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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 SubstringFunction extends AbstractFunction {
31 public static final String NAME = "Substring";
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 || params.size() > 3)
41 throw new QueryException("Function " + NAME + " expects two or three parameters.");
42
43 ValueExpr stringParam = getParam(0);
44 QValueType paramValueType = stringParam.getValueType();
45 if ((paramValueType != QValueType.UNDEFINED && paramValueType != QValueType.STRING) || stringParam.isSymbolicIdentifier() || stringParam.isMultiValue())
46 throw new QueryException("Function " + NAME + " needs a string as first parameter.");
47
48 ValueExpr lengthParam = getParam(1);
49 paramValueType = lengthParam.getValueType();
50 if ((paramValueType != QValueType.UNDEFINED && paramValueType != QValueType.LONG) || lengthParam.isSymbolicIdentifier() || lengthParam.isMultiValue())
51 throw new QueryException("Function " + NAME + " needs an integer number as second parameter.");
52
53 if (params.size() == 3) {
54 lengthParam = getParam(2);
55 paramValueType = lengthParam.getValueType();
56 if ((paramValueType != QValueType.UNDEFINED && paramValueType != QValueType.LONG) || lengthParam.isSymbolicIdentifier() || lengthParam.isMultiValue())
57 throw new QueryException("Function " + NAME + " needs an integer number as third parameter.");
58 }
59 }
60
61 public void generateSqlValueExpr(StringBuffer sql, SqlGenerationContext context) throws QueryException {
62 String sqlFunction = context.getJdbcHelper().getSubstringFunction();
63 sql.append(' ').append(sqlFunction).append('(');
64 super.generateSqlValueExpr(sql, context);
65 sql.append(") ");
66 }
67
68 public Object evaluate(QValueType valueType, EvaluationContext evaluationContext) throws QueryException {
69 String value = (String )((ValueExpr)params.get(0)).evaluate(QValueType.STRING, evaluationContext);
70 int pos = ((Long )((ValueExpr)params.get(1)).evaluate(QValueType.LONG, evaluationContext)).intValue();
71 int length = value.length() - pos;
72 if (params.size() == 3)
73 length = ((Long )((ValueExpr)params.get(2)).evaluate(QValueType.LONG, evaluationContext)).intValue();
74 return evaluate(value, pos, length);
75 }
76
77 public Object evaluate(QValueType valueType, Document document, Version version, EvaluationContext evaluationContext) throws QueryException {
78 String value = (String )((ValueExpr)params.get(0)).evaluate(QValueType.STRING, document, version, evaluationContext);
79 int pos = ((Long )((ValueExpr)params.get(1)).evaluate(QValueType.LONG, document, version, evaluationContext)).intValue();
80 int length = value.length() - pos;
81 if (params.size() == 3)
82 length = ((Long )((ValueExpr)params.get(2)).evaluate(QValueType.LONG, evaluationContext)).intValue();
83 return evaluate(value, pos, length);
84 }
85
86 protected Object evaluate(String value, int pos, int length) throws QueryException {
87 if (value == null)
88 return null;
89 else if (pos < 1)
90 throw new QueryException("Position parameter of " + NAME + " function cannot be less than one.");
91 else if (length < 0)
92 throw new QueryException("Length parameter of " + NAME + " function cannot be negative.");
93 else if (pos > value.length())
94 return "";
95 else {
96 int endIndex = pos + length;
97 if (endIndex > value.length() + 1)
98 endIndex = value.length() + 1;
99 return value.substring(pos - 1, endIndex - 1);
101 }
102 }
103
104 public QValueType getValueType() {
105 return QValueType.STRING;
106 }
107
108 public String getTitle(Locale locale) {
109 return getExpression();
110 }
111
112 public QValueType getOutputValueType() {
113 return QValueType.STRING;
114 }
115
116 public Object getOutputValue(Document document, Version version, EvaluationContext evaluationContext) throws QueryException {
117 return evaluate(null, document, version, evaluationContext);
118 }
119 }
120
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