add an option for quoting values of the first column that start with the comment character #505

src/main/java/com/univocity/parsers/common/AbstractWriter.java

@@ -96,6 +96,8 @@ protected DummyFormat createDefaultFormat() {
 	};
 	private final int errorContentLength;
 
+	protected final boolean processComments;
+
 	/**
 	 * All writers must support, at the very least, the settings provided by {@link CommonWriterSettings}. The AbstractWriter requires its configuration to be
 	 * properly initialized.
@@ -202,6 +204,7 @@ public AbstractWriter(Writer writer, S settings) {
 		this.expandRows = settings.getExpandIncompleteRows();
 		this.columnReorderingEnabled = settings.isColumnReorderingEnabled();
 		this.whitespaceRangeStart = settings.getWhitespaceRangeStart();
+		this.processComments = settings.isCommentProcessingEnabled();
 		this.appender = new WriterCharAppender(settings.getMaxCharsPerColumn(), "", whitespaceRangeStart, settings.getFormat());
 		this.rowAppender = new WriterCharAppender(settings.getMaxCharsPerColumn(), "", whitespaceRangeStart, settings.getFormat());
 

src/main/java/com/univocity/parsers/common/CommonWriterSettings.java

@@ -49,6 +49,8 @@ public abstract class CommonWriterSettings<F extends Format> extends CommonSetti
 
 	private boolean columnReorderingEnabled = false;
 
+	private boolean commentProcessingEnabled = true;
+
 	/**
 	 * Returns the String representation of an empty value (defaults to null)
 	 *
@@ -228,4 +230,27 @@ public boolean isColumnReorderingEnabled() {
 	public void setColumnReorderingEnabled(boolean columnReorderingEnabled) {
 		this.columnReorderingEnabled = columnReorderingEnabled;
 	}
+
+	/**
+	 * Indicates whether the writer will check for comment lines is enabled.
+	 * If {@code true}, the writer will always quote values of the first column that start with the comment character.
+	 * Defaults to {@code true}
+	 *
+	 * @return flag indicating whether the writer will check for comment lines
+	 * If disabled/false then writer wont quote values of the first column that start with the comment character.
+	 */
+	public boolean isCommentProcessingEnabled() {
+		return commentProcessingEnabled;
+	}
+
+	/**
+	 * Configures whether the writer will check for comment lines.
+	 * Defaults to {@code true}
+	 *
+	 * @param commentProcessingEnabled flag determining whether comment lines check should be performed
+	 *                                 If disabled/false then writer wont quote values of the first column that start with the comment character.
+	 */
+	public void setCommentProcessingEnabled(boolean commentProcessingEnabled) {
+		this.commentProcessingEnabled = commentProcessingEnabled;
+	}
 }

src/main/java/com/univocity/parsers/csv/CsvWriter.java

@@ -320,7 +320,7 @@ private boolean append(int columnIndex, boolean isElementQuoted, boolean allowTr
 		}
 
 		final int length = element.length();
-		if (start < length && (element.charAt(start) == quoteChar || columnIndex == 0 && element.charAt(0) == comment)) {
+		if (start < length && (element.charAt(start) == quoteChar || columnIndex == 0 && element.charAt(0) == comment && processComments)) {
 			isElementQuoted = true;
 		}
 

src/test/java/com/univocity/parsers/issues/github/Github_505.java

@@ -0,0 +1,42 @@
+package com.univocity.parsers.issues.github;
+
+import com.univocity.parsers.csv.CsvParser;
+import com.univocity.parsers.csv.CsvParserSettings;
+import com.univocity.parsers.csv.CsvWriter;
+import com.univocity.parsers.csv.CsvWriterSettings;
+import org.testng.annotations.Test;
+
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.util.List;
+
+import static org.testng.Assert.assertEquals;
+
+/**
+ * From: https://github.com/uniVocity/univocity-parsers/issues/505
+ */
+public class Github_505 {
+
+	@Test
+	public void testCommentCharWriting() {
+		StringWriter sw1 = new StringWriter();
+		{
+			CsvWriterSettings writerSettings = new CsvWriterSettings();
+			writerSettings.setCommentProcessingEnabled(false);
+			CsvWriter writer = new CsvWriter(sw1, writerSettings);
+			writer.writeRow(new String[]{"#field1", "field2"});
+			writer.close();
+		}
+		assertEquals(sw1.toString(), "#field1,field2\n");
+
+		StringWriter sw2 = new StringWriter();
+		{
+			CsvWriterSettings writerSettings = new CsvWriterSettings();
+			writerSettings.setCommentProcessingEnabled(true);
+			CsvWriter writer = new CsvWriter(sw2, writerSettings);
+			writer.writeRow(new String[]{"#field1", "field2"});
+			writer.close();
+		}
+		assertEquals(sw2.toString(), "\"#field1\",field2\n");
+	}
+}