From 150ba94d14d89d1187e010464a63eaddf10e2225 Mon Sep 17 00:00:00 2001
From: Bruno Iljazovic <bruno.iljazovic@mireo.com>
Date: Thu, 18 Sep 2025 20:25:30 +0200
Subject: [PATCH] Drop Spirit dependency

Summary: Ref #36

Reviewers: ivica

Reviewed By: ivica

Subscribers: miljen

Differential Revision: https://repo.mireo.local/D37107
---
 CMakeLists.txt                                |   3 -
 build.jam                                     |   3 -
 .../boost/mqtt5/impl/codecs/base_decoders.hpp | 441 +++++++-----------
 .../mqtt5/impl/codecs/message_decoders.hpp    |  64 +--
 include/boost/mqtt5/impl/endpoints.hpp        |  94 ++--
 test/cmake_subdir_test/CMakeLists.txt         |  14 +-
 test/unit/endpoints.cpp                       |   4 +-
 vcpkg.json                                    |   3 +-
 8 files changed, 250 insertions(+), 376 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 47a9fe3..8944f4b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,12 +49,9 @@ else()
     Boost::container
     Boost::core
     Boost::endian
-    Boost::fusion
-    Boost::optional
     Boost::random
     Boost::range
     Boost::smart_ptr
-    Boost::spirit
     Boost::system
     Boost::type_traits
     Threads::Threads
diff --git a/build.jam b/build.jam
index d44988d..f4bec20 100644
--- a/build.jam
+++ b/build.jam
@@ -13,12 +13,9 @@ constant boost_dependencies :
     /boost/container//boost_container
     /boost/core//boost_core
     /boost/endian//boost_endian
-    /boost/fusion//boost_fusion
-    /boost/optional//boost_optional
     /boost/random//boost_random
     /boost/range//boost_range
     /boost/smart_ptr//boost_smart_ptr
-    /boost/spirit//boost_spirit
     /boost/system//boost_system
     /boost/type_traits//boost_type_traits
     ;
diff --git a/include/boost/mqtt5/impl/codecs/base_decoders.hpp b/include/boost/mqtt5/impl/codecs/base_decoders.hpp
index 61640c7..c6ee082 100644
--- a/include/boost/mqtt5/impl/codecs/base_decoders.hpp
+++ b/include/boost/mqtt5/impl/codecs/base_decoders.hpp
@@ -12,11 +12,7 @@
 
 #include <boost/mqtt5/detail/traits.hpp>
 
-#include <boost/fusion/adapted/std_tuple.hpp>
-#include <boost/fusion/container/deque.hpp>
-#include <boost/optional/optional.hpp>
-#include <boost/spirit/home/x3.hpp>
-#include <boost/spirit/home/x3/binary/binary.hpp>
+#include <boost/endian/conversion.hpp>
 
 #include <cstdint>
 #include <string>
@@ -24,217 +20,49 @@
 
 namespace boost::mqtt5::decoders {
 
-namespace x3 = boost::spirit::x3;
-
-template <typename T>
-struct convert { using type = T; };
-
-template <typename ...Args>
-struct convert<boost::fusion::deque<Args...>> {
-    using type = std::tuple<typename convert<Args>::type...>;
-};
-
-template <typename T>
-struct convert<boost::optional<T>> {
-    using type = std::optional<T>;
-};
-
-template <typename T>
-struct convert<std::vector<T>> {
-    using type = std::vector<typename convert<T>::type>;
-};
-
-template <typename T, typename Parser>
-constexpr auto as(Parser&& p) {
-    return x3::rule<struct _, T>{} = std::forward<Parser>(p);
-}
-
-
 template <typename It, typename Parser>
 auto type_parse(It& first, const It last, const Parser& p) {
-    using ctx_type = decltype(x3::make_context<struct _>(std::declval<Parser&>()));
-    using attr_type = typename x3::traits::attribute_of<Parser, ctx_type>::type;
-
-    using rv_type = typename convert<attr_type>::type;
+    using rv_type = typename Parser::attribute_type;
 
     std::optional<rv_type> rv;
     rv_type value {};
-    if (x3::phrase_parse(first, last, as<rv_type>(p), x3::eps(false), value))
-        rv = std::move(value);
-    return rv;
-}
-
-
-template <typename AttributeType, typename It, typename Parser>
-auto type_parse(It& first, const It last, const Parser& p) {
-    std::optional<AttributeType> rv;
-    AttributeType value {};
-    if (x3::phrase_parse(first, last, as<AttributeType>(p), x3::eps(false), value))
+    if (p.parse(first, last, value))
         rv = std::move(value);
     return rv;
 }
 
 namespace basic {
 
-template <typename T>
-constexpr auto to(T& arg) {
-    return [&](auto& ctx) {
-        using ctx_type = decltype(ctx);
-        using attr_type = decltype(x3::_attr(std::declval<const ctx_type&>()));
-        if constexpr (detail::is_boost_iterator<attr_type>)
-            arg = T { x3::_attr(ctx).begin(), x3::_attr(ctx).end() };
-        else
-            arg = x3::_attr(ctx);
-    };
-}
+template <typename Attr>
+struct int_parser {
+    using attribute_type = Attr;
 
