forked from detekt/detekt
/
UnusedPrivateMember.kt
344 lines (299 loc) · 14.6 KB
/
UnusedPrivateMember.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
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
package io.gitlab.arturbosch.detekt.rules.style
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.DetektVisitor
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.rules.isAbstract
import io.gitlab.arturbosch.detekt.rules.isActual
import io.gitlab.arturbosch.detekt.rules.isExpect
import io.gitlab.arturbosch.detekt.rules.isExternal
import io.gitlab.arturbosch.detekt.rules.isMainFunction
import io.gitlab.arturbosch.detekt.rules.isOpen
import io.gitlab.arturbosch.detekt.rules.isOperator
import io.gitlab.arturbosch.detekt.rules.isOverride
import org.jetbrains.kotlin.descriptors.FunctionDescriptor
import org.jetbrains.kotlin.descriptors.PropertyDescriptor
import org.jetbrains.kotlin.lexer.KtSingleValueToken
import org.jetbrains.kotlin.lexer.KtTokens
import org.jetbrains.kotlin.name.Name
import org.jetbrains.kotlin.psi.KtArrayAccessExpression
import org.jetbrains.kotlin.psi.KtClass
import org.jetbrains.kotlin.psi.KtClassOrObject
import org.jetbrains.kotlin.psi.KtFile
import org.jetbrains.kotlin.psi.KtFunction
import org.jetbrains.kotlin.psi.KtNameReferenceExpression
import org.jetbrains.kotlin.psi.KtNamedDeclaration
import org.jetbrains.kotlin.psi.KtNamedFunction
import org.jetbrains.kotlin.psi.KtOperationReferenceExpression
import org.jetbrains.kotlin.psi.KtParameter
import org.jetbrains.kotlin.psi.KtPrimaryConstructor
import org.jetbrains.kotlin.psi.KtProperty
import org.jetbrains.kotlin.psi.KtPropertyDelegate
import org.jetbrains.kotlin.psi.KtReferenceExpression
import org.jetbrains.kotlin.psi.KtSecondaryConstructor
import org.jetbrains.kotlin.psi.KtValueArgumentName
import org.jetbrains.kotlin.psi.psiUtil.containingClassOrObject
import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
import org.jetbrains.kotlin.psi.psiUtil.isPrivate
import org.jetbrains.kotlin.psi.psiUtil.isProtected
import org.jetbrains.kotlin.resolve.BindingContext
import org.jetbrains.kotlin.resolve.calls.util.getResolvedCall
import org.jetbrains.kotlin.types.expressions.OperatorConventions
import org.jetbrains.kotlin.util.OperatorNameConventions
private const val ARRAY_GET_METHOD_NAME = "get"
/**
* Reports unused private properties, function parameters and functions.
* If these private elements are unused they should be removed. Otherwise, this dead code
* can lead to confusion and potential bugs.
*/
@ActiveByDefault(since = "1.16.0")
class UnusedPrivateMember(config: Config = Config.empty) : Rule(config) {
override val defaultRuleIdAliases: Set<String> = setOf("UNUSED_VARIABLE", "UNUSED_PARAMETER", "unused")
override val issue: Issue = Issue(
"UnusedPrivateMember",
Severity.Maintainability,
"Private member is unused and should be removed.",
Debt.FIVE_MINS
)
@Configuration("unused private member names matching this regex are ignored")
private val allowedNames: Regex by config("(_|ignored|expected|serialVersionUID)", String::toRegex)
override fun visit(root: KtFile) {
super.visit(root)
root.acceptUnusedMemberVisitor(UnusedFunctionVisitor(allowedNames, bindingContext))
root.acceptUnusedMemberVisitor(UnusedParameterVisitor(allowedNames))
root.acceptUnusedMemberVisitor(UnusedPropertyVisitor(allowedNames))
}
private fun KtFile.acceptUnusedMemberVisitor(visitor: UnusedMemberVisitor) {
accept(visitor)
visitor.getUnusedReports(issue).forEach { report(it) }
}
}
private abstract class UnusedMemberVisitor(protected val allowedNames: Regex) : DetektVisitor() {
abstract fun getUnusedReports(issue: Issue): List<CodeSmell>
}
private class UnusedFunctionVisitor(
allowedNames: Regex,
private val bindingContext: BindingContext
