Accept string literals for parseable types

GtkBuilder knows some class-specific parsing methods, so we can use
string literals for these types and pass them straight to the XML.

gtkblueprinttool/ast.py

@@ -376,7 +376,7 @@ class LiteralValue(Value):
             try:
                 int(self.tokens["value"])
             except:
-                raise CompileError(f"Cannot convert {self.tokens['value']} to integer")
+                raise CompileError(f"Cannot convert {self.group.tokens['value']} to integer")
 
         elif isinstance(type, gir.UIntType):
             try:
@@ -384,19 +384,31 @@ class LiteralValue(Value):
                 if int(self.tokens["value"]) < 0:
                     raise Exception()
             except:
-                raise CompileError(f"Cannot convert {self.tokens['value']} to unsigned integer")
+                raise CompileError(f"Cannot convert {self.group.tokens['value']} to unsigned integer")
 
         elif isinstance(type, gir.FloatType):
             try:
                 float(self.tokens["value"])
             except:
-                raise CompileError(f"Cannot convert {self.tokens['value']} to float")
+                raise CompileError(f"Cannot convert {self.group.tokens['value']} to float")
 
         elif isinstance(type, gir.StringType):
             pass
 
+        elif isinstance(type, gir.Class) or isinstance(type, gir.Interface):
+            parseable_types = [
+                "Gdk.Paintable",
+                "Gdk.Texture",
+                "Gdk.Pixbuf",
+                "GLib.File",
+                "Gtk.ShortcutTrigger",
+                "Gtk.ShortcutAction",
+            ]
+            if type.full_name not in parseable_types:
+                raise CompileError(f"Cannot convert {self.group.tokens['value']} to {type.full_name}")
+
         elif type is not None:
-            raise CompileError(f"Cannot convert {self.tokens['value']} to {type.full_name}")
+            raise CompileError(f"Cannot convert {self.group.tokens['value']} to {type.full_name}")
 
 
 class Flag(AstNode):

tests/samples/parseable.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+Gtk.Shortcut {
+  trigger: "Escape";
+}

tests/samples/parseable.ui

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <object class="GtkShortcut">
+    <property name="trigger">Escape</property>
+  </object>
+</interface>

tests/test_samples.py

@@ -104,6 +104,7 @@ class TestSamples(unittest.TestCase):
         self.assert_sample("layout")
         self.assert_sample("menu")
         self.assert_sample("object_prop")
+        self.assert_sample("parseable")
         self.assert_sample("property")
         self.assert_sample("signal")
         self.assert_sample("size_group")