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IDEA-204701 Redundant collection operation: suggest emptyIterator()

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This commit is contained in:
Tagir Valeev
2018-12-25 16:17:24 +07:00
parent 566fbe08a3
commit 9fa4497ced
3 changed files with 51 additions and 1 deletions
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java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/redundantCollectionOperation/afterEmptyIterator.java
+8
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@@ -0,0 +1,8 @@
// "Replace with 'Collections.emptyIterator()'" "true"
import java.util.*;
class Test {
Iterator<String> test() {
return Collections.emptyIterator();
}
}
java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/redundantCollectionOperation/beforeEmptyIterator.java
+8
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@@ -0,0 +1,8 @@
// "Replace with 'Collections.emptyIterator()'" "true"
import java.util.*;
class Test {
Iterator<String> test() {
return new ArrayList<String>().iter<caret>ator();
}
}
plugins/InspectionGadgets/src/com/siyeh/ig/redundancy/RedundantCollectionOperationInspection.java
+35 -1
View File
@@ -35,6 +35,11 @@ public class RedundantCollectionOperationInspection extends AbstractBaseJavaLoca
staticCall(CommonClassNames.JAVA_UTIL_COLLECTIONS, "singleton", "singletonList").parameterCount(1),
staticCall(CommonClassNames.JAVA_UTIL_LIST, "of").parameterTypes("E"),
staticCall(CommonClassNames.JAVA_UTIL_SET, "of").parameterTypes("E"));
private static final CallMatcher EMPTY_COLLECTION =
anyOf(
staticCall(CommonClassNames.JAVA_UTIL_COLLECTIONS, "emptyList", "emptySet").parameterCount(0),
staticCall(CommonClassNames.JAVA_UTIL_LIST, "of").parameterCount(0),
staticCall(CommonClassNames.JAVA_UTIL_SET, "of").parameterCount(0));
private static final CallMatcher CONTAINS_ALL =
instanceCall(CommonClassNames.JAVA_UTIL_COLLECTION, "containsAll").parameterTypes(CommonClassNames.JAVA_UTIL_COLLECTION);
private static final CallMatcher CONTAINS =
@@ -54,6 +59,7 @@ public class RedundantCollectionOperationInspection extends AbstractBaseJavaLoca
private static final CallMatcher COLLECTIONS_SORT = staticCall(CommonClassNames.JAVA_UTIL_COLLECTIONS, "sort");
private static final CallMatcher LIST_SORT = instanceCall(CommonClassNames.JAVA_UTIL_LIST, "sort").parameterTypes(
CommonClassNames.JAVA_UTIL_COMPARATOR);
private static final CallMatcher ITERABLE_ITERATOR = instanceCall(CommonClassNames.JAVA_LANG_ITERABLE, "iterator").parameterCount(0);
private static final CallMapper<RedundantCollectionOperationHandler> HANDLERS =
new CallMapper<RedundantCollectionOperationHandler>()
@@ -63,7 +69,8 @@ public class RedundantCollectionOperationInspection extends AbstractBaseJavaLoca
.register(anyOf(CONTAINS, CONTAINS_KEY), ContainsBeforeAddRemoveHandler::handler)
.register(REMOVE_BY_INDEX, RedundantIndexOfHandler::handler)
.register(AS_LIST, RedundantAsListForIterationHandler::handler)
.register(AS_LIST, RedundantSortAsListHandler::handler);
.register(AS_LIST, RedundantSortAsListHandler::handler)
.register(ITERABLE_ITERATOR, RedundantEmptyIteratorHandler::handler);
@NotNull
@Override
@@ -517,6 +524,33 @@ public class RedundantCollectionOperationInspection extends AbstractBaseJavaLoca
}
}
private static class RedundantEmptyIteratorHandler implements RedundantCollectionOperationHandler {
@Override
public void performFix(@NotNull Project project, @NotNull PsiMethodCallExpression call) {
PsiType type = call.getType();
PsiType elementType = PsiUtil.substituteTypeParameter(type, CommonClassNames.JAVA_UTIL_ITERATOR, 0, false);
elementType = GenericsUtil.getVariableTypeByExpressionType(elementType);
String replacement = CommonClassNames.JAVA_UTIL_COLLECTIONS + "."
+ (elementType == null ? "" : "<" + elementType.getCanonicalText() + ">") + "emptyIterator()";
PsiElement result = new CommentTracker().replaceAndRestoreComments(call, replacement);
RemoveRedundantTypeArgumentsUtil.removeRedundantTypeArguments(result);
JavaCodeStyleManager.getInstance(project).shortenClassReferences(result);
}
@NotNull
@Override
public String getReplacement() {
return "Collections.emptyIterator()";
}
static RedundantEmptyIteratorHandler handler(PsiMethodCallExpression call) {
if (!PsiUtil.isLanguageLevel7OrHigher(call)) return null;
PsiExpression qualifier = PsiUtil.skipParenthesizedExprDown(call.getMethodExpression().getQualifierExpression());
if (!EMPTY_COLLECTION.matches(qualifier) && !ConstructionUtils.isEmptyCollectionInitializer(qualifier)) return null;
return new RedundantEmptyIteratorHandler();
}
}
private static class RedundantCollectionOperationFix implements LocalQuickFix {
private final RedundantCollectionOperationHandler myHandler;