4 files changed, 107 insertions, 7 deletions
diff --git a/bsie/utils/__init__.py b/bsie/utils/__init__.py
index 3981dc7..9cb60ed 100644
--- a/bsie/utils/__init__.py
+++ b/bsie/utils/__init__.py
@@ -4,21 +4,24 @@ Part of the bsie module.
 A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
-# imports
+# standard imports
 import typing
 
 # inner-module imports
 from . import bsfs
+from . import filematcher
 from . import namespaces as ns
 from . import node
-from . import filematcher
+from .loading import safe_load, unpack_qualified_name
 
 # exports
 __all__: typing.Sequence[str] = (
-    'filematcher',
     'bsfs',
+    'filematcher',
     'node',
     'ns',
+    'safe_load',
+    'unpack_qualified_name',
     )
 
 ## EOF ##
diff --git a/bsie/utils/errors.py b/bsie/utils/errors.py
new file mode 100644
index 0000000..5fafd5b
--- /dev/null
+++ b/bsie/utils/errors.py
@@ -0,0 +1,45 @@
+"""Common BSIE exceptions.
+
+Part of the bsie module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# imports
+import typing
+
+# exports
+__all__: typing.Sequence[str] = (
+    'BuilderError',
+    'ExtractorError',
+    'LoaderError',
+    'ReaderError',
+    )
+
+
+## code ##
+
+class _BSIEError(Exception):
+    """Generic BSIE error."""
+
+class BuilderError(_BSIEError):
+    """The Builder failed to create an instance."""
+
+class LoaderError(BuilderError):
+    """Failed to load a module or class."""
+
+class ExtractorError(_BSIEError):
+    """The Extractor failed to process the given content."""
+
+class ReaderError(_BSIEError):
+    """The Reader failed to read the given file."""
+
+class ProgrammingError(_BSIEError):
+    """An assertion-like error that indicates a code-base issue."""
+
+class UnreachableError(ProgrammingError):
+    """Bravo, you've reached a point in code that should logically not be reachable."""
+
+class ParserError(_BSIEError):
+    """Failed to parse due to invalid syntax or structures."""
+
+## EOF ##
diff --git a/bsie/utils/filematcher/parser.py b/bsie/utils/filematcher/parser.py
index 0654742..2f82875 100644
--- a/bsie/utils/filematcher/parser.py
+++ b/bsie/utils/filematcher/parser.py
@@ -7,16 +7,14 @@ Author: Matthias Baumgartner, 2021
 # standard imports
 import typing
 
-# non-standard imports
+# external imports
 import pyparsing
 from pyparsing import printables, alphas8bit, punc8bit, QuotedString, Word, \
                       delimitedList, Or, CaselessKeyword, Group, oneOf, Optional
 
-# bsie imports
-from bsie.base import errors
-
 # inner-module imports
 from . import matcher
+from .. import errors
 
 # exports
 __all__: typing.Sequence[str] = (
diff --git a/bsie/utils/loading.py b/bsie/utils/loading.py
new file mode 100644
index 0000000..eb05c35
--- /dev/null
+++ b/bsie/utils/loading.py
@@ -0,0 +1,54 @@
+"""
+
+Part of the bsie module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import importlib
+import typing
+
+# inner-module imports
+from . import errors
+
+# exports
+__all__: typing.Sequence[str] = (
+    'safe_load',
+    'unpack_qualified_name',
+    )
+
+
+## code ##
+
+def safe_load(module_name: str, class_name: str):
+    """Get a class from a module. Raise BuilderError if anything goes wrong."""
+    try:
+        # load the module
+        module = importlib.import_module(module_name)
+    except Exception as err:
+        # cannot import module
+        raise errors.LoaderError(f'cannot load module {module_name}') from err
+
+    try:
+        # get the class from the module
+        cls = getattr(module, class_name)
+    except Exception as err:
+        # cannot find the class
+        raise errors.LoaderError(f'cannot load class {class_name} from module {module_name}') from err
+
+    return cls
+
+
+def unpack_qualified_name(name):
+    """Split a name into its module and class component (dot-separated)."""
+    if not isinstance(name, str):
+        raise TypeError(name)
+    if '.' not in name:
+        raise ValueError('name must be a qualified class name.')
+    module_name, class_name = name[:name.rfind('.')], name[name.rfind('.')+1:]
+    if module_name == '':
+        raise ValueError('name must be a qualified class name.')
+    return module_name, class_name
+
+
+## EOF ##