1 /*
2 * Copyright (c) 2011-2024 Qulice.com
3 *
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met: 1) Redistributions of source code must retain the above
9 * copyright notice, this list of conditions and the following
10 * disclaimer. 2) Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following
12 * disclaimer in the documentation and/or other materials provided
13 * with the distribution. 3) Neither the name of the Qulice.com nor
14 * the names of its contributors may be used to endorse or promote
15 * products derived from this software without specific prior written
16 * permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
20 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
22 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
23 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
27 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
29 * OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31 package com.qulice.pmd.rules;
32
33 import java.util.List;
34 import java.util.Map;
35 import net.sourceforge.pmd.lang.java.ast.ASTArgumentList;
36 import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration;
37 import net.sourceforge.pmd.lang.java.ast.ASTReturnStatement;
38 import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclarator;
39 import net.sourceforge.pmd.lang.java.ast.JavaNode;
40 import net.sourceforge.pmd.lang.java.rule.AbstractJavaRule;
41 import net.sourceforge.pmd.lang.symboltable.NameDeclaration;
42 import net.sourceforge.pmd.lang.symboltable.NameOccurrence;
43
44 /**
45 * Rule to check unnecessary local variables.
46 *
47 * @since 0.4
48 */
49 public final class UnnecessaryLocalRule extends AbstractJavaRule {
50 @Override
51 public Object visit(final ASTMethodDeclaration meth, final Object data) {
52 Object ndata = data;
53 if (!meth.isAbstract() && !meth.isNative()) {
54 ndata = super.visit(meth, data);
55 }
56 return ndata;
57 }
58
59 @Override
60 public Object visit(final ASTReturnStatement rtn, final Object data) {
61 final ASTVariableDeclarator name =
62 rtn.getFirstChildOfType(ASTVariableDeclarator.class);
63 if (name != null) {
64 this.usages(rtn, data, name);
65 }
66 return data;
67 }
68
69 @Override
70 public Object visit(final ASTArgumentList rtn, final Object data) {
71 final List<ASTVariableDeclarator> names =
72 rtn.findChildrenOfType(ASTVariableDeclarator.class);
73 for (final ASTVariableDeclarator name : names) {
74 this.usages(rtn, data, name);
75 }
76 return data;
77 }
78
79 /**
80 * Report when number of variable usages is equal to zero.
81 * @param node Node to check.
82 * @param data Context.
83 * @param name Variable name.
84 */
85 private void usages(final JavaNode node, final Object data,
86 final ASTVariableDeclarator name) {
87 final Map<NameDeclaration, List<NameOccurrence>> vars = name
88 .getScope().getDeclarations();
89 for (final Map.Entry<NameDeclaration, List<NameOccurrence>> entry
90 : vars.entrySet()) {
91 final List<NameOccurrence> usages = entry.getValue();
92 if (usages.size() > 1) {
93 continue;
94 }
95 for (final NameOccurrence occ: usages) {
96 if (occ.getLocation().equals(name)) {
97 this.asCtx(data).addViolation(
98 node, name.getImage()
99 );
100 }
101 }
102 }
103 }
104 }