YAML I/O add support for validate()

MappingTrait template specializations can now have a validate() method which 
performs semantic checking. For details, see <http://llvm.org/docs/YamlIO.html>.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195286 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 48 insertions, 1 deletions

diff --git a/include/llvm/Support/YAMLTraits.h b/include/llvm/Support/YAMLTraits.h
index 27c1393b3a..1716a9d36e 100644
--- a/include/llvm/Support/YAMLTraits.h
+++ b/include/llvm/Support/YAMLTraits.h
@@ -44,6 +44,8 @@ template<class T>
 struct MappingTraits {
   // Must provide:
   // static void mapping(IO &io, T &fields);
+  // Optionally may provide:
+  // static StringRef validate(IO &io, T &fields);
 };
 
 
@@ -226,6 +228,23 @@ public:
   static bool const value = (sizeof(test<MappingTraits<T> >(0)) == 1);
 };
 
+// Test if MappingTraits<T>::validate() is defined on type T.
+template <class T>
+struct has_MappingValidateTraits
+{
+  typedef StringRef (*Signature_validate)(class IO&, T&);
+
+  template <typename U>
+  static char test(SameType<Signature_validate, &U::validate>*);
+
+  template <typename U>
+  static double test(...);
+
+public:
+  static bool const value = (sizeof(test<MappingTraits<T> >(0)) == 1);
+};
+
+
 
 // Test if SequenceTraits<T> is defined on type T.
 template <class T>
@@ -309,7 +328,15 @@ struct missingTraits : public  llvm::integral_constant<bool,
                                       && !has_SequenceTraits<T>::value
                                       && !has_DocumentListTraits<T>::value >  {};
 
+template<typename T>
+struct validatedMappingTraits : public  llvm::integral_constant<bool,
+                                       has_MappingTraits<T>::value
+                                    && has_MappingValidateTraits<T>::value> {};
 
+template<typename T>
+struct unvalidatedMappingTraits : public  llvm::integral_constant<bool,
+                                        has_MappingTraits<T>::value
+                                    && !has_MappingValidateTraits<T>::value> {};
 // Base class for Input and Output.
 class IO {
 public:
@@ -483,7 +510,27 @@ yamlize(IO &io, T &Val, bool) {
 
 
 template<typename T>
-typename llvm::enable_if_c<has_MappingTraits<T>::value, void>::type
+typename llvm::enable_if_c<validatedMappingTraits<T>::value, void>::type
+yamlize(IO &io, T &Val, bool) {
+  io.beginMapping();
+  if (io.outputting()) {
+    StringRef Err = MappingTraits<T>::validate(io, Val);
+    if (!Err.empty()) {
+      llvm::errs() << Err << "\n";
+      assert(Err.empty() && "invalid struct trying to be written as yaml");
+    }
+  }
+  MappingTraits<T>::mapping(io, Val);
+  if (!io.outputting()) {
+    StringRef Err = MappingTraits<T>::validate(io, Val);
+    if (!Err.empty())
+      io.setError(Err);
+  }
+  io.endMapping();
+}
+
+template<typename T>
+typename llvm::enable_if_c<unvalidatedMappingTraits<T>::value, void>::type
 yamlize(IO &io, T &Val, bool) {
   io.beginMapping();
   MappingTraits<T>::mapping(io, Val);