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|
--[[
Copyright (c) 2012-2017 Kaarle Ritvanen
See LICENSE file for license details
--]]
--- @module aconf.model
local M = {}
local err = require('aconf.error')
local raise = err.raise
local object = require('aconf.object')
local class = object.class
local isinstance = object.isinstance
local super = object.super
local pth = require('aconf.path')
local util = require('aconf.util')
local copy = util.copy
local setdefaults = util.setdefaults
local update = util.update
function M.null_addr(path, name)
local comps = pth.split(path)
table.insert(comps, pth.escape(name))
return pth.join('/null', table.unpack(comps))
end
M.BoundMember = class()
function M.BoundMember:init(parent, name, field)
local pmt = getmetatable(parent)
if pmt.maddr and name ~= pth.wildcard then self.addr = pmt.maddr(name)
else
self.addr = field.addr or pth.escape(name)
if type(self.addr) == 'function' then
self.addr = self.addr(pmt.path, name)
end
self.addr = pth.to_absolute(self.addr, pmt.addr)
end
--- get parent object of an object.
-- @function node.parent
-- @tparam node.TreeNode node object
-- @treturn node.TreeNode parent object
local context = {
txn=pmt.txn,
privileged=pmt.privileged,
parent=parent,
path=pth.join(pmt.path, name),
addr=self.addr
}
local mt = {}
function mt.__index(t, k)
local member = field[k]
if type(member) ~= 'function' then return member end
return function(self, ...) return member(field, context, ...) end
end
setmetatable(self, mt)
end
--- non-leaf object. An instance of this class represents
-- a non-leaf object in the data model, in the context of a specific
-- transaction. These instances appear as Lua tables, such that their
-- children may be read and written by using their relative path name
-- as the key. If the child is of complex type, it is possible to
-- assign a structure of Lua tables as the value. This results in
-- replacing the entire subtree with the provided sturcture. Providing
-- a string in lieu of a complex value is handled by interpreting the
-- string as a path and copying the subtree it refers to. Comparison
-- of these instances with the == operator returns true if the
-- instances represent the same object.
-- @klass node.TreeNode
M.TreeNode = class()
local function equal_tns(tn1, tn2)
return getmetatable(tn1).path == getmetatable(tn2).path
end
function M.TreeNode:init(context, params)
local mt = getmetatable(self)
update(mt, context)
--- get the name of the object, i.e. the last component of its
-- absolute path.
-- @function node.name
-- @tparam node.TreeNode node object
-- @treturn string name
mt.name = pth.name(mt.path)
mt.__eq = equal_tns
mt.__pairs = M.pairs
if not (mt.txn and mt.txn.user) then mt.privileged = true end
mt.escalate = mt.privileged and self or mt.class(
setdefaults(
{
parent=mt.parent and getmetatable(mt.parent).escalate,
privileged=true
},
context
),
params
)
function mt.get(k, options) return mt.load(k, options) end
function mt._fetch(path, create)
if #path == 0 then return self end
local name = path[1]
table.remove(path, 1)
if name == pth.up then
if not mt.parent then
raise(mt.path, 'Root object does not have parent')
end
return getmetatable(mt.parent)._fetch(path, create)
end
local options = {}
if create then
options.create = true
if #path == 0 then options.dereference = false end
end
local next = mt.get(name, options)
if next == nil and (not create or #path > 0) then
raise(mt.path, 'Subordinate does not exist: '..name)
end
if #path == 0 then return next end
if type(next) ~= 'table' then
raise(pth.join(mt.path, name), 'Is a primitive value')
end
return getmetatable(next)._fetch(path, create)
end
function mt.fetch(path, create)
if pth.is_absolute(path) and mt.path > '/' then
assert(not create)
return mt.txn:fetch(path, mt.privileged)
end
return mt._fetch(pth.split(path), create)
end
function mt._search(path, prefix)
if #path == 0 then return {{path=prefix, value=self}} end
local mt = getmetatable(self)
local name = path[1]
table.remove(path, 1)
local function collect(name)
local next = mt.load(name, {dereference=false})
if not next then return {} end
if isinstance(next, M.TreeNode) then
return getmetatable(next)._search(
copy(path), pth.join(prefix, name)
)
end
assert(#path == 0)
return {
{
value=next,
deleted=function(path) mt.member(name):deleted(path) end
}
}
end
if name == pth.wildcard then
local res = {}
for _, member in ipairs(mt.members()) do
util.extend(res, collect(member))
end
return res
end
return collect(name)
end
