From b1d45485191fd4dd2e98bde5e11a3ac4fa50fbfd Mon Sep 17 00:00:00 2001
From: BlackMATov <blackmatov@gmail.com>
Date: Wed, 10 Oct 2018 04:40:36 +0700
Subject: [PATCH] basic_string_hash class

---
 headers/enduro2d/utils/_utils.hpp         |  13 +-
 headers/enduro2d/utils/strings.hpp        |  54 +++++++
 headers/enduro2d/utils/strings.inl        | 170 ++++++++++++++++++++++
 sources/enduro2d/utils/strings.cpp        |  20 +++
 untests/sources/untests_utils/strings.cpp |  39 +++++
 5 files changed, 294 insertions(+), 2 deletions(-)

diff --git a/headers/enduro2d/utils/_utils.hpp b/headers/enduro2d/utils/_utils.hpp
index e781757f..1e858619 100644
--- a/headers/enduro2d/utils/_utils.hpp
+++ b/headers/enduro2d/utils/_utils.hpp
@@ -24,6 +24,9 @@ namespace e2d
 
     template < typename T >
     class module;
+
+    template < typename Char >
+    class basic_string_hash;
 }
 
 namespace e2d
@@ -38,6 +41,11 @@ namespace e2d
     using str16_view = basic_string_view<char16_t>;
     using str32_view = basic_string_view<char32_t>;
 
+    using str_hash = basic_string_hash<char>;
+    using wstr_hash = basic_string_hash<wchar_t>;
+    using str16_hash = basic_string_hash<char16_t>;
+    using str32_hash = basic_string_hash<char32_t>;
+
     struct seconds_tag {};
     struct milliseconds_tag {};
     struct microseconds_tag {};
@@ -53,10 +61,11 @@ namespace e2d
 namespace e2d
 {
     class noncopyable {
+    public:
+        noncopyable(const noncopyable&) = delete;
+        noncopyable& operator=(const noncopyable&) = delete;
     protected:
         noncopyable() = default;
         ~noncopyable() = default;
-        noncopyable(const noncopyable&) = delete;
-        noncopyable& operator=(const noncopyable&) = delete;
     };
 }
diff --git a/headers/enduro2d/utils/strings.hpp b/headers/enduro2d/utils/strings.hpp
index 877cf7ed..d9bed535 100644
--- a/headers/enduro2d/utils/strings.hpp
+++ b/headers/enduro2d/utils/strings.hpp
@@ -10,6 +10,55 @@
 
 #include "_utils.hpp"
 
+namespace e2d
+{
+    template < typename Char >
+    class basic_string_hash final {
+    public:
+        static std::size_t empty_hash() noexcept;
+    public:
+        basic_string_hash() noexcept;
+        ~basic_string_hash() noexcept;
+
+        basic_string_hash(basic_string_hash&& other) noexcept;
+        basic_string_hash& operator=(basic_string_hash&& other) noexcept;
+
+        basic_string_hash(const basic_string_hash& other) noexcept;
+        basic_string_hash& operator=(const basic_string_hash& other) noexcept;
+
+        explicit basic_string_hash(basic_string_view<Char> str) noexcept;
+
+        basic_string_hash& assign(basic_string_hash&& other) noexcept;
+        basic_string_hash& assign(const basic_string_hash& other) noexcept;
+        basic_string_hash& assign(basic_string_view<Char> str) noexcept;
+
+        void swap(basic_string_hash& other) noexcept;
+        void clear() noexcept;
+        bool empty() const noexcept;
+
+        std::size_t hash() const noexcept;
+    private:
+        static std::size_t calculate_hash(
+            basic_string_view<Char> str) noexcept;
+        static void debug_check_collisions(
+            std::size_t hash, basic_string_view<Char> str) noexcept;
+    private:
+        std::size_t hash_ = empty_hash();
+    };
+
+    template < typename Char >
+    void swap(basic_string_hash<Char>& l, basic_string_hash<Char>& r) noexcept;
+
+    template < typename Char >
+    bool operator<(basic_string_hash<Char> l, basic_string_hash<Char> r) noexcept;
+
+    template < typename Char >
+    bool operator==(basic_string_hash<Char> l, basic_string_hash<Char> r) noexcept;
+
+    template < typename Char >
+    bool operator!=(basic_string_hash<Char> l, basic_string_hash<Char> r) noexcept;
+}
+
 namespace e2d
 {
     str make_utf8(str_view src);
@@ -32,6 +81,11 @@ namespace e2d
     str32 make_utf32(str16_view src);
     str32 make_utf32(str32_view src);
 
