Add Cursor.findRow(RowId) for moving to a specific Table row using only the RowId

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@864 f203690c-595d-4dc9-a70b-905162fa7fd2

4 files changed, 73 insertions, 9 deletions

diff --git a/src/main/java/com/healthmarketscience/jackcess/Cursor.java b/src/main/java/com/healthmarketscience/jackcess/Cursor.java
index b9c47f1..956f545 100644
--- a/src/main/java/com/healthmarketscience/jackcess/Cursor.java
+++ b/src/main/java/com/healthmarketscience/jackcess/Cursor.java
@@ -224,6 +224,15 @@ public interface Cursor extends Iterable<Row>
    *         otherwise
    */
   public boolean moveToPreviousRow() throws IOException;
+  
+  /**
+   * Moves to the row with the given rowId.  If the row is not found (or an
+   * exception is thrown), the cursor is restored to its previous state.
+   * 
+   * @return {@code true} if a valid row was found with the given id,
+   *         {@code false} if no row was found
+   */
+  public boolean findRow(RowId rowId) throws IOException;
 
   /**
    * Moves to the first row (as defined by the cursor) where the given column
diff --git a/src/main/java/com/healthmarketscience/jackcess/impl/CursorImpl.java b/src/main/java/com/healthmarketscience/jackcess/impl/CursorImpl.java
index 06cda47..1521e3b 100644
--- a/src/main/java/com/healthmarketscience/jackcess/impl/CursorImpl.java
+++ b/src/main/java/com/healthmarketscience/jackcess/impl/CursorImpl.java
@@ -38,6 +38,7 @@ import com.healthmarketscience.jackcess.Column;
 import com.healthmarketscience.jackcess.Cursor;
 import com.healthmarketscience.jackcess.CursorBuilder;
 import com.healthmarketscience.jackcess.Row;
+import com.healthmarketscience.jackcess.RowId;
 import com.healthmarketscience.jackcess.RuntimeIOException;
 import com.healthmarketscience.jackcess.impl.TableImpl.RowState;
 import com.healthmarketscience.jackcess.util.ColumnMatcher;
@@ -417,6 +418,34 @@ public abstract class CursorImpl implements Cursor
     return(!_curPos.equals(getDirHandler(moveForward).getEndPosition()));
   }
 
+  public boolean findRow(RowId rowId) throws IOException
+  {
+    RowIdImpl rowIdImpl = (RowIdImpl)rowId;
+    PositionImpl curPos = _curPos;
+    PositionImpl prevPos = _prevPos;
+    boolean found = false;
+    try {
+      reset(MOVE_FORWARD);
+      if(TableImpl.positionAtRowHeader(_rowState, rowIdImpl) == null) {
+        return false;
+      }
+      restorePosition(getRowPosition(rowIdImpl));
+      if(!isCurrentRowValid()) {
+        return false;
+      }
+      found = true;
+      return true;
+    } finally {
+      if(!found) {
+        try {
+          restorePosition(curPos, prevPos);
+        } catch(IOException e) {
+          LOG.error("Failed restoring position", e);
+        }
+      }
+    }
+  }
+
   public boolean findFirstRow(Column columnPattern, Object valuePattern)
     throws IOException
   {
@@ -688,6 +717,13 @@ public abstract class CursorImpl implements Cursor
     return getClass().getSimpleName() + " CurPosition " + _curPos +
       ", PrevPosition " + _prevPos;
   }
+
+  /**
+   * Returns the appropriate position information for the given row (which is
+   * the current row and is valid).
+   */
+  protected abstract PositionImpl getRowPosition(RowIdImpl rowId) 
+    throws IOException;
     
   /**
    * Finds the next non-deleted row after the given row (as defined by this
diff --git a/src/main/java/com/healthmarketscience/jackcess/impl/IndexCursorImpl.java b/src/main/java/com/healthmarketscience/jackcess/impl/IndexCursorImpl.java
index c2f0280..68870d9 100644
--- a/src/main/java/com/healthmarketscience/jackcess/impl/IndexCursorImpl.java
+++ b/src/main/java/com/healthmarketscience/jackcess/impl/IndexCursorImpl.java
@@ -121,6 +121,18 @@ public class IndexCursorImpl extends CursorImpl implements IndexCursor
     return cursor;
   }  
 
+  private Set<String> getIndexEntryPattern()
+  {
+    if(_indexEntryPattern == null) {
+      // init our set of index column names
+      _indexEntryPattern = new HashSet<String>();
+      for(IndexData.ColumnDescriptor col : getIndex().getColumns()) {
+        _indexEntryPattern.add(col.getName());
+      }
+    }
+    return _indexEntryPattern;
+  }
+
   public IndexImpl getIndex() {
     return _index;
   }
@@ -223,6 +235,15 @@ public class IndexCursorImpl extends CursorImpl implements IndexCursor
   }
 
   @Override
+  protected PositionImpl getRowPosition(RowIdImpl rowId) throws IOException
+  {
+    // we need to get the index entry which corresponds with this row
+    Row row = getTable().getRow(getRowState(), rowId, getIndexEntryPattern());
+    _entryCursor.beforeEntry(getTable().asRow(row));
+    return new IndexPosition(_entryCursor.getNextEntry());
+  }
+
+  @Override
   protected boolean findAnotherRowImpl(
       ColumnImpl columnPattern, Object valuePattern, boolean moveForward,
       ColumnMatcher columnMatcher)
@@ -348,16 +369,8 @@ public class IndexCursorImpl extends CursorImpl implements IndexCursor
                                              ColumnMatcher columnMatcher)
     throws IOException
   {
-    if(_indexEntryPattern == null) {
-      // init our set of index column names
-      _indexEntryPattern = new HashSet<String>();
-      for(IndexData.ColumnDescriptor col : getIndex().getColumns()) {
-        _indexEntryPattern.add(col.getName());
-      }
-    }
-
     // check the next row to see if it actually matches
-    Row row = getCurrentRow(_indexEntryPattern);
+    Row row = getCurrentRow(getIndexEntryPattern());
 
     for(IndexData.ColumnDescriptor col : getIndex().getColumns()) {
       String columnName = col.getName();
diff --git a/src/main/java/com/healthmarketscience/jackcess/impl/TableScanCursor.java b/src/main/java/com/healthmarketscience/jackcess/impl/TableScanCursor.java
index 9fe8dc4..0f5e37f 100644
--- a/src/main/java/com/healthmarketscience/jackcess/impl/TableScanCursor.java
+++ b/src/main/java/com/healthmarketscience/jackcess/impl/TableScanCursor.java
@@ -85,6 +85,12 @@ public class TableScanCursor extends CursorImpl
   }
 
   @Override
+  protected PositionImpl getRowPosition(RowIdImpl rowId) throws IOException
+  {
+    return new ScanPosition(rowId);
+  }
+
+  @Override
   protected PositionImpl findAnotherPosition(
       RowState rowState, PositionImpl curPos, boolean moveForward)
     throws IOException