function mt.search(path) return mt._search(pth.split(path), '') end
function mt._has_permission(permission) end
-- TODO audit trail
function mt.has_permission(permission)
if mt.privileged then return true end
local user = mt.txn.user
local res = user.superuser or mt._has_permission(permission)
if res ~= nil then return res end
res = mt.txn.user:check_permission(permission..mt.path)
if res ~= nil then return res end
if ({create=true, delete=true})[permission] then
permission = 'modify'
end
return getmetatable(mt.parent).has_permission(permission)
end
function mt.check_permission(permission)
if not mt.has_permission(permission) then
raise('forbidden', permission..mt.path)
end
end
function mt.removable() end
function mt.value_removable(v)
if isinstance(v, M.TreeNode) then return getmetatable(v).removable() end
end
local function key_removable(k)
if not mt.removing_permitted() then return false end
local res = mt.value_removable(mt.load(k, {dereference=false}))
if res == nil then return params.editable end
return res
end
function mt.check_removable(k)
if not (mt.privileged or key_removable(k)) then
raise(pth.join(mt.path, k), 'Cannot be deleted')
end
end
function mt.meta()
if not mt._meta then
mt._meta = {type=params.dtype, ['ui-name']=mt.ui_name}
if mt.txn then mt.init_meta(mt._meta) end
end
local res = copy(mt._meta)
res.removable = {}
for _, key in ipairs(mt.members()) do
if key_removable(key) then table.insert(res.removable, key) end
end
return res
end
if not mt.txn then return end
mt.ui_name = mt.parent and getmetatable(mt.parent).member_ui_name(mt.name)
function mt.save(k, v) rawset(self, k, v) end
function mt.__index(t, k) return mt.get(k, {private=true}) end
function mt.__newindex(t, k, v) mt.save(k, v) end
mt.txn.validable[mt.path] = mt.addr
end
--- collection object, inherits @{node.TreeNode}. An instance of this class
-- represents a collection object in the data model, in the context of
-- a specific transaction. The path of a collection member is that of
-- the collection augmented by the respective key. The size of the
-- collection can be queried using the # operator.
-- @klass node.Collection
M.Collection = class(M.TreeNode)
function M.Collection:init(context, params)
super(self, M.Collection):init(
context, setdefaults(params, {dtype='collection'})
)
self.init = nil
local mt = getmetatable(self)
mt.field = M.BoundMember(self, pth.wildcard, params.field)
function mt.topology() return mt.field:topology() end
function mt.member(name)
return M.BoundMember(self, name, params.field)
end
function mt.load(k, options) return mt.member(k):load(options) end
function mt.removing_permitted() return mt.has_permission('delete') end
if not mt.txn then return end
mt.ui_member = params.ui_member or mt.ui_name:gsub('s$', '')
function mt.member_ui_name(name)
return name ~= pth.wildcard and mt.ui_member..' '..name or nil
end
function mt.mmeta(name)
return update(mt.field:meta(), {['ui-name']=mt.member_ui_name(name)})
end
function mt.init_meta(meta)
update(
meta,
{
editable=params.editable and mt.has_permission('create'),
members=mt.field:meta(),
required=params.required,
['ui-member']=mt.ui_member,
widget=params.layout
}
)
end
local function validate_key(k)
if params.key then
local kf = M.BoundMember(self, k, object.toinstance(params.key))
if kf:normalize(k) ~= k then
raise(mt.path, 'Invalid member name: '..k)
end
kf:validate(k)
end
end
function mt.members()
return util.filter(
function(k) return err.call(validate_key, k) end,
mt.txn:get(mt.addr) or {}
)
end
function mt.__len() return #mt.members() end
function mt.validate()
if #mt.members() > 0 then return end
if params.required then raise(mt.path, 'Collection cannot be empty') end
if params.destroy then
mt.txn:set(mt.addr)
validate(mt.parent)
end
end
function mt.save(k, v)
if not mt.privileged then
local delete = v == nil
local old = mt.load(k, {dereference=false})
if old == nil then
if delete then return end
if not params.editable then
raise(mt.path, 'Collection is not editable')
end
mt.check_permission('create')
elseif delete then mt.check_removable(k)
elseif type(old) == 'table' then
mt.check_removable(k)
mt.check_permission('create')
else mt.check_permission('modify') end
end
validate_key(k)
mt.member(k):save(v)
end
end
--- list object, inherits @{node.Collection}. An instance of this
-- class represents a list object in the data model, in the context of
-- a specific transaction. A list is an ordered collection of
-- members. The path of a list member is that of the list augmented by
-- the index of the member.
