merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer'

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

third_party/immer/extra/fuzzer/flex-vector.cpp

@@ -0,0 +1,150 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#include "fuzzer_input.hpp"
+
+#include <immer/box.hpp>
+#include <immer/flex_vector.hpp>
+
+#include <array>
+
+extern "C" int LLVMFuzzerTestOneInput(const std::uint8_t* data,
+                                      std::size_t size)
+{
+    constexpr auto var_count = 8;
+    constexpr auto bits      = 2;
+
+    using vector_t =
+        immer::flex_vector<int, immer::default_memory_policy, bits, bits>;
+    using size_t = std::uint8_t;
+
+    auto vars = std::array<vector_t, var_count>{};
+
+    auto is_valid_var = [&](auto idx) { return idx >= 0 && idx < var_count; };
+    auto is_valid_var_neq = [](auto other) {
+        return [=](auto idx) {
+            return idx >= 0 && idx < var_count && idx != other;
+        };
+    };
+    auto is_valid_index = [](auto& v) {
+        return [&](auto idx) { return idx >= 0 && idx < v.size(); };
+    };
+    auto is_valid_size = [](auto& v) {
+        return [&](auto idx) { return idx >= 0 && idx <= v.size(); };
+    };
+    auto can_concat = [](auto&& v1, auto&& v2) {
+        using size_type = decltype(v1.size());
+        auto max        = std::numeric_limits<size_type>::max() >> (bits * 4);
+        return v1.size() < max && v2.size() < max;
+    };
+    return fuzzer_input{data, size}.run([&](auto& in) {
+        enum ops
+        {
+            op_push_back,
+            op_update,
+            op_take,
+            op_drop,
+            op_concat,
+            op_push_back_move,
+            op_update_move,
+            op_take_move,
+            op_drop_move,
+            op_concat_move_l,
+            op_concat_move_r,
+            op_concat_move_lr,
+            op_insert,
+            op_erase,
+            op_compare,
+        };
+        auto src = read<char>(in, is_valid_var);
+        auto dst = read<char>(in, is_valid_var);
+        switch (read<char>(in)) {
+        case op_push_back: {
+            vars[dst] = vars[src].push_back(42);
+            break;
+        }
+        case op_update: {
+            auto idx  = read<size_t>(in, is_valid_index(vars[src]));
+            vars[dst] = vars[src].update(idx, [](auto x) { return x + 1; });
+            break;
+        }
+        case op_take: {
+            auto idx  = read<size_t>(in, is_valid_size(vars[src]));
+            vars[dst] = vars[src].take(idx);
+            break;
+        }
+        case op_drop: {
+            auto idx  = read<size_t>(in, is_valid_size(vars[src]));
+            vars[dst] = vars[src].drop(idx);
+            break;
+        }
+        case op_concat: {
+            auto src2 = read<char>(in, is_valid_var);
+            if (can_concat(vars[src], vars[src2]))
+                vars[dst] = vars[src] + vars[src2];
+            break;
+        }
+        case op_push_back_move: {
+            vars[dst] = std::move(vars[src]).push_back(21);
+            break;
+        }
+        case op_update_move: {
+            auto idx = read<size_t>(in, is_valid_index(vars[src]));
+            vars[dst] =
+                std::move(vars[src]).update(idx, [](auto x) { return x + 1; });
+            break;
+        }
+        case op_take_move: {
+            auto idx  = read<size_t>(in, is_valid_size(vars[src]));
+            vars[dst] = std::move(vars[src]).take(idx);
+            break;
+        }
+        case op_drop_move: {
+            auto idx  = read<size_t>(in, is_valid_size(vars[src]));
+            vars[dst] = std::move(vars[src]).drop(idx);
+            break;
+        }
+        case op_concat_move_l: {
+            auto src2 = read<char>(in, is_valid_var_neq(src));
+            if (can_concat(vars[src], vars[src2]))
+                vars[dst] = std::move(vars[src]) + vars[src2];
+            break;
+        }
+        case op_concat_move_r: {
+            auto src2 = read<char>(in, is_valid_var_neq(src));
+            if (can_concat(vars[src], vars[src2]))
+                vars[dst] = vars[src] + std::move(vars[src2]);
+            break;
+        }
+        case op_concat_move_lr: {
+            auto src2 = read<char>(in, is_valid_var_neq(src));
+            if (can_concat(vars[src], vars[src2]))
+                vars[dst] = std::move(vars[src]) + std::move(vars[src2]);
+        }
+        case op_compare: {
+            using std::swap;
+            if (vars[src] == vars[dst])
+                swap(vars[src], vars[dst]);
+            break;
+        }
+        case op_erase: {
+            auto idx  = read<size_t>(in, is_valid_index(vars[src]));
+            vars[dst] = vars[src].erase(idx);
+            break;
+        }
+        case op_insert: {
+            auto idx  = read<size_t>(in, is_valid_size(vars[src]));
+            vars[dst] = vars[src].insert(idx, immer::box<int>{42});
+            break;
+        }
+        default:
+            break;
+        };
+        return true;
+    });
+}