42 lines
1.2 KiB
C#
42 lines
1.2 KiB
C#
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using Sawmill;
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namespace InnovEnergy.Lib.SrcGen.Trees;
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using T = ForwardTree<String>;
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public static class PrefixTree
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{
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public static Tree<String> Create(IEnumerable<String> strings, String root = "")
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{
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var children = strings.Select(s => new T(s)).ToList();
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var tree = new T(root, children);
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var forwardTree = tree
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.Rewrite(GroupByPrefix)
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.Rewrite(ConcatUnaryNodes);
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return new Tree<String>(forwardTree);
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}
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private static T GroupByPrefix(T tree)
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{
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var newChildren = tree
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.Children
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.Where(s => s.Node.Length > 0)
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.GroupBy(s => s.Node[..1], s => new T(s.Node[1..]))
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.Select(g => GroupByPrefix(new T(g.Key, g.ToList())))
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.ToList();
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return newChildren.Count == 0
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? tree // leaf
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: new T(tree.Node, newChildren);
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}
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private static T ConcatUnaryNodes(ForwardTree<String> tree)
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{
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return tree.Children.Count == 1 && tree.Children[0] is var child
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? new T(tree.Node + child.Node, child.Children)
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: tree;
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}
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}
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