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, 52 insertions, 12 deletions

diff --git a/source/core/slang-file-system.cpp b/source/core/slang-file-system.cpp
index 208c4d834..283dab712 100644
--- a/source/core/slang-file-system.cpp
+++ b/source/core/slang-file-system.cpp
@@ -7,14 +7,14 @@
 namespace Slang
 {
 
-// Allocate static const storage for the various interface IDs that the Slang API needs to expose
-
 SLANG_FORCE_INLINE static SlangResult _checkExt(FileSystemStyle style) { return Index(style) >= Index(FileSystemStyle::Ext) ? SLANG_OK : SLANG_E_NOT_IMPLEMENTED; }
 SLANG_FORCE_INLINE static SlangResult _checkMutable(FileSystemStyle style) { return Index(style) >= Index(FileSystemStyle::Mutable) ? SLANG_OK : SLANG_E_NOT_IMPLEMENTED; }
 
 SLANG_FORCE_INLINE static bool _canCast(FileSystemStyle style, const Guid& guid)
 {
-    if (guid == ISlangUnknown::getTypeGuid() || guid == ISlangFileSystem::getTypeGuid())
+    if (guid == ISlangUnknown::getTypeGuid() ||
+        guid == ISlangCastable::getTypeGuid() ||
+        guid == ISlangFileSystem::getTypeGuid())
     {
         return true;
     }
@@ -81,11 +81,26 @@ static SlangResult _calcCombinedPath(SlangPathType fromPathType, const char* fro
 /* static */OSFileSystem OSFileSystem::g_ext(FileSystemStyle::Ext);
 /* static */OSFileSystem OSFileSystem::g_mutable(FileSystemStyle::Mutable);
 
+void* OSFileSystem::castAs(const Guid& guid)
+{
+    if (auto ptr = getInterface(guid))
+    {
+        return ptr;
+    }
+    return getObject(guid);
+}
+
 ISlangUnknown* OSFileSystem::getInterface(const Guid& guid)
 {
     return _canCast(m_style, guid) ? static_cast<ISlangFileSystem*>(this) : nullptr;
 }
 
+void* OSFileSystem::getObject(const Guid& guid)
+{
+    SLANG_UNUSED(guid);
+    return nullptr;
+}
+
 static String _fixPathDelimiters(const char* pathIn)
 {
 #if SLANG_WINDOWS_FAMILY
@@ -245,21 +260,31 @@ SlangResult OSFileSystem::createDirectory(const char* path)
     }
 }
 
-SLANG_NO_THROW SlangResult SLANG_MCALL CacheFileSystem::queryInterface(SlangUUID const& uuid, void** outObject)
+void* CacheFileSystem::castAs(const Guid& guid)
+{
+    if (auto ptr = getInterface(guid))
+    {
+        return ptr;
+    }
+    return getObject(guid);
+}
+
+void* CacheFileSystem::getInterface(const Guid& guid)
 {
-    if (uuid == CacheFileSystem::getTypeGuid())
+    if (_canCast(FileSystemStyle::Ext, guid))
     {
-        *outObject = this;
-        return SLANG_OK;
+        return static_cast<ISlangFileSystemExt*>(this);
     }
+    return nullptr;
+}
 
-    if (_canCast(FileSystemStyle::Ext, uuid))
+void* CacheFileSystem::getObject(const Guid& guid)
+{
+    if (guid == CacheFileSystem::getTypeGuid())
     {
-        addReference();
-        *outObject = static_cast<ISlangFileSystemExt*>(this);
-        return SLANG_OK;
+        return this;
     }
-    return SLANG_E_NO_INTERFACE;
+    return nullptr;
 }
 
 CacheFileSystem::CacheFileSystem(ISlangFileSystem* fileSystem, UniqueIdentityMode uniqueIdentityMode, PathStyle pathStyle) 
@@ -770,6 +795,21 @@ ISlangUnknown* RelativeFileSystem::getInterface(const Guid& guid)
     return _canCast(m_style, guid) ? static_cast<ISlangMutableFileSystem*>(this) : nullptr;
 }
 
+void* RelativeFileSystem::getObject(const Guid& guid)
+{
+    SLANG_UNUSED(guid);
+    return nullptr;
+}
+
+void* RelativeFileSystem::castAs(const Guid& guid)
+{
+    if (auto ptr = getInterface(guid))
+    {
+        return ptr;
+    }
+    return getObject(guid);
+}
+
 SlangResult RelativeFileSystem::_calcCombinedPathInner(SlangPathType fromPathType, const char* fromPath, const char* path, ISlangBlob** outPath)
 {
     ISlangFileSystemExt* fileSystem = _getExt();