Refactor buffers_prefix:

* Tidy up tests
* Increase code coverage
* Correct behavior for default constructed iterators

CHANGELOG.md

@@ -6,6 +6,7 @@ Version 200
 * Refactor buffers_adaptor
 * Refactor buffers_range
 * Fix and refactor buffers_cat
+* Refactor buffers_prefix
 
 API Changes:
 

include/boost/beast/core/buffers_prefix.hpp

@@ -11,8 +11,8 @@
 #define BOOST_BEAST_BUFFERS_PREFIX_HPP
 
 #include <boost/beast/core/detail/config.hpp>
+#include <boost/beast/core/buffer_traits.hpp>
 #include <boost/beast/core/type_traits.hpp>
-#include <boost/asio/buffer.hpp>
 #include <boost/optional/optional.hpp> // for in_place_init_t
 #include <algorithm>
 #include <cstdint>
@@ -49,13 +49,19 @@ class buffers_prefix_view
         std::size_t dist);
 
 public:
-    /// The type for each element in the list of buffers.
+    /** The type for each element in the list of buffers.
-    using value_type = typename std::conditional<
+
-        std::is_convertible<typename
+        If the type of the underlying sequence is a mutable buffer
-            std::iterator_traits<iter_type>::value_type,
+        sequence, then `value_type` is `net::mutable_buffer`. Otherwise,
-                net::mutable_buffer>::value,
+        `value_type` is `net::const_buffer`.
-                    net::mutable_buffer,
+
-                        net::const_buffer>::type;
+        @see buffers_type
+    */
+#if BOOST_BEAST_DOXYGEN
+    using value_type = __see_below__;
+#else
+    using value_type = buffers_type<ConstBufferSequence>;
+#endif
 
 #if BOOST_BEAST_DOXYGEN
     /// A bidirectional iterator type that may be used to read elements.

include/boost/beast/core/impl/buffers_prefix.hpp

@@ -26,7 +26,7 @@ class buffers_prefix_view<Buffers>::const_iterator
     friend class buffers_prefix_view<Buffers>;
 
     buffers_prefix_view const* b_ = nullptr;
-    std::size_t remain_;
+    std::size_t remain_ = 0;
     iter_type it_;
 
 public:
@@ -49,20 +49,7 @@ public:
     bool
     operator==(const_iterator const& other) const
     {
-        return
+        return b_ == other.b_ && it_ == other.it_;
-            (b_ == nullptr) ?
-            (
-                other.b_ == nullptr ||
-                other.it_ == other.b_->end_
-            ):(
-                (other.b_ == nullptr) ?
-                (
-                    it_ == b_->end_
-                ): (
-                    b_ == other.b_ &&
-                    it_ == other.it_
-                )
-            );
     }
 
     bool
@@ -111,7 +98,8 @@ public:
     }
 
 private:
-    const_iterator(buffers_prefix_view const& b,
+    const_iterator(
+        buffers_prefix_view const& b,
         std::true_type)
         : b_(&b)
         , remain_(b.remain_)
@@ -119,7 +107,8 @@ private:
     {
     }
 
-    const_iterator(buffers_prefix_view const& b,
+    const_iterator(
+        buffers_prefix_view const& b,
         std::false_type)
         : b_(&b)
         , remain_(b_->size_)
@@ -222,18 +211,22 @@ buffers_prefix_view(
 
 template<class Buffers>
 auto
-buffers_prefix_view<Buffers>::begin() const ->
+buffers_prefix_view<Buffers>::
+begin() const ->
     const_iterator
 {
-    return const_iterator{*this, std::false_type{}};
+    return const_iterator{
+        *this, std::false_type{}};
 }
 
 template<class Buffers>
 auto
-buffers_prefix_view<Buffers>::end() const ->
+buffers_prefix_view<Buffers>::
+end() const ->
     const_iterator
 {
-    return const_iterator{*this, std::true_type{}};
+    return const_iterator{
+        *this, std::true_type{}};
 }
 
 template<class Buffers>

test/beast/core/buffer_test.hpp

@@ -205,6 +205,7 @@ void test_mutable_buffers(
 {
     using net::buffer_size;
     string_view src = "Hello, world!";
+    BOOST_ASSERT(buffer_size(b) <= src.size());
     if(src.size() > buffer_size(b))
         src = {src.data(), buffer_size(b)};
     net::buffer_copy(b, net::const_buffer(

test/beast/core/buffers_prefix.cpp

@@ -10,11 +10,11 @@
 // Test that header file is self-contained.
 #include <boost/beast/core/buffers_prefix.hpp>
 
