Export python bindings

INSTALL

@@ -23,3 +23,6 @@ then either choose path a or b:
    $ make export
    this produces a tarball with a Libint library that can be unpacked, configured, and compiled elsewhere.
 
+Python:
+ $ cmake -DPYTHON_EXECUTABLE=`which python3` -DLIBINT2_PYTHON=ON .
+ $ cd python && make -j2 libint2-python

export/Makefile

@@ -104,3 +104,4 @@ exportdir::
 	echo "set(LIBINT2_LIBRARY_CXX_SRC" > $(TOPDIR)/$(EXPORTDIR)/srclist.cmake
 	ls $(TOPDIR)/$(EXPORTDIR)/src >> $(TOPDIR)/$(EXPORTDIR)/srclist.cmake
 	echo ")" >> $(TOPDIR)/$(EXPORTDIR)/srclist.cmake
+	cp -rap $(SRCTOPDIR)/python $(TOPDIR)/$(EXPORTDIR)/

export/cmake/CMakeLists.txt.export

@@ -32,6 +32,7 @@ redefaultable_option(REQUIRE_CXX_API "C++11 Libint interface" ON)
 redefaultable_option(ENABLE_FORTRAN "Fortran03+ Libint interface" OFF)
 redefaultable_option(ENABLE_MPFR "Use GNU MPFR library for high-precision testing (EXPERTS ONLY)" OFF)
 redefaultable_option(LIBINT2_BUILD_SHARED_AND_STATIC_LIBS "Build in one shot static and shared library variants. Uses -fPIC." OFF)
+redefaultable_option(LIBINT2_PYTHON "Python bindings" OFF)
 if (NOT LIBINT2_REALTYPE)
     set(LIBINT2_REALTYPE double)
 endif()
@@ -187,7 +188,7 @@ if (NOT CMAKE_CXX_EXTENSIONS)
   set_target_properties(libint2_obj PROPERTIES CXX_EXTENSIONS OFF)
 endif(NOT CMAKE_CXX_EXTENSIONS)
 
-if(BUILD_SHARED_LIBS OR LIBINT2_BUILD_SHARED_AND_STATIC_LIBS)
+if(BUILD_SHARED_LIBS OR LIBINT2_BUILD_SHARED_AND_STATIC_LIBS OR LIBINT2_PYTHON)
   set_target_properties(libint2_obj PROPERTIES POSITION_INDEPENDENT_CODE ON)
 endif()
 
@@ -508,3 +509,19 @@ feature_summary(WHAT ALL
 # appendix: misc details
 ###############################################################################
 SET(CMAKE_COLOR_MAKEFILE ON)
+
+if (LIBINT2_PYTHON)
+  add_subdirectory(python)
+  target_compile_definitions(
+    libint2-python
+    PRIVATE
+    __COMPILING_LIBINT2
+    )
+  target_include_directories(
+    libint2-python
+    PRIVATE
+    ${PROJECT_SOURCE_DIR}/include
+    ${PROJECT_BINARY_DIR}/include
+    ${EIGEN3_INCLUDE_DIR}
+    )
+endif()

python/CMakeLists.txt

@@ -6,10 +6,10 @@ set(CMAKE_CXX_STANDARD 17)
 add_compile_options(-Wall)
 
 if (TARGET libint2_obj)
-  set(python_libint2_target libint2_obj)
+  set(libint2_python_target libint2_obj)
 else()
   find_package(Libint2 REQUIRED)
-  set(python_libint2_target Libint2::cxx)
+  set(libint2_python_target Libint2::cxx)
 endif()
 
 include(FetchContent)
@@ -23,7 +23,12 @@ FetchContent_MakeAvailable(pybind11)
 
 #find_package(Eigen3 3.3 REQUIRED)
 
-pybind11_add_module(libint2-python MODULE src/libint2/_libint2.cc src/libint2/engine.cc)
+pybind11_add_module(
+  libint2-python MODULE
+  EXCLUDE_FROM_ALL
+  src/libint2/_libint2.cc
+  src/libint2/engine.cc
+  )
 
 set_target_properties(
   libint2-python
@@ -32,7 +37,7 @@ set_target_properties(
   OUTPUT_NAME _libint2
   )
 
-target_link_libraries(libint2-python PUBLIC ${python_libint2_target})
+target_link_libraries(libint2-python PUBLIC ${libint2_python_target})
 
 # if (Eigen3::Eigen)
 #   target_link_libraries(libint2-python INTERFACE Eigen3::Eigen)
@@ -48,7 +53,7 @@ enable_testing()
 
 # add the executable
 add_test(
-  NAME test_libint
+  NAME libint2-python
   COMMAND ${PYTHON_EXECUTABLE} -m setup test
   WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
   )

python/src/libint2/_libint2.cc

@@ -1,5 +1,4 @@
 #include <libint2.hpp>
-#include <libint2/libint2_params.h>
 #include <libint2/chemistry/sto3g_atomic_density.h>
 #include <Eigen/Dense>
 #include <tuple>