From 619def44c1cca9f3cdf63544d5f24f2c7a7d9b77 Mon Sep 17 00:00:00 2001
From: Klaus Aehlig <klaus.aehlig@huawei.com>
Date: Tue, 22 Feb 2022 17:03:21 +0100
Subject: Initial self-hosting commit

This is the initial version of our tool that is able to
build itself. In can be bootstrapped by

  ./bin/bootstrap.py

Co-authored-by: Oliver Reiche <oliver.reiche@huawei.com>
Co-authored-by: Victor Moreno <victor.moreno1@huawei.com>
---
 .../build_engine/expression/expression.hpp         | 380 +++++++++++++++++++++
 1 file changed, 380 insertions(+)
 create mode 100644 src/buildtool/build_engine/expression/expression.hpp

(limited to 'src/buildtool/build_engine/expression/expression.hpp')

diff --git a/src/buildtool/build_engine/expression/expression.hpp b/src/buildtool/build_engine/expression/expression.hpp
new file mode 100644
index 00000000..ffcd01c8
--- /dev/null
+++ b/src/buildtool/build_engine/expression/expression.hpp
@@ -0,0 +1,380 @@
+#ifndef INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EXPRESSION_HPP
+#define INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EXPRESSION_HPP
+
+#include <exception>
+#include <functional>
+#include <memory>
+#include <optional>
+#include <string>
+#include <type_traits>
+#include <variant>
+#include <vector>
+
+#include "fmt/core.h"
+#include "gsl-lite/gsl-lite.hpp"
+#include "src/buildtool/build_engine/base_maps/entity_name_data.hpp"
+#include "src/buildtool/build_engine/expression/expression_ptr.hpp"
+#include "src/buildtool/build_engine/expression/function_map.hpp"
+#include "src/buildtool/build_engine/expression/linked_map.hpp"
+#include "src/buildtool/build_engine/expression/target_node.hpp"
+#include "src/buildtool/build_engine/expression/target_result.hpp"
+#include "src/buildtool/common/artifact_description.hpp"
+#include "src/buildtool/crypto/hash_generator.hpp"
+#include "src/utils/cpp/atomic.hpp"
+#include "src/utils/cpp/hex_string.hpp"
+#include "src/utils/cpp/json.hpp"
+
+class Expression {
+    friend auto operator+(Expression const& /*lhs*/, Expression const & /*rhs*/)
+        -> Expression;
+
+  public:
+    using none_t = std::monostate;
+    using number_t = double;
+    using artifact_t = ArtifactDescription;
+    using result_t = TargetResult;
+    using node_t = TargetNode;
+    using list_t = std::vector<ExpressionPtr>;
+    using map_t = LinkedMap<std::string, ExpressionPtr, ExpressionPtr>;
+    using name_t = BuildMaps::Base::EntityName;
+
+    template <class T, size_t kIndex = 0>
+    static consteval auto IsValidType() -> bool {
+        if constexpr (kIndex < std::variant_size_v<decltype(data_)>) {
+            return std::is_same_v<
+                       T,
+                       std::variant_alternative_t<kIndex, decltype(data_)>> or
+                   IsValidType<T, kIndex + 1>();
+        }
+        return false;
+    }
+
+    class ExpressionTypeError : public std::exception {
+      public:
+        explicit ExpressionTypeError(std::string const& msg) noexcept
+            : msg_{"ExpressionTypeError: " + msg} {}
+        [[nodiscard]] auto what() const noexcept -> char const* final {
+            return msg_.c_str();
+        }
+
+      private:
+        std::string msg_;
+    };
+
+    Expression() noexcept = default;
+    ~Expression() noexcept = default;
+    Expression(Expression const& other) noexcept
+        : data_{other.data_}, hash_{other.hash_.load()} {}
+    Expression(Expression&& other) noexcept
+        : data_{std::move(other.data_)}, hash_{other.hash_.load()} {}
+    auto operator=(Expression const& other) noexcept -> Expression& {
+        if (this != &other) {
+            data_ = other.data_;
+        }
+        hash_ = other.hash_.load();
+        return *this;
+    }
+    auto operator=(Expression&& other) noexcept -> Expression& {