-#include <boost/beast/core/buffers_suffix.hpp>
+#include "buffer_test.hpp"
+
 #include <boost/beast/core/buffers_to_string.hpp>
 #include <boost/beast/core/type_traits.hpp>
 #include <boost/beast/_experimental/unit_test/suite.hpp>
-#include <boost/asio/buffer.hpp>
 #include <string>
 
 namespace boost {
@@ -23,109 +23,19 @@ namespace beast {
 class buffers_prefix_test : public beast::unit_test::suite
 {
 public:
-    template<class ConstBufferSequence>
+    void
-    static
+    testBufferSequence()
-    std::size_t
-    bsize1(ConstBufferSequence const& bs)
     {
-        std::size_t n = 0;
+        char buf[13];
-        for(auto it = bs.begin(); it != bs.end(); ++it)
+        auto const b =
-            n += net::buffer_size(*it);
+            buffers_triple(buf, sizeof(buf));
-        return n;
+        for(std::size_t i = 1; i <= sizeof(buf); ++i)
+            test_buffer_sequence(*this,
+                buffers_prefix(i, b));
     }
 
-    template<class ConstBufferSequence>
+    void
-    static
+    testInPlaceInit()
-    std::size_t
-    bsize2(ConstBufferSequence const& bs)
-    {
-        std::size_t n = 0;
-        for(auto it = bs.begin(); it != bs.end(); it++)
-            n += net::buffer_size(*it);
-        return n;
-    }
-
-    template<class ConstBufferSequence>
-    static
-    std::size_t
-    bsize3(ConstBufferSequence const& bs)
-    {
-        std::size_t n = 0;
-        for(auto it = bs.end(); it != bs.begin();)
-            n += net::buffer_size(*--it);
-        return n;
-    }
-
-    template<class ConstBufferSequence>
-    static
-    std::size_t
-    bsize4(ConstBufferSequence const& bs)
-    {
-        std::size_t n = 0;
-        for(auto it = bs.end(); it != bs.begin();)
-        {
-            it--;
-            n += net::buffer_size(*it);
-        }
-        return n;
-    }
-
-    template<class BufferType>
-    void testMatrix()
-    {
-        using net::buffer_size;
-        std::string s = "Hello, world";
-        BEAST_EXPECT(s.size() == 12);
-        for(std::size_t x = 1; x < 4; ++x) {
-        for(std::size_t y = 1; y < 4; ++y) {
-        std::size_t z = s.size() - (x + y);
-        {
-            std::array<BufferType, 3> bs{{
-                BufferType{&s[0], x},
-                BufferType{&s[x], y},
-                BufferType{&s[x+y], z}}};
-            for(std::size_t i = 0; i <= s.size() + 1; ++i)
-            {
-                auto pb = buffers_prefix(i, bs);
-                BEAST_EXPECT(buffers_to_string(pb) == s.substr(0, i));
-                auto pb2 = pb;
-                BEAST_EXPECT(buffers_to_string(pb2) == buffers_to_string(pb));
-                pb = buffers_prefix(0, bs);
-                pb2 = pb;
-                BEAST_EXPECT(buffer_size(pb2) == 0);
-                pb2 = buffers_prefix(i, bs);
-                BEAST_EXPECT(buffers_to_string(pb2) == s.substr(0, i));
-            }
-        }
-        }}
-    }
-
-    void testEmptyBuffers()
-    {
-        using net::buffer_size;
-
-        auto pb0 = buffers_prefix(0, net::mutable_buffer{});
-        BEAST_EXPECT(buffer_size(pb0) == 0);
-        auto pb1 = buffers_prefix(1, net::mutable_buffer{});
-        BEAST_EXPECT(buffer_size(pb1) == 0);
-        BEAST_EXPECT(net::buffer_copy(pb0, pb1) == 0);
-
-#if 0
-        using pb_type = decltype(pb0);
-        buffers_suffix<pb_type> cb(pb0);
-        BEAST_EXPECT(buffer_size(cb) == 0);
-        BEAST_EXPECT(net::buffer_copy(cb, pb1) == 0);
-        cb.consume(1);
-        BEAST_EXPECT(buffer_size(cb) == 0);
-        BEAST_EXPECT(net::buffer_copy(cb, pb1) == 0);
-
-        auto pbc = buffers_prefix(2, cb);
-        BEAST_EXPECT(buffer_size(pbc) == 0);
-        BEAST_EXPECT(net::buffer_copy(pbc, cb) == 0);
-#endif
-    }
-
-    void testInPlaceInit()
     {
         {
             class test_buffers
@@ -166,6 +76,7 @@ public:
                 2, boost::in_place_init, c, sizeof(c));
             BEAST_EXPECT(buffer_size(v) == 2);
         }
+
         {
             char c[2];
             buffers_prefix_view<net::mutable_buffer> v(
@@ -174,56 +85,56 @@ public:
         }
     }
 
