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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package attribute // import "go.opentelemetry.io/otel/attribute"
// Iterator allows iterating over the set of attributes in order, sorted by
// key.
type Iterator struct {
storage *Set
idx int
}
// MergeIterator supports iterating over two sets of attributes while
// eliminating duplicate values from the combined set. The first iterator
// value takes precedence.
type MergeIterator struct {
one oneIterator
two oneIterator
current KeyValue
}
type oneIterator struct {
iter Iterator
done bool
attr KeyValue
}
// Next moves the iterator to the next position. Returns false if there are no
// more attributes.
func (i *Iterator) Next() bool {
i.idx++
return i.idx < i.Len()
}
// Label returns current KeyValue. Must be called only after Next returns
// true.
//
// Deprecated: Use Attribute instead.
func (i *Iterator) Label() KeyValue {
return i.Attribute()
}
// Attribute returns the current KeyValue of the Iterator. It must be called
// only after Next returns true.
func (i *Iterator) Attribute() KeyValue {
kv, _ := i.storage.Get(i.idx)
return kv
}
// IndexedLabel returns current index and attribute. Must be called only
// after Next returns true.
//
// Deprecated: Use IndexedAttribute instead.
func (i *Iterator) IndexedLabel() (int, KeyValue) {
return i.idx, i.Attribute()
}
// IndexedAttribute returns current index and attribute. Must be called only
// after Next returns true.
func (i *Iterator) IndexedAttribute() (int, KeyValue) {
return i.idx, i.Attribute()
}
// Len returns a number of attributes in the iterated set.
func (i *Iterator) Len() int {
return i.storage.Len()
}
// ToSlice is a convenience function that creates a slice of attributes from
// the passed iterator. The iterator is set up to start from the beginning
// before creating the slice.
func (i *Iterator) ToSlice() []KeyValue {
l := i.Len()
if l == 0 {
return nil
}
i.idx = -1
slice := make([]KeyValue, 0, l)
for i.Next() {
slice = append(slice, i.Attribute())
}
return slice
}
// NewMergeIterator returns a MergeIterator for merging two attribute sets.
// Duplicates are resolved by taking the value from the first set.
func NewMergeIterator(s1, s2 *Set) MergeIterator {
mi := MergeIterator{
one: makeOne(s1.Iter()),
two: makeOne(s2.Iter()),
}
return mi
}
func makeOne(iter Iterator) oneIterator {
oi := oneIterator{
iter: iter,
}
oi.advance()
return oi
}
func (oi *oneIterator) advance() {
if oi.done = !oi.iter.Next(); !oi.done {
oi.attr = oi.iter.Attribute()
}
}
// Next returns true if there is another attribute available.
func (m *MergeIterator) Next() bool {
if m.one.done && m.two.done {
return false
}
if m.one.done {
m.current = m.two.attr
m.two.advance()
return true
}
if m.two.done {
m.current = m.one.attr
m.one.advance()
return true
}
if m.one.attr.Key == m.two.attr.Key {
m.current = m.one.attr // first iterator attribute value wins
m.one.advance()
m.two.advance()
return true
}
if m.one.attr.Key < m.two.attr.Key {
m.current = m.one.attr
m.one.advance()
return true
}
m.current = m.two.attr
m.two.advance()
return true
}
// Label returns the current value after Next() returns true.
//
// Deprecated: Use Attribute instead.
func (m *MergeIterator) Label() KeyValue {
return m.current
}
// Attribute returns the current value after Next() returns true.
func (m *MergeIterator) Attribute() KeyValue {
return m.current
}
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