Add lookup expressions

blueprintcompiler/language/__init__.py

@@ -2,6 +2,7 @@
 templates. """
 
 from .attributes import BaseAttribute, BaseTypedAttribute
+from .expression import Expr
 from .gobject_object import Object, ObjectContent
 from .gobject_property import Property
 from .gobject_signal import Signal

blueprintcompiler/language/expression.py

@@ -0,0 +1,63 @@
+# expressions.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 *
+
+
+expr = Pratt()
+
+
+class Expr(AstNode):
+    grammar = expr
+
+    def emit_xml(self, xml: XmlEmitter):
+        self.children[-1].emit_xml(xml)
+
+
+class InfixExpr(AstNode):
+    @property
+    def lhs(self):
+        children = list(self.parent_by_type(Expr).children)
+        return children[children.index(self) - 1]
+
+
+class IdentExpr(AstNode):
+    grammar = UseIdent("ident")
+
+    def emit_xml(self, xml: XmlEmitter):
+        xml.start_tag("constant")
+        xml.put_text(self.tokens["ident"])
+        xml.end_tag()
+
+
+class LookupOp(InfixExpr):
+    grammar = [".", UseIdent("property")]
+
+    def emit_xml(self, xml: XmlEmitter):
+        xml.start_tag("lookup", name=self.tokens["property"])
+        self.lhs.emit_xml(xml)
+        xml.end_tag()
+
+
+expr.children = [
+    Prefix(IdentExpr),
+    Prefix(["(", Expr, ")"]),
+    Infix(10, LookupOp),
+]

blueprintcompiler/language/gobject_property.py

@@ -18,6 +18,7 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
 
+from .expression import Expr
 from .gobject_object import Object
 from .gtkbuilder_template import Template
 from .values import Value, TranslatedStringValue
@@ -26,19 +27,27 @@ from .common import *
 
 class Property(AstNode):
     grammar = AnyOf(
-        Statement(
+        [
             UseIdent("name"),
             ":",
             Keyword("bind"),
-            UseIdent("bind_source").expected("the ID of a source object to bind from"),
+            UseIdent("bind_source"),
             ".",
-            UseIdent("bind_property").expected("a property name to bind from"),
+            UseIdent("bind_property"),
             ZeroOrMore(AnyOf(
                 ["no-sync-create", UseLiteral("no_sync_create", True)],
                 ["inverted", UseLiteral("inverted", True)],
                 ["bidirectional", UseLiteral("bidirectional", True)],
                 Match("sync-create").warn("sync-create is deprecated in favor of no-sync-create"),
             )),
+            ";",
+        ],
+        Statement(
+            UseIdent("name"),
+            UseLiteral("binding", True),
+            ":",
+            "bind",
+            Expr,
         ),
         Statement(
             UseIdent("name"),
@@ -154,7 +163,13 @@ class Property(AstNode):
             self.children[Object][0].emit_xml(xml)
             xml.end_tag()
         elif value is None:
-            xml.put_self_closing("property", **props)
+            if self.tokens["binding"]:
+                xml.start_tag("binding", **props)
+                for x in self.children:
+                    x.emit_xml(xml)
+                xml.end_tag()
+            else:
+                xml.put_self_closing("property", **props);
         else:
             xml.start_tag("property", **props)
             value.emit_xml(xml)