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/language/gobject_signal.py

@@ -0,0 +1,101 @@
+# gobject_signal.py
+#
+# Copyright 2022 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 .common import *
+
+
+class Signal(AstNode):
+    grammar = Statement(
+        UseIdent("name"),
+        Optional([
+            "::",
+            UseIdent("detail_name").expected("a signal detail name"),
+        ]),
+        "=>",
+        UseIdent("handler").expected("the name of a function to handle the signal"),
+        Match("(").expected("argument list"),
+        Optional(UseIdent("object")).expected("object identifier"),
+        Match(")").expected(),
+        ZeroOrMore(AnyOf(
+            [Keyword("swapped"), UseLiteral("swapped", True)],
+            [Keyword("after"), UseLiteral("after", True)],
+        )),
+    )
+
+
+    @property
+    def gir_signal(self):
+        if self.gir_class is not None:
+            return self.gir_class.signals.get(self.tokens["name"])
+
+
+    @property
+    def gir_class(self):
+        return self.parent.parent.gir_class
+
+
+    @validate("name")
+    def signal_exists(self):
+        if self.gir_class is None:
+            # Objects that we have no gir data on should not be validated
+            # This happens for classes defined by the app itself
+            return
+
+        if isinstance(self.parent.parent, Template):
+            # If the signal is part of a template, it might be defined by
+            # the application and thus not in gir
+            return
+
+        if self.gir_signal is None:
+            raise CompileError(
+                f"Class {self.gir_class.full_name} does not contain a signal called {self.tokens['name']}",
+                did_you_mean=(self.tokens["name"], self.gir_class.signals.keys())
+            )
+
+
+    @validate("object")
+    def object_exists(self):
+        object_id = self.tokens["object"]
+        if object_id is None:
+            return
+
+        if self.root.objects_by_id.get(object_id) is None:
+            raise CompileError(
+                f"Could not find object with ID '{object_id}'"
+            )
+
+
+    @docs("name")
+    def signal_docs(self):
+        if self.gir_signal is not None:
+            return self.gir_signal.doc
+
+
+    def emit_xml(self, xml: XmlEmitter):
+        name = self.tokens["name"]
+        if self.tokens["detail_name"]:
+            name += "::" + self.tokens["detail_name"]
+        xml.put_self_closing(
+            "signal",
+            name=name,
+            handler=self.tokens["handler"],
+            swapped="true" if self.tokens["swapped"] else None,
+            object=self.tokens["object"]
+        )