~alcinnz/haskell-stylist

ref: e5b85906e0829a01e2df4bd5c41451c8e18917a4 haskell-stylist/src/Data/CSS/Style/Selector/Specificity.hs -rw-r--r-- 1.7 KiB
e5b85906 — Adrian Cochrane Add support for psuedoelements/classes. 4 years ago 
                                                                                
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
module Data.CSS.Style.Selector.Specificity(
        OrderedRuleStore(..)
    ) where

import Data.CSS.Syntax.Selector
import Data.CSS.Style.Common
import Data.List

type Vec = (Int, Int, Int)
computeSpecificity :: Selector -> Vec
computeSpecificity (Element sel) = computeSpecificity' sel
computeSpecificity (Child upSel sel) = computeSpecificity upSel `add` computeSpecificity' sel
computeSpecificity (Descendant upSel sel) = computeSpecificity upSel `add` computeSpecificity' sel
computeSpecificity (Adjacent upSel sel) = computeSpecificity upSel `add` computeSpecificity' sel
computeSpecificity (Sibling upSel sel) = computeSpecificity upSel `add` computeSpecificity' sel

computeSpecificity' :: [SimpleSelector] -> Vec
computeSpecificity' (Tag _:sel) = computeSpecificity' sel `add` (0, 0, 1)
computeSpecificity' (Psuedoelement _:sel) = computeSpecificity' sel `add` (0, 0, 1)
computeSpecificity' (Class _:sel) = computeSpecificity' sel `add` (0, 1, 0)
computeSpecificity' (Psuedoclass _ _:sel) = computeSpecificity' sel `add` (0, 1, 0)
computeSpecificity' (Property _ _:sel) = computeSpecificity' sel `add` (0, 1, 0)
computeSpecificity' (Id _:sel) = computeSpecificity' sel `add` (1, 0, 0)
computeSpecificity' [] = (0, 0, 0)

add :: Vec -> Vec -> Vec
add (a, b, c) (x, y, z) = (a + x, b + y, c + z)

data OrderedRuleStore inner = OrderedRuleStore inner Int

instance RuleStore inner => RuleStore (OrderedRuleStore inner) where
    new = OrderedRuleStore new 0
    addStyleRule (OrderedRuleStore self count) priority rule = OrderedRuleStore (
            addStyleRule self priority $ rule {
                rank = (priority, computeSpecificity $ selector rule, count)
            }
        ) (count + 1)
    lookupRules (OrderedRuleStore self _) el = sort $ lookupRules self el