) : UnusedMemberVisitor(allowedNames) {
private val functionDeclarations = mutableMapOf<String, MutableList<KtFunction>>()
private val functionReferences = mutableMapOf<String, MutableList<KtReferenceExpression>>()
private val propertyDelegates = mutableListOf<KtPropertyDelegate>()
@Suppress("ComplexMethod")
override fun getUnusedReports(issue: Issue): List<CodeSmell> {
val propertyDelegateResultingDescriptors by lazy(LazyThreadSafetyMode.NONE) {
propertyDelegates.flatMap { it.resultingDescriptors() }
}
return functionDeclarations
.filterNot { (_, functions) ->
// Without a binding context we can't know if an operator is called. So we ignore it to avoid
// false positives. More context at #4242
bindingContext == BindingContext.EMPTY && functions.any { it.isOperator() }
}
.flatMap { (functionName, functions) ->
val isOperator = functions.any { it.isOperator() }
val references = functionReferences[functionName].orEmpty()
val unusedFunctions = when {
(functions.size > 1 || isOperator) && bindingContext != BindingContext.EMPTY -> {
val functionNameAsName = Name.identifier(functionName)
val referencesViaOperator = if (isOperator) {
val operatorToken = OperatorConventions.getOperationSymbolForName(functionNameAsName)
val operatorValue = (operatorToken as? KtSingleValueToken)?.value
val directReferences = operatorValue?.let { functionReferences[it] }.orEmpty()
val assignmentReferences = when (operatorToken) {
KtTokens.PLUS,
KtTokens.MINUS,
KtTokens.MUL,
KtTokens.DIV,
KtTokens.PERC -> operatorValue?.let { functionReferences["$it="] }.orEmpty()
else -> emptyList()
}
val containingReferences = if (functionNameAsName == OperatorNameConventions.CONTAINS) {
listOf(KtTokens.IN_KEYWORD, KtTokens.NOT_IN).flatMap {
functionReferences[it.value].orEmpty()
}
} else emptyList()
directReferences + assignmentReferences + containingReferences
} else {
emptyList()
}
val referenceDescriptors = (references + referencesViaOperator)
.mapNotNull { it.getResolvedCall(bindingContext)?.resultingDescriptor }
.map { it.original }
.let {
if (functionNameAsName in OperatorNameConventions.DELEGATED_PROPERTY_OPERATORS) {
it + propertyDelegateResultingDescriptors
} else {
it
}
}
functions.filterNot {
bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, it] in referenceDescriptors
}
}
references.isEmpty() -> functions
else -> emptyList()
}
unusedFunctions.map {
CodeSmell(issue, Entity.atName(it), "Private function `$functionName` is unused.")
}
}
}
override fun visitNamedFunction(function: KtNamedFunction) {
if (!isDeclaredInsideAnInterface(function) && function.isPrivate()) {
collectFunction(function)
}
super.visitNamedFunction(function)
}
private fun isDeclaredInsideAnInterface(function: KtNamedFunction) =
function.getStrictParentOfType<KtClass>()?.isInterface() == true
private fun collectFunction(function: KtNamedFunction) {
val name = function.nameAsSafeName.identifier
if (!allowedNames.matches(name)) {
functionDeclarations.getOrPut(name) { mutableListOf() }.add(function)
}
}
private fun KtPropertyDelegate.resultingDescriptors(): List<FunctionDescriptor> {
val property = this.parent as? KtProperty ?: return emptyList()
val propertyDescriptor =
bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, property] as? PropertyDescriptor
return listOfNotNull(propertyDescriptor?.getter, propertyDescriptor?.setter).mapNotNull {
bindingContext[BindingContext.DELEGATED_PROPERTY_RESOLVED_CALL, it]?.resultingDescriptor
}
}
override fun visitPropertyDelegate(delegate: KtPropertyDelegate) {
super.visitPropertyDelegate(delegate)
propertyDelegates.add(delegate)
}
/*
* We need to collect all private function declarations and references to these functions
* for the whole file as Kotlin allows access to private and internal object declarations
* from everywhere in the file.
