From 75d2c7ee774831213f292158779e7992163dcbdd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Hern=C3=A1ndez=20Cordero?= <ahcorde@gmail.com>
Date: Wed, 31 Jul 2024 17:48:30 +0200
Subject: [PATCH] Support empy3 and empy4
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Alejandro Hernández Cordero <ahcorde@gmail.com>
---
 colcon_core/shell/template/__init__.py | 66 +++++++++++++++++++-------
 1 file changed, 49 insertions(+), 17 deletions(-)

diff --git a/colcon_core/shell/template/__init__.py b/colcon_core/shell/template/__init__.py
index 508fc43e..a4293a42 100644
--- a/colcon_core/shell/template/__init__.py
+++ b/colcon_core/shell/template/__init__.py
@@ -3,20 +3,26 @@
 
 from io import StringIO
 import os
-
 from colcon_core.logging import colcon_logger
+from packaging import version
 try:
     from em import Configuration
     from em import Interpreter
+    import em
 except ImportError as e:
     try:
-        import em  # noqa: F401
-    except ImportError:
-        e.msg += " The Python package 'empy' must be installed"
+        from em import Interpreter
+        from em import OVERRIDE_OPT
+        import em
+    except ImportError as e:
+        try:
+            import em  # noqa: F401
+        except ImportError:
+            e.msg += " The Python package 'empy' must be installed"
+            raise e from None
+        e.msg += " The Python package 'empy' must be installed and 'em' must " \
+            'not be installed since both packages share the same namespace'
         raise e from None
-    e.msg += " The Python package 'empy' must be installed and 'em' must " \
-        'not be installed since both packages share the same namespace'
-    raise e from None
 
 logger = colcon_logger.getChild(__name__)
 
@@ -35,14 +41,24 @@ def expand_template(template_path, destination_path, data):
     output = StringIO()
     interpreter = None
     try:
-        config = Configuration(
-            defaultRoot=str(template_path),
-            defaultStdout=output,
-            useProxy=False)
-        interpreter = CachingInterpreter(config=config, dispatcher=False)
+
+        if version.parse(em.__version__) >= version.parse('4.0.0'):
+            config = Configuration(
+                defaultRoot=str(template_path),
+                defaultStdout=output,
+                useProxy=False)
+            interpreter = CachingInterpreter(config=config, dispatcher=False)
+        else:
+            # disable OVERRIDE_OPT to avoid saving / restoring stdout
+            interpreter = CachingInterpreter(
+                output=output, options={OVERRIDE_OPT: False})
         with template_path.open('r') as h:
             content = h.read()
-        interpreter.string(content, locals=data)
+        if version.parse(em.__version__) >= version.parse('4.0.0'):
+            interpreter.string(content, locals=data)
+        else:
+            interpreter.string(content, str(template_path), locals=data)
+
         output = output.getvalue()
     except Exception as e:  # noqa: F841
         logger.error(
@@ -63,8 +79,20 @@ def expand_template(template_path, destination_path, data):
 
 cached_tokens = {}
 
+empy_inheritance = None
+if version.parse(em.__version__) >= version.parse('4.0.0'):
+    empy_inheritance = Interpreter
+else:
+    class BypassStdoutInterpreter(Interpreter):
+        """Interpreter for EmPy which keeps `stdout` unchanged."""
+
+        def installProxy(self):  # noqa: D102 N802
+            # avoid replacing stdout with ProxyFile
+            pass
+
+    empy_inheritance = BypassStdoutInterpreter
 
-class CachingInterpreter(Interpreter):
+class CachingInterpreter(empy_inheritance):
     """Interpreter for EmPy which which caches parsed tokens."""
 
     def parse(self, scanner, locals=None):  # noqa: A002 D102
@@ -86,6 +114,10 @@ def parse(self, scanner, locals=None):  # noqa: A002 D102
         self.invoke('atParse', scanner=scanner, locals=locals)
         for token in tokens:
             self.invoke('atToken', token=token)
-            self.run(token, locals)
-            scanner.accumulate()
-        return True
+            if version.parse(em.__version__) >= version.parse('4.0.0'):
+                self.run(token, locals)
+                scanner.accumulate()
+            else:
+                token.run(self, locals)
+        if version.parse(em.__version__) >= version.parse('4.0.0'):
+            return True