-template <typename LenParser, typename Subject, typename Enable = void>
-class scope_limit {};
-
-template <typename LenParser, typename Subject>
-class scope_limit<
-    LenParser, Subject,
-    std::enable_if_t<x3::traits::is_parser<LenParser>::value>
-> :
-    public x3::unary_parser<Subject, scope_limit<LenParser, Subject>>
-{
-    using base_type = x3::unary_parser<Subject, scope_limit<LenParser, Subject>>;
-    LenParser _lp;
-public:
-    using ctx_type =
-        decltype(x3::make_context<struct _>(std::declval<Subject&>()));
-    using attribute_type =
-        typename x3::traits::attribute_of<Subject, ctx_type>::type;
-
-    static bool const has_attribute = true;
-
-    scope_limit(const LenParser& lp, const Subject& subject) :
-        base_type(subject), _lp(lp)
-    {}
-
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(
-        It& first, const It last,
-        const Ctx& ctx, RCtx& rctx, Attr& attr
-    ) const {
-
-        It iter = first;
-        typename x3::traits::attribute_of<LenParser, Ctx>::type len;
-        if (!_lp.parse(iter, last, ctx, rctx, len))
-            return false;
-        if (iter + len > last)
+    template <typename It>
+    bool parse(It& first, const It last, Attr& attr) const {
+        constexpr size_t byte_size = sizeof(Attr);
+        if (std::distance(first, last) < static_cast<ptrdiff_t>(byte_size))
             return false;
 
-        if (!base_type::subject.parse(iter, iter + len, ctx, rctx, attr))
-            return false;
+        using namespace boost::endian;
+        attr = endian_load<Attr, sizeof(Attr), order::big>(
+            reinterpret_cast<const uint8_t*>(static_cast<const char*>(&*first))
+        );
+        first += sizeof(Attr);
 
-        first = iter;
         return true;
     }
 };
 
-template <typename Size, typename Subject>
-class scope_limit<
-    Size, Subject,
-    std::enable_if_t<std::is_arithmetic_v<Size>>
-> :
-    public x3::unary_parser<Subject, scope_limit<Size, Subject>>
-{
-    using base_type = x3::unary_parser<Subject, scope_limit<Size, Subject>>;
-    size_t _limit;
-public:
-    using ctx_type =
-        decltype(x3::make_context<struct _>(std::declval<Subject&>()));
-    using attribute_type =
-        typename x3::traits::attribute_of<Subject, ctx_type>::type;
+inline constexpr int_parser<uint8_t> byte_;
+inline constexpr int_parser<uint16_t> word_;
+inline constexpr int_parser<uint32_t> dword_;
 
-    static bool const has_attribute = true;
-
-    scope_limit(Size limit, const Subject& subject) :
-        base_type(subject), _limit(limit)
-    {}
-
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(
-        It& first, const It last,
-        const Ctx& ctx, RCtx& rctx, Attr& attr
-    ) const {
-
-        It iter = first;
-        if (iter + _limit > last)
-            return false;
-
-        if (!base_type::subject.parse(iter, iter + _limit, ctx, rctx, attr))
-            return false;
-
-        first = iter;
-        return true;
-    }
-};
-
-template <typename LenParser, typename Enable = void>
-struct scope_limit_gen {
-    template <typename Subject>
-    auto operator[](const Subject& p) const {
-        return scope_limit<LenParser, Subject> { _lp, x3::as_parser(p) };
-    }
-    LenParser _lp;
-};
-
-template <typename Size>
-struct scope_limit_gen<
-    Size,
-    std::enable_if_t<std::is_arithmetic_v<Size>>
-> {
-    template <typename Subject>
-    auto operator[](const Subject& p) const {
-        return scope_limit<Size, Subject> { limit, x3::as_parser(p) };
-    }
-    Size limit;
-};
-
-template <
-    typename Parser,
-    std::enable_if_t<x3::traits::is_parser<Parser>::value, bool> = true
->
-scope_limit_gen<Parser> scope_limit_(const Parser& p) {
-    return { p };
-}
-
-template <
-    typename Size,
-    std::enable_if_t<std::is_arithmetic_v<Size>, bool> = true
->
-scope_limit_gen<Size> scope_limit_(Size limit) {
-    return { limit };
-}
-
-struct verbatim_parser : x3::parser<verbatim_parser> {
-    using attribute_type = std::string;
-    static bool const has_attribute = true;
-
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(It& first, const It last, const Ctx&, RCtx&, Attr& attr) const {
-        attr = std::string { first, last };
-        first = last;
-        return true;
-    }
-};
-
-constexpr auto verbatim_ = verbatim_parser{};
-
-struct varint_parser : x3::parser<varint_parser> {
+struct varint_parser {
     using attribute_type = int32_t;
-    static bool const has_attribute = true;
 
