From ff5493188293eab30f1294241461abebe29e56fa Mon Sep 17 00:00:00 2001
From: Joao Paulo Magalhaes <dev@jpmag.me>
Date: Sun, 1 May 2022 16:59:50 +0100
Subject: [PATCH] [fix] double-quoted emitter should escape carriage return to
 ensure roundtrip equivalence

re #253
---
 changelog/current.md        | 12 ++++++++++++
 src/c4/yml/emit.def.hpp     |  7 +++++++
 test/test_double_quoted.cpp | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)

diff --git a/changelog/current.md b/changelog/current.md
index e54c6502..153b5279 100644
--- a/changelog/current.md
+++ b/changelog/current.md
@@ -19,3 +19,15 @@
   =VAL :foo
   =VAL :bar
   ```
+- Fix [#253](https://github.com/biojppm/rapidyaml/issues/253): double-quoted emitter should encode carriage-return `\r` to preserve roundtrip equivalence:
+  ```yaml
+  Tree tree;
+  NodeRef root = tree.rootref();
+  root |= MAP;
+  root["s"] = "t\rt";
+  root["s"] |= _WIP_VAL_DQUO;
+  std::string s = emitrs<std::string>(tree);
+  EXPECT_EQ(s, "s: \"t\\rt\"\n");
+  Tree tree2 = parse_in_arena(to_csubstr(s));
+  EXPECT_EQ(tree2["s"].val(), tree["s"].val());
+  ```
diff --git a/src/c4/yml/emit.def.hpp b/src/c4/yml/emit.def.hpp
index 01b58618..2898eaca 100644
--- a/src/c4/yml/emit.def.hpp
+++ b/src/c4/yml/emit.def.hpp
@@ -767,6 +767,13 @@ void Emitter<Writer>::_write_scalar_dquo(csubstr s, size_t ilevel)
                 pos = i;
             }
         }
+        else if(C4_UNLIKELY(curr == '\r'))
+        {
+            csubstr sub = s.range(pos, i);
+            this->Writer::_do_write(sub);  // write everything up to (excluding) this char
+            this->Writer::_do_write("\\r"); // write the escaped char
+            pos = i+1;
+        }
     }
     // write missing characters at the end of the string
     if(pos < s.len)
diff --git a/test/test_double_quoted.cpp b/test/test_double_quoted.cpp
index 5ee7d5cf..9820c7fd 100644
--- a/test/test_double_quoted.cpp
+++ b/test/test_double_quoted.cpp
@@ -399,6 +399,41 @@ TEST(double_quoted, error_on_bad_utf_codepoints)
     verify_error_is_reported("bad value  \\U"  , R"(foo: "\Ukokokoko")");
 }
 
+TEST(double_quoted, github253)
+{
+    {
+        Tree tree;
+        NodeRef root = tree.rootref();
+        root |= MAP;
+        root["t"] = "t't\\nt";
+        root["t"] |= _WIP_VAL_DQUO;
+        std::string s = emitrs<std::string>(tree);
+        Tree tree2 = parse_in_arena(to_csubstr(s));
+        EXPECT_EQ(tree2["t"].val(), tree["t"].val());
+    }
+    {
+        Tree tree;
+        NodeRef root = tree.rootref();
+        root |= MAP;
+        root["t"] = "t't\\nt";
+        root["t"] |= _WIP_VAL_SQUO;
+        std::string s = emitrs<std::string>(tree);
+        Tree tree2 = parse_in_arena(to_csubstr(s));
+        EXPECT_EQ(tree2["t"].val(), tree["t"].val());
+    }
+    {
+        Tree tree;
+        NodeRef root = tree.rootref();
+        root |= MAP;
+        root["s"] = "t\rt";
+        root["s"] |= _WIP_VAL_DQUO;
+        std::string s = emitrs<std::string>(tree);
+        EXPECT_EQ(s, "s: \"t\\rt\"\n");
+        Tree tree2 = parse_in_arena(to_csubstr(s));
+        EXPECT_EQ(tree2["s"].val(), tree["s"].val());
+    }
+}
+
 
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------