+    str_hash make_hash(str_view src);
+    wstr_hash make_hash(wstr_view src);
+    str16_hash make_hash(str16_view src);
+    str32_hash make_hash(str32_view src);
+
     namespace strings
     {
         class format_error;
diff --git a/headers/enduro2d/utils/strings.inl b/headers/enduro2d/utils/strings.inl
index 3f942315..42410251 100644
--- a/headers/enduro2d/utils/strings.inl
+++ b/headers/enduro2d/utils/strings.inl
@@ -11,6 +11,176 @@
 #include "_utils.hpp"
 #include "strings.hpp"
 
+namespace e2d
+{
+    template < typename Char >
+    std::size_t basic_string_hash<Char>::empty_hash() noexcept {
+        static std::size_t hash = calculate_hash(basic_string_view<Char>());
+        return hash;
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>::basic_string_hash() noexcept = default;
+
+    template < typename Char >
+    basic_string_hash<Char>::~basic_string_hash() noexcept = default;
+
+    template < typename Char >
+    basic_string_hash<Char>::basic_string_hash(
+        basic_string_hash&& other) noexcept
+    {
+        assign(std::move(other));
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>& basic_string_hash<Char>::operator=(
+        basic_string_hash&& other) noexcept
+    {
+        return assign(std::move(other));
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>::basic_string_hash(
+        const basic_string_hash& other) noexcept
+    {
+        assign(other);
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>& basic_string_hash<Char>::operator=(
+        const basic_string_hash& other) noexcept
+    {
+        return assign(other);
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>::basic_string_hash(
+        basic_string_view<Char> str) noexcept
+    {
+        assign(str);
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>& basic_string_hash<Char>::assign(
+        basic_string_hash&& other) noexcept
+    {
+        if ( this != &other ) {
+            swap(other);
+            other.clear();
+        }
+        return *this;
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>& basic_string_hash<Char>::assign(
+        const basic_string_hash& other) noexcept
+    {
+        if ( this != &other ) {
+            hash_ = other.hash_;
+        }
+        return *this;
+    }
+
+    template < typename Char >
+    basic_string_hash<Char>& basic_string_hash<Char>::assign(
+        basic_string_view<Char> str) noexcept
+    {
+        hash_ = calculate_hash(str);
+        return *this;
+    }
+
+    template < typename Char >
+    void basic_string_hash<Char>::swap(basic_string_hash& other) noexcept {
+        using std::swap;
+        swap(hash_, other.hash_);
+    }
+
+    template < typename Char >
+    void basic_string_hash<Char>::clear() noexcept {
+        hash_ = empty_hash();
+    }
+
+    template < typename Char >
+    bool basic_string_hash<Char>::empty() const noexcept {
+        return hash_ == empty_hash();
+    }
+
+    template < typename Char >
+    std::size_t basic_string_hash<Char>::hash() const noexcept {
+        return hash_;
+    }
+
+    template < typename Char >
+    std::size_t basic_string_hash<Char>::calculate_hash(
+        basic_string_view<Char> str) noexcept
+    {
+        std::size_t hash = std::hash<basic_string_view<Char>>()(str);
+        debug_check_collisions(hash, str);
+        return hash;
+    }
+
+    template < typename Char >
+    void basic_string_hash<Char>::debug_check_collisions(
+        std::size_t hash, basic_string_view<Char> str) noexcept
+    {
+    #if defined(E2D_BUILD_MODE) && E2D_BUILD_MODE == E2D_BUILD_MODE_DEBUG
+        try {
+            static std::mutex mutex;
+            static hash_map<std::size_t, basic_string<Char>> table;
+            std::lock_guard<std::mutex> guard(mutex);
+            const auto iter = table.find(hash);
+            if ( iter != table.end() ) {
+                E2D_ASSERT_MSG(
+                    iter->second == str,
+                    "basic_string_hash: hash collision detected");
+            } else {
+                table.insert(std::make_pair(hash, str));
+            }
+        } catch (...) {
+            E2D_ASSERT_MSG(false, "basic_string_hash: unexpected exception");
+            throw;
+        }
+    #else
+        E2D_UNUSED(hash, str);
+    #endif
+    }
+}
+
+namespace e2d
+{
+    template < typename Char >
+    void swap(basic_string_hash<Char>& l, basic_string_hash<Char>& r) noexcept {
+        l.swap(r);
+    }
+
+    template < typename Char >
+    bool operator<(basic_string_hash<Char> l, basic_string_hash<Char> r) noexcept {
+        return l.hash() < r.hash();
+    }
+
+    template < typename Char >
+    bool operator==(basic_string_hash<Char> l, basic_string_hash<Char> r) noexcept {
+        return l.hash() == r.hash();
+    }
+
+    template < typename Char >
+    bool operator!=(basic_string_hash<Char> l, basic_string_hash<Char> r) noexcept {
+        return !(l == r);
+    }
+}
+
+namespace std
+{
+    template < typename Char >
+    struct hash<e2d::basic_string_hash<Char>>
+        : std::unary_function<e2d::basic_string_hash<Char>, std::size_t>
+    {
+        std::size_t operator()(e2d::basic_string_hash<Char> hs) const noexcept {
+            return hs.hash();
+        }
+    };
+}
+
 namespace e2d { namespace strings
 {
     //
diff --git a/sources/enduro2d/utils/strings.cpp b/sources/enduro2d/utils/strings.cpp
index 794e7689..412347e3 100644
--- a/sources/enduro2d/utils/strings.cpp
+++ b/sources/enduro2d/utils/strings.cpp
@@ -238,6 +238,26 @@ namespace e2d
             ? str32()
             : str32(src.cbegin(), src.cend());
     }
+
+    //
+    // make_hash
+    //
+
+    str_hash make_hash(str_view src) {
+        return str_hash(src);
+    }
+
+    wstr_hash make_hash(wstr_view src) {
+        return wstr_hash(src);
+    }
+
+    str16_hash make_hash(str16_view src) {
+        return str16_hash(src);
+    }
+
+    str32_hash make_hash(str32_view src) {
+        return str32_hash(src);
+    }
 }
 
