[YAML] When outputting, provide the ability to write default values.

Previously, if you attempted to write a key/value pair and the
value was equal to the key's default value, we would not output
the value.  Sometimes it is useful to be able to see this value
in the output anyway.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297864 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Support/YAMLTraits.h b/include/llvm/Support/YAMLTraits.h
index cbba9c0..6d02e4a 100644 (file)
--- a/include/llvm/Support/YAMLTraits.h
+++ b/include/llvm/Support/YAMLTraits.h
@@ -689,11 +689,12 @@ private:
     assert(DefaultValue.hasValue() == false &&
            "Optional<T> shouldn't have a value!");
     void *SaveInfo;
-    bool UseDefault;
+    bool UseDefault = true;
     const bool sameAsDefault = outputting() && !Val.hasValue();
     if (!outputting() && !Val.hasValue())
       Val = T();
-    if (this->preflightKey(Key, Required, sameAsDefault, UseDefault,
+    if (Val.hasValue() &&
+        this->preflightKey(Key, Required, sameAsDefault, UseDefault,
                            SaveInfo)) {
       yamlize(*this, Val.getValue(), Required, Ctx);
       this->postflightKey(SaveInfo);
@@ -731,7 +732,7 @@ private:
   }
 
 private:
-  void  *Ctxt;
+  void *Ctxt;
 };
 
 namespace detail {
@@ -1251,6 +1252,13 @@ public:
   Output(llvm::raw_ostream &, void *Ctxt = nullptr, int WrapColumn = 70);
   ~Output() override;
 
+  /// \brief Set whether or not to output optional values which are equal
+  /// to the default value.  By default, when outputting if you attempt
+  /// to write a value that is equal to the default, the value gets ignored.
+  /// Sometimes, it is useful to be able to see these in the resulting YAML
+  /// anyway.
+  void setWriteDefaultValues(bool Write) { WriteDefaultValues = Write; }
+
   bool outputting() override;
   bool mapTag(StringRef, bool) override;
   void beginMapping() override;
@@ -1314,6 +1322,7 @@ private:
   bool                     NeedFlowSequenceComma;
   bool                     EnumerationMatchFound;
   bool                     NeedsNewLine;
+  bool WriteDefaultValues;
 };
 
 /// YAML I/O does conversion based on types. But often native data types

diff --git a/lib/Support/YAMLTraits.cpp b/lib/Support/YAMLTraits.cpp
index 9849b3a..c410b1d 100644 (file)
--- a/lib/Support/YAMLTraits.cpp
+++ b/lib/Support/YAMLTraits.cpp
@@ -398,17 +398,10 @@ bool Input::canElideEmptySequence() {
 //===----------------------------------------------------------------------===//
 
 Output::Output(raw_ostream &yout, void *context, int WrapColumn)
-    : IO(context),
-      Out(yout),
-      WrapColumn(WrapColumn),
-      Column(0),
-      ColumnAtFlowStart(0),
-      ColumnAtMapFlowStart(0),
-      NeedBitValueComma(false),
-      NeedFlowSequenceComma(false),
-      EnumerationMatchFound(false),
-      NeedsNewLine(false) {
-}
+    : IO(context), Out(yout), WrapColumn(WrapColumn), Column(0),
+      ColumnAtFlowStart(0), ColumnAtMapFlowStart(0), NeedBitValueComma(false),
+      NeedFlowSequenceComma(false), EnumerationMatchFound(false),
+      NeedsNewLine(false), WriteDefaultValues(false) {}
 
 Output::~Output() {
 }
@@ -462,7 +455,7 @@ std::vector<StringRef> Output::keys() {
 bool Output::preflightKey(const char *Key, bool Required, bool SameAsDefault,
                           bool &UseDefault, void *&) {
   UseDefault = false;
-  if (Required || !SameAsDefault) {
+  if (Required || !SameAsDefault || WriteDefaultValues) {
     auto State = StateStack.back();
     if (State == inFlowMapFirstKey || State == inFlowMapOtherKey) {
       flowKey(Key);