+        data_ = std::move(other.data_);
+        hash_ = other.hash_.load();
+        return *this;
+    }
+
+    template <class T>
+    requires(IsValidType<std::remove_cvref_t<T>>())
+        // NOLINTNEXTLINE(bugprone-forwarding-reference-overload)
+        explicit Expression(T&& data) noexcept
+        : data_{std::forward<T>(data)} {}
+
+    [[nodiscard]] auto IsNone() const noexcept -> bool { return IsA<none_t>(); }
+    [[nodiscard]] auto IsBool() const noexcept -> bool { return IsA<bool>(); }
+    [[nodiscard]] auto IsNumber() const noexcept -> bool {
+        return IsA<number_t>();
+    }
+    [[nodiscard]] auto IsString() const noexcept -> bool {
+        return IsA<std::string>();
+    }
+    [[nodiscard]] auto IsName() const noexcept -> bool { return IsA<name_t>(); }
+    [[nodiscard]] auto IsArtifact() const noexcept -> bool {
+        return IsA<artifact_t>();
+    }
+    [[nodiscard]] auto IsResult() const noexcept -> bool {
+        return IsA<result_t>();
+    }
+    [[nodiscard]] auto IsNode() const noexcept -> bool { return IsA<node_t>(); }
+    [[nodiscard]] auto IsList() const noexcept -> bool { return IsA<list_t>(); }
+    [[nodiscard]] auto IsMap() const noexcept -> bool { return IsA<map_t>(); }
+
+    [[nodiscard]] auto Bool() const -> bool { return Cast<bool>(); }
+    [[nodiscard]] auto Number() const -> number_t { return Cast<number_t>(); }
+    [[nodiscard]] auto Name() const -> name_t { return Cast<name_t>(); }
+    [[nodiscard]] auto String() const& -> std::string const& {
+        return Cast<std::string>();
+    }
+    [[nodiscard]] auto String() && -> std::string {
+        return std::move(*this).Cast<std::string>();
+    }
+    [[nodiscard]] auto Artifact() const& -> artifact_t const& {
+        return Cast<artifact_t>();
+    }
+    [[nodiscard]] auto Artifact() && -> artifact_t {
+        return std::move(*this).Cast<artifact_t>();
+    }
+    [[nodiscard]] auto Result() const& -> result_t const& {
+        return Cast<result_t>();
+    }
+    [[nodiscard]] auto Result() && -> result_t {
+        return std::move(*this).Cast<result_t>();
+    }
+    [[nodiscard]] auto Node() const& -> node_t const& { return Cast<node_t>(); }
+    [[nodiscard]] auto Node() && -> node_t {
+        return std::move(*this).Cast<node_t>();
+    }
+    [[nodiscard]] auto List() const& -> list_t const& { return Cast<list_t>(); }
+    [[nodiscard]] auto List() && -> list_t {
+        return std::move(*this).Cast<list_t>();
+    }
+    [[nodiscard]] auto Map() const& -> map_t const& { return Cast<map_t>(); }
+    [[nodiscard]] auto Map() && -> map_t {
+        return std::move(*this).Cast<map_t>();
+    }
+
+    [[nodiscard]] auto At(std::string const& key)
+        const& -> std::optional<std::reference_wrapper<ExpressionPtr const>> {
+        auto value = Map().Find(key);
+        if (value) {
+            return value;
+        }
+        return std::nullopt;
+    }
+
+    [[nodiscard]] auto At(
+        std::string const& key) && -> std::optional<ExpressionPtr> {
+        auto value = std::move(*this).Map().Find(key);
+        if (value) {
+            return std::move(*value);
+        }
+        return std::nullopt;
+    }
+
+    template <class T>
+    requires(IsValidType<std::remove_cvref_t<T>>() or
+             std::is_same_v<std::remove_cvref_t<T>, ExpressionPtr>)
+        [[nodiscard]] auto Get(std::string const& key, T&& default_value) const
+        -> ExpressionPtr {
+        auto value = At(key);
+        if (value) {
+            return value->get();
+        }
+        if constexpr (std::is_same_v<std::remove_cvref_t<T>, ExpressionPtr>) {
+            return std::forward<T>(default_value);
+        }
+        else {
+            return ExpressionPtr{std::forward<T>(default_value)};
+        }
+    }
+
+    template <class T>
