expressions: Validate lookup expressions

blueprintcompiler/language/expression.py

@@ -50,12 +50,26 @@ class IdentExpr(AstNode):
     def is_this(self):
         return self.parent_by_type(Scope).this_name == self.tokens["ident"]
 
+    @validate()
+    def exists(self):
+        if self.is_this:
+            return
+
+        scope = self.parent_by_type(Scope)
+        if self.tokens["ident"] not in scope.variables:
+            raise CompileError(
+                f"Could not find object with ID '{self.tokens['ident']}'",
+                did_you_mean=(self.tokens['ident'], scope.variables.keys()),
+            )
+
     @property
     def gir_type(self):
+        scope = self.parent_by_type(Scope)
+
         if self.is_this:
-            return self.parent_by_type(Scope).this_type
-        else:
-            return None
+            return scope.this_type
+        elif self.tokens["ident"] in scope.variables:
+            return scope.variables[self.tokens["ident"]].gir_class
 
     def emit_xml(self, xml: XmlEmitter):
         if self.is_this:
@@ -93,7 +107,21 @@ class LookupOp(InfixExpr):
 
     @property
     def gir_type(self):
-        return None
+        if parent_type := self.lhs.gir_type:
+            if prop := parent_type.properties.get(self.tokens["property"]):
+                return prop.type
+
+    @validate("property")
+    def property_exists(self):
+        if parent_type := self.lhs.gir_type:
+            if not (isinstance(parent_type, gir.Class) or isinstance(parent_type, gir.Interface)):
+                raise CompileError(f"Type {parent_type.full_name} does not have properties")
+            elif self.tokens["property"] not in parent_type.properties:
+                raise CompileError(
+                    f"{parent_type.full_name} does not have a property called {self.tokens['property']}",
+                    hints=["Do you need to cast the previous expression?"],
+                    did_you_mean=(self.tokens['property'], parent_type.properties.keys()),
+                )
 
     def emit_xml(self, xml: XmlEmitter):
         if isinstance(self.lhs, IdentExpr) and self.lhs.is_this:

tests/sample_errors/expr_lookup_prop.blp

@@ -0,0 +1,9 @@
+using Gtk 4.0;
+
+Box {
+  Label label {
+    visible: bind label.parent.something;
+    margin-start: bind label.margin-start.other;
+    label: bind nothing.parent.label;
+  }
+}

tests/sample_errors/expr_lookup_prop.err

@@ -0,0 +1,3 @@
+5,32,9,Gtk.Widget does not have a property called something
+6,43,5,Type int does not have properties
+7,17,7,Could not find object with ID 'nothing'

tests/samples/expr_closure.ui

@@ -10,7 +10,7 @@
     <binding name="visible-child">
       <lookup name="parent" type="GtkButton">
         <closure function="my_closure" type="GtkButton">
-          <lookup name="parent">
+          <lookup name="parent" type="GtkBox">
             <constant>box</constant>
           </lookup>
         </closure>

tests/samples/expr_lookup.blp

@@ -5,5 +5,5 @@ Overlay {
 }
 
 Label {
-  label: bind ((Label) label.parent.child).label;
+  label: bind ((Label) ((Overlay) label.parent).child).label;
 }

tests/samples/expr_lookup.ui

@@ -9,8 +9,8 @@
   <object class="GtkLabel">
     <binding name="label">
       <lookup name="label" type="GtkLabel">
-        <lookup name="child">
-          <lookup name="parent">
+        <lookup name="child" type="GtkOverlay">
+          <lookup name="parent" type="GtkLabel">
             <constant>label</constant>
           </lookup>
         </lookup>

tests/samples/lambda.ui

@@ -8,7 +8,7 @@
   </object>
   <object class="GtkBoolFilter">
     <property name="expression">
-      <lookup name="invert">
+      <lookup name="invert" type="GtkBoolFilter">
         <constant>filter</constant>
       </lookup>
     </property>

tests/test_samples.py

@@ -187,6 +187,7 @@ class TestSamples(unittest.TestCase):
         self.assert_sample_error("duplicates")
         self.assert_sample_error("empty")
         self.assert_sample_error("enum_member_dne")
+        self.assert_sample_error("expr_lookup_prop")
         self.assert_sample_error("filters_in_non_file_filter")
         self.assert_sample_error("gtk_3")
         self.assert_sample_error("gtk_exact_version")