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(
-        It& first, const It last,
-        const Ctx& ctx, RCtx&, Attr& attr
-    ) const {
-
-        It iter = first;
-        x3::skip_over(iter, last, ctx);
+    template <typename It>
+    bool parse(It& first, const It last, int32_t& attr) const {
+        auto iter = first;
 
         if (iter == last)
             return false;
@@ -262,22 +90,17 @@ struct varint_parser : x3::parser<varint_parser> {
     }
 };
 
-constexpr varint_parser varint_{};
+inline constexpr varint_parser varint_;
 
-struct len_prefix_parser : x3::parser<len_prefix_parser> {
+struct len_prefix_parser {
     using attribute_type = std::string;
-    static bool const has_attribute = true;
 
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(
-        It& first, const It last,
-        const Ctx& ctx, RCtx& rctx, Attr& attr
-    ) const {
-        It iter = first;
-        x3::skip_over(iter, last, ctx);
+    template <typename It>
+    bool parse(It& first, const It last, std::string& attr) const {
+        auto iter = first;
 
-        typename x3::traits::attribute_of<decltype(x3::big_word), Ctx>::type len;
-        if (x3::big_word.parse(iter, last, ctx, rctx, len)) {
+        typename decltype(word_)::attribute_type len;
+        if (word_.parse(iter, last, len)) {
             if (std::distance(iter, last) < len)
                 return false;
         }
@@ -290,44 +113,25 @@ struct len_prefix_parser : x3::parser<len_prefix_parser> {
     }
 };
 
-constexpr len_prefix_parser utf8_ {};
-constexpr len_prefix_parser binary_ {};
-
-/*
-     Boost Spirit incorrectly deduces atribute type for a parser of the form
-         (eps(a) | parser1) >> (eps(b) | parser)
-    and we had to create if_ parser to remedy the issue
-*/
+inline constexpr len_prefix_parser utf8_ {};
+inline constexpr len_prefix_parser binary_ {};
 
 template <typename Subject>
-class conditional_parser :
-    public x3::unary_parser<Subject, conditional_parser<Subject>> {
+struct conditional_parser {
+    using subject_attr_type = typename Subject::attribute_type;
+    using attribute_type = std::optional<subject_attr_type>;
 
-    using base_type = x3::unary_parser<Subject, conditional_parser<Subject>>;
-    bool _condition;
-public:
-    using ctx_type =
-        decltype(x3::make_context<struct _>(std::declval<Subject&>()));
-    using subject_attr_type =
-        typename x3::traits::attribute_of<Subject, ctx_type>::type;
+    Subject p;
+    bool condition;
 
-    using attribute_type = boost::optional<subject_attr_type>;
-    static bool const has_attribute = true;
-
-    conditional_parser(const Subject& s, bool condition) :
-        base_type(s), _condition(condition) {}
-
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(
-        It& first, const It last,
-        const Ctx& ctx, RCtx& rctx, Attr& attr
-    ) const {
-        if (!_condition)
+    template <typename It>
+    bool parse(It& first, const It last, attribute_type& attr) const {
+        if (!condition)
             return true;
 
-        It iter = first;
+        auto iter = first;
         subject_attr_type sattr {};
-        if (!base_type::subject.parse(iter, last, ctx, rctx, sattr))
+        if (!p.parse(iter, last, sattr))
             return false;
 
         attr.emplace(std::move(sattr));
@@ -340,59 +144,155 @@ struct conditional_gen {
     bool _condition;
 
     template <typename Subject>
-    auto operator[](const Subject& p) const {
-        return conditional_parser<Subject> { p, _condition };
+    conditional_parser<Subject> operator[](const Subject& p) const {
+        return { p, _condition };
     }
 };
 