-- @klass node.List
M.List = class(M.Collection)
local function _ipairs(mt, i)
i = i + 1
local v = mt.load(i, {create=false})
if v == nil then return end
return i, v
end
function M.List:init(context, params)
super(self, M.List):init(context, setdefaults(params, {dtype='list'}))
local mt = getmetatable(self)
if not mt.txn then return end
local function expand() return mt.txn:expand(mt.field.addr) end
function mt.maddr(i)
local addrs = expand()
if not addrs[1] then
addrs[1] = pth.join(
'/',
table.unpack(
util.map(
function(c) return c == pth.wildcard and 1 or c end,
pth.split(mt.field.addr)
)
)
)
end
if addrs[i] then return addrs[i] end
local comps = pth.split(addrs[#addrs])
comps[#comps] = comps[#comps] + i - #addrs
return pth.join('/', table.unpack(comps))
end
function mt.members() return util.keys(expand()) end
local tmt = getmetatable(mt.escalate)
mt._save = mt.save
local function check_index(i, max)
if type(i) ~= 'number' or math.floor(i) ~= i or i < 1 or i > max then
raise(mt.path, 'Invalid list index: '..i)
end
end
function mt.save(k, v)
local len = #mt.members()
if v == nil then
check_index(k, len)
mt.check_removable(k)
while k < len do
tmt._save(k, tmt.load(k + 1, {dereference=false}))
k = k + 1
end
tmt._save(len)
else
check_index(k, len + 1)
mt._save(k, v)
end
end
--- inserts a member to a list or set
-- @function node.insert
-- @tparam node.List list list or set
-- @param v value to be inserted
-- @tparam ?int i index. By default, the element is inserted at the
-- end of the list. This parameter is not applicable when inserting
-- to a @{node.Set} instance.
function mt.insert(v, i)
assert(v ~= nil)
local len = #mt.members()
local max = len + 1
if i then check_index(i, max)
else i = max end
mt.check_permission('create')
for j = len,i,-1 do
tmt._save(j + 1, tmt.load(j, {dereference=false}))
end
tmt._save(i, v)
end
function mt.__ipairs(t) return _ipairs, mt, 0 end
end
-- experimental
M.Mixed = class(M.Collection)
function M.Mixed:init(context, params)
super(self, M.Mixed):init(context, params)
-- TODO dynamic meta: list non-leaf children
local mt = getmetatable(self)
mt.meta = {type='mixed', ['ui-name']=mt.path}
function mt.mmeta(name)
return {type='mixed', ['ui-name']=pth.join(mt.path, name)}
end
end
local function meta_func(attr)
return function(node, ...)
local res = getmetatable(node)[attr]
if type(res) == 'function' then return res(...) end
return res
end
end
for _, mf in ipairs{
'addr',
'check_permission',
'contains',
'escalate',
'fetch',
'has_permission',
'insert',
'meta',
'mmeta',
'name',
'parent',
'path',
'save',
'search',
'topology'
} do M[mf] = meta_func(mf) end
function M.pairs(tbl, dereference)
if not isinstance(tbl, M.TreeNode) then return pairs(tbl) end
local mt = getmetatable(tbl)
local res = {}
for _, member in ipairs(mt.members()) do
res[member] = mt.load(member, {dereference=dereference})
end
return pairs(res)
end
return M
|