json_loader.h

/*
 * SPDX-FileCopyrightText: 2013 Barefoot Networks, Inc.
 * Copyright 2013-present Barefoot Networks, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef IR_JSON_LOADER_H_
#define IR_JSON_LOADER_H_
 
#include <map>
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <unordered_map>
#include <utility>
#include <variant>
 
#include "absl/container/flat_hash_set.h"
#include "ir.h"
#include "json_parser.h"
#include "lib/bitvec.h"
#include "lib/cstring.h"
#include "lib/ltbitmatrix.h"
#include "lib/match.h"
#include "lib/null.h"
#include "lib/ordered_map.h"
#include "lib/ordered_set.h"
#include "lib/safe_vector.h"
 
namespace P4 {
 
class JSONLoader {
    template <typename T>
    class has_fromJSON {
        typedef char small;
        typedef struct {
            char c[2];
        } big;
 
        template <typename C>
        static small test(decltype(&C::fromJSON));
        template <typename C>
        static big test(...);
 
     public:
        static const bool value = sizeof(test<T>(0)) == sizeof(char);
    };
 
    using NodeReferences = std::unordered_map<int, IR::Node *>;
    std::shared_ptr<NodeReferences> node_refs;
    std::unique_ptr<JsonData> json_root;
    const JsonData *json = nullptr;
    JsonData::LocationInfo *locinfo = nullptr;
    std::unique_ptr<absl::flat_hash_set<P4::cstring, Util::Hash>> decoded;
    bool (*errfn)(const JSONLoader &, std::string_view msg) = nullptr;
 
    JSONLoader(const JsonData *json, std::shared_ptr<NodeReferences> refs,
               JsonData::LocationInfo *locinfo)
        : node_refs(std::move(refs)), json(json), locinfo(locinfo) {}
 
 public:
    explicit JSONLoader(std::istream &in, JsonData::LocationInfo *li = nullptr)
        : node_refs(std::make_shared<NodeReferences>()), locinfo(li) {
        in >> json_root;
        json = json_root.get();
    }
 
    JSONLoader(const JSONLoader &unpacker, std::string_view field)
        : node_refs(unpacker.node_refs), json(nullptr), locinfo(unpacker.locinfo) {
        if (!unpacker) return;
        if (auto *obj = unpacker.json->to<JsonObject>()) {
            if (auto it = obj->find(field); it != obj->end()) {
                if (unpacker.decoded) unpacker.decoded->emplace(field);
                json = it->second.get();
            }
        }
    }
 
    explicit operator bool() const { return json != nullptr; }
    template <typename T>
    [[nodiscard]] bool is() const {
        return json && json->is<T>();
    }
    template <typename T>
    [[nodiscard]] const T &as() const {
        return json->as<T>();
    }
    template <typename T>
    [[nodiscard]] const T *to() const {
        return json ? json->to<T>() : nullptr;
    }
 
    std::string locdesc(const JsonData &d) const {
        if (!locinfo) return "";
        return locinfo->desc(d);
    }
    std::string locdesc() const {
        if (!json) return "";
        return locdesc(*json);
    }
    std::string locdesc(std::string_view field) const {
        if (!locinfo || !json) return "";
        if (auto *obj = json->to<JsonObject>())
            if (auto it = obj->find(field); it != obj->end()) return locinfo->desc(*it->second);
        return locdesc();
    }
 
    bool error(std::string_view msg) const {
        if ((!errfn || errfn(*this, msg)) && JsonData::strict) throw JsonData::error(msg, json);
        return false;
    }
 
    void track_decode() {
        BUG_CHECK(json && json->is<JsonObject>(), "JSONLoader::track_decode on non-JsonObject");
        if (!decoded) decoded = std::make_unique<absl::flat_hash_set<P4::cstring, Util::Hash>>();
    }
 
    template <typename FN>
    void undecoded(FN fn) {
        BUG_CHECK(decoded, "Called JSONLoader::undecoded without track_decode");
        for (auto &el : *json->to<JsonObject>())
            if (!decoded->count(el.first)) fn(*this, el.first, *el.second);
    }
 