-inline conditional_gen if_(bool condition) {
+constexpr conditional_gen if_(bool condition) {
     return { condition };
 }
 
+struct verbatim_parser {
+    using attribute_type = std::string;
+
+    template <typename It>
+    bool parse(It& first, const It last, std::string& attr) const {
+        attr = std::string { first, last };
+        first = last;
+        return true;
+    }
+};
+
+inline constexpr auto verbatim_ = verbatim_parser{};
+
+template <typename... Ps>
+struct seq_parser {
+    using attribute_type = std::tuple<typename Ps::attribute_type...>;
+
+    std::tuple<Ps...> parsers;
+
+    template <typename It>
+    bool parse(It& first, const It last, attribute_type& attr) const {
+        return parse_impl(
+            first, last, attr, std::make_index_sequence<sizeof...(Ps)>{}
+        );
+    }
+
+private:
+    template <typename It, size_t... Is>
+    bool parse_impl(
+        It& first, const It last, attribute_type& attr,
+        std::index_sequence<Is...>
+    ) const {
+        auto iter = first;
+        bool rv = (
+            std::get<Is>(parsers).parse(iter, last, std::get<Is>(attr))
+                && ...
+        );
+        if (rv)
+            first = iter;
+        return rv;
+    }
+};
+
+template <typename... Ps, typename P2>
+constexpr seq_parser<Ps..., P2> operator>>(
+    const seq_parser<Ps...>& p1, const P2& p2
+) {
+    return { std::tuple_cat(p1.parsers, std::make_tuple(p2)) };
+}
+
+template <typename P1, typename P2>
+constexpr seq_parser<P1, P2> operator>>(const P1& p1, const P2& p2) {
+    return { std::make_tuple(p1, p2) };
+}
+
+template <typename Attr>
+struct attr_parser {
+    using attribute_type = Attr;
+
+    Attr attr;
+
+    template <typename It>
+    bool parse(It&, const It, Attr& attr) const {
+        attr = this->attr;
+        return true;
+    }
+};
+
+template <typename Attr>
+constexpr attr_parser<Attr> attr(const Attr& val) {
+    return { val };
+}
+
+template <typename Subject>
+struct plus_parser {
+    using subject_attr_type = typename Subject::attribute_type;
+    using attribute_type = std::vector<subject_attr_type>;
+
+    Subject p;
+
+    template <typename It, typename Attr>
+    bool parse(It& first, const It last, Attr& attr) const {
+        bool success = false;
+        while (first < last) {
+            subject_attr_type sattr {};
+            auto iter = first;
+            if (!p.parse(iter, last, sattr)) break;
+
+            success = true;
+            first = iter;
+            attr.push_back(std::move(sattr));
+        }
+
+        return success;
+    }
+};
+
+template <typename P>
+constexpr plus_parser<P> operator+(const P& p) {
+    return { p };
+}
+
 } // end namespace basic
 
-
 namespace prop {
 
-namespace basic = boost::mqtt5::decoders::basic;
-
 namespace detail {
 
-template <typename It, typename Ctx, typename RCtx, typename Prop>
-bool parse_to_prop(
-    It& iter, const It last,
-    const Ctx& ctx, RCtx& rctx, Prop& prop
-) {
+template <typename It, typename Prop>
+bool parse_to_prop(It& iter, const It last, Prop& prop) {
     using namespace boost::mqtt5::detail;
     using prop_type = std::remove_reference_t<decltype(prop)>;
 
     bool rv = false;
 
     if constexpr (std::is_same_v<prop_type, uint8_t>)
-        rv = x3::byte_.parse(iter, last, ctx, rctx, prop);
+        rv = basic::byte_.parse(iter, last, prop);
     else if constexpr (std::is_same_v<prop_type, uint16_t>)
-        rv = x3::big_word.parse(iter, last, ctx, rctx, prop);
+        rv = basic::word_.parse(iter, last, prop);
     else if constexpr (std::is_same_v<prop_type, int32_t>)
-        rv = basic::varint_.parse(iter, last, ctx, rctx, prop);
+        rv = basic::varint_.parse(iter, last, prop);
     else if constexpr (std::is_same_v<prop_type, uint32_t>)
-        rv = x3::big_dword.parse(iter, last, ctx, rctx, prop);
+        rv = basic::dword_.parse(iter, last, prop);
     else if constexpr (std::is_same_v<prop_type, std::string>)
-        rv = basic::utf8_.parse(iter, last, ctx, rctx, prop);
+        rv = basic::utf8_.parse(iter, last, prop);
 