*/
override fun visitReferenceExpression(expression: KtReferenceExpression) {
super.visitReferenceExpression(expression)
val name = when (expression) {
is KtOperationReferenceExpression -> expression.getReferencedName()
is KtNameReferenceExpression -> expression.getReferencedName()
is KtArrayAccessExpression -> ARRAY_GET_METHOD_NAME
else -> null
} ?: return
functionReferences.getOrPut(name) { mutableListOf() }.add(expression)
}
}
private class UnusedParameterVisitor(allowedNames: Regex) : UnusedMemberVisitor(allowedNames) {
private val unusedParameters: MutableSet<KtParameter> = mutableSetOf()
override fun getUnusedReports(issue: Issue): List<CodeSmell> {
return unusedParameters.map {
CodeSmell(issue, Entity.atName(it), "Function parameter `${it.nameAsSafeName.identifier}` is unused.")
}
}
override fun visitClassOrObject(klassOrObject: KtClassOrObject) {
if (klassOrObject.isExpect()) return
super.visitClassOrObject(klassOrObject)
}
override fun visitClass(klass: KtClass) {
if (klass.isInterface()) return
if (klass.isExternal()) return
super.visitClass(klass)
}
override fun visitNamedFunction(function: KtNamedFunction) {
if (!function.isRelevant()) {
return
}
collectParameters(function)
super.visitNamedFunction(function)
}
private fun collectParameters(function: KtNamedFunction) {
val parameters = mutableMapOf<String, KtParameter>()
function.valueParameterList?.parameters?.forEach { parameter ->
val name = parameter.nameAsSafeName.identifier
if (!allowedNames.matches(name)) {
parameters[name] = parameter
}
}
function.accept(object : DetektVisitor() {
override fun visitProperty(property: KtProperty) {
if (property.isLocal) {
val name = property.nameAsSafeName.identifier
parameters.remove(name)
}
super.visitProperty(property)
}
override fun visitReferenceExpression(expression: KtReferenceExpression) {
if (expression.parent !is KtValueArgumentName) {
parameters.remove(expression.text.removeSurrounding("`"))
}
super.visitReferenceExpression(expression)
}
})
unusedParameters.addAll(parameters.values)
}
private fun KtNamedFunction.isRelevant() = !isAllowedToHaveUnusedParameters()
private fun KtNamedFunction.isAllowedToHaveUnusedParameters() =
isAbstract() || isOpen() || isOverride() || isOperator() || isMainFunction() || isExternal() ||
isExpect() || isActual() || isProtected()
}
private class UnusedPropertyVisitor(allowedNames: Regex) : UnusedMemberVisitor(allowedNames) {
private val properties = mutableSetOf<KtNamedDeclaration>()
private val nameAccesses = mutableSetOf<String>()
override fun getUnusedReports(issue: Issue): List<CodeSmell> {
return properties
.filter { it.nameAsSafeName.identifier !in nameAccesses }
.map {
CodeSmell(
issue,
Entity.atName(it),
"Private property `${it.nameAsSafeName.identifier}` is unused."
)
}
}
override fun visitParameter(parameter: KtParameter) {
super.visitParameter(parameter)
if (parameter.isLoopParameter) {
val destructuringDeclaration = parameter.destructuringDeclaration
if (destructuringDeclaration != null) {
for (variable in destructuringDeclaration.entries) {
maybeAddUnusedProperty(variable)
}
} else {
maybeAddUnusedProperty(parameter)
}
}
}
override fun visitPrimaryConstructor(constructor: KtPrimaryConstructor) {
super.visitPrimaryConstructor(constructor)
constructor.valueParameters
.filter {
(it.isPrivate() || (!it.hasValOrVar() && !constructor.isActual())) &&
it.containingClassOrObject?.isExpect() == false
}
.forEach { maybeAddUnusedProperty(it) }
}
override fun visitSecondaryConstructor(constructor: KtSecondaryConstructor) {
super.visitSecondaryConstructor(constructor)
constructor.valueParameters.forEach { maybeAddUnusedProperty(it) }
}
private fun maybeAddUnusedProperty(it: KtNamedDeclaration) {
if (!allowedNames.matches(it.nameAsSafeName.identifier)) {
properties.add(it)
}
}
override fun visitProperty(property: KtProperty) {
if (property.isPrivate() && property.isMemberOrTopLevel() || property.isLocal) {
maybeAddUnusedProperty(property)
}
super.visitProperty(property)
}
private fun KtProperty.isMemberOrTopLevel() = isMember || isTopLevel
override fun visitReferenceExpression(expression: KtReferenceExpression) {
nameAccesses.add(expression.text.removeSurrounding("`"))
super.visitReferenceExpression(expression)
}
}