Handle platform specific line terminators gracefully in multiline strings

README.md

@@ -708,6 +708,8 @@ elements in RDF lists.
 \* Adapted from [EditorConfig](https://editorconfig.org/#file-format-details)
 
 ## Release Notes
+* Unreleased
+  * Replace Platform-dependent line terminators in multiline strings with unix style newlines (`\n`, `\r`, and `\r\n` -> `\n`) 
 * 1.2.16:
   * Bugfix: Empty RDF lists are formatted as empty set of parenthesis again
 * 1.2.15:

src/main/java/de/atextor/turtle/formatter/TurtleFormatter.java

@@ -66,7 +66,7 @@ public class TurtleFormatter implements Function<Model, String>, BiConsumer<Mode
      * need to escape single quotes.
      * </p>
      */
-    private static final Pattern STRING_ESCAPE_SEQUENCES = Pattern.compile( "[\t\b\n\r\f\"\\\\]" );
+    private static final Pattern STRING_ESCAPE_SEQUENCES = Pattern.compile( "(\r\n)|[\t\b\n\r\f\"\\\\]" );
 
     private final FormattingStyle style;
 
@@ -680,13 +680,15 @@ private String quoteAndEscape( final RDFNode node ) {
         final String quote = switch ( style.quoteStyle ) {
             case ALWAYS_SINGE_QUOTES -> "\"";
             case ALWAYS_TRIPLE_QUOTES -> "\"\"\"";
-            case TRIPLE_QUOTES_FOR_MULTILINE -> value.contains( "\n" ) ? "\"\"\"" : "\"";
+            case TRIPLE_QUOTES_FOR_MULTILINE -> (value.contains( "\n" ) || value.contains("\r"))? "\"\"\"" : "\"";
         };
 
+
         final Map<String, String> characterReplacements = Map.of(
             "\t", "\\\\t",
             "\b", "\\\\b",
-            "\r", "\\\\r",
+            "\r", quote.equals( "\"" ) ? "\\\\r": "\n", // in multiline strings that were read with mac style endings, replace \r with \n
+            "\r\n", quote.equals( "\"" ) ? "\\\\r\\\\n": "\n", // in multiline strings that were read with windows style endings, replace \r\n with \n
             "\f", "\\\\f",
             "\n", quote.equals( "\"" ) ? "\\\\n" : "\n", // Don't escape line breaks in triple-quoted strings
             "\"", quote.equals( "\"" ) ? "\\\\\"" : "\"", // Don't escape quotes in triple-quoted strings

src/test/java/de/atextor/turtle/formatter/TurtleFormatterTest.java

@@ -1230,6 +1230,98 @@ public void testEmptyList() {
         assertThat(result.trim()).isEqualTo(expected);
     }
 
+    @Test
+    public void testMultilineStrings(){
+        String content =   """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+           :thing :value \"""
+                First Line
+                Second Line
+                Third Line
+           \""" .
+           """;
+        String expected = """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+
+           :thing :value \"""
+                First Line
+                Second Line
+                Third Line
+           \""" .""";
+        final FormattingStyle style = FormattingStyle.DEFAULT;
+        final TurtleFormatter formatter = new TurtleFormatter(style);
+        final String result = formatter.applyToContent(content);
+        assertThat(result.trim()).isEqualTo(expected);
+    }
+
+    @Test
+    public void testStringsWithUnixStyleNewlinesToMultilineStrings(){
+        String content =   """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+           :thing :value "\\n     First Line\\n     Second Line\\n     Third Line\\n" .
+           """;
+        String expected = """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+
+           :thing :value \"""
+                First Line
+                Second Line
+                Third Line
+           \""" .""";
+        final FormattingStyle style = FormattingStyle.DEFAULT;
+        final TurtleFormatter formatter = new TurtleFormatter(style);
+        final String result = formatter.applyToContent(content);
+        assertThat(result.trim()).isEqualTo(expected);
+    }
+
+    @Test
+    public void testStringsWithWindowsStyleNewlinesToMultilineStrings(){
+        String content =   """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+           :thing :value "\\r\\n     First Line\\r\\n     Second Line\\r\\n     Third Line\\r\\n" .
+           """;
+        String expected = """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+
+           :thing :value \"""
+                First Line
+                Second Line
+                Third Line
+           \""" .""";
+        final FormattingStyle style = FormattingStyle.DEFAULT;
+        final TurtleFormatter formatter = new TurtleFormatter(style);
+        final String result = formatter.applyToContent(content);
+        assertThat(result.trim()).isEqualTo(expected);
+    }
+
+    @Test
+    public void testStringsWithMacStyleNewlinesToMultilineStrings(){
+        String content =   """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+           :thing :value "\\r     First Line\\r     Second Line\\r     Third Line\\r" .
+           """;
+        String expected = """
+           @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+           @prefix : <http://example.com/ns#> .
+
+           :thing :value \"""
+                First Line
+                Second Line
+                Third Line
+           \""" .""";
+        final FormattingStyle style = FormattingStyle.DEFAULT;
+        final TurtleFormatter formatter = new TurtleFormatter(style);
+        final String result = formatter.applyToContent(content);
+        assertThat(result.trim()).isEqualTo(expected);
+    }
+
 
     private Model modelFromString( final String content ) {
         final Model model = ModelFactory.createDefaultModel();