 private:
    const IR::Node *get_node(NodeFactoryFn factory = nullptr) {
        if (!json || !json->is<JsonObject>()) {
            error("node is not a JsonObject");
            return nullptr;
        }
        track_decode();
        int id;
        auto success = load("Node_ID", id) || error("missing field Node_ID");
        if (!success) return nullptr;
        if (id >= 0) {
            if (node_refs->find(id) == node_refs->end()) {
                cstring type;
                if (!factory) {
                    auto success = load("Node_Type", type) || error("missing field Node_Type");
                    if (!success) return nullptr;
                    factory = get(IR::unpacker_table, type);
                }
                if (factory) {
                    auto *node = factory(*this)->to<IR::Node>();
                    CHECK_NULL(node);
                    node_refs->emplace(id, node);
                    // Creating JsonObject from source_info read from jsonFile
                    // and setting SourceInfo for each node
                    // when "--fromJSON" flag is used
                    node->sourceInfoFromJSON(*this);
                } else {
                    error("no Node factory for " + type);
                    return nullptr;
                }
            }
            return node_refs->at(id);
        }
        error("invalid Node_ID " + std::to_string(id));
        return nullptr;
    }
 
    template <typename T>
    void unpack_json(safe_vector<T> &v) {
        T temp;
        v.clear();
        for (auto &e : as<JsonVector>()) {
            load(e, temp);
            v.push_back(temp);
        }
    }
 
    template <typename T>
    void unpack_json(std::set<T> &v) {
        T temp;
        v.clear();
        for (auto &e : as<JsonVector>()) {
            load(e, temp);
            v.insert(temp);
        }
    }
 
    template <typename T>
    void unpack_json(ordered_set<T> &v) {
        T temp;
        v.clear();
        for (auto &e : as<JsonVector>()) {
            load(e, temp);
            v.insert(temp);
        }
    }
 
    template <typename T>
    void unpack_json(IR::Vector<T> &v) {
        v = get_node(NodeFactoryFn(&IR::Vector<T>::fromJSON))->as<IR::Vector<T>>();
    }
    template <typename T>
    void unpack_json(const IR::Vector<T> *&v) {
        v = get_node(NodeFactoryFn(&IR::Vector<T>::fromJSON))->checkedTo<IR::Vector<T>>();
    }
    template <typename T>
    void unpack_json(IR::IndexedVector<T> &v) {
        v = get_node(NodeFactoryFn(&IR::IndexedVector<T>::fromJSON))->as<IR::IndexedVector<T>>();
    }
    template <typename T>
    void unpack_json(const IR::IndexedVector<T> *&v) {
        v = get_node(NodeFactoryFn(&IR::IndexedVector<T>::fromJSON))
                ->checkedTo<IR::IndexedVector<T>>();
    }
    template <class T, template <class K, class V, class COMP, class ALLOC> class MAP, class COMP,
              class ALLOC>
    void unpack_json(IR::NameMap<T, MAP, COMP, ALLOC> &m) {
        m = get_node(NodeFactoryFn(&IR::NameMap<T, MAP, COMP, ALLOC>::fromJSON))
                ->as<IR::NameMap<T, MAP, COMP, ALLOC>>();
    }
    template <class T, template <class K, class V, class COMP, class ALLOC> class MAP, class COMP,
              class ALLOC>
    void unpack_json(const IR::NameMap<T, MAP, COMP, ALLOC> *&m) {
        m = get_node(NodeFactoryFn(&IR::NameMap<T, MAP, COMP, ALLOC>::fromJSON))
                ->checkedTo<IR::NameMap<T, MAP, COMP, ALLOC>>();
    }
 
    template <typename K, typename V>
    void unpack_json(std::map<K, V> &v) {
        std::pair<K, V> temp;
        v.clear();
        if (is<JsonVector>()) {
            for (auto &e : as<JsonVector>()) {
                load(e, temp);
                v.insert(temp);
            }
        } else {
            for (auto &e : as<JsonObject>()) {
                load(JsonString(e.first), temp.first);
                load(e.second, temp.second);
                v.insert(temp);
            }
        }
    }
    template <typename K, typename V>
    void unpack_json(ordered_map<K, V> &v) {
        std::pair<K, V> temp;
        v.clear();
        if (is<JsonVector>()) {
            for (auto &e : as<JsonVector>()) {
                load(e, temp);
                v.insert(temp);
            }
        } else {
            for (auto &e : as<JsonObject>()) {
                load(JsonString(e.first), temp.first);
                load(e.second, temp.second);
                v.insert(temp);
            }
        }
    }
    template <typename V>
    void unpack_json(string_map<V> &v) {
        std::pair<cstring, V> temp;
        v.clear();
        for (auto &e : as<JsonObject>()) {
            temp.first = e.first;
            load(e.second, temp.second);
            v.insert(temp);
        }
    }
 
