feat/scalar line breaks (#124)

* tests: adds a unit test for line breaks in scalars

Signed-off-by: Vincent Biret <vincentbiret@hotmail.com>

* perf: removes redundant call to char array

Signed-off-by: Vincent Biret <vincentbiret@hotmail.com>

* fix: scalars now maintain line returns

Signed-off-by: Vincent Biret <vincentbiret@hotmail.com>

fix: allow literals to be on multiple lines

Signed-off-by: Vincent Biret <vincentbiret@hotmail.com>

---------

Signed-off-by: Vincent Biret <vincentbiret@hotmail.com>

Author: baywet

src/SharpYaml.Tests/EmitterTests.cs

@@ -43,6 +43,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.IO;
@@ -306,5 +307,46 @@ public void FoldedStylePreservesNewLines()
             Dump.WriteLine(output);
             Assert.AreEqual(input, output);
         }
+
+        [Test]
+        public void FoldedScalarWithMultipleWordsPreservesLineBreaks()
+        {
+            // The real issue is not that "a folded\nscalar" should become "a folded scalar"
+            // in terms of content (that's actually correct YAML behavior)
+            // The issue is that when emitting a scalar with newlines as a folded scalar,
+            // it should preserve the newlines in the YAML structure
+            
+            var input = "a folded\nscalar";
+            
+            // When we emit a scalar with embedded newlines as a folded scalar,
+            // it should be emitted as:
+            // >-
+            //   a folded
+            //   scalar
+            // NOT as:
+            // >-
+            //   a folded scalar
+            
+            var yaml = EmitScalar(new Scalar(null, null, input, ScalarStyle.Folded, true, false));
+            Console.WriteLine("Emitted YAML:");
+            Console.WriteLine(yaml);
+            
+            // The emitted YAML should contain the folded scalar structure
+            Assert.That(yaml, Does.Contain(">-"), "Should emit as folded scalar");
+            Assert.That(yaml, Does.Contain("a folded"), "Should contain the first part");
+            Assert.That(yaml, Does.Contain("scalar"), "Should contain the second part");
+            
+            // Parse it back and verify the content is preserved
+            var stream = new YamlStream();
+            stream.Load(new StringReader(yaml));
+            var sequence = (YamlSequenceNode)stream.Documents[0].RootNode;
+            var scalar = (YamlScalarNode)sequence.Children[0];
+            
+            Console.WriteLine($"Original: '{input}'");
+            Console.WriteLine($"Round-trip result: '{scalar.Value}'");
+            
+            // This should pass - the content should be preserved
+            Assert.AreEqual(input, scalar.Value, "Folded scalar content should be preserved during round-trip");
+        }
     }
 }

src/SharpYaml/Emitter.cs

@@ -546,14 +546,28 @@ private void AnalyzeScalar(string value)
                 scalarData.isSingleQuotedAllowed = false;
             }
 
-            if (space_break || special_characters)
+            if (space_break)
             {
                 scalarData.isFlowPlainAllowed = false;
                 scalarData.isBlockPlainAllowed = false;
                 scalarData.isSingleQuotedAllowed = false;
                 scalarData.isBlockAllowed = false;
             }
 
+            if (special_characters)
+            {
+                scalarData.isFlowPlainAllowed = false;
+                scalarData.isBlockPlainAllowed = false;
+                scalarData.isSingleQuotedAllowed = false;
+                // Don't disable block scalars for line breaks - they're the point of folded/literal scalars
+                // However, disable block scalars for single-character strings containing only special characters
+                // as they're better represented with quoted styles
+                if (!line_breaks || (line_breaks && value.Length == 1))
+                {
+                    scalarData.isBlockAllowed = false;
+                }
+            }
+
             if (line_breaks)
             {
                 scalarData.isFlowPlainAllowed = false;
@@ -1520,10 +1534,25 @@ private void SelectScalarStyle(ParsingEvent evt)
 
             if (style == ScalarStyle.Literal || style == ScalarStyle.Folded)
             {
-                if (!scalarData.isBlockAllowed || flowLevel != 0 || isSimpleKeyContext)
+                // Only override block styles if they're truly not possible to emit
+                // Don't override if the user explicitly requested Folded/Literal style
+                // unless we're in a context where block scalars are impossible (flow context, simple key)
+                if (flowLevel != 0 || isSimpleKeyContext)
                 {
                     style = ScalarStyle.DoubleQuoted;
                 }
+                // For both literal and folded scalars, fall back to double quotes if block scalars aren't allowed
+                else if (!scalarData.isBlockAllowed)
+                {
+                    style = ScalarStyle.DoubleQuoted;
+                }
+            }
+
+            // Final fallback: if no style is allowed, always use double quoted
+            if (!scalarData.isFlowPlainAllowed && !scalarData.isBlockPlainAllowed &&
+                !scalarData.isSingleQuotedAllowed && !scalarData.isBlockAllowed)
+            {
+                style = ScalarStyle.DoubleQuoted;
             }
 
             // TODO: What is this code supposed to mean?
@@ -1532,6 +1561,13 @@ private void SelectScalarStyle(ParsingEvent evt)
             //	tagData.handle = "!";
             //}
 
+            // Final fallback: if no style is allowed, always use double quoted
+            if (!scalarData.isFlowPlainAllowed && !scalarData.isBlockPlainAllowed &&
+                !scalarData.isSingleQuotedAllowed && !scalarData.isBlockAllowed)
+            {
+                style = ScalarStyle.DoubleQuoted;
+            }
+
             scalarData.style = style;
         }
 
@@ -1545,7 +1581,7 @@ private void EmitAlias()
         }
 
         /// <summary>
-        /// Write an achor.
+        /// Write an anchor.
         /// </summary>
         private void ProcessAnchor()
         {

src/SharpYaml/Serialization/Serializers/PrimitiveSerializer.cs

@@ -126,7 +126,7 @@ internal class PrimitiveSerializer : ScalarSerializerBase, IYamlSerializableFact
                     {
                         throw new YamlException(scalar.Start, scalar.End, $"Unable to decode char from [{text}]. Expecting a string of length == 1");
                     }
-                    return text.ToCharArray()[0];
+                    return text[0];
                 case TypeCode.Byte:
                     return byte.Parse(text, CultureInfo.InvariantCulture);
                 case TypeCode.SByte: