Added ability to emit folded strings

include/yaml-cpp/emittermanip.h

@@ -25,6 +25,7 @@ enum EMITTER_MANIP {
   SingleQuoted,
   DoubleQuoted,
   Literal,
+  Folded,
 
   // bool manipulators
   YesNoBool,      // yes, no

src/emitter.cpp

@@ -681,7 +681,7 @@ Emitter& Emitter::Write(const std::string& str) {
       Utils::ComputeStringFormat(str, m_pState->GetStringFormat(),
                                  m_pState->CurGroupFlowType(), escapeNonAscii);
 
-  if (strFormat == StringFormat::Literal)
+  if (strFormat == StringFormat::Literal || strFormat == StringFormat::Folded)
     m_pState->SetMapKeyFormat(YAML::LongKey, FmtScope::Local);
 
   PrepareNode(EmitterNodeType::Scalar);
@@ -699,6 +699,9 @@ Emitter& Emitter::Write(const std::string& str) {
     case StringFormat::Literal:
       Utils::WriteLiteralString(m_stream, str,
                                 m_pState->CurIndent() + m_pState->GetIndent());
+    case StringFormat::Folded:
+      Utils::WriteFoldedString(m_stream, str,
+                                m_pState->CurIndent() + m_pState->GetIndent());
       break;
   }
 

src/emitterstate.cpp

@@ -238,6 +238,7 @@ bool EmitterState::SetStringFormat(EMITTER_MANIP value, FmtScope::value scope) {
     case SingleQuoted:
     case DoubleQuoted:
     case Literal:
+    case Folded:
       _Set(m_strFmt, value, scope);
       return true;
     default:

src/emitterutils.cpp

@@ -282,6 +282,11 @@ StringFormat::value ComputeStringFormat(const std::string& str,
         return StringFormat::Literal;
       }
       return StringFormat::DoubleQuoted;
+    case Folded:
+      if (IsValidLiteralScalar(str, flowType, escapeNonAscii)) {
+        return StringFormat::Folded;
+      }
+      return StringFormat::DoubleQuoted;
     default:
       break;
   }
@@ -369,6 +374,22 @@ bool WriteLiteralString(ostream_wrapper& out, const std::string& str,
   return true;
 }
 
+bool WriteFoldedString(ostream_wrapper& out, const std::string& str,
+                        std::size_t indent) {
+  out << ">\n";
+  out << IndentTo(indent);
+  int codePoint;
+  for (std::string::const_iterator i = str.begin();
+       GetNextCodePointAndAdvance(codePoint, i, str.end());) {
+    if (codePoint == '\n') {
+      out << "\n" << IndentTo(indent);
+    } else {
+      WriteCodePoint(out, codePoint);
+    }
+  }
+  return true;
+}
+
 bool WriteChar(ostream_wrapper& out, char ch) {
   if (('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z')) {
     out << ch;

src/emitterutils.h

@@ -21,7 +21,7 @@ namespace YAML {
 class Binary;
 
 struct StringFormat {
-  enum value { Plain, SingleQuoted, DoubleQuoted, Literal };
+  enum value { Plain, SingleQuoted, DoubleQuoted, Literal, Folded };
 };
 
 namespace Utils {
@@ -35,6 +35,8 @@ bool WriteDoubleQuotedString(ostream_wrapper& out, const std::string& str,
                              bool escapeNonAscii);
 bool WriteLiteralString(ostream_wrapper& out, const std::string& str,
                         std::size_t indent);
+bool WriteFoldedString(ostream_wrapper& out, const std::string& str,
+                        std::size_t indent);
 bool WriteChar(ostream_wrapper& out, char ch);
 bool WriteComment(ostream_wrapper& out, const std::string& str,
                   std::size_t postCommentIndent);