ManyToOneJoinExpr


1   /*
2    * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3    *
4    * This file is part of Resin(R) Open Source
5    *
6    * Each copy or derived work must preserve the copyright notice and this
7    * notice unmodified.
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9    * Resin Open Source is free software; you can redistribute it and/or modify
10   * it under the terms of the GNU General Public License as published by
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12   * (at your option) any later version.
13   *
14   * Resin Open Source is distributed in the hope that it will be useful,
15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17   * of NON-INFRINGEMENT.  See the GNU General Public License for more
18   * details.
19   *
20   * You should have received a copy of the GNU General Public License
21   * along with Resin Open Source; if not, write to the
22   *   Free Software Foundation, Inc.
23   *   59 Temple Place, Suite 330
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25   *
26   * @author Scott Ferguson
27   */
28  
29  package com.caucho.amber.expr;
30  
31  import com.caucho.amber.query.FromItem;
32  import com.caucho.amber.query.QueryParser;
33  import com.caucho.amber.table.ForeignColumn;
34  import com.caucho.amber.table.LinkColumns;
35  import com.caucho.util.CharBuffer;
36  
37  /**
38   * Links two tables.
39   *
40   * The parent table is "b" in "b.next".
41   * The child table is "b.next"
42   *
43   * The source is "b", i.e. the parent.
44   * The target is "b.next", i.e. the child.
45   */
46  public class ManyToOneJoinExpr extends JoinExpr {
47    private LinkColumns _linkColumns;
48  
49    private FromItem _sourceFromItem;
50    private FromItem _targetFromItem;
51  
52    /**
53     * Creates the expr.
54     */
55    public ManyToOneJoinExpr(LinkColumns link,
56                             FromItem source,
57                             FromItem target)
58    {
59      _linkColumns = link;
60  
61      _sourceFromItem = source;
62      _targetFromItem = target;
63  
64      // commented out: jpa/10c9
65      // if (source == null || target == null)
66  
67      if (target == null)
68        throw new NullPointerException  ();
69    }
70  
71    /**
72     * Returns true for a boolean expression.
73     */
74    public boolean isBoolean()
75    {
76      return true;
77    }
78  
79    /**
80     * Returns true for a many-to-many expression.
81     */
82    public boolean isManyToMany()
83    {
84      if (_sourceFromItem == null)
85        return false;
86  
87      return _sourceFromItem.getJoinExpr() instanceof OneToManyJoinExpr;
88    }
89  
90    /**
91     * Binds the expression as a select item.
92     */
93    public AmberExpr bindSelect(QueryParser parser)
94    {
95      return this;
96    }
97  
98    /**
99     * Binds the link to the from item.
100    */
101   public boolean bindToFromItem()
102   {
103     if (_targetFromItem.getJoinExpr() == null ||
104         _targetFromItem.getJoinExpr().equals(this)) {
105       _targetFromItem.setJoinExpr(this);
106       return true;
107     }
108     else if (_sourceFromItem.getJoinExpr() == null) {
109       _sourceFromItem.setJoinExpr(new OneToManyJoinExpr(_linkColumns,
110                                                         _sourceFromItem,
111                                                         _targetFromItem));
112 
113       return true;
114     }
115     else
116       return false;
117   }
118 
119   /**
120    * Returns the target join clause.
121    */
122   public FromItem getJoinTarget()
123   {
124     return _targetFromItem;
125   }
126 
127   /**
128    * Returns the target join clause.
129    */
130   public FromItem getJoinParent()
131   {
132     return _sourceFromItem;
133   }
134 
135   /**
136    * Returns true if the expression uses the from item.
137    */
138   public boolean usesFrom(FromItem from, int type, boolean isNot)
139   {
140     return from == _targetFromItem || from == _sourceFromItem;
141   }
142 
143   /**
144    * Returns true if the expression uses the from item.
145    */
146   @Override  
147   public boolean exists(FromItem from)
148   {
149     return false;
150   }
151 
152   /**
153    * Returns the id expr with the joined expression.
154    */
155   public AmberExpr replace(KeyColumnExpr id)
156   {
157     PathExpr parent = (PathExpr) id.getParent();
158 
159     if (parent.getChildFromItem() != _targetFromItem)
160       return id;
161 
162     ForeignColumn sourceColumn = _linkColumns.getSourceColumn(id.getColumn());
163 
164     if (sourceColumn == null)
165       throw new IllegalStateException  (id.getColumn().getName());
166 
167     return new ColumnExpr(_sourceFromItem.getIdExpr(), sourceColumn);
168   }
169 
170   /**
171    * Returns the id expr with the joined expression.
172    */
173   public AmberExpr replace(IdExpr id)
174   {
175     return id;
176   }
177 
178   /**
179    * Generates the where expression.
180    */
181   public void generateWhere(CharBuffer cb)
182   {
183     String   sourceName = null;
184 
185     // jpa/10c9
186     if (_sourceFromItem != null)
187       sourceName = _sourceFromItem.getName();
188 
189     String   targetName = _targetFromItem.getName();
190 
191     cb.append(_linkColumns.generateWhere(sourceName,
192                                          targetName));
193   }
194 
195   /**
196    * Generates the (update) where expression.
197    */
198   public void generateUpdateWhere(CharBuffer cb)
199   {
200     generateWhere(cb);
201   }
202 
203   /**
204    * Generates the having expression.
205    */
206   public void generateHaving(CharBuffer cb)
207   {
208     generateWhere(cb);
209   }
210 
211   /**
212    * Generates the where expression.
213    */
214   public void generateJoin(CharBuffer cb)
215   {
216     cb.append(_linkColumns.generateJoin(_sourceFromItem.getName(),
217                                         _targetFromItem.getName()));
218   }
219 
220   /**
221    * Test for equality.
222    */
223   public boolean equals(Object   o)
224   {
225     if (! (o instanceof ManyToOneJoinExpr))
226       return false;
227 
228     ManyToOneJoinExpr joinExpr = (ManyToOneJoinExpr) o;
229 
230     return (_linkColumns.equals(joinExpr._linkColumns) &&
231             _sourceFromItem.equals(joinExpr._sourceFromItem) &&
232             _targetFromItem.equals(joinExpr._targetFromItem));
233   }
234 
235 
236   public String   toString()
237   {
238     return ("ManyToOneJoinExpr[" + _linkColumns + "," +
239             _sourceFromItem + "," + _targetFromItem + "]");
240   }
241 }
242
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