index returns the current element's index.
// Does not modify the state of the iterator.
Index() int
// Begin resets the iterator to its initial state (one-before-first)
// Call Next() to fetch the first element if any.
Begin()
// First moves the iterator to the first element and returns true if there was a first element in the container.
// If First() returns true, then first element's index and value can be retrieved by Index() and Value().
// Modifies the state of the iterator.
First() bool
}
// IteratorWithKey is a stateful iterator for ordered containers whose elements are key value pairs.
type IteratorWithKey interface {
// Next moves the iterator to the next element and returns true if there was a next element in the container.
// If Next() returns true, then next element's key and value can be retrieved by Key() and Value().
// If Next() was called for the first time, then it will point the iterator to the first element if it exists.
// Modifies the state of the iterator.
Next() bool
// Value returns the current element's value.
// Does not modify the state of the iterator.
Value() interface{}
// Key returns the current element's key.
// Does not modify the state of the iterator.
Key() interface{}
// Begin resets the iterator to its initial state (one-before-first)
// Call Next() to fetch the first element if any.
Begin()
// First moves the iterator to the first element and returns true if there was a first element in the container.
// If First() returns true, then first element's key and value can be retrieved by Key() and Value().
// Modifies the state of the iterator.
First() bool
}
// ReverseIteratorWithIndex is stateful iterator for ordered containers whose values can be fetched by an index.
//
// Essentially it is the same as IteratorWithIndex, but provides additional:
//
// Prev() function to enable traversal in reverse
//
// Last() function to move the iterator to the last element.
//
// End() function to move the iterator past the last element (one-past-the-end).
type ReverseIteratorWithIndex interface {
// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
// If Prev() returns true, then previous element's index and value can be retrieved by Index() and Value().
// Modifies the state of the iterator.
Prev() bool
// End moves the iterator past the last element (one-past-the-end).
// Call Prev() to fetch the last element if any.
End()
// Last moves the iterator to the last element and returns true if there was a last element in the container.
// If Last() returns true, then last element's index and value can be retrieved by Index() and Value().
// Modifies the state of the iterator.
Last() bool
IteratorWithIndex
}
// ReverseIteratorWithKey is a stateful iterator for ordered containers whose elements are key value pairs.
//
// Essentially it is the same as IteratorWithKey, but provides additional:
//
// Prev() function to enable traversal in reverse
//
// Last() function to move the iterator to the last element.
type ReverseIteratorWithKey interface {
// Prev moves the iterator to the previous element and returns true if there was a previous element in the container.
// If Prev() returns true, then previous element's key and value can be retrieved by Key() and Value().
// Modifies the state of the iterator.
Prev() bool
// End moves the iterator past the last element (one-past-the-end).
// Call Prev() to fetch the last element if any.
End()
// Last moves the iterator to the last element and returns true if there was a last element in the container.
// If Last() returns true, then last element's key and value can be retrieved by Key() and Value().
// Modifies the state of the iterator.
Last() bool
IteratorWithKey
}