     else if constexpr (is_optional<prop_type>) {
         typename prop_type::value_type val;
-        rv = parse_to_prop(iter, last, ctx, rctx, val);
+        rv = parse_to_prop(iter, last, val);
         if (rv) prop.emplace(std::move(val));
     }
 
     else if constexpr (is_pair<prop_type>) {
-        rv = parse_to_prop(iter, last, ctx, rctx, prop.first);
-        rv = parse_to_prop(iter, last, ctx, rctx, prop.second);
+        rv = parse_to_prop(iter, last, prop.first);
+        rv = parse_to_prop(iter, last, prop.second);
     }
 
     else if constexpr (is_vector<prop_type> || is_small_vector<prop_type>) {
         typename std::remove_reference_t<prop_type>::value_type value;
-        rv = parse_to_prop(iter, last, ctx, rctx, value);
+        rv = parse_to_prop(iter, last, value);
         if (rv) prop.push_back(std::move(value));
     }
 
@@ -402,28 +302,21 @@ bool parse_to_prop(
 } // end namespace detail
 
 template <typename Props>
-class prop_parser : public x3::parser<prop_parser<Props>> {
-public:
+struct prop_parser {
     using attribute_type = Props;
-    static bool const has_attribute = true;
 
-    template <typename It, typename Ctx, typename RCtx, typename Attr>
-    bool parse(
-        It& first, const It last,
-        const Ctx& ctx, RCtx& rctx, Attr& attr
-    ) const {
-
-        It iter = first;
-        x3::skip_over(iter, last, ctx);
+    template <typename It>
+    bool parse(It& first, const It last, Props& attr) const {
+        auto iter = first;
 
         if (iter == last)
             return true;
 
         int32_t props_length;
-        if (!basic::varint_.parse(iter, last, ctx, rctx, props_length))
+        if (!basic::varint_.parse(iter, last, props_length))
             return false;
 
-        const It scoped_last = iter + props_length;
+        const auto scoped_last = iter + props_length;
         // attr = Props{};
 
         while (iter < scoped_last) {
@@ -433,10 +326,8 @@ public:
 
             attr.apply_on(
                 prop_id,
-                [&rv, &iter, scoped_last, &ctx, &rctx](auto& prop) {
-                    rv = detail::parse_to_prop(
-                        iter, scoped_last, ctx, rctx, prop
-                    );
+                [&rv, &iter, scoped_last](auto& prop) {
+                    rv = detail::parse_to_prop(iter, scoped_last, prop);
                 }
             );
 
@@ -450,13 +341,11 @@ public:
     }
 };
 
-
 template <typename Props>
 constexpr auto props_ = prop_parser<Props> {};
 
 } // end namespace prop
 
-
 } // end namespace boost::mqtt5::decoders
 
 #endif // !BOOST_MQTT5_BASE_DECODERS_HPP
diff --git a/include/boost/mqtt5/impl/codecs/message_decoders.hpp b/include/boost/mqtt5/impl/codecs/message_decoders.hpp
index ecdf7d4..f761179 100644
--- a/include/boost/mqtt5/impl/codecs/message_decoders.hpp
+++ b/include/boost/mqtt5/impl/codecs/message_decoders.hpp
@@ -32,7 +32,7 @@ using fixed_header = std::tuple<
 inline std::optional<fixed_header> decode_fixed_header(
     byte_citer& it, const byte_citer last
 ) {
-    auto fixed_header_ = x3::byte_ >> basic::varint_;
+    constexpr auto fixed_header_ = basic::byte_ >> basic::varint_;
     return type_parse(it, last, fixed_header_);
 }
 
@@ -41,7 +41,7 @@ using packet_id = uint16_t;
 inline std::optional<packet_id> decode_packet_id(
     byte_citer& it
 ) {
-    auto packet_id_ = x3::big_word;
+    constexpr auto packet_id_ = basic::word_;
     return type_parse(it, it + sizeof(uint16_t), packet_id_);
 }
 
@@ -58,11 +58,11 @@ using connect_message = std::tuple<
 inline std::optional<connect_message> decode_connect(
     uint32_t remain_length, byte_citer& it
 ) {
-    auto var_header_ =
+    constexpr auto var_header_ =
         basic::utf8_ >> // MQTT
-        x3::byte_ >> // (num 5)
-        x3::byte_ >> // conn_flags_
-        x3::big_word >> // keep_alive
+        basic::byte_ >> // (num 5)
+        basic::byte_ >> // conn_flags_
+        basic::word_ >> // keep_alive
         prop::props_<connect_props>;
 
     const byte_citer end = it + remain_length;
@@ -124,9 +124,7 @@ using connack_message = std::tuple<
 inline std::optional<connack_message> decode_connack(
     uint32_t remain_length, byte_citer& it
 ) {
-    auto connack_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> x3::byte_ >> prop::props_<connack_props>
-    ];
+    constexpr auto connack_ = basic::byte_ >> basic::byte_ >> prop::props_<connack_props>;
     return type_parse(it, it + remain_length, connack_);
 }
 
