Add buffer_protocol example and test

new_features/buffer_protocol/CMakeLists.txt

@@ -0,0 +1,66 @@
+CMAKE_MINIMUM_REQUIRED(VERSION 3.2)
+
+PROJECT(BufferProtocolTest CXX)
+
+FIND_PACKAGE(pybind11 CONFIG REQUIRED)
+
+SET(BINDING_PREFIX binding CACHE STRING "Binding subfolder name")
+
+# list of headers
+SET(HDR buffer_protocol.hpp)
+# list of source files
+SET(SRC )
+
+FIND_PROGRAM( BINDER binder HINTS ${CMAKE_CURRENT_SOURCE_DIR}/../../_build/source )
+
+SET(BINDING_PATH ${CMAKE_CURRENT_SOURCE_DIR}/${BINDING_PREFIX})
+
+SET( BINDING_CONFIG       ${CMAKE_CURRENT_SOURCE_DIR}/binding.cfg  CACHE FILEPATH "Binding config file")
+SET( BINDING_INCLUDE_FILE ${CMAKE_CURRENT_SOURCE_DIR}/includes.hpp CACHE FILEPATH "Binding include file")
+
+# Reconfigure if any of the listed files is modified
+SET_PROPERTY( DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS 
+	${BINDER}
+	${BINDING_CONFIG} 
+	${BINDING_INCLUDE_FILE} 
+	${HDR}
+	${BINDING_PATH}
+)
+
+# Run binder and generate binding files
+EXECUTE_PROCESS(
+	WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+	COMMAND ${CMAKE_COMMAND} -E make_directory ${BINDING_PREFIX}
+	COMMAND ${BINDER} -root-module ${CMAKE_PROJECT_NAME} --prefix ${BINDING_PREFIX}
+		--config ${BINDING_CONFIG} ${BINDING_INCLUDE_FILE} -- -std=c++17 -fPIC -fpermissive  -I${CMAKE_CURRENT_SOURCE_DIR}
+	COMMAND_ECHO STDOUT
+	OUTPUT_FILE ${CMAKE_PROJECT_NAME}.binder.out
+	ERROR_FILE ${CMAKE_PROJECT_NAME}.binder.log
+	RESULT_VARIABLE res
+)
+
+IF(NOT res EQUAL "0")
+	MESSAGE( FATAL_ERROR "Binder command line failed, logs in ${CMAKE_PROJECT_NAME}.binder.log")
+ENDIF()
+
+
+IF(EXISTS "${BINDING_PATH}/${CMAKE_PROJECT_NAME}.sources")
+	file(STRINGS ${BINDING_PATH}/${CMAKE_PROJECT_NAME}.sources BIND_SRC)
+	list(TRANSFORM BIND_SRC PREPEND "${BINDING_PREFIX}/")
+	MESSAGE(STATUS "BIND_SRC = ${BIND_SRC}")
+ENDIF()
+
+INCLUDE_DIRECTORIES(
+	${CMAKE_CURRENT_SOURCE_DIR}
+	${pybind11_INCLUDE_DIRS}
+)
+
+ADD_LIBRARY(${CMAKE_PROJECT_NAME} SHARED ${SRC} ${BIND_SRC} ${BINDING_INCLUDE_FILE} )
+
+# Don't add lib prefix
+SET_TARGET_PROPERTIES(${CMAKE_PROJECT_NAME} PROPERTIES PREFIX "")
+SET_TARGET_PROPERTIES(${CMAKE_PROJECT_NAME} PROPERTIES LINKER_LANGUAGE CXX)
+
+# Compilation flags
+TARGET_COMPILE_OPTIONS(${CMAKE_PROJECT_NAME} PRIVATE -w -std=c++17 -fPIC -fpermissive)
+

new_features/buffer_protocol/addon_Matrix.hpp

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+#include "buffer_protocol.hpp"
+#include <pybind11/pybind11.h>
+namespace py = pybind11;
+
+template<class T>
+void addon_Matrix(T &c)
+{
+	c.def_buffer([](buffer_protocol_example::Matrix &m) -> py::buffer_info {
+			return py::buffer_info(
+				m.data(),                               /* Pointer to buffer */
+				sizeof(float),                          /* Size of one scalar */
+				py::format_descriptor<float>::format(), /* Python struct-style format descriptor */
+				2,                                      /* Number of dimensions */
+				{ m.rows(), m.cols() },                 /* Buffer dimensions */
+				{ sizeof(float) * m.cols(),             /* Strides (in bytes) for each index */
+				sizeof(float) }
+			);
+		});
+}

new_features/buffer_protocol/binding.cfg

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+#
++namespace buffer_protocol_example
+
+# --- class 
++buffer_protocol buffer_protocol_example::Matrix
++include_for_class buffer_protocol_example::Matrix "addon_Matrix.hpp"
++add_on_binder buffer_protocol_example::Matrix addon_Matrix

new_features/buffer_protocol/buffer_protocol.hpp

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+
+#pragma once
+
+namespace buffer_protocol_example {
+
+	class Matrix {
+	public:
+		Matrix(int rows, int cols) : m_rows(rows), m_cols(cols) {
+			m_data = new float[rows*cols];
+			for(int i =0; i<rows*cols; i++) m_data[i] = 0;
+		}
+		float get(int i, int j) { return m_data[i*m_cols+j];}
+		float *data() { return m_data; }
+		int rows() const { return m_rows; }
+		int cols() const { return m_cols; }
+	private:
+		int m_rows, m_cols;
+		float *m_data;
+	};
+
+}
+
+

new_features/buffer_protocol/buffer_protocol.py

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+
+from _build import BufferProtocolTest
+import numpy as np
+m = BufferProtocolTest.buffer_protocol_example.Matrix(3,2)
+m1 = np.array(m, copy=False)
+m1[2,1] = 4
+assert m1[2,1] == m.get(2,1), "Failure: error in sharing data/buffer protocol for Matrix()"
+print("Success: Buffer protocol is working for Matrix class")

new_features/buffer_protocol/includes.hpp

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+
+#include <buffer_protocol.hpp>