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package iradix
import "bytes"
// Iterator is used to iterate over a set of nodes
// in pre-order
type Iterator struct {
node *Node
stack []edges
}
// SeekPrefixWatch is used to seek the iterator to a given prefix
// and returns the watch channel of the finest granularity
func (i *Iterator) SeekPrefixWatch(prefix []byte) (watch <-chan struct{}) {
// Wipe the stack
i.stack = nil
n := i.node
watch = n.mutateCh
search := prefix
for {
// Check for key exhaution
if len(search) == 0 {
i.node = n
return
}
// Look for an edge
_, n = n.getEdge(search[0])
if n == nil {
i.node = nil
return
}
// Update to the finest granularity as the search makes progress
watch = n.mutateCh
// Consume the search prefix
if bytes.HasPrefix(search, n.prefix) {
search = search[len(n.prefix):]
} else if bytes.HasPrefix(n.prefix, search) {
i.node = n
return
} else {
i.node = nil
return
}
}
}
// SeekPrefix is used to seek the iterator to a given prefix
func (i *Iterator) SeekPrefix(prefix []byte) {
i.SeekPrefixWatch(prefix)
}
// Next returns the next node in order
func (i *Iterator) Next() ([]byte, interface{}, bool) {
// Initialize our stack if needed
if i.stack == nil && i.node != nil {
i.stack = []edges{
edges{
edge{node: i.node},
},
}
}
for len(i.stack) > 0 {
// Inspect the last element of the stack
n := len(i.stack)
last := i.stack[n-1]
elem := last[0].node
// Update the stack
if len(last) > 1 {
i.stack[n-1] = last[1:]
} else {
i.stack = i.stack[:n-1]
}
// Push the edges onto the frontier
if len(elem.edges) > 0 {
i.stack = append(i.stack, elem.edges)
}
// Return the leaf values if any
if elem.leaf != nil {
return elem.leaf.key, elem.leaf.val, true
}
}
return nil, nil, false
}
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