MultiValuedCellJoinOperation.java

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package com.google.refine.operations.cell;

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONWriter;

import com.google.refine.expr.ExpressionUtils;
import com.google.refine.history.HistoryEntry;
import com.google.refine.model.AbstractOperation;
import com.google.refine.model.Cell;
import com.google.refine.model.Column;
import com.google.refine.model.Project;
import com.google.refine.model.Row;
import com.google.refine.model.changes.MassRowChange;
import com.google.refine.operations.OperationRegistry;

public class MultiValuedCellJoinOperation extends AbstractOperation {
    final protected String    _columnName;
    final protected String    _keyColumnName;
    final protected String    _separator;

    static public AbstractOperation reconstruct(Project project, JSONObject obj) throws Exception {
        return new MultiValuedCellJoinOperation(
            obj.getString("columnName"),
            obj.getString("keyColumnName"),
            obj.getString("separator")
        );
    }
    
    public MultiValuedCellJoinOperation(
        String      columnName,
        String      keyColumnName,
        String    separator
    ) {
        _columnName = columnName;
        _keyColumnName = keyColumnName;
        _separator = separator;
    }

    @Override
    public void write(JSONWriter writer, Properties options)
            throws JSONException {
        
        writer.object();
        writer.key("op"); writer.value(OperationRegistry.s_opClassToName.get(this.getClass()));
        writer.key("description"); writer.value(getBriefDescription(null));
        writer.key("columnName"); writer.value(_columnName);
        writer.key("keyColumnName"); writer.value(_keyColumnName);
        writer.key("separator"); writer.value(_separator);
        writer.endObject();
    }
    
    @Override
    protected String getBriefDescription(Project project) {
        return "Join multi-valued cells in column " + _columnName;
    }

    @Override
    protected HistoryEntry createHistoryEntry(Project project, long historyEntryID) throws Exception {
        Column column = project.columnModel.getColumnByName(_columnName);
        if (column == null) {
            throw new Exception("No column named " + _columnName);
        }
        int cellIndex = column.getCellIndex();
        
        Column keyColumn = project.columnModel.getColumnByName(_keyColumnName);
        if (keyColumn == null) {
            throw new Exception("No key column named " + _keyColumnName);
        }
        int keyCellIndex = keyColumn.getCellIndex();
        
        List<Row> newRows = new ArrayList<Row>();
        
        int oldRowCount = project.rows.size();
        for (int r = 0; r < oldRowCount; r++) {
            Row oldRow = project.rows.get(r);
            
            if (oldRow.isCellBlank(keyCellIndex)) {
                newRows.add(oldRow.dup());
                continue;
            }
            
            int r2 = r + 1;
            while (r2 < oldRowCount && project.rows.get(r2).isCellBlank(keyCellIndex)) {
                r2++;
            }
            
            if (r2 == r + 1) {
                newRows.add(oldRow.dup());
                continue;
            }
            
            StringBuffer sb = new StringBuffer();
            for (int r3 = r; r3 < r2; r3++) {
                Object value = project.rows.get(r3).getCellValue(cellIndex);
                if (ExpressionUtils.isNonBlankData(value)) {
                    if (sb.length() > 0) {
                        sb.append(_separator);
                    }
                    sb.append(value.toString());
                }
            }
            
            for (int r3 = r; r3 < r2; r3++) {
                Row newRow = project.rows.get(r3).dup();
                if (r3 == r) {
                    newRow.setCell(cellIndex, new Cell(sb.toString(), null));
                } else {
                    newRow.setCell(cellIndex, null);
                }
                
                if (!newRow.isEmpty()) {
                    newRows.add(newRow);
                }
            }
            
            r = r2 - 1; // r will be incremented by the for loop anyway
        }
        
        return new HistoryEntry(
            historyEntryID,
            project, 
            getBriefDescription(null), 
            this, 
            new MassRowChange(newRows)
        );
    }

}