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16 package org.outerj.daisy.query.model.functions;
17
18 import org.outerj.daisy.query.model.AbstractFunction;
19 import org.outerj.daisy.query.model.ValueExpr;
20 import org.outerj.daisy.query.model.QValueType;
21 import org.outerj.daisy.query.model.SqlGenerationContext;
22 import org.outerj.daisy.query.QueryContext;
23 import org.outerj.daisy.repository.query.QueryException;
24 import org.outerj.daisy.repository.query.EvaluationContext;
25 import org.outerj.daisy.repository.Document;
26 import org.outerj.daisy.repository.Version;
27
28 import java.util.Locale  ;
29
30 public class LeftFunction extends AbstractFunction {
31 public static final String NAME = "Left";
32
33 public String getFunctionName() {
34 return NAME;
35 }
36
37 public void prepare(QueryContext context) throws QueryException {
38 super.prepare(context);
39
40 if (params.size() != 2)
41 throw new QueryException("Function " + getFunctionName() + " expects exactly two parameters.");
42 ValueExpr stringParam = getParam(0);
43 QValueType paramValueType = stringParam.getValueType();
44 if ((paramValueType != QValueType.UNDEFINED && paramValueType != QValueType.STRING) || stringParam.isSymbolicIdentifier() || stringParam.isMultiValue())
45 throw new QueryException("Function " + getFunctionName() + " needs a string as first parameter.");
46
47 ValueExpr lengthParam = getParam(1);
48 paramValueType = lengthParam.getValueType();
49 if ((paramValueType != QValueType.UNDEFINED && paramValueType != QValueType.LONG) || lengthParam.isSymbolicIdentifier() || lengthParam.isMultiValue())
50 throw new QueryException("Function " + getFunctionName() + " needs an integer number as second parameter.");
51 }
52
53 public void generateSqlValueExpr(StringBuffer sql, SqlGenerationContext context) throws QueryException {
54 String sqlFunction = getFunctionName(context);
55 sql.append(' ').append(sqlFunction).append('(');
56 super.generateSqlValueExpr(sql, context);
57 sql.append(") ");
58 }
59
60 protected String getFunctionName(SqlGenerationContext context) {
61 return context.getJdbcHelper().getStringLeftFunction();
62 }
63
64 public Object evaluate(QValueType valueType, EvaluationContext evaluationContext) throws QueryException {
65 String value = (String )((ValueExpr)params.get(0)).evaluate(QValueType.STRING, evaluationContext);
66 int length = ((Long )((ValueExpr)params.get(1)).evaluate(QValueType.LONG, evaluationContext)).intValue();
67 return evaluate(value, length);
68 }
69
70 public Object evaluate(QValueType valueType, Document document, Version version, EvaluationContext evaluationContext) throws QueryException {
71 String value = (String )((ValueExpr)params.get(0)).evaluate(QValueType.STRING, document, version, evaluationContext);
72 int length = ((Long )((ValueExpr)params.get(1)).evaluate(QValueType.LONG, document, version, evaluationContext)).intValue();
73 return evaluate(value, length);
74 }
75
76 protected Object evaluate(String value, int length) throws QueryException {
77 if (value == null)
78 return null;
79 else if (length < 0)
80 throw new QueryException("Length parameter of " + getFunctionName() + " function cannot be negative.");
81 else if (length > value.length())
82 return value;
83 else
84 return value.substring(0, length);
85 }
86
87 public QValueType getValueType() {
88 return QValueType.STRING;
89 }
90
91 public String getTitle(Locale locale) {
92 return getExpression();
93 }
94
95 public QValueType getOutputValueType() {
96 return QValueType.STRING;
97 }
98
99 public Object getOutputValue(Document document, Version version, EvaluationContext evaluationContext) throws QueryException {
100 return evaluate(null, document, version, evaluationContext);
101 }
102 }
103 |
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