language: Add expression literals

Add expression literals, so you can set properties of type
Gtk.Expression.

tests/sample_errors/expr_item_not_cast.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+BoolFilter {
+  expression: expr item.visible;
+}

tests/sample_errors/expr_item_not_cast.err

@@ -0,0 +1 @@
+4,20,4,"item" must be cast to its object type

tests/sample_errors/expr_value_assignment.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+Label {
+  label: expr 1;
+}

tests/sample_errors/expr_value_assignment.err

@@ -0,0 +1 @@
+4,10,4,Cannot convert Gtk.Expression to string

tests/sample_errors/expr_value_closure_arg.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+BoolFilter {
+  expression: expr $closure(item as <Entry>) as <bool>;
+}

tests/sample_errors/expr_value_closure_arg.err

@@ -0,0 +1 @@
+4,29,4,"item" can only be used for looking up properties

tests/sample_errors/expr_value_item.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+BoolFilter {
+  expression: expr item as <Label>;
+}

tests/sample_errors/expr_value_item.err

@@ -0,0 +1 @@
+4,20,4,"item" can only be used for looking up properties

tests/samples/bind_expr_prop.blp

@@ -0,0 +1,9 @@
+using Gtk 4.0;
+
+BoolFilter filter1 {
+  expression: expr true;
+}
+
+BoolFilter filter2 {
+  expression: bind filter1.expression;
+}

tests/samples/bind_expr_prop.ui

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <object class="GtkBoolFilter" id="filter1">
+    <property name="expression">
+      <constant type="gboolean">true</constant>
+    </property>
+  </object>
+  <object class="GtkBoolFilter" id="filter2">
+    <property name="expression" bind-source="filter1" bind-property="expression" bind-flags="sync-create"/>
+  </object>
+</interface>

tests/samples/bind_literal.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+Label {
+  label: bind "Hello, world!";
+}

tests/samples/bind_literal.ui

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <object class="GtkLabel">
+    <binding name="label">
+      <constant type="gchararray">Hello, world!</constant>
+    </binding>
+  </object>
+</interface>

tests/samples/expr_value.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+BoolFilter {
+  expression: expr item as <Entry>.visible;
+}

tests/samples/expr_value.ui

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <object class="GtkBoolFilter">
+    <property name="expression">
+      <lookup name="visible" type="GtkEntry"></lookup>
+    </property>
+  </object>
+</interface>

tests/samples/expr_value_closure.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+BoolFilter {
+  expression: expr $closure(item as <Entry>.visible) as <bool>;
+}

tests/samples/expr_value_closure.ui

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <object class="GtkBoolFilter">
+    <property name="expression">
+      <closure function="closure" type="gboolean">
+        <lookup name="visible" type="GtkEntry"></lookup>
+      </closure>
+    </property>
+  </object>
+</interface>

tests/samples/expr_value_literal.blp

@@ -0,0 +1,5 @@
+using Gtk 4.0;
+
+BoolFilter {
+  expression: expr true;
+}

tests/samples/expr_value_literal.ui

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <object class="GtkBoolFilter">
+    <property name="expression">
+      <constant type="gboolean">true</constant>
+    </property>
+  </object>
+</interface>

tests/test_samples.py

@@ -198,6 +198,7 @@ class TestSamples(unittest.TestCase):
                 "adw_breakpoint_template",
                 "expr_closure",
                 "expr_closure_args",
+                "expr_value_closure",
                 "parseable",
                 "signal",
                 "signal_not_swapped",