Support empy3 and empy4

Signed-off-by: Alejandro Hernández Cordero <ahcorde@gmail.com>

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