1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape 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. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.graph.query.model;
25
26 import java.util.Collections;
27 import java.util.HashMap;
28 import java.util.Map;
29 import org.modeshape.common.util.CheckArg;
30
31 /**
32 * The arithmetic operators.
33 */
34 public enum ArithmeticOperator {
35
36 ADD("+", Arity.BINARY, 20),
37 SUBTRACT("-", Arity.BINARY, 19),
38 MULTIPLY("*", Arity.BINARY, 18),
39 DIVIDE("/", Arity.BINARY, 17);
40
41 public static enum Arity {
42 UNARY,
43 BINARY;
44 }
45
46 private static final Map<String, ArithmeticOperator> OPERATORS_BY_SYMBOL;
47 static {
48 Map<String, ArithmeticOperator> opsBySymbol = new HashMap<String, ArithmeticOperator>();
49 for (ArithmeticOperator operator : ArithmeticOperator.values()) {
50 opsBySymbol.put(operator.symbol(), operator);
51 }
52 OPERATORS_BY_SYMBOL = Collections.unmodifiableMap(opsBySymbol);
53 }
54
55 private final String symbol;
56 private final Arity arity;
57 private final int precedence;
58
59 private ArithmeticOperator( String symbol,
60 Arity arity,
61 int precedence ) {
62 this.symbol = symbol;
63 this.arity = arity;
64 this.precedence = precedence;
65 }
66
67 /**
68 * Get the symbol for this operator
69 *
70 * @return the symbolic representation; never null
71 */
72 public String symbol() {
73 return symbol;
74 }
75
76 /**
77 * Get the 'arity' of the operator.
78 *
79 * @return the number of parameters required
80 * @see #isUnary()
81 * @see #isBinary()
82 */
83 public Arity arity() {
84 return arity;
85 }
86
87 /**
88 * Return whether this is an unary operator.
89 *
90 * @return true if this operator is unary, or false otherwise
91 * @see #arity()
92 * @see #isBinary()
93 */
94 public boolean isUnary() {
95 return arity == Arity.UNARY;
96 }
97
98 /**
99 * Return whether this is an binary operator.
100 *
101 * @return true if this operator is binary, or false otherwise
102 * @see #arity()
103 * @see #isUnary()
104 */
105 public boolean isBinary() {
106 return arity == Arity.BINARY;
107 }
108
109 /**
110 * Determine whether this operator has a higher precedence than the supplied operator.
111 *
112 * @param operator the other operator; may not be null
113 * @return true if this operator has a higher precedence, or false otherwise
114 */
115 public boolean precedes( ArithmeticOperator operator ) {
116 return this.precedence > operator.precedence;
117 }
118
119 /**
120 * {@inheritDoc}
121 *
122 * @see java.lang.Enum#toString()
123 */
124 @Override
125 public String toString() {
126 return symbol;
127 }
128
129 /**
130 * Attempt to find the Operator given a symbol. The matching is done independent of case.
131 *
132 * @param symbol the symbol
133 * @return the Operator having the supplied symbol, or null if there is no Operator with the supplied symbol
134 * @throws IllegalArgumentException if the symbol is null
135 */
136 public static ArithmeticOperator forSymbol( String symbol ) {
137 CheckArg.isNotNull(symbol, "symbol");
138 return OPERATORS_BY_SYMBOL.get(symbol.toUpperCase());
139 }
140 }