70 lines
1.7 KiB
Nix
70 lines
1.7 KiB
Nix
{lib, ...}: input: rec {
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content = lib.trim input;
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parts = let
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sects = lib.splitString "\n\n" content;
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in {
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rules = builtins.elemAt sects 0
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|> lib.splitString "\n"
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|> map (lib.splitString "|")
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|> builtins.foldl' (acc: el:
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let
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b = builtins.elemAt el 0;
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a = builtins.elemAt el 1;
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in
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acc // {
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${b} = acc.${b} or [] ++ [a];
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}) {};
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updates = builtins.elemAt sects 1
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|> lib.splitString "\n"
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|> map (lib.splitString ",");
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}
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;
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check = {rules, update}: builtins.attrNames rules
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|> map
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(ruleName: let
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i = lib.lists.findFirstIndex (x: x == ruleName) null update;
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before = if isNull i then [] else lib.sublist (0) (i) update;
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in {
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inherit before;
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rules = rules.${ruleName};
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})
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|> builtins.foldl'
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(valid: {rules, before}: valid && builtins.all (e: !builtins.any (r: r == e) rules) before)
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true
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;
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getValid = {rules, updates}:
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builtins.filter (update: check {inherit rules update;}) updates;
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getMiddles = list: list
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|> map (row: builtins.elemAt row ((builtins.length row) / 2))
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|> map lib.strings.toInt
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;
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sum = builtins.foldl' (a: n: a + n) 0;
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part1result = parts
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|> getValid
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|> getMiddles
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|> sum
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;
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sortUpdate = rules: update:
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builtins.sort (fst: snd: builtins.any (rule: rule == fst) (rules.${snd} or [])) update
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;
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getInvalid = {rules, updates}:
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builtins.filter (update: !check {inherit rules update;}) updates;
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part2result = parts
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|> getInvalid
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|> map (sortUpdate parts.rules)
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|> getMiddles
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|> sum
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;
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}
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