lsp: Code cleanup

gtkblueprinttool/ast_utils.py

@@ -0,0 +1,90 @@
+# ast_utils.py
+#
+# Copyright 2021 James Westman <james@jwestman.net>
+#
+# This file is free software; you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation; either version 3 of the
+# License, or (at your option) any later version.
+#
+# This file is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+from .errors import *
+
+class Validator:
+    def __init__(self, func, token_name=None, end_token_name=None):
+        self.func = func
+        self.token_name = token_name
+        self.end_token_name = end_token_name
+
+    def __get__(self, instance, owner):
+        if instance is None:
+            return self
+
+        key = "_validation_result_" + self.func.__name__
+
+        if key + "_err" in instance.__dict__:
+            # If the validator has failed before, raise a generic Exception.
+            # We want anything that depends on this validation result to
+            # fail, but not report the exception twice.
+            raise AlreadyCaughtError()
+
+        if key not in instance.__dict__:
+            try:
+                instance.__dict__[key] = self.func(instance)
+            except CompileError as e:
+                # Mark the validator as already failed so we don't print the
+                # same message again
+                instance.__dict__[key + "_err"] = True
+
+                # This mess of code sets the error's start and end positions
+                # from the tokens passed to the decorator, if they have not
+                # already been set
+                if self.token_name is not None and e.start is None:
+                    group = instance.group.tokens.get(self.token_name)
+                    if self.end_token_name is not None and group is None:
+                        group = instance.group.tokens[self.end_token_name]
+                    e.start = group.start
+                if (self.token_name is not None or self.end_token_name is not None) and e.end is None:
+                    e.end = instance.group.tokens[self.end_token_name or self.token_name].end
+
+                # Re-raise the exception
+                raise e
+
+        # Return the validation result (which other validators, or the code
+        # generation phase, might depend on)
+        return instance.__dict__[key]
+
+
+def validate(*args, **kwargs):
+    """ Decorator for functions that validate an AST node. Exceptions raised
+    during validation are marked with range information from the tokens. Also
+    creates a cached property out of the function. """
+
+    def decorator(func):
+        return Validator(func, *args, **kwargs)
+
+    return decorator
+
+
+class Docs:
+    def __init__(self, func, token_name=None):
+        self.func = func
+        self.token_name = token_name
+
+
+def docs(*args, **kwargs):
+    """ Decorator for functions that return documentation for tokens. """
+
+    def decorator(func):
+        return Docs(func, *args, **kwargs)
+
+    return decorator