William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 1 | package iradix |
| 2 | |
| 3 | // rawIterator visits each of the nodes in the tree, even the ones that are not |
| 4 | // leaves. It keeps track of the effective path (what a leaf at a given node |
| 5 | // would be called), which is useful for comparing trees. |
| 6 | type rawIterator struct { |
| 7 | // node is the starting node in the tree for the iterator. |
| 8 | node *Node |
| 9 | |
| 10 | // stack keeps track of edges in the frontier. |
| 11 | stack []rawStackEntry |
| 12 | |
| 13 | // pos is the current position of the iterator. |
| 14 | pos *Node |
| 15 | |
| 16 | // path is the effective path of the current iterator position, |
| 17 | // regardless of whether the current node is a leaf. |
| 18 | path string |
| 19 | } |
| 20 | |
| 21 | // rawStackEntry is used to keep track of the cumulative common path as well as |
| 22 | // its associated edges in the frontier. |
| 23 | type rawStackEntry struct { |
| 24 | path string |
| 25 | edges edges |
| 26 | } |
| 27 | |
| 28 | // Front returns the current node that has been iterated to. |
| 29 | func (i *rawIterator) Front() *Node { |
| 30 | return i.pos |
| 31 | } |
| 32 | |
| 33 | // Path returns the effective path of the current node, even if it's not actually |
| 34 | // a leaf. |
| 35 | func (i *rawIterator) Path() string { |
| 36 | return i.path |
| 37 | } |
| 38 | |
| 39 | // Next advances the iterator to the next node. |
| 40 | func (i *rawIterator) Next() { |
| 41 | // Initialize our stack if needed. |
| 42 | if i.stack == nil && i.node != nil { |
| 43 | i.stack = []rawStackEntry{ |
| 44 | rawStackEntry{ |
| 45 | edges: edges{ |
| 46 | edge{node: i.node}, |
| 47 | }, |
| 48 | }, |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | for len(i.stack) > 0 { |
| 53 | // Inspect the last element of the stack. |
| 54 | n := len(i.stack) |
| 55 | last := i.stack[n-1] |
| 56 | elem := last.edges[0].node |
| 57 | |
| 58 | // Update the stack. |
| 59 | if len(last.edges) > 1 { |
| 60 | i.stack[n-1].edges = last.edges[1:] |
| 61 | } else { |
| 62 | i.stack = i.stack[:n-1] |
| 63 | } |
| 64 | |
| 65 | // Push the edges onto the frontier. |
| 66 | if len(elem.edges) > 0 { |
| 67 | path := last.path + string(elem.prefix) |
| 68 | i.stack = append(i.stack, rawStackEntry{path, elem.edges}) |
| 69 | } |
| 70 | |
| 71 | i.pos = elem |
| 72 | i.path = last.path + string(elem.prefix) |
| 73 | return |
| 74 | } |
| 75 | |
| 76 | i.pos = nil |
| 77 | i.path = "" |
| 78 | } |