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52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
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#pragma once
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#include "Luau/DenseHash.h"
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#include "Luau/Id.h"
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#include "Luau/UnionFind.h"
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#include <utility>
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#include <vector>
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namespace Luau::EqSat
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{
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/// Each e-class is a set of e-nodes representing equivalent terms from a given language,
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/// and an e-node is a function symbol paired with a list of children e-classes.
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template<typename L, typename D>
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struct EClass {
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Id id;
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std::vector<L> nodes;
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D data;
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std::vector<std::pair<L, Id>> parents;
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};
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/// In Definition 2.1, an EGraph is composed with a tuple (U, M, H) where
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/// - U: [`EGraph::u`]
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/// - M: [`EGraph::m`]
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/// - H: [`EGraph::h`]
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///
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/// See <https://arxiv.org/pdf/2004.03082>.
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template<typename L, typename N>
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struct EGraph
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{
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// TODO: static_assert L <: Language
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// TODO: static_assert N <: Analysis<L>
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private:
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/// A union-find data structure 𝑈 stores an equivalence relation over e-class ids.
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UnionFind u;
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/// The e-class map 𝑀 maps e-class ids to e-classes. All equivalent e-class ids map to the same
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/// e-class, i.e., 𝑎 ≡id 𝑏 iff 𝑀[𝑎] is the same set as 𝑀[𝑏]. An e-class id 𝑎 is said to refer to the
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/// e-class 𝑀[find(𝑎)].
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DenseHashMap<Id, EClass<L, typename N::Data>> m;
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/// The hashcons 𝐻 is a map from e-nodes to e-node ids.
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///
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/// Author note: the paper says this maps from e-nodes to e-class ids, but the
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/// corresponding map in the egg crate called `memo`, they map it to e-node ids?
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DenseHashMap<EClass<L, typename N::Data>, Id> h;
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};
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} // namespace Luau::EqSat
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