+    requires(IsValidType<T>()) [[nodiscard]] auto Value() const& noexcept
+        -> std::optional<std::reference_wrapper<T const>> {
+        if (GetIndexOf<T>() == data_.index()) {
+            return std::make_optional(std::ref(std::get<T>(data_)));
+        }
+        return std::nullopt;
+    }
+
+    template <class T>
+    requires(IsValidType<T>()) [[nodiscard]] auto Value() && noexcept
+        -> std::optional<T> {
+        if (GetIndexOf<T>() == data_.index()) {
+            return std::make_optional(std::move(std::get<T>(data_)));
+        }
+        return std::nullopt;
+    }
+
+    template <class T>
+    [[nodiscard]] auto operator==(T const& other) const noexcept -> bool {
+        if constexpr (std::is_same_v<T, Expression>) {
+            return (&data_ == &other.data_) or (ToHash() == other.ToHash());
+        }
+        else {
+            return IsValidType<T>() and (GetIndexOf<T>() == data_.index()) and
+                   ((static_cast<void const*>(&data_) ==
+                     static_cast<void const*>(&other)) or
+                    (std::get<T>(data_) == other));
+        }
+    }
+
+    template <class T>
+    [[nodiscard]] auto operator!=(T const& other) const noexcept -> bool {
+        return !(*this == other);
+    }
+    [[nodiscard]] auto operator[](
+        std::string const& key) const& -> ExpressionPtr const&;
+    [[nodiscard]] auto operator[](std::string const& key) && -> ExpressionPtr;
+    [[nodiscard]] auto operator[](
+        ExpressionPtr const& key) const& -> ExpressionPtr const&;
+    [[nodiscard]] auto operator[](ExpressionPtr const& key) && -> ExpressionPtr;
+    [[nodiscard]] auto operator[](size_t pos) const& -> ExpressionPtr const&;
+    [[nodiscard]] auto operator[](size_t pos) && -> ExpressionPtr;
+
+    enum class JsonMode { SerializeAll, SerializeAllButNodes, NullForNonJson };
+
+    [[nodiscard]] auto ToJson(JsonMode mode = JsonMode::SerializeAll) const
+        -> nlohmann::json;
+    [[nodiscard]] auto IsCacheable() const -> bool;
+    [[nodiscard]] auto ToString() const -> std::string;
+    [[nodiscard]] auto ToHash() const noexcept -> std::string;
+    [[nodiscard]] auto ToIdentifier() const noexcept -> std::string {
+        return ToHexString(ToHash());
+    }
+
+    [[nodiscard]] static auto FromJson(nlohmann::json const& json) noexcept
+        -> ExpressionPtr;
+
+    inline static ExpressionPtr const kNone = Expression::FromJson("null"_json);
+    inline static ExpressionPtr const kEmptyMap =
+        Expression::FromJson("{}"_json);
+    inline static ExpressionPtr const kEmptyList =
+        Expression::FromJson("[]"_json);
+    inline static ExpressionPtr const kEmptyMapExpr =
+        Expression::FromJson(R"({"type": "empty_map"})"_json);
+
+  private:
+    inline static HashGenerator const hash_gen_{
+        HashGenerator::HashType::SHA256};
+
+    std::variant<none_t,
+                 bool,
+                 number_t,
+                 std::string,
+                 name_t,
+                 artifact_t,
+                 result_t,
+                 node_t,
+                 list_t,
+                 map_t>
+        data_{none_t{}};
+
+    mutable atomic_shared_ptr<std::string> hash_{};
+    mutable std::atomic<bool> hash_loading_{};
+
+    template <class T, std::size_t kIndex = 0>
+    requires(IsValidType<T>()) [[nodiscard]] static consteval auto GetIndexOf()
+        -> std::size_t {
+        static_assert(kIndex < std::variant_size_v<decltype(data_)>,
+                      "kIndex out of range");
+        if constexpr (std::is_same_v<
+                          T,
+                          std::variant_alternative_t<kIndex,
+                                                     decltype(data_)>>) {
+            return kIndex;
+        }
+        else {
