Add support to FancyFlexTable for finding/inserting items

The code to find an existing item in the table and to find the correct
insert position for a new item is useful for different callers and
should be in the table class.

Change-Id: Ia0f9dbd0f9beb6b356989973bb4426aacd0671b3
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/AccountGroupMembersScreen.java

@@ -290,28 +290,12 @@ public class AccountGroupMembersScreen extends AccountGroupScreen {
           return str == null ? "" : str;
         }
       };
-      int insertPosition = table.getRowCount();
+      int insertPos = getInsertRow(c, info);
-      int left = 1;
+      if (insertPos >= 0) {
-      int right = table.getRowCount() - 1;
+        table.insertRow(insertPos);
-      while (left <= right) {
+        applyDataRowStyle(insertPos);
-        int middle = (left + right) >>> 1; // (left+right)/2
+        populate(insertPos, info);
-        AccountInfo i = getRowItem(middle);
-        int cmp = c.compare(i, info);
-
-        if (cmp < 0) {
-          left = middle + 1;
-        } else if (cmp > 0) {
-          right = middle - 1;
-        } else {
-          // group is already contained in the table
-          return;
-        }
       }
-      insertPosition = left;
-
-      table.insertRow(insertPosition);
-      applyDataRowStyle(insertPosition);
-      populate(insertPosition, info);
     }
 
     void populate(final int row, final AccountInfo i) {
@@ -405,29 +389,12 @@ public class AccountGroupMembersScreen extends AccountGroupScreen {
           return (str == null) ? "" : str;
         }
       };
-
+      int insertPos = getInsertRow(c, info);
-      int insertPosition = table.getRowCount();
+      if (insertPos >= 0) {
-      int left = 1;
+        table.insertRow(insertPos);
-      int right = table.getRowCount() - 1;
+        applyDataRowStyle(insertPos);
-      while (left <= right) {
+        populate(insertPos, info);
-        int middle = (left + right) >>> 1; // (left+right)/2
-        GroupInfo i = getRowItem(middle);
-        int cmp = c.compare(i, info);
-
-        if (cmp < 0) {
-          left = middle + 1;
-        } else if (cmp > 0) {
-          right = middle - 1;
-        } else {
-          // group is already contained in the table
-          return;
-        }
       }
-      insertPosition = left;
-
-      table.insertRow(insertPosition);
-      applyDataRowStyle(insertPosition);
-      populate(insertPosition, info);
     }
 
     void populate(final int row, final GroupInfo i) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/FancyFlexTable.java

@@ -25,6 +25,7 @@ import com.google.gwt.user.client.ui.HTMLTable.CellFormatter;
 import com.google.gwt.user.client.ui.Widget;
 import com.google.gwtexpui.safehtml.client.SafeHtml;
 
+import java.util.Comparator;
 import java.util.Iterator;
 
 public abstract class FancyFlexTable<RowItem> extends Composite {
@@ -58,6 +59,71 @@ public abstract class FancyFlexTable<RowItem> extends Composite {
     setRowItem(table.getCellFormatter().getElement(row, 0), item);
   }
 
+  /**
+   * Finds an item in the table.
+   *
+   * @param comparator comparator by which the items in the table are sorted
+   * @param item the item that should be found
+   * @return if the item is found the number of the row that contains the item;
+   *         if the item is not found <code>-1</code>
+   */
+  protected int findRowItem(Comparator<RowItem> comparator, RowItem item) {
+    int row = lookupRowItem(comparator, item);
+    if (row < table.getRowCount()
+        && comparator.compare(item, getRowItem(row)) == 0) {
+      return row;
+    }
+    return -1;
+  }
+
+  /**
+   * Finds the number of the row where a new item should be inserted into the
+   * table.
+   *
+   * @param comparator comparator by which the items in the table are sorted
+   * @param item the new item that should be inserted
+   * @return if the item is not yet contained in the table, the number of the
+   *         row where the new item should be inserted; if the item is already
+   *         contained in the table <code>-1</code>
+   */
+  protected int getInsertRow(Comparator<RowItem> comparator, RowItem item) {
+    int row = lookupRowItem(comparator, item);
+    if (row >= table.getRowCount()
+        || comparator.compare(item, getRowItem(row)) != 0) {
+      return row;
+    }
+    return -1;
+  }
+
+  /**
+   * Makes a binary search for the given row item over the table.
+   *
+   * @param comparator comparator by which the items in the table are sorted
+   * @param item the item that should be looked up
+   * @return if the item is found the number of the row that contains the item;
+   *         if the item is not found the number of the row where the item
+   *         should be inserted according to the given comparator.
+   */
+  private int lookupRowItem(Comparator<RowItem> comparator, RowItem item) {
+    int left = 1;
+    int right = table.getRowCount() - 1;
+    while (left <= right) {
+      int middle = (left + right) >>> 1; // (left+right)/2
+      RowItem i = getRowItem(middle);
+      int cmp = comparator.compare(i, item);
+
+      if (cmp < 0) {
+        left = middle + 1;
+      } else if (cmp > 0) {
+        right = middle - 1;
+      } else {
+        // item is already contained in the table
+        return middle;
+      }
+    }
+    return left;
+  }
+
   protected void resetHtml(final SafeHtml body) {
     for (final Iterator<Widget> i = table.iterator(); i.hasNext();) {
       i.next();