Make ISlangFileSystem derive from ICastable (#2386)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Make ISlangFileSystem derive from ICastable.

* Make ArchiveFileSystem into an interface
Make file systems atomically reference counted.

* Small fix.

* Some small fixes to work around issues of ICastable on ISlangFileSystem

* Use ISlangFileSystem derived type instead of IArchiveFileSystem. Can always get other interface with castAs.

* Some small fixes around change of interface returned from archive type functions.

* Remove CacheFileSystem member from linkage. Can access easily from m_fileSystemExt if necessary with as cast.

* Fix RiffFileSystem casting issue.

* Add a check around CacheFileSystem.

1 files changed, 19 insertions, 1 deletions

diff --git a/source/slang/slang-workspace-version.cpp b/source/slang/slang-workspace-version.cpp
index ebfe9218a..914393320 100644
--- a/source/slang/slang-workspace-version.cpp
+++ b/source/slang/slang-workspace-version.cpp
@@ -348,15 +348,33 @@ WorkspaceVersion* Workspace::createVersionForCompletion()
         ContentAssistCheckingMode::Completion;
     return currentCompletionVersion.Ptr();
 }
+
+void* Workspace::getObject(const Guid& uuid)
+{
+    SLANG_UNUSED(uuid);
+    return nullptr;
+}
+
 void* Workspace::getInterface(const Guid& uuid)
 {
-    if (uuid == ISlangUnknown::getTypeGuid() || uuid == ISlangFileSystem::getTypeGuid())
+    if (uuid == ISlangUnknown::getTypeGuid() || 
+        uuid == ISlangCastable::getTypeGuid() ||
+        uuid == ISlangFileSystem::getTypeGuid())
     {
         return static_cast<ISlangFileSystem*>(this);
     }
     return nullptr;
 }
 
+void* Workspace::castAs(const Guid& guid)
+{
+    if (auto ptr = getInterface(guid))
+    {
+        return ptr;
+    }
+    return getObject(guid);
+}
+
 void DocumentVersion::setText(const String& newText)
 {
     text = newText;