reorganization: Rename extensions -> language

I want all language elements to be defined in the same folder, rather
than having the "core" language split by parsing/AST/completions and the rest
split by language element.

blueprintcompiler/extensions/gtk_size_group.py

@@ -1,76 +0,0 @@
-# gtk_size_group.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 .. import ast
-from ..ast_utils import AstNode, validate
-from ..completions_utils import *
-from ..lsp_utils import Completion, CompletionItemKind
-from ..parse_tree import *
-from ..parser_utils import *
-from ..xml_emitter import XmlEmitter
-
-
-class Widget(AstNode):
-    grammar = UseIdent("name")
-
-    @validate("name")
-    def obj_widget(self):
-        object = self.root.objects_by_id.get(self.tokens["name"])
-        type = self.root.gir.get_type("Widget", "Gtk")
-        if object is None:
-            raise CompileError(
-                f"Could not find object with ID {self.tokens['name']}",
-                did_you_mean=(self.tokens['name'], self.root.objects_by_id.keys()),
-            )
-        elif object.gir_class and not object.gir_class.assignable_to(type):
-            raise CompileError(
-                f"Cannot assign {object.gir_class.full_name} to {type.full_name}"
-            )
-
-    def emit_xml(self, xml: XmlEmitter):
-        xml.put_self_closing("widget", name=self.tokens["name"])
-
-
-class Widgets(AstNode):
-    grammar = [
-        Keyword("widgets"),
-        "[",
-        Delimited(Widget, ","),
-        "]",
-    ]
-
-    @validate("widgets")
-    def container_is_size_group(self):
-        self.validate_parent_type("Gtk", "SizeGroup", "size group properties")
-
-    def emit_xml(self, xml: XmlEmitter):
-        xml.start_tag("widgets")
-        for child in self.children:
-            child.emit_xml(xml)
-        xml.end_tag()
-
-
-@completer(
-    applies_in=[ast.ObjectContent],
-    applies_in_subclass=("Gtk", "SizeGroup"),
-    matches=new_statement_patterns,
-)
-def size_group_completer(ast_node, match_variables):
-    yield Completion("widgets", CompletionItemKind.Snippet, snippet="widgets [$0]")