Initial support for dumping DWARF corresponding to Swift code

src/common/language.h

Index: src/common/language.h
diff --git a/src/common/language.h b/src/common/language.h
index bbe303347a32a160f6da2aeb69284e6563620e2f..057861995083172b4ad2f3cefd325c0971250867 100644
--- a/src/common/language.h
+++ b/src/common/language.h
@@ -77,9 +77,25 @@ class Language {
   virtual string MakeQualifiedName (const string &parent_name,
                                     const string &name) const = 0;
 
+  enum DemangleResult {
+    // Demangling was not performed because it’s not appropriate to attempt.
+    kDontDemangle = -1,
+
+    kDemangleSuccess,
+    kDemangleFailure,
+  };
+
+  // Wraps abi::__cxa_demangle() or similar for languages where appropriate.
+  virtual DemangleResult DemangleName(const string& mangled,
+                                      std::string* demangled) const {
+    demangled->clear();
+    return kDontDemangle;
+  }
+
   // Instances for specific languages.
   static const Language * const CPlusPlus,
                         * const Java,
+                        * const Swift,
                         * const Assembler;
 };