/
AvoidReferentialEquality.kt
79 lines (71 loc) · 3.04 KB
/
AvoidReferentialEquality.kt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
package io.gitlab.arturbosch.detekt.rules.bugs
import io.gitlab.arturbosch.detekt.api.CodeSmell
import io.gitlab.arturbosch.detekt.api.Config
import io.gitlab.arturbosch.detekt.api.Debt
import io.gitlab.arturbosch.detekt.api.Entity
import io.gitlab.arturbosch.detekt.api.Issue
import io.gitlab.arturbosch.detekt.api.Rule
import io.gitlab.arturbosch.detekt.api.Severity
import io.gitlab.arturbosch.detekt.api.config
import io.gitlab.arturbosch.detekt.api.internal.ActiveByDefault
import io.gitlab.arturbosch.detekt.api.internal.Configuration
import io.gitlab.arturbosch.detekt.api.internal.RequiresTypeResolution
import io.gitlab.arturbosch.detekt.api.simplePatternToRegex
import io.gitlab.arturbosch.detekt.rules.fqNameOrNull
import org.jetbrains.kotlin.lexer.KtTokens.EQEQEQ
import org.jetbrains.kotlin.lexer.KtTokens.EXCLEQEQEQ
import org.jetbrains.kotlin.psi.KtBinaryExpression
import org.jetbrains.kotlin.resolve.calls.util.getType
/**
* Kotlin supports two types of equality: structural equality and referential equality. While there are
* use cases for both, checking for referential equality for some types (such as `String` or `List`) is
* likely not intentional and may cause unexpected results.
*
* <noncompliant>
* val areEqual = "aString" === otherString
* val areNotEqual = "aString" !== otherString
* </noncompliant>
*
* <compliant>
* val areEqual = "aString" == otherString
* val areNotEqual = "aString" != otherString
* </compliant>
*/
@RequiresTypeResolution
@ActiveByDefault(since = "1.21.0")
class AvoidReferentialEquality(config: Config) : Rule(config) {
override val issue = Issue(
"AvoidReferentialEquality",
Severity.Warning,
"Avoid using referential equality and prefer to use referential equality checks instead.",
Debt.FIVE_MINS
)
@Configuration(
"Specifies those types for which referential equality checks are considered a rule violation. " +
"The types are defined by a list of simple glob patterns (supporting `*` and `?` wildcards) " +
"that match the fully qualified type name."
)
private val forbiddenTypePatterns: List<Regex> by config(
listOf(
"kotlin.String"
)
) { it.map(String::simplePatternToRegex) }
override fun visitBinaryExpression(expression: KtBinaryExpression) {
super.visitBinaryExpression(expression)
checkBinaryExpression(expression)
}
private fun checkBinaryExpression(expression: KtBinaryExpression) {
if (expression.operationToken != EQEQEQ && expression.operationToken != EXCLEQEQEQ) return
val checkedType = expression.left?.getType(bindingContext)?.fqNameOrNull() ?: return
val fullyQualifiedType = checkedType.asString()
if (forbiddenTypePatterns.any { it.matches(fullyQualifiedType) }) {
report(
CodeSmell(
issue,
Entity.from(expression),
"Checking referential equality may lead to unwanted results."
)
)
}
}
}