Re-submit r190469: YAMLIO: Fix string quoting logic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190485 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/YAMLTraits.cpp

@@ -15,6 +15,7 @@
 #include "llvm/Support/YAMLParser.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstring>
+#include <cctype>
 using namespace llvm;
 using namespace yaml;
 
@@ -508,9 +509,20 @@ void Output::endBitSetScalar() {
 }
 
 void Output::scalarString(StringRef &S) {
+  const char ScalarSafeChars[] = "abcdefghijklmnopqrstuvwxyz"
+      "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-/^., \t";
+
   this->newLineCheck();
-  if (S.find('\n') == StringRef::npos) {
+  if (S.empty()) {
-    // No embedded new-line chars, just print string.
+    // Print '' for the empty string because leaving the field empty is not
+    // allowed.
+    this->outputUpToEndOfLine("''");
+    return;
+  }
+  if (S.find_first_not_of(ScalarSafeChars) == StringRef::npos &&
+      !isspace(S.front()) && !isspace(S.back())) {
+    // If the string consists only of safe characters, print it out without
+    // quotes.
     this->outputUpToEndOfLine(S);
     return;
   }

unittests/Support/YAMLIOTest.cpp

@@ -273,7 +273,64 @@ TEST(YAMLIO, TestReadWriteBuiltInTypes) {
   }
 }
 
+struct StringTypes {
+  llvm::StringRef str1;
+  llvm::StringRef str2;
+  llvm::StringRef str3;
+  llvm::StringRef str4;
+  llvm::StringRef str5;
+};
 
+namespace llvm {
+namespace yaml {
+  template <>
+  struct MappingTraits<StringTypes> {
+    static void mapping(IO &io, StringTypes& st) {
+      io.mapRequired("str1",      st.str1);
+      io.mapRequired("str2",      st.str2);
+      io.mapRequired("str3",      st.str3);
+      io.mapRequired("str4",      st.str4);
+      io.mapRequired("str5",      st.str5);
+    }
+  };
+}
+}
+
+TEST(YAMLIO, TestReadWriteStringTypes) {
+  std::string intermediate;
+  {
+    StringTypes map;
+    map.str1 = "'aaa";
+    map.str2 = "\"bbb";
+    map.str3 = "`ccc";
+    map.str4 = "@ddd";
+    map.str5 = "";
+
+    llvm::raw_string_ostream ostr(intermediate);
+    Output yout(ostr);
+    yout << map;
+  }
+
+  llvm::StringRef flowOut(intermediate);
+  EXPECT_NE(llvm::StringRef::npos, flowOut.find("'''aaa"));
+  EXPECT_NE(llvm::StringRef::npos, flowOut.find("'\"bbb'"));
+  EXPECT_NE(llvm::StringRef::npos, flowOut.find("'`ccc'"));
+  EXPECT_NE(llvm::StringRef::npos, flowOut.find("'@ddd'"));
+  EXPECT_NE(llvm::StringRef::npos, flowOut.find("''\n"));
+
+  {
+    Input yin(intermediate);
+    StringTypes map;
+    yin >> map;
+
+    EXPECT_FALSE(yin.error());
+    EXPECT_TRUE(map.str1.equals("'aaa"));
+    EXPECT_TRUE(map.str2.equals("\"bbb"));
+    EXPECT_TRUE(map.str3.equals("`ccc"));
+    EXPECT_TRUE(map.str4.equals("@ddd"));
+    EXPECT_TRUE(map.str5.equals(""));
+  }
+}
 
 //===----------------------------------------------------------------------===//
 //  Test ScalarEnumerationTraits