 namespace e2d { namespace strings
diff --git a/untests/sources/untests_utils/strings.cpp b/untests/sources/untests_utils/strings.cpp
index 3e1cdb3d..03030de7 100644
--- a/untests/sources/untests_utils/strings.cpp
+++ b/untests/sources/untests_utils/strings.cpp
@@ -18,6 +18,45 @@ namespace
 }
 
 TEST_CASE("strings") {
+    {
+        REQUIRE(str_hash().empty());
+        REQUIRE(str_hash("").empty());
+        REQUIRE_FALSE(str_hash("1").empty());
+
+        REQUIRE(str_hash().hash() == str_hash().hash());
+        REQUIRE(str_hash().hash() == str_hash({null_utf8,0}).hash());
+        REQUIRE(str_hash().hash() == wstr_hash({null_wide,0}).hash());
+        REQUIRE(str_hash().hash() == str16_hash({null_utf16,0}).hash());
+        REQUIRE(str_hash().hash() == str32_hash({null_utf32,0}).hash());
+        REQUIRE(str_hash("hello").hash() == str_hash("hello").hash());
+        REQUIRE(str_hash("world").hash() == str_hash("world").hash());
+        REQUIRE(str_hash("hello").hash() != str_hash("world").hash());
+
+        REQUIRE(str_hash() == str_hash());
+        REQUIRE(str_hash() == make_hash({null_utf8,0}));
+        REQUIRE(wstr_hash() == make_hash({null_wide,0}));
+        REQUIRE(str16_hash() == make_hash({null_utf16,0}));
+        REQUIRE(str32_hash() == make_hash({null_utf32,0}));
+        REQUIRE(str_hash("hello") == make_hash("hello"));
+        REQUIRE(str_hash("world") == make_hash("world"));
+        REQUIRE(str_hash("hello") != make_hash("world"));
+
+        REQUIRE(str_hash("hello").assign("world") == make_hash("world"));
+        REQUIRE(str_hash("hello").assign(make_hash("world")) == make_hash("world"));
+        {
+            str_hash s("hello");
+            s.clear();
+            REQUIRE(s.empty());
+            REQUIRE(s == str_hash());
+        }
+        {
+            str_hash s1("hello");
+            str_hash s2("world");
+            s1.swap(s2);
+            REQUIRE(s2 == str_hash("hello"));
+            REQUIRE(s1 == make_hash("world"));
+        }
+    }
     {
         REQUIRE(make_utf8("hello") == "hello");
         REQUIRE(make_utf8(L"hello") == "hello");