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trie.coffee
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trie.coffee
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class TrieNode
constructor: (@key) ->
@children = {}
@value = null
class Trie
constructor: ->
@root = new TrieNode
_find_node: (key_path, node_path=null) ->
node = @root
node_path.push @root if node_path
for i in [0...key_path.length]
child_key = key_path.charCodeAt i
node = node.children[child_key]
return null unless node?
node_path.push node if node_path?
node
set: (key_path, value) ->
node = @root
for i in [0...key_path.length]
child_key = key_path.charCodeAt i
unless node.children[child_key]?
node.children[child_key] = new TrieNode child_key
node = node.children[child_key]
node.value = value
@
get: (key_path) ->
node = @_find_node key_path
if node? then node.value else null
has: (key_path) ->
(@get key_path)?
_expand_from: (node, key_path_prefix, out_paths) ->
out_paths.push key_path_prefix if node.value?
for child_key, child of node.children
child_key = String.fromCharCode child_key
@_expand_from child, key_path_prefix + child_key, out_paths
prefix_match: (key_path_prefix) ->
node = @_find_node key_path_prefix
return [] unless node?
key_paths = []
@_expand_from node, key_path_prefix, key_paths
key_paths
remove: (key_path) ->
node_path = []
node = @_find_node key_path, node_path
return false unless node?
node.value = null
for i in [node_path.length-1 ... 0]
[current_node, parent_node] = [node_path[i], node_path[i-1]]
if not current_node.value? and (Object.keys current_node.children).length is 0
delete parent_node.children[current_node.key]
true
exports.Trie = Trie
exports.TrieNode = TrieNode