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--!A cross-platform build utility based on Lua
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Copyright (C) 2015 - 2019, TBOOX Open Source Group.
--
-- @author OpportunityLiu
-- @file hashset.lua
--
-- define module
local hashset = hashset or {}
local hashset_impl = hashset.__index or {}
-- load modules
local table = require("base/table")
-- representaion for nil key
hashset._NIL = setmetatable({}, {__tostring = function() return "nil" end })
function hashset._to_key(key)
if key == nil then
key = hashset._NIL
end
return key
end
-- make a new hashset
function hashset.new()
return setmetatable({ _DATA = {}, _SIZE = 0 }, hashset)
end
-- construct from list of items
function hashset.of(...)
local result = hashset.new()
local data = table.pack(...)
for i = 1, data.n do
result:insert(data[i])
end
return result
end
-- construct from an array
function hashset.from(array)
assert(array)
return hashset.of(table.unpack(array))
end
-- check value is in hashset
function hashset_impl:has(value)
value = hashset._to_key(value)
return self._DATA[value] or false
end
-- insert value to hashset, returns false if value has already in the hashset
function hashset_impl:insert(value)
value = hashset._to_key(value)
local result = not (self._DATA[value] or false)
if result then
self._DATA[value] = true
self._SIZE = self._SIZE + 1
end
return result
end
-- remove value from hashset, returns false if value is not in the hashset
function hashset_impl:remove(value)
value = hashset._to_key(value)
local result = self._DATA[value] or false
if result then
self._DATA[value] = nil
self._SIZE = self._SIZE - 1
end
return result
end
-- convert hashset to an array, nil in the set will be ignored
function hashset_impl:to_array()
local result = {}
for k,_ in pairs(self._DATA) do
if k ~= hashset._NIL then
table.insert(result, k)
end
end
return result
end
-- get size of hashset
function hashset_impl:size()
return self._SIZE
end
-- get data of hashset
function hashset_impl:data()
return self._DATA
end
-- clear hashset
function hashset_impl:clear()
self._DATA = {}
self._SIZE = 0
end
-- return module
hashset.__index = hashset_impl
return hashset
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