[CSV-329] Fix byte tracking for supplementary delimiters

src/changes/changes.xml

@@ -53,6 +53,7 @@
       <action type="fix" dev="ggregory" due-to="Ruiqi Dong, Gary Gregory" issue="CSV-325">CSVParser applies characterOffset to bytePosition (#604).</action>
       <action type="fix" dev="ggregory" due-to="Ruiqi Dong, Gary Gregory" issue="CSV-326">CSVPrinter Reader printing with quote and escape can emit CSV that its parser cannot read back.</action>
       <action type="fix" dev="ggregory" due-to="Ruiqi Dong, Gary Gregory" issue="CSV-327">CSVParser applies maxRows to record numbers instead of rows produced when setRecordNumber(...) is used.</action>
+      <action type="fix" dev="ggregory" due-to="Ruiqi Dong, Gary Gregory" issue="CSV-329">CSVParser with trackBytes enabled throws on multi-character delimiters containing supplementary Unicode characters.</action>
       <action type="fix" dev="ggregory" due-to="Ruiqi Dong, Gary Gregory" issue="CSV-328">CSVFormat.Builder.setNullString(String) can build an invalid quoted null string after setQuote(null).</action>
       <action type="fix" dev="ggregory" due-to="OldTruckDriver, Gary Gregory" issue="CSV-326">Escape Reader values with quote and escape (#606).</action>
       <action type="fix" dev="ggregory" due-to="Dexter.k, Gary Gregory">Clear escape delimiter buffer before peek in Lexer.isEscapeDelimiter() (#608, #611).</action>

src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java

@@ -108,9 +108,11 @@ long getBytesRead() {
     }
 
     private long getEncodedCharLength(final char[] buf, final int offset, final int length) throws CharacterCodingException {
-        int len = 0;
-        for (int i = offset; i < length; i++) {
-            len += getEncodedCharLength(buf[i]);
+        long len = 0;
+        int previous = lastChar;
+        for (int i = offset; i < offset + length; i++) {
+            len += getEncodedCharLength(previous, buf[i]);
+            previous = buf[i];
         }
         return len;
     }
@@ -141,8 +143,12 @@ private long getEncodedCharLength(final char[] buf, final int offset, final int
      * @throws CharacterCodingException if the character cannot be encoded.
      */
     private int getEncodedCharLength(final int current) throws CharacterCodingException {
+        return getEncodedCharLength(lastChar, current);
+    }
+
+    private int getEncodedCharLength(final int previous, final int current) throws CharacterCodingException {
         final char cChar = (char) current;
-        final char lChar = (char) lastChar;
+        final char lChar = (char) previous;
         if (!Character.isSurrogate(cChar)) {
             return encoder.encode(CharBuffer.wrap(new char[] { cChar })).limit();
         }
@@ -218,6 +224,9 @@ public int read(final char[] buf, final int offset, final int length) throws IOE
             return 0;
         }
         final int len = super.read(buf, offset, length);
+        if (encoder != null && len > 0) {
+            this.bytesRead += getEncodedCharLength(buf, offset, len);
+        }
         if (len > 0) {
             for (int i = offset; i < offset + len; i++) {
                 final char ch = buf[i];
@@ -233,9 +242,6 @@ public int read(final char[] buf, final int offset, final int length) throws IOE
         } else if (len == EOF) {
             lastChar = EOF;
         }
-        if (encoder != null) {
-            this.bytesRead += getEncodedCharLength(buf, offset, len);
-        }
         position += len;
         return len;
     }

src/test/java/org/apache/commons/csv/CSVParserTest.java

@@ -666,6 +666,31 @@ void testGetBytePositionMultiCharacterDelimiter() throws IOException {
         }
     }
 
+    /**
+     * Tests <a href="https://issues.apache.org/jira/browse/CSV-329">CSV-329</a>.
+     */
+    @Test
+    void testGetBytePositionMultiCharacterDelimiterWithSupplementaryCharacter() throws IOException {
+        final String delimiter = "x😀";
+        final String code = "ax😀b\ncx😀d\n";
+        final CSVFormat format = CSVFormat.DEFAULT.builder().setDelimiter(delimiter).get();
+        try (CSVParser parser = CSVParser.builder()
+                .setReader(new StringReader(code))
+                .setFormat(format)
+                .setCharset(UTF_8)
+                .setTrackBytes(true)
+                .get()) {
+            final CSVRecord first = parser.nextRecord();
+            final CSVRecord second = parser.nextRecord();
+            assertNotNull(first);
+            assertNotNull(second);
+            assertValuesEquals(new String[] { "a", "b" }, first);
+            assertValuesEquals(new String[] { "c", "d" }, second);
+            assertEquals(0, first.getBytePosition());
+            assertEquals("ax😀b\n".getBytes(UTF_8).length, second.getBytePosition());
+        }
+    }
+
     @Test
     void testGetBytePositionWithCharacterOffsetAndMultiBytePrefix() throws Exception {
         final String row0 = "é,x\n";

src/test/java/org/apache/commons/csv/ExtendedBufferedReaderTest.java

@@ -26,6 +26,7 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 
 import java.io.StringReader;
+import java.nio.charset.StandardCharsets;
 
 import org.junit.jupiter.api.Test;
 
@@ -104,6 +105,19 @@ void testReadingInDifferentBuffer() throws Exception {
         }
     }
 
+    @Test
+    void testReadingSupplementaryCharacterTracksBytes() throws Exception {
+        final String input = "😀";
+        final char[] buffer = new char[input.length()];
+        try (ExtendedBufferedReader reader = new ExtendedBufferedReader(new StringReader(input), StandardCharsets.UTF_8, true)) {
+            assertEquals(input.length(), reader.read(buffer, 0, buffer.length));
+            assertArrayEquals(input.toCharArray(), buffer);
+            assertEquals(input.getBytes(StandardCharsets.UTF_8).length, reader.getBytesRead());
+            assertEquals(input.length(), reader.getPosition());
+            assertEquals(input.charAt(input.length() - 1), reader.getLastChar());
+        }
+    }
+
     @Test
     void testReadLine() throws Exception {
         try (ExtendedBufferedReader br = createBufferedReader("")) {