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|
--- A Map class.
-- @class module
-- @name pl.Map
--[[
module ('pl.Map')
]]
local tablex = require 'pl.tablex'
local utils = require 'pl.utils'
local stdmt = utils.stdmt
local is_callable = utils.is_callable
local tmakeset,deepcompare,merge,keys,difference,tupdate = tablex.makeset,tablex.deepcompare,tablex.merge,tablex.keys,tablex.difference,tablex.update
local pretty_write = require 'pl.pretty' . write
local Map = stdmt.Map
local Set = stdmt.Set
local List = stdmt.List
local class = require 'pl.class'
-- the Map class ---------------------
class(nil,nil,Map)
local function makemap (m)
return setmetatable(m,Map)
end
function Map:_init (t)
local mt = getmetatable(t)
if mt == Set or mt == Map then
self:update(t)
else
return t -- otherwise assumed to be a map-like table
end
end
local function makelist(t)
return setmetatable(t,List)
end
--- list of keys.
Map.keys = tablex.keys
--- list of values.
Map.values = tablex.values
--- return an iterator over all key-value pairs.
function Map:iter ()
return pairs(self)
end
--- return a List of all key-value pairs, sorted by the keys.
function Map:items()
local ls = makelist(tablex.pairmap (function (k,v) return makelist {k,v} end, self))
ls:sort(function(t1,t2) return t1[1] < t2[1] end)
return ls
end
-- Will return the existing value, or if it doesn't exist it will set
-- a default value and return it.
function Map:setdefault(key, defaultval)
return self[key] or self:set(key,defaultval) or defaultval
end
--- size of map.
-- note: this is a relatively expensive operation!
-- @class function
-- @name Map:len
Map.len = tablex.size
--- put a value into the map.
-- @param key the key
-- @param val the value
function Map:set (key,val)
self[key] = val
end
--- get a value from the map.
-- @param key the key
-- @return the value, or nil if not found.
function Map:get (key)
return rawget(self,key)
end
local index_by = tablex.index_by
-- get a list of values indexed by a list of keys.
-- @param keys a list-like table of keys
-- @return a new list
function Map:getvalues (keys)
return makelist(index_by(self,keys))
end
Map.iter = pairs
Map.update = tablex.update
function Map:__eq (m)
-- note we explicitly ask deepcompare _not_ to use __eq!
return deepcompare(self,m,true)
end
function Map:__tostring ()
return pretty_write(self,'')
end
return Map
|
