Reorganize the parser/AST code

The code is now organized by syntax: `menu {}` in one file, `style` in
another, etc. This should make it easier to add syntax in the future.

gtkblueprinttool/completions_utils.py

@@ -0,0 +1,73 @@
+# completions_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
+
+
+import typing as T
+
+from . import ast
+from .tokenizer import Token, TokenType
+from .lsp_utils import Completion
+
+
+new_statement_patterns = [
+    [(TokenType.OPEN_BLOCK, None)],
+    [(TokenType.CLOSE_BLOCK, None)],
+    [(TokenType.STMT_END, None)],
+]
+
+
+def applies_to(*ast_types):
+    """ Decorator describing which AST nodes the completer should apply in. """
+    def decorator(func):
+        for c in ast_types:
+            c.completers.append(func)
+        return func
+    return decorator
+
+def completer(applies_in: T.List, matches: T.List=[]):
+    def decorator(func):
+        def inner(prev_tokens: T.List[Token], ast_node: ast.AstNode):
+            any_match = len(matches) == 0
+            match_variables: T.List[str] = []
+
+            for pattern in matches:
+                match_variables = []
+
+                if len(pattern) <= len(prev_tokens):
+                    for i in range(0, len(pattern)):
+                        type, value = pattern[i]
+                        token = prev_tokens[i - len(pattern)]
+                        if token.type != type or (value is not None and str(token) != value):
+                            break
+                        if value is None:
+                            match_variables.append(str(token))
+                    else:
+                        any_match = True
+                        break
+
+            if not any_match:
+                return
+
+            yield from func(ast_node, match_variables)
+
+        for c in applies_in:
+            c.completers.append(inner)
+        return inner
+
+    return decorator