Improvements around StringBlob (#2921)

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

* Small fixes and improvements around reflection tool.

* Make PrettyWriter printing a class.

* Improvements around handling StringBlob and storing stdlib source in ISlangBlob.

* Fix some issues with comments around StringBlob.

* Default initialize StringBlob fields.

1 files changed, 23 insertions, 22 deletions

diff --git a/source/core/slang-blob.h b/source/core/slang-blob.h
index aa503a6e5..f439a4eae 100644
--- a/source/core/slang-blob.h
+++ b/source/core/slang-blob.h
@@ -31,11 +31,10 @@ protected:
     void* getObject(const Guid& guid);
 };
 
-/** A blob that uses a `String` for its storage.
-NOTE! Returns length *WITHOUT* terminating 0, even though there is one.
+/** A blob that uses a `StringRepresentation` for its storage.
 
-NOTE! Whilst BobBase is atomic ref counted, the contained string *is not*. 
-There is a reasonable argument that StringBlob should contain it's own copy of the string contents.
+By design the StringBlob owns a unique reference to the StringRepresentation. 
+This is because StringBlob, implements an interface which should work across threads.
 */
 class StringBlob : public BlobBase
 {
@@ -46,37 +45,39 @@ public:
     virtual SLANG_NO_THROW void* SLANG_MCALL castAs(const SlangUUID& guid) SLANG_OVERRIDE;
 
     // ISlangBlob
-    SLANG_NO_THROW void const* SLANG_MCALL getBufferPointer() SLANG_OVERRIDE { return m_string.getBuffer(); }
-    SLANG_NO_THROW size_t SLANG_MCALL getBufferSize() SLANG_OVERRIDE { return m_string.getLength(); }
+    SLANG_NO_THROW void const* SLANG_MCALL getBufferPointer() SLANG_OVERRIDE { return m_chars; }
+    SLANG_NO_THROW size_t SLANG_MCALL getBufferSize() SLANG_OVERRIDE { return m_charsCount; }
 
-    static ComPtr<ISlangBlob> create(const String& in) { return ComPtr<ISlangBlob>(new StringBlob(in)); }
+        /// Since in is not being moved will *always* create a new representation, unless the in is empty
+    static ComPtr<ISlangBlob> create(const String& in);
+        /// Create from a slice
+    static ComPtr<ISlangBlob> create(const UnownedStringSlice& slice);
 
         /// Moves from in into the created blob. 
         /// NOTE! That will only use the representation from in, if it is *unique*
         /// otherwise it will make a new copy.
-        /// This is so that StringBlob won't hold a reference count via a string held externally.
-        /// In contrast StringBlob::create *may* share the representation.
     static ComPtr<ISlangBlob> moveCreate(String& in);
     static ComPtr<ISlangBlob> moveCreate(String&& in);
 
-protected:
-        /// A type that is only used to differentiate a constructor. Can construct with 
-        /// MoveUnique{}
-    struct MoveUnique {};
-
-    explicit StringBlob(String const& string)
-        : m_string(string)
-    {}
+        /// Dtor
+    ~StringBlob();
 
-    StringBlob(MoveUnique, String& string);
-    StringBlob() {}
+protected:
+        /// Use when rep *must* be unique (ie nullptr, and has a ref count of 1, that can be `taken` by the blob
+    void _uniqueInit(StringRepresentation* uniqueRep);
+        /// Init with a rep when can't be owned.
+    void _init(StringRepresentation* rep);
+        /// Init with a representation that has been moved.
+    void _moveInit(StringRepresentation* rep);
 
-        /// Get the contained string
-    SLANG_FORCE_INLINE const String& getString() const { return m_string; }
+        /// Checks that m_rep is either nullptr or has a ref count of 1 (ie it is owned by the blob)
+    SLANG_FORCE_INLINE void _checkRep() const { SLANG_ASSERT(m_rep == nullptr || m_rep->isUniquelyReferenced()); }
 
     void* getObject(const Guid& guid);
 
-    String m_string;
+    char* m_chars = nullptr;                ///< Pointer to the contained data. 
+    size_t m_charsCount = 0;                ///< The amount of chars *not* including terminating 0
+    StringRepresentation* m_rep = nullptr;  ///< Holds actual bytes. Can be nullptr if it's an empty string. 
 };
 
 class ListBlob : public BlobBase