@@ -144,10 +142,10 @@ inline std::optional<publish_message> decode_publish(
     uint8_t flags = control_byte & 0b1111;
     auto qos = qos_e((flags >> 1) & 0b11);
 
-    auto publish_ = basic::scope_limit_(remain_length)[
-        basic::utf8_ >> basic::if_(qos != qos_e::at_most_once)[x3::big_word] >>
-            x3::attr(flags) >> prop::props_<publish_props> >> basic::verbatim_
-    ];
+    auto publish_ =
+        basic::utf8_ >> basic::if_(qos != qos_e::at_most_once)[basic::word_] >>
+            basic::attr(flags) >> prop::props_<publish_props> >>
+            basic::verbatim_;
     return type_parse(it, it + remain_length, publish_);
 }
 
@@ -161,9 +159,7 @@ inline std::optional<puback_message> decode_puback(
 ) {
     if (remain_length == 0)
         return puback_message {};
-    auto puback_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> prop::props_<puback_props>
-    ];
+    constexpr auto puback_ = basic::byte_ >> prop::props_<puback_props>;
     return type_parse(it, it + remain_length, puback_);
 }
 
@@ -177,9 +173,7 @@ inline std::optional<pubrec_message> decode_pubrec(
 ) {
     if (remain_length == 0)
         return pubrec_message {};
-    auto pubrec_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> prop::props_<pubrec_props>
-    ];
+    constexpr auto pubrec_ = basic::byte_ >> prop::props_<pubrec_props>;
     return type_parse(it, it + remain_length, pubrec_);
 }
 
@@ -193,9 +187,7 @@ inline std::optional<pubrel_message> decode_pubrel(
 ) {
     if (remain_length == 0)
         return pubrel_message {};
-    auto pubrel_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> prop::props_<pubrel_props>
-    ];
+    constexpr auto pubrel_ = basic::byte_ >> prop::props_<pubrel_props>;
     return type_parse(it, it + remain_length, pubrel_);
 }
 
@@ -209,9 +201,7 @@ inline std::optional<pubcomp_message> decode_pubcomp(
 ) {
     if (remain_length == 0)
         return pubcomp_message {};
-    auto pubcomp_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> prop::props_<pubcomp_props>
-    ];
+    constexpr auto pubcomp_ = basic::byte_ >> prop::props_<pubcomp_props>;
     return type_parse(it, it + remain_length, pubcomp_);
 }
 
@@ -223,9 +213,7 @@ using subscribe_message = std::tuple<
 inline std::optional<subscribe_message> decode_subscribe(
     uint32_t remain_length, byte_citer& it
 ) {
-    auto subscribe_ = basic::scope_limit_(remain_length)[
-        prop::props_<subscribe_props> >> +(basic::utf8_ >> x3::byte_)
-    ];
+    constexpr auto subscribe_ = prop::props_<subscribe_props> >> +(basic::utf8_ >> basic::byte_);
     return type_parse(it, it + remain_length, subscribe_);
 }
 
@@ -237,9 +225,7 @@ using suback_message = std::tuple<
 inline std::optional<suback_message> decode_suback(
     uint32_t remain_length, byte_citer& it
 ) {
-    auto suback_ = basic::scope_limit_(remain_length)[
-        prop::props_<suback_props> >> +x3::byte_
-    ];
+    constexpr auto suback_ = prop::props_<suback_props> >> +basic::byte_;
     return type_parse(it, it + remain_length, suback_);
 }
 
@@ -251,9 +237,7 @@ using unsubscribe_message = std::tuple<
 inline std::optional<unsubscribe_message> decode_unsubscribe(
     uint32_t remain_length, byte_citer& it
 ) {
-    auto unsubscribe_ = basic::scope_limit_(remain_length)[
-        prop::props_<unsubscribe_props> >> +basic::utf8_
-    ];
+    constexpr auto unsubscribe_ = prop::props_<unsubscribe_props> >> +basic::utf8_;
     return type_parse(it, it + remain_length, unsubscribe_);
 }
 
