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--- CSS query module for LuaXML
-- @module luaxml-cssquery
-- @author Michal Hoftich <michal.h21@gmail.com
local parse_query = require("luaxml-parse-query")
-- the string.explode function is provided by LuaTeX
-- this is alternative for stock Lua
-- source: http://lua-users.org/wiki/SplitJoin
local function string_split(str, sep)
local sep, fields = sep or ":", {}
local pattern = string.format("([^%s]+)", sep)
str:gsub(pattern, function(c) fields[#fields+1] = c end)
return fields
end
string.explode = string.explode or string_split
--- CssQuery constructor
-- @function cssquery
-- @return CssQuery object
local function cssquery()
--- @type CssQuery
local CssQuery = {}
CssQuery.__index = CssQuery
CssQuery.__debug = false
CssQuery.querylist = {}
function CssQuery.debug(self)
self.__debug = true
end
function CssQuery:debug_print(text)
if self.__debug then
print("[CSS Object]: " .. text)
end
end
--- Calculate CSS specificity of the query
-- @param query table created by CssQuery:prepare_selector() function
-- @return integer speficity value
function CssQuery:calculate_specificity(query)
local query = query or {}
local specificity = 0
for _, item in ipairs(query.query or {}) do
for key, value in pairs(item) do
if key == "id" then
specificity = specificity + 100
elseif key == "tag" then
specificity = specificity + 1
else
specificity = specificity + 10
end
end
end
return specificity
end
-- save element position in the current siblings list
local function make_nth(curr_el)
local pos = 0
local el_pos = 0
-- get current node list
local siblings = curr_el:get_siblings()
if siblings then
for _, other_el in ipairs(siblings) do
-- number the elements
if other_el:is_element() then
pos = pos + 1
other_el.nth = pos
-- save the current element position
if other_el == curr_el then
el_pos = pos
end
end
end
else
return false
end
return el_pos
end
local function test_first_child(el, nth)
local el_pos = el.nth or make_nth(el)
return el_pos == 1
end
-- test element for nth-child selector
local function test_nth_child(el, nth)
local el_pos = el.nth or make_nth(el)
-- we support only the nth-child(number) form
return el_pos == tonumber(nth)
end
--- Test prepared querylist
-- @param domobj DOM element to test
-- @param querylist [optional] List of queries to test
-- @return table with CSS queries, which match the selected DOM element
function CssQuery:match_querylist(domobj, querylist)
local matches = {}
-- querylist can be explicit, saved queries can be used otherwise
local querylist = querylist or self.querylist
local function test_part(key, value, el)
-- print("testing", key, value, el:get_element_name())
if key == "tag" then
return el:get_element_name() == value
elseif key == "id" then
local id = el:get_attribute "id"
return id and id == value
elseif key == "class" then
local class = el:get_attribute "class"
if not class then return false end
local c = {}
for part in class:gmatch "([^%s]+)" do
c[part] = true
end
return c[value] == true
elseif key == "nth-child" then
return test_nth_child(el, value)
elseif key == "first-child" then
return test_first_child(el, value)
end
-- TODO: Add more cases
-- just return true for not supported selectors
return true
end
local function test_object(query, el)
-- test one object in CSS selector
local matched = {}
for key, value in pairs(query) do
matched[#matched+1] = test_part(key, value, el)
end
if #matched == 0 then return false end
for k, v in ipairs(matched) do
if v ~= true then return false end
end
return true
end
local function match_query(query, el)
local query = query or {}
local object = table.remove(query) -- get current object from the query stack
if not object then return true end -- if the query stack is empty, then we can be sure that it matched previous items
if not el:is_element() then return false end -- if there is object to test, but current node isn't element, test failed
local result = test_object(object, el)
if result then
return match_query(query, el:get_parent())
end
return false
end
for _,element in ipairs(querylist) do
local query = {}
for k,v in ipairs(element.query) do query[k] = v end
if #query > 0 then -- don't try to match empty query
local result = match_query(query, domobj)
if result then matches[#matches+1] = element end
end
end
return matches
end
--- Get elements that match the selector
-- @return table with DOM_Object elements
function CssQuery:get_selector_path(
domobj, -- DOM_Object
selectorlist -- querylist table created using CssQuery:prepare_selector
)
local nodelist = {}
domobj:traverse_elements(function(el)
local matches = self:match_querylist(el, selectorlist)
self:debug_print("Matching " .. el:get_element_name() .." "..#matches)
if #matches > 0 then nodelist[#nodelist+1] = el
end
end)
return nodelist
end
--- Parse CSS selector to a query table.
-- XML namespaces can be supported using
-- namespace|element syntax
-- @return table querylist
function CssQuery:prepare_selector(
selector -- string CSS selector query
)
local querylist = {}
local function parse_selector(item)
local query = {}
-- for i = #item, 1, -1 do
-- local part = item[i]
for _, part in ipairs(item) do
local t = {}
for _, atom in ipairs(part) do
local key = atom[1]
local value = atom[2]
-- support for XML namespaces in selectors
-- the namespace should be added using "|"
-- like namespace|element
if key=="tag" then
-- LuaXML doesn't support namespaces, so it is necessary
-- to match namespace:element
value=value:gsub("|", ":")
end
t[key] = value
end
query[#query + 1] = t
end
return query
end
-- for item in selector:gmatch("([^%s]+)") do
-- elements[#elements+1] = parse_selector(item)
-- end
local parts = parse_query.parse_query(selector) or {}
-- several selectors may be separated using ",", we must process them separately
local sources = selector:explode(",")
for i, part in ipairs(parts) do
querylist[#querylist+1] = {query = parse_selector(part), source = sources[i]}
end
return querylist
end
--- Add selector to CSS object list of selectors,
-- func is called when the selector matches a DOM object
-- params is table which will be passed to the func
-- @return integer number of elements in the prepared selector
function CssQuery:add_selector(
selector, -- CSS selector string
func, -- function which will be executed on matched elements
params -- table with parameters for the function
)
local selector_list = self:prepare_selector(selector)
for k, query in ipairs(selector_list) do
query.specificity = self:calculate_specificity(query)
query.func = func
query.params = params
table.insert(self.querylist, query)
end
self:sort_querylist()
return #selector_list
end
--- Sort selectors according to their specificity
-- It is called automatically when the selector is added
-- @return querylist table
function CssQuery:sort_querylist(
querylist -- [optional] querylist table
)
local querylist = querylist or self.querylist
table.sort(self.querylist, function(a,b)
return a.specificity > b.specificity
end)
return querylist
end
--- It tests list of queries agaings a DOM element and executes the
--- coresponding function that is saved for the matched query.
-- @return nothing
function CssQuery:apply_querylist(
domobj, -- DOM element
querylist -- querylist table
)
for _, query in ipairs(querylist) do
-- use default empty function which will pass to another match
local func = query.func or function() return true end
local params = query.params or {}
local status = func(domobj, params)
-- break the execution when the function return false
if status == false then
break
end
end
end
return setmetatable({}, CssQuery)
end
return cssquery
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