Add method for detecting start of line

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1306322 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -111,6 +111,16 @@ abstract class Lexer {
         return (c == '\n' || c == '\r');
     }
 
+    /**
+     * Checks if the current character represents the start of a line:
+     * a CR, LF or is at the start of the file.
+     * 
+     * @param c
+     * @return true if the character is at the start of a line.
+     */
+    boolean isStartOfLine(int c) {
+        return c == '\n' || c == '\r' || c == ExtendedBufferedReader.UNDEFINED;
+    }
     /**
      * @return true if the given character indicates end of file
      */