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{-# LANGUAGE OverloadedStrings #-}
-- | Fast lookup & storage for style rules.
-- INTERNAL MODULE.
module Data.CSS.Style.Selector.Index (
StyleIndex(..),
rulesForElement
) where
-- TODO do performance tests to decide beside between strict/lazy.
import Data.HashMap.Strict
import Data.List (nub)
import Data.CSS.Style.Common
import Data.Hashable
import Data.Text (unpack, pack)
import Data.CSS.Syntax.Tokens (serialize) -- for easy hashing
-- | Fast lookup & storage for style rules.
data StyleIndex = StyleIndex {
indexed :: HashMap SimpleSelector [StyleRule'],
unindexed :: [StyleRule']
}
lookup' :: SimpleSelector -> HashMap SimpleSelector [a] -> [a]
lookup' = lookupDefault []
instance RuleStore StyleIndex where
new = StyleIndex {indexed = empty, unindexed = []}
addStyleRule self _ rule | [] == properties rule = self
| otherwise = addRuleForSelector self rule $ simpleSelector $ selector rule
lookupRules self element = nub $ Prelude.foldr (++) [] rules
where
get key = lookup' key index
index = indexed self
rules = unindexed self : Prelude.map get (testsForElement element)
-- | LEGACY TESTING API.
rulesForElement :: StyleIndex -> Element -> [StyleRule] -- For testing
rulesForElement self element = Prelude.map inner $ lookupRules self element
---
simpleSelector :: Selector -> [SimpleSelector]
simpleSelector (Element s) = s
simpleSelector (Child _ s) = s
simpleSelector (Descendant _ s) = s
simpleSelector (Adjacent _ s) = s
simpleSelector (Sibling _ s) = s
addRuleForSelector :: StyleIndex -> StyleRule' -> [SimpleSelector] -> StyleIndex
addRuleForSelector self@(StyleIndex index _) rule sel
| Just key <- selectorKey sel = self {
indexed = insert key (rule : lookup' key index) index
}
| otherwise = self {unindexed = rule : unindexed self}
selectorKey :: [SimpleSelector] -> Maybe SimpleSelector
selectorKey (tok@(Tag _) : _) = Just tok
selectorKey (tok@(Id _) : _) = Just tok
selectorKey (tok@(Class _) : _) = Just tok
selectorKey (Property prop _ : _) = Just $ Property prop Exists
selectorKey (_ : tokens) = selectorKey tokens
selectorKey [] = Nothing
----
testsForAttributes :: [Attribute] -> [SimpleSelector]
testsForElement :: Element -> [SimpleSelector]
testsForElement element =
(Tag $ name element) : (testsForAttributes $ attributes element)
testsForAttributes (Attribute "class" value:attrs) =
(Prelude.map (\s -> Class $ pack s) $ words value) ++
(Property "class" Exists : testsForAttributes attrs)
testsForAttributes (Attribute "id" value:attrs) =
(Prelude.map (\s -> Id $ pack s) $ words value) ++
(Property "id" Exists : testsForAttributes attrs)
testsForAttributes (Attribute elName _:attrs) =
Property elName Exists : testsForAttributes attrs
testsForAttributes [] = []
-- Implement hashable for SimpleSelector here because it proved challenging to automatically derive it.
instance Hashable SimpleSelector where
hashWithSalt seed (Tag tag) = seed `hashWithSalt` (0::Int) `hashWithSalt` unpack tag
hashWithSalt seed (Id i) = seed `hashWithSalt` (1::Int) `hashWithSalt` unpack i
hashWithSalt seed (Class class_) = seed `hashWithSalt` (2::Int) `hashWithSalt` unpack class_
hashWithSalt seed (Property prop test) =
seed `hashWithSalt` (3::Int) `hashWithSalt` unpack prop `hashWithSalt` test
hashWithSalt seed (Psuedoclass p args) =
seed `hashWithSalt` (4::Int) `hashWithSalt` p `hashWithSalt` serialize args
instance Hashable PropertyTest where
hashWithSalt seed Exists = seed `hashWithSalt` (0::Int)
hashWithSalt seed (Equals val) = seed `hashWithSalt` (1::Int) `hashWithSalt` unpack val
hashWithSalt seed (Suffix val) = seed `hashWithSalt` (2::Int) `hashWithSalt` unpack val
hashWithSalt seed (Prefix val) = seed `hashWithSalt` (3::Int) `hashWithSalt` unpack val
hashWithSalt seed (Substring val) = seed `hashWithSalt` (4::Int) `hashWithSalt` unpack val
hashWithSalt seed (Include val) = seed `hashWithSalt` (5::Int) `hashWithSalt` unpack val
hashWithSalt seed (Dash val) = seed `hashWithSalt` (6::Int) `hashWithSalt` unpack val