Criterion.java

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package com.google.refine.sorting;

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

import com.google.refine.expr.ExpressionUtils;
import com.google.refine.model.Column;
import com.google.refine.model.Project;
import com.google.refine.model.Record;
import com.google.refine.model.Row;

abstract public class Criterion {
    public String columnName;
    protected int cellIndex;

    // These take on positive and negative values to indicate where blanks and errors
    // go relative to non-blank values. They are also relative to each another.
    // Blanks and errors are not affected by the reverse flag.
    public int blankPosition = 1;
    public int errorPosition = 2;

    public boolean reverse;

    public void initializeFromJSON(Project project, JSONObject obj) 
            throws JSONException {
        if (obj.has("column") && !obj.isNull("column")) {
            columnName = obj.getString("column");

            Column column = project.columnModel.getColumnByName(columnName);
            cellIndex = column != null ? column.getCellIndex() : -1;
        }

        if (obj.has("blankPosition") && !obj.isNull("blankPosition")) {
            blankPosition = obj.getInt("blankPosition");
        }
        if (obj.has("errorPosition") && !obj.isNull("errorPosition")) {
            errorPosition = obj.getInt("errorPosition");
        }

        if (obj.has("reverse") && !obj.isNull("reverse")) {
            reverse = obj.getBoolean("reverse");
        }
    }


    // TODO: We'd like things to be more strongly typed a la the following, but
    // it's too involved to change right now
//    abstract public class Key implements Comparable<Key> {
//        abstract public int compareTo(Key key);
//    }
    
    abstract public class KeyMaker {
        public Object makeKey(Project project, Record record) {
            Object error = null;
            Object finalKey = null;

            for (int r = record.fromRowIndex; r < record.toRowIndex; r++) {
                Object key = makeKey(project, project.rows.get(r), r);
                if (ExpressionUtils.isError(key)) {
                    error = key;
                } else if (ExpressionUtils.isNonBlankData(key)) {
                    if (finalKey == null) {
                        finalKey = key;
                    } else {
                        int c = compareKeys(finalKey, key);
                        if (reverse) {
                            if (c < 0) { // key > finalKey
                                finalKey = key;
                            }
                        } else {
                            if (c > 0) { // key < finalKey
                                finalKey = key;
                            }
                        }
                    }
                }
            }

            if (finalKey != null) {
                return finalKey;
            } else if (error != null) {
                return error;
            } else {
                return null;
            }
        }

        public Object makeKey(Project project, Row row, int rowIndex) {
            if (cellIndex < 0) {
                return null;
            } else {
                Object value = row.getCellValue(cellIndex);
                return makeKey(value);
            }
        }

        abstract public int compareKeys(Object key1, Object key2);

        abstract protected Object makeKey(Object value);
    }
    abstract public KeyMaker createKeyMaker();
}