@@ -265,9 +249,7 @@ using unsuback_message = std::tuple<
 inline std::optional<unsuback_message> decode_unsuback(
     uint32_t remain_length, byte_citer& it
 ) {
-    auto unsuback_ = basic::scope_limit_(remain_length)[
-        prop::props_<unsuback_props> >> +x3::byte_
-    ];
+    constexpr auto unsuback_ = prop::props_<unsuback_props> >> +basic::byte_;
     return type_parse(it, it + remain_length, unsuback_);
 }
 
@@ -281,9 +263,7 @@ inline std::optional<disconnect_message> decode_disconnect(
 ) {
     if (remain_length == 0)
         return disconnect_message {};
-    auto disconnect_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> prop::props_<disconnect_props>
-    ];
+    constexpr auto disconnect_ = basic::byte_ >> prop::props_<disconnect_props>;
     return type_parse(it, it + remain_length, disconnect_);
 }
 
@@ -297,9 +277,7 @@ inline std::optional<auth_message> decode_auth(
 ) {
     if (remain_length == 0)
         return auth_message {};
-    auto auth_ = basic::scope_limit_(remain_length)[
-        x3::byte_ >> prop::props_<auth_props>
-    ];
+    constexpr auto auth_ = basic::byte_ >> prop::props_<auth_props>;
     return type_parse(it, it + remain_length, auth_);
 }
 
diff --git a/include/boost/mqtt5/impl/endpoints.hpp b/include/boost/mqtt5/impl/endpoints.hpp
index 5ae041b..e3d01b7 100644
--- a/include/boost/mqtt5/impl/endpoints.hpp
+++ b/include/boost/mqtt5/impl/endpoints.hpp
@@ -8,9 +8,8 @@
 #ifndef BOOST_MQTT5_ENDPOINTS_HPP
 #define BOOST_MQTT5_ENDPOINTS_HPP
 
-#include <boost/mqtt5/types.hpp>
-
 #include <boost/mqtt5/detail/log_invoke.hpp>
+#include <boost/mqtt5/detail/internal_types.hpp>
 
 #include <boost/asio/append.hpp>
 #include <boost/asio/associated_allocator.hpp>
@@ -23,7 +22,6 @@
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/post.hpp>
 #include <boost/asio/prepend.hpp>
-#include <boost/spirit/home/x3.hpp>
 
 #include <array>
 #include <chrono>
@@ -155,16 +153,6 @@ class endpoints {
     template <typename Owner, typename Handler>
     friend class resolve_op;
 
-    template <typename T>
-    static constexpr auto to_(T& arg) {
-        return [&](auto& ctx) { arg = boost::spirit::x3::_attr(ctx); };
-    }
-
-    template <typename T, typename Parser>
-    static constexpr auto as_(Parser&& p){
-        return boost::spirit::x3::rule<struct _, T>{} = std::forward<Parser>(p);
-    }
-
 public:
     template <typename Executor>
     endpoints(
@@ -202,38 +190,72 @@ public:
     }
 
     void brokers(std::string hosts, uint16_t default_port) {
-        namespace x3 = boost::spirit::x3;
-
         _servers.clear();
 
-        std::string host, port, path;
-
         // loosely based on RFC 3986
-        auto unreserved_ = x3::char_("-a-zA-Z_0-9._~");
-        auto digit_ = x3::char_("0-9");
-        auto separator_ = x3::char_(',');
+        for (auto it = hosts.cbegin(), end = hosts.cend(); it != end;) {
+            skip_spaces(it, end);
 
-        auto host_ = as_<std::string>(+unreserved_)[to_(host)];
-        auto port_ = as_<std::string>(':' >> +digit_)[to_(port)];
-        auto path_ = as_<std::string>(+(x3::char_('/') >> *unreserved_))[to_(path)];
-        auto uri_ = *x3::omit[x3::space] >> (host_ >> -port_ >> -path_) >>
-            (*x3::omit[x3::space] >> x3::omit[separator_ | x3::eoi]);
+            auto host = std::string(match_while("A-Za-z0-9._~-", it, end));
+            if (host.empty()) break;
 