-    void testIterators()
+    template<class BufferType>
+    void
+    testPrefixes()
     {
-        char b[3];
+        using net::buffer_size;
-        std::array<net::const_buffer, 3> bs{{
+        std::string s = "Hello, world";
-            net::const_buffer{&b[0], 1},
+        BEAST_EXPECT(s.size() == 12);
-            net::const_buffer{&b[1], 1},
+        for(std::size_t x = 1; x < 4; ++x) {
-            net::const_buffer{&b[2], 1}}};
+        for(std::size_t y = 1; y < 4; ++y) {
-        auto pb = buffers_prefix(2, bs);
+        {
-        BEAST_EXPECT(bsize1(pb) == 2);
+            std::size_t z = s.size() - (x + y);
-        BEAST_EXPECT(bsize2(pb) == 2);
+            std::array<BufferType, 3> bs{{
-        BEAST_EXPECT(bsize3(pb) == 2);
+                BufferType{&s[0], x},
-        BEAST_EXPECT(bsize4(pb) == 2);
+                BufferType{&s[x], y},
+                BufferType{&s[x+y], z}}};
+            for(std::size_t i = 0; i <= s.size() + 1; ++i)
+            {
+                auto pb = buffers_prefix(i, bs);
+                BEAST_EXPECT(buffers_to_string(pb) == s.substr(0, i));
+                auto pb2 = pb;
+                BEAST_EXPECT(buffers_to_string(pb2) == buffers_to_string(pb));
+                pb = buffers_prefix(0, bs);
+                pb2 = pb;
+                BEAST_EXPECT(buffer_size(pb2) == 0);
+                pb2 = buffers_prefix(i, bs);
+                BEAST_EXPECT(buffers_to_string(pb2) == s.substr(0, i));
+            }
+        }
+        } }
+    }
+
+    void testEmpty()
+    {
+        using net::buffer_size;
+
+        auto pb0 = buffers_prefix(0, net::mutable_buffer{});
+        BEAST_EXPECT(buffer_size(pb0) == 0);
+        auto pb1 = buffers_prefix(1, net::mutable_buffer{});
+        BEAST_EXPECT(buffer_size(pb1) == 0);
+        BEAST_EXPECT(net::buffer_copy(pb0, pb1) == 0);
     }
 
     void
-    testDefaultIterators()
+    run() override
     {
-        // default ctor is one past the end
+        testBufferSequence();
-        char b[3];
-        std::array<net::const_buffer, 3> bs{{
-            net::const_buffer{&b[0], 1},
-            net::const_buffer{&b[1], 1},
-            net::const_buffer{&b[2], 1}}};
-        auto pb = buffers_prefix(2, bs);
-        decltype(pb)::const_iterator it;
-        BEAST_EXPECT(pb.end() == it);
-        BEAST_EXPECT(it == pb.end());
-        decltype(pb)::const_iterator it2;
-        BEAST_EXPECT(it == it2);
-        BEAST_EXPECT(it2 == it);
-        it = pb.end();
-        it2 = pb.end();
-        BEAST_EXPECT(it == it2);
-        BEAST_EXPECT(it2 == it);
-        decltype(pb)::const_iterator it3(it2);
-        BEAST_EXPECT(it3 == it2);
-        it = pb.begin();
-        BEAST_EXPECT(it != it3);
-        it = it3;
-        BEAST_EXPECT(it == it3);
-    }
-
-    void run() override
-    {
-        testMatrix<net::const_buffer>();
-        testMatrix<net::mutable_buffer>();
-        testEmptyBuffers();
         testInPlaceInit();
-        testIterators();
+        testPrefixes<net::const_buffer>();
-        testDefaultIterators();
+        testPrefixes<net::mutable_buffer>();
+        testEmpty();
     }
 };