PMD - 3.7

Clover coverage report - PMD - 3.7

Coverage timestamp: Wed May 31 2006 09:25:59 EDT

FRAMES NO FRAMES

file stats:	LOC:	103		Methods:	4
	NCLOC:	55		Classes:	1

Source file

Conditionals

Statements

Methods

TOTAL

InefficientEmptyStringCheck.java

92.9%

95.2%

100%

94.9%

1		package net.sourceforge.pmd.rules.strings;
2
3		import net.sourceforge.pmd.AbstractRule;
4		import net.sourceforge.pmd.ast.ASTEqualityExpression;
5		import net.sourceforge.pmd.ast.ASTLiteral;
6		import net.sourceforge.pmd.ast.ASTPrimitiveType;
7		import net.sourceforge.pmd.ast.ASTVariableDeclaratorId;
8		import net.sourceforge.pmd.ast.Node;
9		import net.sourceforge.pmd.ast.SimpleNode;
10		import net.sourceforge.pmd.symboltable.NameOccurrence;
11
12		import java.util.Iterator;
13		import java.util.List;
14
15		/**
16		* This rule finds code which inefficiently determines empty strings. This code
17		* <p/>
18		* <pre>
19		* if(str.trim().length()==0){....
20		* </pre>
21		* <p/>
22		* is quite inefficient as trim() causes a new String to be created. Smarter
23		* code to check for an empty string would be:
24		* <p/>
25		* <pre>
26		* Character.isWhitespace(str.charAt(i));
27		* </pre>
28		*
29		* @author acaplan
30		*/
31		public class InefficientEmptyStringCheck extends AbstractRule {
32
33	14	public Object visit(ASTVariableDeclaratorId node, Object data) {
34	14	SimpleNode nameNode = node.getTypeNameNode();
35	14	if (nameNode instanceof ASTPrimitiveType) {
36	5	return data;
37		}
38
39	9	if (!"String".equals(node.getNameDeclaration().getTypeImage())) {
40	0	return data;
41		}
42
43	9	List declars = node.getUsages();
44	9	for (Iterator i = declars.iterator(); i.hasNext();) {
45	9	NameOccurrence occ = (NameOccurrence) i.next();
46	9	if (!isStringLength(occ)) {
47	2	continue;
48		}
49	7	ASTEqualityExpression equality = (ASTEqualityExpression) occ
50		.getLocation().getFirstParentOfType(ASTEqualityExpression.class);
51	7	if (equality != null && isCompareZero(equality)) {
52	3	addViolation(data, occ.getLocation());
53		}
54		}
55	9	return data;
56		}
57
58		/**
59		* We only need to report if this is comparing against 0
60		*
61		* @param equality
62		* @return true if this is comparing to 0 else false
63		*/
64	5	private boolean isCompareZero(ASTEqualityExpression equality) {
65	5	return (checkComparison(equality, 0) \|\| checkComparison(equality, 1));
66
67		}
68
69		/**
70		* Determine if we're dealing with String.length method
71		*
72		* @param occ The name occurance
73		* @return true if it's String.length, else false
74		*/
75	9	private boolean isStringLength(NameOccurrence occ) {
76	9	if (occ.getNameForWhichThisIsAQualifier() != null
77		&& occ.getNameForWhichThisIsAQualifier().getImage().indexOf("trim") != -1) {
78	8	Node pExpression = occ.getLocation().jjtGetParent().jjtGetParent();
79	8	if (pExpression.jjtGetNumChildren() >= 3
80		&& "length"
81		.equals(((SimpleNode) pExpression.jjtGetChild(2))
82		.getImage())) {
83	7	return true;
84		}
85		}
86	2	return false;
87		}
88
89		/**
90		* Checks if the equality expression passed in is of comparing against the
91		* value passed in as i
92		*
93		* @param equality
94		* @param i The ordinal in the equality expression to check
95		* @return true if the value in position i is 0, else false
96		*/
97	10	private boolean checkComparison(ASTEqualityExpression equality, int i) {
98	10	return (equality.jjtGetChild(i).jjtGetChild(0).jjtGetChild(0) instanceof ASTLiteral && "0"
99		.equals(((SimpleNode) equality.jjtGetChild(i).jjtGetChild(0)
100		.jjtGetChild(0)).getImage()));
101		}
102
103		}