From ebb0e70b8de7186cb3a908bfda7c769a6bf0e9f5 Mon Sep 17 00:00:00 2001
From: Michael Vandeberg <mvandeberg@users.noreply.github.com>
Date: Fri, 15 May 2026 14:55:37 -0600
Subject: [PATCH] Migrate burl example to capy post-#262 buffer API
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

cppalliance/capy#262 removes the `slice_of<>` class template and the
slice CPOs (`prefix`, etc.). The `burl` example's `any_stream`
type-erasure used both:

- The virtual `async_write_some`/`async_read_some` signatures took
  `capy::slice_of<boost::span<capy::const_buffer const>>`/`mutable`
  parameters.
- The outer rate-limited templates used `capy::prefix(buffers, n)`
  to limit each underlying call to the remaining byte budget.

Migration:

- Change the virtual signatures to take the underlying
  `boost::span<X const>` directly, plus a `std::size_t max_bytes`
  parameter carrying the byte budget. The implementation wraps the
  span in `capy::buffer_slice(span, 0, max_bytes)` and forwards
  `s.data()` to the inner stream.
- The outer templates pass `buffers, wr_remain_` / `buffers,
  rd_remain_` directly through the virtual; the slicing happens
  on the receiving side.
- Replace the `<boost/capy/buffers/slice.hpp>` include with
  `<boost/capy/buffers/buffer_slice.hpp>`.

The `burl` example remains disabled in CMake (pre-existing — its
asio dependency requires a `boost::asio::any_completion_handler.hpp`
that isn't in the pinned asio build). This migration keeps the
source in sync with the new capy API so it can be re-enabled when
the asio dependency is resolved.
---
 example/client/burl/any_stream.hpp | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/example/client/burl/any_stream.hpp b/example/client/burl/any_stream.hpp
index ed13e94d..c5a7be84 100644
--- a/example/client/burl/any_stream.hpp
+++ b/example/client/burl/any_stream.hpp
@@ -16,7 +16,7 @@
 #include <boost/asio/coroutine.hpp>
 #include <boost/asio/immediate.hpp>
 #include <boost/asio/steady_timer.hpp>
-#include <boost/capy/buffers/slice.hpp>
+#include <boost/capy/buffers/buffer_slice.hpp>
 #include <boost/core/span.hpp>
 #include <boost/http/parser.hpp>
 #include <boost/http/serializer.hpp>
@@ -56,20 +56,26 @@ class any_stream
 
             virtual void
             async_write_some(
-                const capy::slice_of<boost::span<capy::const_buffer const>>& buffers,
+                boost::span<capy::const_buffer const> buffers,
+                std::size_t max_bytes,
                 asio::any_completion_handler<void(error_code, std::size_t)>
                     handler) override
             {
-                stream_.async_write_some(buffers, std::move(handler));
+                auto s = capy::buffer_slice(buffers, 0, max_bytes);
+                stream_.async_write_some(
+                    s.data(), std::move(handler));
             }
 
             virtual void
             async_read_some(
-                const capy::slice_of<boost::span<capy::mutable_buffer const>>& buffers,
+                boost::span<capy::mutable_buffer const> buffers,
+                std::size_t max_bytes,
                 asio::any_completion_handler<void(error_code, std::size_t)>
                     handler) override
             {
-                stream_.async_read_some(buffers, std::move(handler));
+                auto s = capy::buffer_slice(buffers, 0, max_bytes);
+                stream_.async_read_some(
+                    s.data(), std::move(handler));
             }
 
             virtual void
@@ -153,7 +159,7 @@ class any_stream
                         }
                         BOOST_ASIO_CORO_YIELD
                         stream_->async_write_some(
-                            capy::prefix(buffers, wr_remain_),
+                            buffers, wr_remain_,
                             std::move(self));
                         wr_remain_ -= n;
                         self.complete(ec, n);
@@ -191,7 +197,7 @@ class any_stream
                         }
                         BOOST_ASIO_CORO_YIELD
                         stream_->async_read_some(
-                            capy::prefix(buffers, rd_remain_),
+                            buffers, rd_remain_,
                             std::move(self));
                         rd_remain_ -= n;
                         self.complete(ec, n);
@@ -226,12 +232,14 @@ class any_stream
 
         virtual void
         async_write_some(
-            const capy::slice_of<boost::span<capy::const_buffer const>>&,
+            boost::span<capy::const_buffer const>,
+            std::size_t,
             asio::any_completion_handler<void(error_code, std::size_t)>) = 0;
 
         virtual void
         async_read_some(
-            const capy::slice_of<boost::span<capy::mutable_buffer const>>&,
+            boost::span<capy::mutable_buffer const>,
+            std::size_t,
             asio::any_completion_handler<void(error_code, std::size_t)>) = 0;
 
         virtual void async_shutdown(