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1
16 package org.outerj.daisy.query.model.functions;
17
18 import org.outerj.daisy.repository.Document;
19 import org.outerj.daisy.repository.Version;
20 import org.outerj.daisy.repository.query.QueryException;
21 import org.outerj.daisy.repository.query.EvaluationContext;
22 import org.outerj.daisy.query.QueryContext;
23 import org.outerj.daisy.query.model.*;
24
25 import java.util.Locale  ;
26
27 public class LengthFunction extends AbstractFunction {
28 public static final String NAME = "Length";
29
30 public String getFunctionName() {
31 return NAME;
32 }
33
34 public void prepare(QueryContext context) throws QueryException {
35 super.prepare(context);
36
37 if (params.size() != 1)
38 throw new QueryException("Function " + NAME + " expects exactly one parameter.");
39 ValueExpr param = getParam(0);
40 QValueType paramValueType = param.getValueType();
41 if ((paramValueType != QValueType.UNDEFINED && paramValueType != QValueType.STRING) || param.isSymbolicIdentifier() || param.isMultiValue())
42 throw new QueryException("Function " + NAME + " needs a string as parameter.");
43 }
44
45 public void generateSqlValueExpr(StringBuffer sql, SqlGenerationContext context) throws QueryException {
46 String [] sqlFunction = context.getJdbcHelper().getStringLengthFunction();
47 sql.append(' ').append(sqlFunction[0]);
48 super.generateSqlValueExpr(sql, context);
49 sql.append(sqlFunction[1]).append(' ');
50 }
51
52 public Object evaluate(QValueType valueType, EvaluationContext evaluationContext) throws QueryException {
53 String value = (String )((ValueExpr)params.get(0)).evaluate(QValueType.STRING, evaluationContext);
54 return evaluate(value);
55 }
56
57 public Object evaluate(QValueType valueType, Document document, Version version, EvaluationContext evaluationContext) throws QueryException {
58 String value = (String )((ValueExpr)params.get(0)).evaluate(QValueType.STRING, document, version, evaluationContext);
59 return evaluate(value);
60 }
61
62 private Object evaluate(String value) {
63 if (value == null)
64 return null;
65 else
66 return new Long (value.length());
67 }
68
69 public QValueType getValueType() {
70 return QValueType.LONG;
71 }
72
73 public String getTitle(Locale locale) {
74 return getExpression();
75 }
76
77 public QValueType getOutputValueType() {
78 return QValueType.LONG;
79 }
80
81 public Object getOutputValue(Document document, Version version, EvaluationContext evaluationContext) throws QueryException {
82 return evaluate(null, document, version, evaluationContext);
83 }
84 }
85 |
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