01: /*
02: * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
03: *
04: * This file is part of Resin(R) Open Source
05: *
06: * Each copy or derived work must preserve the copyright notice and this
07: * notice unmodified.
08: *
09: * 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
11: * the Free Software Foundation; either version 2 of the License, or
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 SoftwareFoundation, Inc.
23: * 59 Temple Place, Suite 330
24: * Boston, MA 02111-1307 USA
25: *
26: * @author Scott Ferguson
27: */
28:
29: package com.caucho.db.sql;
30:
31: import com.caucho.log.Log;
32:
33: import java.sql.SQLException;
34: import java.util.ArrayList;
35: import java.util.logging.Logger;
36:
37: class ConcatExpr extends Expr {
38: private static final Logger log = Log.open(ConcatExpr.class);
39:
40: private Expr _left;
41: private Expr _right;
42:
43: ConcatExpr(Expr left, Expr right) {
44: _left = left;
45: _right = right;
46: }
47:
48: protected Expr bind(Query query) throws SQLException {
49: _left = _left.bind(query);
50: _right = _right.bind(query);
51:
52: return this ;
53: }
54:
55: /**
56: * Returns the type of the expression.
57: */
58: public Class getType() {
59: return String.class;
60: }
61:
62: /**
63: * Returns the cost based on the given FromList.
64: */
65: public long subCost(ArrayList<FromItem> fromList) {
66: return _left.subCost(fromList) + _right.subCost(fromList);
67: }
68:
69: /**
70: * Evaluates the expression as a string.
71: */
72: public String evalString(QueryContext context) throws SQLException {
73: String leftValue = _left.evalString(context);
74: String rightValue = _right.evalString(context);
75:
76: if (leftValue == null)
77: return rightValue;
78:
79: if (rightValue == null)
80: return leftValue;
81:
82: return leftValue + rightValue;
83: }
84:
85: /**
86: * Evaluates aggregate functions during the group phase.
87: *
88: * @param state the current database tuple
89: */
90: public void evalGroup(QueryContext context) throws SQLException {
91: _left.evalGroup(context);
92: _right.evalGroup(context);
93: }
94:
95: public String toString() {
96: return "(" + _left + " || " + _right + ")";
97: }
98: }
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