    template <typename K, typename V>
    void unpack_json(std::multimap<K, V> &v) {
        std::pair<K, V> temp;
        v.clear();
        if (is<JsonVector>()) {
            for (auto &e : as<JsonVector>()) {
                load(e, temp);
                v.insert(temp);
            }
        } else {
            for (auto &e : as<JsonObject>()) {
                load(JsonString(e.first), temp.first);
                load(e.second, temp.second);
                v.insert(temp);
            }
        }
    }
 
    template <typename T>
    void unpack_json(std::vector<T> &v) {
        T temp;
        v.clear();
        for (auto &e : as<JsonVector>()) {
            load(e, temp);
            v.push_back(temp);
        }
    }
 
    template <typename T, typename U>
    void unpack_json(std::pair<T, U> &v) {
        load("first", v.first) || error("missing field first");
        load("second", v.second) || error("missing field second");
    }
 
    template <typename T>
    void unpack_json(std::optional<T> &v) {
        bool isValid = false;
        load("valid", isValid) || error("missing field valid");
        if (!isValid) {
            v = std::nullopt;
            return;
        }
        T value;
        auto success = load("value", value) || error("missing field value");
        if (!success) {
            v = std::nullopt;
            return;
        }
        v = std::move(value);
    }
 
    template <int N, class Variant>
    std::enable_if_t<N == std::variant_size_v<Variant>> unpack_variant(int /*target*/,
                                                                       Variant & /*variant*/) {
        BUG("Error traversing variant during load");
    }
 
    template <int N, class Variant>
    std::enable_if_t<(N < std::variant_size_v<Variant>)> unpack_variant(int target,
                                                                        Variant &variant) {
        if (N == target) {
            variant.template emplace<N>();
            load("value", std::get<N>(variant)) || error("missing field value");
        } else
            unpack_variant<N + 1>(target, variant);
    }
 
    template <class... Types>
    void unpack_json(std::variant<Types...> &v) {
        int index = -1;
        load("variant_index", index) || error("missing field variant_index");
        unpack_variant<0>(index, v);
    }
 
    void unpack_json(bool &v) { v = as<JsonBoolean>(); }
 
    template <typename T>
    std::enable_if_t<std::is_integral_v<T>> unpack_json(T &v) {
        v = as<JsonNumber>();
    }
    void unpack_json(big_int &v) { v = as<JsonNumber>().val; }
    void unpack_json(std::string &v) {
        if (is<JsonString>()) v = as<JsonString>();
    }
    void unpack_json(cstring &v) {
        if (is<JsonString>())
            v = cstring(as<JsonString>());
        else if (is<JsonNull>())
            v = cstring();
    }
    void unpack_json(IR::ID &v) {
        if (!json->is<JsonNull>()) v.name = as<JsonString>();
    }
 
    void unpack_json(LTBitMatrix &m) {
        if (auto *s = json->to<JsonString>()) s->c_str() >> m;
    }
 
    void unpack_json(bitvec &v) {
        if (auto *s = json->to<JsonString>()) s->c_str() >> v;
    }
 
    template <typename T>
    std::enable_if_t<std::is_enum_v<T>> unpack_json(T &v) {
        if (auto *s = json->to<JsonString>()) *s >> v;
    }
 
    void unpack_json(match_t &v) {
        if (auto *s = json->to<JsonString>()) s->c_str() >> v;
    }
 
    template <typename T>
    std::enable_if_t<has_fromJSON<T>::value && !std::is_base_of_v<IR::INode, T> &&
                     std::is_pointer_v<decltype(T::fromJSON(std::declval<JSONLoader &>()))>>
    unpack_json(T *&v) {
        v = T::fromJSON(*this);
    }
 
