Package com.google.refine.operations.column

Source Code of com.google.refine.operations.column.ColumnAdditionOperation

/*

Copyright 2010, Google Inc.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
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    * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above
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contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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*/

package com.google.refine.operations.column;

import java.io.Serializable;
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.browsing.Engine;
import com.google.refine.browsing.FilteredRows;
import com.google.refine.browsing.RowVisitor;
import com.google.refine.expr.Evaluable;
import com.google.refine.expr.ExpressionUtils;
import com.google.refine.expr.MetaParser;
import com.google.refine.expr.WrappedCell;
import com.google.refine.history.Change;
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.CellAtRow;
import com.google.refine.model.changes.ColumnAdditionChange;
import com.google.refine.operations.EngineDependentOperation;
import com.google.refine.operations.OnError;
import com.google.refine.operations.OperationRegistry;
import com.google.refine.operations.cell.TextTransformOperation;

public class ColumnAdditionOperation extends EngineDependentOperation {
    final protected String     _baseColumnName;
    final protected String     _expression;
    final protected OnError    _onError;
   
    final protected String     _newColumnName;
    final protected int        _columnInsertIndex;

    static public AbstractOperation reconstruct(Project project, JSONObject obj) throws Exception {
        JSONObject engineConfig = obj.getJSONObject("engineConfig");
       
        return new ColumnAdditionOperation(
            engineConfig,
            obj.getString("baseColumnName"),
            obj.getString("expression"),
            TextTransformOperation.stringToOnError(obj.getString("onError")),
            obj.getString("newColumnName"),
            obj.getInt("columnInsertIndex")
        );
    }
   
    public ColumnAdditionOperation(
        JSONObject     engineConfig,
        String         baseColumnName,
        String         expression,
        OnError        onError,
        String         newColumnName,
        int            columnInsertIndex
    ) {
        super(engineConfig);
       
        _baseColumnName = baseColumnName;
        _expression = expression;
        _onError = onError;
       
        _newColumnName = newColumnName;
        _columnInsertIndex = columnInsertIndex;
    }

    @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("engineConfig"); writer.value(getEngineConfig());
        writer.key("newColumnName"); writer.value(_newColumnName);
        writer.key("columnInsertIndex"); writer.value(_columnInsertIndex);
        writer.key("baseColumnName"); writer.value(_baseColumnName);
        writer.key("expression"); writer.value(_expression);
        writer.key("onError"); writer.value(TextTransformOperation.onErrorToString(_onError));
        writer.endObject();
    }

    @Override
    protected String getBriefDescription(Project project) {
        return "Create column " + _newColumnName +
            " at index " + _columnInsertIndex +
            " based on column " + _baseColumnName +
            " using expression " + _expression;
    }

    protected String createDescription(Column column, List<CellAtRow> cellsAtRows) {
        return "Create new column " + _newColumnName +
            " based on column " + column.getName() +
            " by filling " + cellsAtRows.size() +
            " rows with " + _expression;
    }
   
    @Override
    protected HistoryEntry createHistoryEntry(Project project, long historyEntryID) throws Exception {
        Engine engine = createEngine(project);
       
        Column column = project.columnModel.getColumnByName(_baseColumnName);
        if (column == null) {
            throw new Exception("No column named " + _baseColumnName);
        }
        if (project.columnModel.getColumnByName(_newColumnName) != null) {
            throw new Exception("Another column already named " + _newColumnName);
        }
       
        List<CellAtRow> cellsAtRows = new ArrayList<CellAtRow>(project.rows.size());
       
        FilteredRows filteredRows = engine.getAllFilteredRows();
        filteredRows.accept(project, createRowVisitor(project, cellsAtRows));
       
        String description = createDescription(column, cellsAtRows);
       
        Change change = new ColumnAdditionChange(_newColumnName, _columnInsertIndex, cellsAtRows);
       
        return new HistoryEntry(
            historyEntryID, project, description, this, change);
    }

    protected RowVisitor createRowVisitor(Project project, List<CellAtRow> cellsAtRows) throws Exception {
        Column column = project.columnModel.getColumnByName(_baseColumnName);
       
        Evaluable eval = MetaParser.parse(_expression);
        Properties bindings = ExpressionUtils.createBindings(project);
       
        return new RowVisitor() {
            int              cellIndex;
            Properties       bindings;
            List<CellAtRow>  cellsAtRows;
            Evaluable        eval;
           
            public RowVisitor init(int cellIndex, Properties bindings, List<CellAtRow> cellsAtRows, Evaluable eval) {
                this.cellIndex = cellIndex;
                this.bindings = bindings;
                this.cellsAtRows = cellsAtRows;
                this.eval = eval;
                return this;
            }
           
            @Override
            public void start(Project project) {
                // nothing to do
            }

            @Override
            public void end(Project project) {
                // nothing to do
            }
           
            @Override
            public boolean visit(Project project, int rowIndex, Row row) {
                Cell cell = row.getCell(cellIndex);
                Cell newCell = null;

                ExpressionUtils.bind(bindings, row, rowIndex, _baseColumnName, cell);
               
                Object o = eval.evaluate(bindings);
                if (o != null) {
                    if (o instanceof Cell) {
                        newCell = (Cell) o;
                    } else if (o instanceof WrappedCell) {
                        newCell = ((WrappedCell) o).cell;
                    } else {
                        Serializable v = ExpressionUtils.wrapStorable(o);
                        if (ExpressionUtils.isError(v)) {
                            if (_onError == OnError.SetToBlank) {
                                return false;
                            } else if (_onError == OnError.KeepOriginal) {
                                v = cell != null ? cell.value : null;
                            }
                        }
                       
                        if (v != null) {
                            newCell = new Cell(v, null);
                        }
                    }
                }
               
                if (newCell != null) {
                    cellsAtRows.add(new CellAtRow(rowIndex, newCell));
                }
               
                return false;
            }
        }.init(column.getCellIndex(), bindings, cellsAtRows, eval);
    }
}
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