Added support for persistent types to the
expression parser.  You can use a persistent
type like this:

(lldb) expr struct $foo { int a; int b; };
(lldb) struct $foo i; i.a = 2; i.b = 3; i
($foo) $0 = {
  (int) a = 2
  (int) b = 3
}

typedefs work similarly.

This patch affects the following files:

test/expression_command/persistent_types/*
  A test case for persistent types,
  in particular structs and typedefs.

ClangForward.h
  Added TypeDecl, needed to declare some
  functions in ASTResultSynthesizer.h

ClangPersistentVariables.[h,cpp]
  Added a list of persistent types to the
  persistent variable store.

ASTResultSynthesizer.[h,cpp]
  Made the AST result synthesizer iterate
  across TypeDecls in the expression, and
  record any persistent types found.  Also
  made a minor documentation fix.

ClangUserExpression.[h,cpp]
  Extended the user expression class to
  keep the state needed to report the
  persistent variable store for the target
  to the AST result synthesizers. 

  Also introduced a new error code for
  expressions that executed normally but
  did not return a result.

CommandObjectExpression.cpp
  Improved output for expressions (like 
  declarations of new persistent types) that
  don't return a result.  This is no longer
  treated as an error.


git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@138383 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Expression/ClangPersistentVariables.cpp b/source/Expression/ClangPersistentVariables.cpp
index c4bf885..3da9dc8 100644
--- a/source/Expression/ClangPersistentVariables.cpp
+++ b/source/Expression/ClangPersistentVariables.cpp
@@ -13,6 +13,8 @@
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/Value.h"
 
+#include "llvm/ADT/StringMap.h"
+
 using namespace lldb;
 using namespace lldb_private;
 
@@ -53,3 +55,21 @@
     ConstString name(name_cstr);
     return name;
 }
+
+void
+ClangPersistentVariables::RegisterPersistentType (const ConstString &name,
+                                                  clang::TypeDecl *type_decl)
+{
+    m_persistent_types.insert(std::pair<const char*, clang::TypeDecl*>(name.GetCString(), type_decl));
+}
+
+clang::TypeDecl *
+ClangPersistentVariables::GetPersistentType (const ConstString &name)
+{
+    PersistentTypeMap::const_iterator i = m_persistent_types.find(name.GetCString());
+    
+    if (i == m_persistent_types.end())
+        return NULL;
+    else
+        return i->second;
+}