LibJS: Implement parsing and evaluation for AssignmentPatterns

e.g. `[...foo] = bar` can now be evaluated :^)

1 files changed, 3 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/SourceRange.h b/Userland/Libraries/LibJS/SourceRange.h
index 936863ecc7..b92208dc32 100644
--- a/Userland/Libraries/LibJS/SourceRange.h
+++ b/Userland/Libraries/LibJS/SourceRange.h
@@ -13,9 +13,12 @@ namespace JS {
 struct Position {
     size_t line { 0 };
     size_t column { 0 };
+    size_t offset { 0 };
 };
 
 struct SourceRange {
+    [[nodiscard]] bool contains(Position const& position) const { return position.offset <= end.offset && position.offset >= start.offset; }
+
     StringView filename;
     Position start;
     Position end;