HLSL: Member-functions: capture body token stream for deferred syntax/semantics.

This is needed for accessing types/variables within a member function body that are
not known until after the struct is finished being declared. However, that funtionality
is not yet present, this is just the deferred processing, which is working for
static member functions.

hlsl/hlslTokenStream.cpp

@@ -64,14 +64,56 @@ HlslToken HlslTokenStream::popTokenBuffer()
     return tokenBuffer[tokenBufferPos];
 }
 
+//
+// Make a new source of tokens, not from the source, but from an
+// already pre-processed token stream.
+//
+// This interrupts current token processing which must be restored
+// later.  Some simplifying assumptions are made (and asserted).
+//
+void HlslTokenStream::pushTokenStream(const TVector<HlslToken>* tokens)
+{
+    // not yet setup to interrupt a stream that has been receded
+    // and not yet reconsumed
+    assert(preTokenStackSize == 0);
+
+    // save current state
+    currentTokenStack.push_back(token);
+
+    // set up new token stream
+    tokenStreamStack.push_back(tokens);
+
+    // start position at first token:
+    token = (*tokens)[0];
+    tokenPosition.push_back(0);
+}
+
+// Undo pushTokenStream(), see above
+void HlslTokenStream::popTokenStream()
+{
+    tokenStreamStack.pop_back();
+    tokenPosition.pop_back();
+    token = currentTokenStack.back();
+    currentTokenStack.pop_back();
+}
+
 // Load 'token' with the next token in the stream of tokens.
 void HlslTokenStream::advanceToken()
 {
     pushTokenBuffer(token);
     if (preTokenStackSize > 0)
         token = popPreToken();
-    else
-        scanner.tokenize(token);
+    else {
+        if (tokenStreamStack.size() == 0)
+            scanner.tokenize(token);
+        else {
+            ++tokenPosition.back();
+            if (tokenPosition.back() >= (int)tokenStreamStack.back()->size())
+                token.tokenClass = EHTokNone;
+            else
+                token = (*tokenStreamStack.back())[tokenPosition.back()];
+        }
+    }
 }
 
 void HlslTokenStream::recedeToken()