Add (and ignore for now) type assertions to QML

You can write "(something as Foo)" to give hints to any tools that you
expect something to be a Foo at this place. This is not a conversion and
ignored at runtime for now. Eventually the compiler will verify that the
type assertions are plausible and error out if they aren't.

Change-Id: I21c8705bb387f7ab2cbc153293dbf477663afe87
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 15 insertions, 0 deletions

diff --git a/src/qml/parser/qqmljs.g b/src/qml/parser/qqmljs.g
index f7b528ce13..ea105e7e22 100644
--- a/src/qml/parser/qqmljs.g
+++ b/src/qml/parser/qqmljs.g
@@ -2513,6 +2513,20 @@ RelationalExpression_In: RelationalExpression_In T_IN ShiftExpression;
     } break;
 ./
 
+TypeAssertExpression_In: RelationalExpression_In T_AS Type;
+/.  case $rule_number: Q_FALLTHROUGH(); ./
+TypeAssertExpression: RelationalExpression T_AS Type;
+/.
+    case $rule_number: {
+        AST::BinaryExpression *node = new (pool) AST::BinaryExpression(sym(1).Expression, QSOperator::As, sym(3).Expression);
+        node->operatorToken = loc(2);
+        sym(1).Node = node;
+    } break;
+./
+
+RelationalExpression_In: TypeAssertExpression_In;
+RelationalExpression: TypeAssertExpression;
+
 EqualityExpression_In: RelationalExpression_In;
 EqualityExpression: RelationalExpression;
 
diff --git a/src/qml/parser/qqmljsast_p.h b/src/qml/parser/qqmljsast_p.h
index fcf9933e67..bc0a467f40 100644
--- a/src/qml/parser/qqmljsast_p.h
+++ b/src/qml/parser/qqmljsast_p.h
@@ -104,6 +104,7 @@ enum Op {
     URShift,
     InplaceURightShift,
     InplaceXor,
+    As,
     Invalid
 };