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Java > Open Source Codes > org > hibernate > dialect > function > SQLFunctionTemplate


1 //$Id: SQLFunctionTemplate.java,v 1.3 2005/04/29 15:32:30 oneovthafew Exp $
2 package org.hibernate.dialect.function;
3
4 import org.hibernate.QueryException;
5 import org.hibernate.engine.Mapping;
6 import org.hibernate.engine.SessionFactoryImplementor;
7 import org.hibernate.type.Type;
8
9 import java.util.ArrayList JavaDoc;
10 import java.util.List JavaDoc;
11
12 /**
13  * Represents HQL functions that can have different representations in different SQL dialects.
14  * E.g. in HQL we can define function <code>concat(?1, ?2)</code> to concatenate two strings
15  * p1 and p2. Target SQL function will be dialect-specific, e.g. <code>(?1 || ?2)</code> for
16  * Oracle, <code>concat(?1, ?2)</code> for MySql, <code>(?1 + ?2)</code> for MS SQL.
17  * Each dialect will define a template as a string (exactly like above) marking function
18  * parameters with '?' followed by parameter's index (first index is 1).
19  *
20  * @author <a HREF="mailto:alex@jboss.org">Alexey Loubyansky</a>
21  * @version <tt>$Revision: 1.3 $</tt>
22  */
23 public class SQLFunctionTemplate implements SQLFunction {
24     private final Type type;
25     private final boolean hasArguments;
26     private final boolean hasParenthesesIfNoArgs;
27
28     private final String JavaDoc template;
29     private final String JavaDoc[] chunks;
30     private final int[] paramIndexes;
31
32     public SQLFunctionTemplate(Type type, String JavaDoc template) {
33         this( type, template, true );
34     }
35
36     public SQLFunctionTemplate(Type type, String JavaDoc template, boolean hasParenthesesIfNoArgs) {
37         this.type = type;
38         this.template = template;
39
40         List JavaDoc chunkList = new ArrayList JavaDoc();
41         List JavaDoc paramList = new ArrayList JavaDoc();
42         StringBuffer JavaDoc chunk = new StringBuffer JavaDoc( 10 );
43         StringBuffer JavaDoc index = new StringBuffer JavaDoc( 2 );
44
45         for ( int i = 0; i < template.length(); ++i ) {
46             char c = template.charAt( i );
47             if ( c == '?' ) {
48                 chunkList.add( chunk.toString() );
49                 chunk.delete( 0, chunk.length() );
50
51                 while ( ++i < template.length() ) {
52                     c = template.charAt( i );
53                     if ( Character.isDigit( c ) ) {
54                         index.append( c );
55                     }
56                     else {
57                         chunk.append( c );
58                         break;
59                     }
60                 }
61
62                 paramList.add( new Integer JavaDoc( Integer.parseInt( index.toString() ) - 1 ) );
63                 index.delete( 0, index.length() );
64             }
65             else {
66                 chunk.append( c );
67             }
68         }
69
70         if ( chunk.length() > 0 ) {
71             chunkList.add( chunk.toString() );
72         }
73
74         chunks = ( String JavaDoc[] ) chunkList.toArray( new String JavaDoc[chunkList.size()] );
75         paramIndexes = new int[paramList.size()];
76         for ( int i = 0; i < paramIndexes.length; ++i ) {
77             paramIndexes[i] = ( ( Integer JavaDoc ) paramList.get( i ) ).intValue();
78         }
79
80         hasArguments = paramIndexes.length > 0;
81         this.hasParenthesesIfNoArgs = hasParenthesesIfNoArgs;
82     }
83
84     /**
85      * Applies the template to passed in arguments.
86      * @param args function arguments
87      *
88      * @return generated SQL function call
89      */
90     public String JavaDoc render(List JavaDoc args, SessionFactoryImplementor factory) {
91         StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
92         for ( int i = 0; i < chunks.length; ++i ) {
93             if ( i < paramIndexes.length ) {
94                 Object JavaDoc arg = paramIndexes[i] < args.size() ? args.get( paramIndexes[i] ) : null;
95                 if ( arg != null ) {
96                     buf.append( chunks[i] ).append( arg );
97                 }
98             }
99             else {
100                 buf.append( chunks[i] );
101             }
102         }
103         return buf.toString();
104     }
105
106     // SQLFunction implementation
107
108     public Type getReturnType(Type columnType, Mapping mapping) throws QueryException {
109         return type;
110     }
111
112     public boolean hasArguments() {
113         return hasArguments;
114     }
115
116     public boolean hasParenthesesIfNoArguments() {
117         return hasParenthesesIfNoArgs;
118     }
119     
120     public String JavaDoc toString() {
121         return template;
122     }
123 }
124
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