From a11ef24b13e9a909e7728c7887f7c394b23624a5 Mon Sep 17 00:00:00 2001
From: BORDEU Felipe <felipe.bordeu@safrangroup.com>
Date: Mon, 2 Dec 2024 18:01:41 +0100
Subject: [PATCH] Support use of system eigen

---
 eigency/__init__.py |  8 ++++++--
 setup.py            | 35 +++++++++++++++++++++++------------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/eigency/__init__.py b/eigency/__init__.py
index 64eced0..7d49738 100644
--- a/eigency/__init__.py
+++ b/eigency/__init__.py
@@ -1,14 +1,18 @@
 import os.path
-from importlib.resources import as_file, files
 
 import numpy as np
 
-__eigen_dir__ = (files(__name__) / "eigen").__str__()
+
+def get_eigency_eigen_dir():
+    from importlib.resources import files
+
+    return (files(__name__) / "eigen").__str__()
 
 
 def get_includes(include_eigen=True):
     root = os.path.dirname(__file__)
     path = [root, np.get_include()]
     if include_eigen:
+        __eigen_dir__ = get_eigency_eigen_dir()
         path.append(os.path.join(root, __eigen_dir__))
     return path
diff --git a/setup.py b/setup.py
index 63d8d9f..97a2f61 100644
--- a/setup.py
+++ b/setup.py
@@ -8,12 +8,18 @@
 
 sys.path.append(".")
 
-import eigency  # noqa: E402
-
 __package_name__ = "eigency"
-__eigen_dir__ = eigency.__eigen_dir__
-__eigen_lib_dir__ = join(basename(__eigen_dir__), "Eigen")
+include_dirs = [np.get_include()]
+if "EIGEN_INC" in os.environ:
+    useSystemEigen = True
+    include_dirs.append(os.environ["EIGEN_INC"])
+else:
+    useSystemEigen = False
+    import eigency  # noqa: E402
 
+    __eigen_dir__ = eigency.get_eigency_eigen_dir()
+    __eigen_lib_dir__ = join(basename(__eigen_dir__), "Eigen")
+    include_dirs.append(__eigen_dir__)
 # Not all users may have cython installed.  If they only want this as a means
 # to access the Eigen header files to compile their own C++ code, then they
 # may not have cython already installed.  Therefore, only require cython
@@ -37,14 +43,14 @@
     Extension(
         "eigency.conversions",
         ["eigency/conversions" + ext],
-        include_dirs=[np.get_include(), __eigen_dir__],
+        include_dirs=include_dirs,
         language="c++",
         define_macros=[("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION")],
     ),
     Extension(
         "eigency.core",
         ["eigency/core" + ext],
-        include_dirs=[np.get_include(), __eigen_dir__],
+        include_dirs=include_dirs,
         language="c++",
         define_macros=[("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION")],
     ),
@@ -61,10 +67,15 @@
 long_description = open("README.md").read()
 
 eigen_data_files = []
-for root, dirs, files in os.walk(join(__eigen_dir__, "Eigen")):
-    for f in files:
-        if f.endswith(".h"):
-            eigen_data_files.append(join(root, f))
+
+exclude_package_data = {}
+if not useSystemEigen:
+    for root, dirs, files in os.walk(join(__eigen_dir__, "Eigen")):
+        for f in files:
+            if f.endswith(".h"):
+                eigen_data_files.append(join(root, f))
+    eigen_data_files.append(join(__eigen_lib_dir__, "*"))
+    exclude_package_data = {__package_name__: [join(__eigen_lib_dir__, "CMakeLists.txt")]}
 
 setup(
     name=__package_name__,
@@ -79,6 +90,6 @@
         ],
     ),
     include_package_data=True,
-    package_data={__package_name__: ["*.h", "*.pxd", "*.pyx", join(__eigen_lib_dir__, "*")] + eigen_data_files},
-    exclude_package_data={__package_name__: [join(__eigen_lib_dir__, "CMakeLists.txt")]},
+    package_data={__package_name__: ["*.h", "*.pxd", "*.pyx"] + eigen_data_files},
+    exclude_package_data=exclude_package_data,
 )