Extract TableConverter interface

TableConverter is not part of the public api but is used by DataTable.
By extracting the interface we can hide the details of how a data table
converts its data.

This will also be usefull once we start moving away from xstream as we
can introduce an XStreamTableConverter and SomeOtherTableConverter.

Author: mpkorstanje

core/src/main/java/cucumber/api/DataTable.java

@@ -3,7 +3,6 @@
 import cucumber.runtime.CucumberException;
 import cucumber.runtime.ParameterInfo;
 import cucumber.runtime.table.DiffableRow;
-import cucumber.runtime.table.TableConverter;
 import cucumber.runtime.table.TableDiffException;
 import cucumber.runtime.table.TableDiffer;
 import cucumber.runtime.table.TablePrinter;
@@ -42,7 +41,7 @@ public static DataTable create(List<?> raw, Locale locale, String... columnNames
 
     private static DataTable create(List<?> raw, Locale locale, String format, String... columnNames) {
         ParameterInfo parameterInfo = new ParameterInfo(null, format, null, null);
-        TableConverter tableConverter = new TableConverter(new LocalizedXStreams(Thread.currentThread().getContextClassLoader()).get(locale), parameterInfo);
+        TableConverter tableConverter = new cucumber.runtime.table.TableConverter(new LocalizedXStreams(Thread.currentThread().getContextClassLoader()).get(locale), parameterInfo);
         return tableConverter.toTable(raw, columnNames);
     }
 

core/src/main/java/cucumber/api/TableConverter.java

@@ -0,0 +1,19 @@
+package cucumber.api;
+
+import java.lang.reflect.Type;
+import java.util.List;
+import java.util.Map;
+
+public interface TableConverter {
+    <T> T convert(DataTable dataTable, Type type, boolean transposed);
+
+    <T> List<T> toList(DataTable dataTable, Type itemType);
+
+    <T> List<List<T>> toLists(DataTable dataTable, Type itemType);
+
+    <K, V> Map<K, V> toMap(DataTable dataTable, Type keyType, Type valueType);
+
+    <K, V> List<Map<K, V>> toMaps(DataTable dataTable, Type keyType, Type valueType);
+
+    DataTable toTable(List<?> objects, String... columnNames);
+}

core/src/main/java/cucumber/runtime/StepDefinitionMatch.java

@@ -2,7 +2,7 @@
 
 import cucumber.api.DataTable;
 import cucumber.api.Scenario;
-import cucumber.runtime.table.TableConverter;
+import cucumber.api.TableConverter;
 import cucumber.runtime.xstream.LocalizedXStreams;
 import cucumber.util.Mapper;
 import gherkin.pickles.PickleCell;
@@ -100,7 +100,7 @@ private ParameterInfo getParameterType(int n, Type argumentType) {
 
     private Object tableArgument(PickleTable stepArgument, int argIndex, LocalizedXStreams.LocalizedXStream xStream) {
         ParameterInfo parameterInfo = getParameterType(argIndex, DataTable.class);
-        TableConverter tableConverter = new TableConverter(xStream, parameterInfo);
+        TableConverter tableConverter = new cucumber.runtime.table.TableConverter(xStream, parameterInfo);
         DataTable table = new DataTable(stepArgument, tableConverter);
         Type type = parameterInfo.getType();
         return tableConverter.convert(table, type, parameterInfo.isTransposed());

core/src/main/java/cucumber/runtime/table/DataTableDiff.java

@@ -1,6 +1,7 @@
 package cucumber.runtime.table;
 
 import cucumber.api.DataTable;
+import cucumber.api.TableConverter;
 import gherkin.pickles.PickleRow;
 import gherkin.pickles.PickleTable;
 

core/src/main/java/cucumber/runtime/table/TableConverter.java

@@ -34,7 +34,7 @@
 /**
  * This class converts a {@link cucumber.api.DataTable} to various other types.
  */
-public class TableConverter {
+public class TableConverter implements cucumber.api.TableConverter {
     private final LocalizedXStreams.LocalizedXStream xStream;
     private final ParameterInfo parameterInfo;
 
@@ -55,6 +55,7 @@ public TableConverter(LocalizedXStreams.LocalizedXStream xStream, ParameterInfo
      * @param transposed whether the table should be transposed first.
      * @return the transformed object.
      */
+    @Override
     public <T> T convert(DataTable dataTable, Type type, boolean transposed) {
         if (transposed) {
             dataTable = dataTable.transpose();
@@ -117,6 +118,7 @@ private <T> List<T> toListOfComplexType(DataTable dataTable, Class<T> itemType)
         }
     }
 
+    @Override
     public <T> List<T> toList(DataTable dataTable, Type itemType) {
         SingleValueConverter itemConverter = xStream.getSingleValueConverter(itemType);
         if (itemConverter != null) {
@@ -141,6 +143,7 @@ private <T> List<T> toList(DataTable dataTable, SingleValueConverter itemConvert
         return Collections.unmodifiableList(result);
     }
 
+    @Override
     public <T> List<List<T>> toLists(DataTable dataTable, Type itemType) {
         try {
             xStream.setParameterInfo(parameterInfo);
@@ -163,6 +166,7 @@ public <T> List<List<T>> toLists(DataTable dataTable, Type itemType) {
         }
     }
 
+    @Override
     public <K, V> Map<K, V> toMap(DataTable dataTable, Type keyType, Type valueType) {
         try {
             xStream.setParameterInfo(parameterInfo);
@@ -188,6 +192,7 @@ public <K, V> Map<K, V> toMap(DataTable dataTable, Type keyType, Type valueType)
         }
     }
 
+    @Override
     public <K, V> List<Map<K, V>> toMaps(DataTable dataTable, Type keyType, Type valueType) {
         try {
             xStream.setParameterInfo(parameterInfo);
@@ -227,6 +232,7 @@ public <K, V> List<Map<K, V>> toMaps(DataTable dataTable, Type keyType, Type val
      * @param columnNames an explicit list of column names
      * @return a DataTable
      */
+    @Override
     public DataTable toTable(List<?> objects, String... columnNames) {
         try {
             xStream.setParameterInfo(parameterInfo);

core/src/test/java/cucumber/runtime/table/ToDataTableTest.java

@@ -26,7 +26,7 @@
 public class ToDataTableTest {
     private static final String DD_MM_YYYY = "dd/MM/yyyy";
     private static final ParameterInfo PARAMETER_INFO = new ParameterInfo(null, DD_MM_YYYY, null, null);
-    private TableConverter tc;
+    private cucumber.api.TableConverter tc;
 
     @Before
     public void createTableConverterWithDateFormat() {