+            return GetIndexOf<T, kIndex + 1>();
+        }
+    }
+
+    template <class T>
+    [[nodiscard]] auto IsA() const noexcept -> bool {
+        return std::holds_alternative<T>(data_);
+    }
+
+    template <class T>
+    [[nodiscard]] auto Cast() const& -> T const& {
+        if (GetIndexOf<T>() == data_.index()) {
+            return std::get<T>(data_);
+        }
+        // throw descriptive ExpressionTypeError
+        throw ExpressionTypeError{
+            fmt::format("Expression is not of type '{}' but '{}'.",
+                        TypeToString<T>(),
+                        TypeString())};
+    }
+
+    template <class T>
+    [[nodiscard]] auto Cast() && -> T {
+        if (GetIndexOf<T>() == data_.index()) {
+            return std::move(std::get<T>(data_));
+        }
+        // throw descriptive ExpressionTypeError
+        throw ExpressionTypeError{
+            fmt::format("Expression is not of type '{}' but '{}'.",
+                        TypeToString<T>(),
+                        TypeString())};
+    }
+
+    template <class T>
+    requires(Expression::IsValidType<T>())
+        [[nodiscard]] static auto TypeToString() noexcept -> std::string {
+        if constexpr (std::is_same_v<T, bool>) {
+            return "bool";
+        }
+        else if constexpr (std::is_same_v<T, Expression::number_t>) {
+            return "number";
+        }
+        else if constexpr (std::is_same_v<T, Expression::name_t>) {
+            return "name";
+        }
+        else if constexpr (std::is_same_v<T, std::string>) {
+            return "string";
+        }
+        else if constexpr (std::is_same_v<T, Expression::artifact_t>) {
+            return "artifact";
+        }
+        else if constexpr (std::is_same_v<T, Expression::result_t>) {
+            return "result";
+        }
+        else if constexpr (std::is_same_v<T, Expression::node_t>) {
+            return "node";
+        }
+        else if constexpr (std::is_same_v<T, Expression::list_t>) {
+            return "list";
+        }
+        else if constexpr (std::is_same_v<T, Expression::map_t>) {
+            return "map";
+        }
+        return "none";
+    }
+
+    template <size_t kIndex = 0>
+    [[nodiscard]] auto TypeStringForIndex() const noexcept -> std::string;
+    [[nodiscard]] auto TypeString() const noexcept -> std::string;
+    [[nodiscard]] auto ComputeHash() const noexcept -> std::string;
+};
+
+[[nodiscard]] inline auto operator+(Expression const& lhs,
+                                    Expression const& rhs) -> Expression {
+    if (lhs.data_.index() != rhs.data_.index()) {
+        throw Expression::ExpressionTypeError{
+            fmt::format("Cannot add expressions of different type: {} != {}",
+                        lhs.TypeString(),
+                        rhs.TypeString())};
+    }
+    if (not lhs.IsList()) {
+        throw Expression::ExpressionTypeError{fmt::format(
+            "Cannot add expressions of type '{}'.", lhs.TypeString())};
+    }
+    auto list = Expression::list_t{};
+    auto const& llist = lhs.List();
+    auto const& rlist = rhs.List();
+    list.reserve(llist.size() + rlist.size());
+    list.insert(list.begin(), llist.begin(), llist.end());
+    list.insert(list.end(), rlist.begin(), rlist.end());
+    return Expression{list};
+}
+
+namespace std {
+template <>
+struct hash<Expression> {
+    [[nodiscard]] auto operator()(Expression const& e) const noexcept
+        -> std::size_t {
+        auto hash = std::size_t{};
+        auto bytes = e.ToHash();
+        std::memcpy(&hash, bytes.data(), std::min(sizeof(hash), bytes.size()));
+        return hash;
+    }
+};
+}  // namespace std
+
+#endif  // INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EXPRESSION_HPP
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