Implement audio::concat effect

libs/audio/include/psemek/audio/effect/concat.hpp

@@ -0,0 +1,12 @@
+#pragma once
+
+#include <psemek/audio/stream.hpp>
+
+#include <vector>
+
+namespace psemek::audio
+{
+
+	stream_ptr concat(std::vector<stream_ptr> streams);
+
+}

libs/audio/source/effect/concat.cpp

@@ -0,0 +1,70 @@
+#include <psemek/audio/effect/concat.hpp>
+
+#include <atomic>
+
+namespace psemek::audio
+{
+
+	namespace
+	{
+
+		struct concat_impl
+			: stream
+		{
+			concat_impl(std::vector<stream_ptr> streams)
+				: streams_(std::move(streams))
+			{
+				length_ = 0;
+				for (auto const & stream : streams_)
+				{
+					if (auto length = stream->length())
+						*length_ += *length;
+					else
+					{
+						length_ = std::nullopt;
+						break;
+					}
+				}
+			}
+
+			std::optional<std::size_t> length() const override
+			{
+				return length_;
+			}
+
+			std::size_t read(float * data, std::size_t sample_count) override
+			{
+				std::size_t count = 0;
+
+				for (; index_ != streams_.size(); ++index_)
+				{
+					count += streams_[index_]->read(data + count, sample_count - count);
+					if (count == sample_count)
+						break;
+				}
+
+				played_.fetch_add(count);
+
+				return count;
+			}
+
+			std::size_t played() const override
+			{
+				return played_;
+			}
+
+		private:
+			std::vector<stream_ptr> streams_;
+			std::optional<std::size_t> length_;
+			std::atomic<std::size_t> played_{0};
+			std::size_t index_{0};
+		};
+
+	}
+
+	stream_ptr concat(std::vector<stream_ptr> streams)
+	{
+		return std::make_shared<concat_impl>(std::move(streams));
+	}
+
+}