Proper view interface for utf_view and grapheme_view

gershnik · Jan 7, 2025 · 0b68469 · 0b68469
1 parent 835945b
commit 0b68469
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Showing 5 changed files with 106 additions and 5 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -7,7 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Added
 
-- `grapheme_view` which provides ability to iterate over grapheme clusters in `sys_string` and any UTF range.
+- `grapheme_view` and `graphemes` adapter which provide ability to iterate over grapheme clusters in `sys_string` and any UTF range.
 
 ### Changed
 

diff --git a/lib/inc/sys_string/grapheme_view.h b/lib/inc/sys_string/grapheme_view.h
@@ -114,9 +114,6 @@ namespace sysstr
         using pointer = typename iterator::pointer;
         using const_pointer = pointer;
 
-        // static const bool borrowed = (ViewType == byref) || 
-        //                                 (ViewType == byval && std::ranges::borrowed_range<range>);
-
     public:
         grapheme_view(const Range & src) noexcept(noexcept(range(src))) :
             m_src(src)
@@ -150,6 +147,15 @@ namespace sysstr
         SYS_STRING_FORCE_INLINE std::default_sentinel_t crend() const requires(is_reversible)
             { return rend(); }
 
+        bool empty() const
+            { return std::ranges::empty(m_src); }
+        explicit operator bool() const
+            { return !std::ranges::empty(m_src); }
+        decltype(auto) front() const
+            { return *this->begin();}
+        decltype(auto) back() const requires(is_reversible)
+            { return *this->rbegin();}
+
         reverse_iterator reverse(iterator it) const requires(is_reversible)
             { return reverse_iterator(it, std::ranges::rend(m_src)); }
 

diff --git a/lib/inc/sys_string/utf_view.h b/lib/inc/sys_string/utf_view.h
@@ -289,7 +289,7 @@ namespace sysstr
             SYS_STRING_FORCE_INLINE static auto range_ref(const range * src) -> const range &
                 { return *src; }
 
-            static constexpr bool is_reversible = ranges::reverse_traversable_range<std::remove_reference_t<range>>;
+            static constexpr bool is_reversible = ranges::reverse_traversable_range<range>;
             static constexpr auto source_encoding = utf_encoding_of<std::ranges::range_value_t<range>>;
 
             using access_iterator = decltype(std::ranges::begin(range_ref(std::declval<stored_type>())));
@@ -358,6 +358,15 @@ namespace sysstr
             SYS_STRING_FORCE_INLINE std::default_sentinel_t crend() const requires(is_reversible)
                 { return rend(); }
 
+            bool empty() const requires(std::ranges::forward_range<Range>)
+                { return std::ranges::empty(range_ref(m_src)); }
+            explicit operator bool() const requires(std::ranges::forward_range<Range>)
+                { return !std::ranges::empty(m_src); }
+            decltype(auto) front() const requires(std::ranges::forward_range<Range>)
+                { return *this->begin();}
+            decltype(auto) back() const requires(is_reversible)
+                { return *this->rbegin();}
+
             reverse_iterator reverse(iterator it) const requires(is_reversible)
                 { return reverse_iterator(it, std::ranges::rend(range_ref(m_src))); }
 

diff --git a/test/test_grapheme.cpp b/test/test_grapheme.cpp
@@ -149,4 +149,29 @@ TEST_CASE("ranges") {
     check_graphemes_reverse_range(as_utf32("ab"s), {U"a", U"b"});
 }
 
+TEST_CASE("view interface") {
+
+    auto view = graphemes("abc"s);
+
+    CHECK(view);
+    CHECK(!view.empty());
+    auto fr = view.front();
+    CHECK(fr.size() == 1);
+    CHECK(fr.front() == 'a');
+    auto bc = view.back();
+    CHECK(bc.size() == 1);
+    CHECK(bc.front() == 'c');
+
+    CHECK(view.begin() == view.cbegin());
+    static_assert(std::is_same_v<decltype(view.end()), std::default_sentinel_t>);
+    static_assert(std::is_same_v<decltype(view.cend()), std::default_sentinel_t>);
+    CHECK(view.rbegin() == view.crbegin());
+    static_assert(std::is_same_v<decltype(view.rend()), std::default_sentinel_t>);
+    static_assert(std::is_same_v<decltype(view.crend()), std::default_sentinel_t>);
+
+    auto empty_view = graphemes(""s);
+    CHECK(!empty_view);
+    CHECK(empty_view.empty());
+}
+
 }
diff --git a/test/test_utf_iteration.cpp b/test/test_utf_iteration.cpp
@@ -750,6 +750,67 @@ TEST_CASE( "Ranges" ) {
     CHECK(std::ranges::equal(std::vector({u'a', u'b', u'c'}) | as_utf8, std::array{'a', 'b', 'c'}));
 }
 
+TEST_CASE("view interface") {
+
+    {
+        auto view = as_utf32("abc"s);
+
+        CHECK(view);
+        CHECK(!view.empty());
+        CHECK(view.front() == U'a');
+        CHECK(view.back() == U'c');
+
+        CHECK(view.begin() == view.cbegin());
+        static_assert(std::is_same_v<decltype(view.end()), std::default_sentinel_t>);
+        static_assert(std::is_same_v<decltype(view.cend()), std::default_sentinel_t>);
+        CHECK(view.rbegin() == view.crbegin());
+        static_assert(std::is_same_v<decltype(view.rend()), std::default_sentinel_t>);
+        static_assert(std::is_same_v<decltype(view.crend()), std::default_sentinel_t>);
+
+        auto empty_view = as_utf32(""s);
+        CHECK(!empty_view);
+        CHECK(empty_view.empty());
+    }
+    {
+        auto view = as_utf16("abc"s);
+
+        CHECK(view);
+        CHECK(!view.empty());
+        CHECK(view.front() == u'a');
+        CHECK(view.back() == u'c');
+
+        CHECK(view.begin() == view.cbegin());
+        static_assert(std::is_same_v<decltype(view.end()), std::default_sentinel_t>);
+        static_assert(std::is_same_v<decltype(view.cend()), std::default_sentinel_t>);
+        CHECK(view.rbegin() == view.crbegin());
+        static_assert(std::is_same_v<decltype(view.rend()), std::default_sentinel_t>);
+        static_assert(std::is_same_v<decltype(view.crend()), std::default_sentinel_t>);
+
+        auto empty_view = as_utf32(""s);
+        CHECK(!empty_view);
+        CHECK(empty_view.empty());
+    }
+    {
+        auto view = as_utf8("abc"s);
+
+        CHECK(view);
+        CHECK(!view.empty());
+        CHECK(view.front() == 'a');
+        CHECK(view.back() == 'c');
+
+        CHECK(view.begin() == view.cbegin());
+        static_assert(std::is_same_v<decltype(view.end()), std::default_sentinel_t>);
+        static_assert(std::is_same_v<decltype(view.cend()), std::default_sentinel_t>);
+        CHECK(view.rbegin() == view.crbegin());
+        static_assert(std::is_same_v<decltype(view.rend()), std::default_sentinel_t>);
+        static_assert(std::is_same_v<decltype(view.crend()), std::default_sentinel_t>);
+
+        auto empty_view = as_utf32(""s);
+        CHECK(!empty_view);
+        CHECK(empty_view.empty());
+    }
+}
+
 #endif
 
 }