-        for (auto b = hosts.begin(); b != hosts.end(); ) {
-            host.clear(); port.clear(); path.clear();
-            if (phrase_parse(b, hosts.end(), uri_, x3::eps(false))) {
-                _servers.push_back({
-                    std::move(host),
-                    port.empty()
-                        ? std::to_string(default_port)
-                        : std::move(port),
-                    std::move(path)
-                });
+            std::string port;
+            if (it < end && *it == ':') {
+                port = std::string(match_while("0-9", ++it, end));
+                if (port.empty()) break;
             }
-            else b = hosts.end();
+
+            std::string path;
+            if (it < end && *it == '/')
+                path = std::string(match_while("/A-Za-z0-9._~-", it, end));
+
+            _servers.push_back({
+                std::move(host),
+                port.empty()
+                    ? std::to_string(default_port)
+                    : std::move(port),
+                std::move(path)
+            });
+
+            skip_spaces(it, end);
+            if (it == end || *it++ != ',') break;
         }
     }
 
+private:
+    static constexpr void skip_spaces(
+        byte_citer& it, const byte_citer& end
+    ) {
+        match_while(" \t\r\n\f\v", it, end);
+    };
+
+
+    static constexpr std::string_view match_while(
+        const char* chs, byte_citer& it, const byte_citer& end
+    ) {
+        if (it == end)
+            return {};
+
+        auto beg = it;
+        while (it < end && is_any_of(chs, *it)) ++it;
+
+        return { &*beg, static_cast<size_t>(it - beg) };
+    }
+
+    static constexpr bool is_any_of(const char* chs, char c) {
+        while (*chs)
+            if (*(chs + 1) == '-' && *(chs + 2)) {
+                if (c >= *chs && c <= *(chs + 2))
+                    return true;
+                chs += 3;
+            }
+            else {
+                if (c == *chs)
+                    return true;
+                ++chs;
+            }
+        return false;
+    }
 };
 
 
diff --git a/test/cmake_subdir_test/CMakeLists.txt b/test/cmake_subdir_test/CMakeLists.txt
index eaf1ad6..6bbfe69 100644
--- a/test/cmake_subdir_test/CMakeLists.txt
+++ b/test/cmake_subdir_test/CMakeLists.txt
@@ -21,12 +21,9 @@ set(deps
   container
   core
   endian
-  fusion
-  optional
   random
   range
   smart_ptr
-  spirit
   system
   type_traits
   
@@ -42,10 +39,11 @@ set(deps
   intrusive
   # logic # Beast dependency
   mp11
+  optional
   preprocessor
   static_assert
   # static_string # Beast dependency
-  type_index
+  # type_index # Beast dependency
   winapi
   move
   function_types
@@ -64,12 +62,8 @@ set(deps
   iterator
   regex
   "function"
-  phoenix
   pool
-  proto
-  thread
   unordered
-  variant
   variant2
   describe
   predef
@@ -77,10 +71,8 @@ set(deps
   lexical_cast
   numeric/conversion
   tokenizer
-  atomic
-  chrono
+  fusion
   exception
-  ratio
 )
 
 foreach(dep IN LISTS deps)
diff --git a/test/unit/endpoints.cpp b/test/unit/endpoints.cpp
index 65a5077..078457b 100644
--- a/test/unit/endpoints.cpp
+++ b/test/unit/endpoints.cpp
@@ -74,7 +74,7 @@ BOOST_FIXTURE_TEST_CASE(single_host, shared_test_data) {
 BOOST_FIXTURE_TEST_CASE(multiple_hosts, shared_test_data) {
     bool finished = false;
     // "example.invalid" will not be resolved
-    ep.brokers("127.0.0.1:1001,127.0.0.1/path1, example.invalid,   localhost:1002/path1/path-2/path.3_", 1000);
+    ep.brokers("127.0.0.1:1001,127.0.0.1/~path1, example.invalid,   localhost:1002/path1/path-2/path.3_", 1000);
 
     asio::co_spawn(ioc, [&]() -> asio::awaitable<void> {
         for (size_t i = 0; i < 3; ++i) {
@@ -90,7 +90,7 @@ BOOST_FIXTURE_TEST_CASE(multiple_hosts, shared_test_data) {
             BOOST_TEST(!eps.empty());
             BOOST_TEST(ap.host == "127.0.0.1");
             BOOST_TEST(ap.port == "1000");
-            BOOST_TEST(ap.path == "/path1");
+            BOOST_TEST(ap.path == "/~path1");
 
             std::tie(ec, eps, ap) = co_await ep.async_next_endpoint(use_nothrow_awaitable);
             BOOST_TEST(ec == success);
diff --git a/vcpkg.json b/vcpkg.json
index f8a829d..65fdfed 100644
--- a/vcpkg.json
+++ b/vcpkg.json
@@ -3,8 +3,7 @@
   "version-semver": "0.0.1",
   "dependencies": [
     "boost-asio",
-    "boost-beast",
-    "boost-spirit"
+    "boost-beast"
   ],
   "default-features": [],
   "features": {