CSV-215 CSV Record mutability

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

@@ -25,6 +25,11 @@
 import java.util.Map;
 import java.util.Map.Entry;
 
+class ImmutableRecordCantBeSetException extends Exception{
+    public ImmutableRecordCantBeSetException(String message){
+        super(message);
+    }
+}
 /**
  * A CSV record parsed from a CSV file.
  *
@@ -49,6 +54,8 @@ public final class CSVRecord implements Serializable, Iterable<String> {
 
     /** The values of the record */
     private final String[] values;
+    /** Determines the mutability of the record*/
+    private boolean isMutable;
 
     CSVRecord(final String[] values, final Map<String, Integer> mapping, final String comment, final long recordNumber,
             final long characterPosition) {
@@ -57,6 +64,34 @@ public final class CSVRecord implements Serializable, Iterable<String> {
         this.mapping = mapping;
         this.comment = comment;
         this.characterPosition = characterPosition;
+        /** By default records are immutable*/
+        this.isMutable = false;
+
+    }
+    /**
+    * Make this instance Mutable.
+    * */
+    public void  makeCSVRecordMutable(){
+        this.isMutable = true;
+    }
+    public boolean isCSVRecordMutable(){
+        return this.isMutable;
+    }
+    /**
+     * Sets a value by index.
+     *
+     * @param index index
+     *            a column index (0-based)
+     * @param value
+     *            a string value to replace the current data
+     *
+     * @throws ImmutableRecordCantBeSetException incase it's called on an immutable instance.
+     */
+    public void set(int index, String value) throws ImmutableRecordCantBeSetException {
+        if(!isMutable){
+            throw new ImmutableRecordCantBeSetException("Attempt to change Immutable CSV Record");
+        }
+        values[index] = value;
     }
 
     /**

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

@@ -178,6 +178,28 @@ public void testToMapWithNoHeader() throws Exception {
             assertTrue("Map is empty.", map.isEmpty());
         }
     }
+    @Test
+    public void testSettingRecordMutable() throws Exception{
+        try(final CSVParser parser = CSVParser.parse("a,b", CSVFormat.newFormat(','))){
+            final CSVRecord shortRec = parser.iterator().next();
+            shortRec.makeCSVRecordMutable();
+            assertTrue(shortRec.isCSVRecordMutable());
+        }
+    }
+    @Test
+    public void testDefaultImmutability() throws Exception{
+        try(final CSVParser parser = CSVParser.parse("a,b", CSVFormat.newFormat(','))){
+            final CSVRecord shortRec = parser.iterator().next();
+            assertFalse(shortRec.isCSVRecordMutable());
+        }
+    }
+    @Test(expected = ImmutableRecordCantBeSetException.class)
+    public void testImmutableRecordSetException() throws Exception{
+        try(final CSVParser parser = CSVParser.parse("a,b", CSVFormat.newFormat(','))){
+            final CSVRecord shortRec = parser.iterator().next();
+            shortRec.set(0,"new value");
+        }
+    }
 
     private void validateMap(final Map<String, String> map, final boolean allowsNulls) {
         assertTrue(map.containsKey("first"));