    template <typename T>
    std::enable_if_t<has_fromJSON<T>::value && !std::is_base_of_v<IR::INode, T> &&
                     std::is_pointer_v<decltype(T::fromJSON(std::declval<JSONLoader &>()))>>
    unpack_json(T &v) {
        v = *(T::fromJSON(*this));
    }
 
    template <typename T>
    std::enable_if_t<has_fromJSON<T>::value && !std::is_base_of<IR::INode, T>::value &&
                     !std::is_pointer_v<decltype(T::fromJSON(std::declval<JSONLoader &>()))>>
    unpack_json(T &v) {
        v = T::fromJSON(*this);
    }
 
    template <typename T>
    std::enable_if_t<has_fromJSON<T>::value && !std::is_base_of<IR::INode, T>::value &&
                     !std::is_pointer_v<decltype(T::fromJSON(std::declval<JSONLoader &>()))>>
    unpack_json(T *&v) {
        v = new T(T::fromJSON(*this));
    }
 
    template <typename T>
    std::enable_if_t<std::is_base_of_v<IR::INode, T>> unpack_json(T &v) {
        v = get_node()->as<T>();
    }
    template <typename T>
    std::enable_if_t<std::is_base_of_v<IR::INode, T>> unpack_json(const T *&v) {
        v = get_node()->checkedTo<T>();
    }
 
    template <typename T, size_t N>
    void unpack_json(T (&v)[N]) {
        if (auto *j = json->to<JsonVector>()) {
            for (size_t i = 0; i < N && i < j->size(); ++i) {
                load(j->at(i), v[i]);
            }
        }
    }
 
 public:
    template <typename T>
    void load(const JsonData &json, T &v) {
        JSONLoader(&json, node_refs, locinfo).unpack_json(v);
    }
 
    template <typename T>
    void load(const std::unique_ptr<JsonData> &json, T &v) {
        JSONLoader(json.get(), node_refs, locinfo).unpack_json(v);
    }
 
    template <typename T>
    bool load(std::string_view field, T *&v) {
        if (auto loader = JSONLoader(*this, field)) {
            loader.unpack_json(v);
            return true;
        } else {
            v = nullptr;
            return false;
        }
    }
 
    template <typename T>
    bool load(std::string_view field, T &v) {
        if (auto loader = JSONLoader(*this, field)) {
            loader.unpack_json(v);
            return true;
        }
        return false;
    }
 
    template <typename T>
    JSONLoader &operator>>(T &v) {
        unpack_json(v);
        return *this;
    }
};
 
template <class T>
IR::Vector<T>::Vector(JSONLoader &json) : VectorBase(json) {
    json.load("vec", vec) || json.error("missing field vec");
}
template <class T>
IR::Node *IR::Vector<T>::fromJSON(JSONLoader &json) {
    return new Vector<T>(json);
}
template <class T>
IR::IndexedVector<T>::IndexedVector(JSONLoader &json) : Vector<T>(json) {
    json.load("declarations", declarations) || json.error("missing field declarations");
}
template <class T>
IR::Node *IR::IndexedVector<T>::fromJSON(JSONLoader &json) {
    return new IndexedVector<T>(json);
}
template <class T, template <class K, class V, class COMP, class ALLOC> class MAP /*= std::map */,
          class COMP /*= std::less<cstring>*/,
          class ALLOC /*= std::allocator<std::pair<cstring, const T*>>*/>
IR::NameMap<T, MAP, COMP, ALLOC>::NameMap(JSONLoader &json) : Node(json) {
    json.load("symbols", symbols) || json.error("missing field symbols");
}
template <class T, template <class K, class V, class COMP, class ALLOC> class MAP /*= std::map */,
          class COMP /*= std::less<cstring>*/,
          class ALLOC /*= std::allocator<std::pair<cstring, const T*>>*/>
IR::Node *IR::NameMap<T, MAP, COMP, ALLOC>::fromJSON(JSONLoader &json) {
    return new IR::NameMap<T, MAP, COMP, ALLOC>(json);
}
 
}  // namespace P4
 
#endif /* IR_JSON_LOADER_H_ */