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+/*
+ * Copyright 2023 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_analysis_lattices_vector_h
+#define wasm_analysis_lattices_vector_h
+
+#include <vector>
+
+#include "../lattice.h"
+#include "bool.h"
+#include "flat.h"
+
+namespace wasm::analysis {
+
+// A lattice whose elements are N-tuples of elements of L. Also written as L^N.
+// N is supplied at run time rather than compile time like it is for Array.
+template<Lattice L> struct Vector {
+  using Element = std::vector<typename L::Element>;
+
+  L lattice;
+  const size_t size;
+
+  Vector(L&& lattice, size_t size) : lattice(std::move(lattice)), size(size) {}
+
+  Element getBottom() const noexcept {
+    return Element(size, lattice.getBottom());
+  }
+
+  Element getTop() const noexcept
+#if __cplusplus >= 202002L
+    requires FullLattice<L>
+#endif
+  {
+    return Element(size, lattice.getTop());
+  }
+
+  // `a` <= `b` if their elements are pairwise <=, etc. Unless we determine
+  // that there is no relation, we must check all the elements.
+  LatticeComparison compare(const Element& a, const Element& b) const noexcept {
+    assert(a.size() == size);
+    assert(b.size() == size);
+    auto result = EQUAL;
+    for (size_t i = 0; i < size; ++i) {
+      switch (lattice.compare(a[i], b[i])) {
+        case NO_RELATION:
+          return NO_RELATION;
+        case EQUAL:
+          continue;
+        case LESS:
+          if (result == GREATER) {
+            // Cannot be both less and greater.
+            return NO_RELATION;
+          }
+          result = LESS;
+          continue;
+        case GREATER:
+          if (result == LESS) {
+            // Cannot be both greater and less.
+            return NO_RELATION;
+          }
+          result = GREATER;
+          continue;
+      }
+    }
+    return result;
+  }
+
+  // Pairwise join on the elements.
+  bool join(Element& joinee, const Element& joiner) const noexcept {
+    assert(joinee.size() == size);
+    assert(joiner.size() == size);
+    bool result = false;
+    for (size_t i = 0; i < size; ++i) {
+      if constexpr (std::is_same_v<typename L::Element, bool>) {
+        // The vector<bool> specialization does not expose references to the
+        // individual bools because they might be in a bitmap, so we need a
+        // workaround.
+        bool e = joinee[i];
+        if (lattice.join(e, joiner[i])) {
+          joinee[i] = e;
+          result = true;
+        }
+      } else {
+        result |= lattice.join(joinee[i], joiner[i]);
+      }
+    }
+
+    return result;
+  }
+
+  // Pairwise meet on the elements.
+  bool meet(Element& meetee, const Element& meeter) const noexcept
+#if __cplusplus >= 202002L
+    requires FullLattice<L>
+#endif
+  {
+    assert(meetee.size() == size);
+    assert(meeter.size() == size);
+    bool result = false;
+    for (size_t i = 0; i < size; ++i) {
+      if constexpr (std::is_same_v<typename L::Element, bool>) {
+        // The vector<bool> specialization does not expose references to the
+        // individual bools because they might be in a bitmap, so we need a
+        // workaround.
+        bool e = meetee[i];
+        if (lattice.meet(e, meeter[i])) {
+          meetee[i] = e;
+          result = true;
+        }
+      } else {
+        result |= lattice.meet(meetee[i], meeter[i]);
+      }
+    }
+    return result;
+  }
+};
+
+#if __cplusplus >= 202002L
+static_assert(FullLattice<Vector<Bool>>);
+static_assert(Lattice<Vector<Flat<bool>>>);
+#endif
+
+} // namespace wasm::analysis
+
+#endif // wasm_analysis_lattices_vector_h