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Expand ListFirstAndLast covered cases to include getList().get(0) (#…
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…424)

* Expand ListFirstAndLast covered cases to include `getList().get(0)`

* Document why we only match on List for now

* Support getFirst and removeFirst where select is methodInvocation

* Handle limited cases where select is not an identifier

* Clarify comments and displayName
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@timtebeek
timtebeek authored Feb 22, 2024
1 parent 6ee5816 commit 367e4fe
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Showing 2 changed files with 129 additions and 8 deletions.
31 changes: 23 additions & 8 deletions src/main/java/org/openrewrite/java/migrate/util/ListFirstAndLast.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,14 +34,15 @@

public class ListFirstAndLast extends Recipe {

// While more SequencedCollections have `*First` and `*Last` methods, only list has `get`, `add`, and `remove` methods that take an index
private static final MethodMatcher ADD_MATCHER = new MethodMatcher("java.util.List add(int, ..)", true); // , * fails
private static final MethodMatcher GET_MATCHER = new MethodMatcher("java.util.List get(int)", true);
private static final MethodMatcher REMOVE_MATCHER = new MethodMatcher("java.util.List remove(int)", true);
private static final MethodMatcher SIZE_MATCHER = new MethodMatcher("java.util.List size()", true);

@Override
public String getDisplayName() {
return "Replace `List` `get`, `add`, and `remove` with `SequencedCollection` `*First` and `*Last` methods";
return "Replace `List.get(int)`, `add(int, Object)`, and `remove(int)` with `SequencedCollection` `*First` and `*Last` methods";
}

@Override
Expand All @@ -67,11 +68,6 @@ private static class FirstLastVisitor extends JavaIsoVisitor<ExecutionContext> {
@Override
public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
J.MethodInvocation mi = super.visitMethodInvocation(method, ctx);
Expression select = mi.getSelect();
if (!(select instanceof J.Identifier)) {
return mi;
}
J.Identifier sequencedCollection = (J.Identifier) select;

final String operation;
if (ADD_MATCHER.matches(mi)) {
Expand All @@ -84,6 +80,22 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, Execu
return mi;
}

// Limit *Last to identifiers for now, as x.get(x.size() - 1) requires the same reference for x
if (mi.getSelect() instanceof J.Identifier) {
return handleSelectIdentifier((J.Identifier) mi.getSelect(), mi, operation);
}

// XXX Maybe handle J.FieldAccess explicitly as well to support *Last on fields too

// For anything else support limited cases, as we can't guarantee the same reference for the collection
if (J.Literal.isLiteralValue(mi.getArguments().get(0), 0)) {
return getMethodInvocation(mi, operation, "First");
}

return mi;
}

private static J.MethodInvocation handleSelectIdentifier(J.Identifier sequencedCollection, J.MethodInvocation mi, String operation) {
final String firstOrLast;
Expression expression = mi.getArguments().get(0);
if (J.Literal.isLiteralValue(expression, 0)) {
Expand All @@ -93,7 +105,10 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, Execu
} else {
return mi;
}
return getMethodInvocation(mi, operation, firstOrLast);
}

private static J.MethodInvocation getMethodInvocation(J.MethodInvocation mi, String operation, String firstOrLast) {
List<Expression> arguments = new ArrayList<>();
final JavaType.Method newMethodType;
JavaType.Method originalMethodType = mi.getMethodType();
Expand Down Expand Up @@ -123,8 +138,8 @@ private static boolean lastElementOfSequencedCollection(J.Identifier sequencedCo
if (expression instanceof J.Binary) {
J.Binary binary = (J.Binary) expression;
if (binary.getOperator() == J.Binary.Type.Subtraction
&& J.Literal.isLiteralValue(binary.getRight(), 1)
&& SIZE_MATCHER.matches(binary.getLeft())) {
&& J.Literal.isLiteralValue(binary.getRight(), 1)
&& SIZE_MATCHER.matches(binary.getLeft())) {
Expression sizeSelect = ((J.MethodInvocation) binary.getLeft()).getSelect();
if (sizeSelect instanceof J.Identifier) {
return sequencedCollection.getSimpleName().equals(((J.Identifier) sizeSelect).getSimpleName());
Expand Down
106 changes: 106 additions & 0 deletions src/test/java/org/openrewrite/java/migrate/util/ListFirstAndLastTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,42 @@ String bar(List<String> collection) {
);
}

@Test
@Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/423")
void getFirstFromMethodInvocation() {
rewriteRun(
//language=java
java(
"""
import java.util.*;
class Foo {
List<String> collection() {
return new ArrayList<>();
}
String bar() {
return collection().get(0);
}
}
""",
"""
import java.util.*;
class Foo {
List<String> collection() {
return new ArrayList<>();
}
String bar() {
return collection().getFirst();
}
}
"""
)
);
}

@Test
void addFirst() {
rewriteRun(
Expand Down Expand Up @@ -91,6 +127,40 @@ void bar(List<String> collection) {
);
}

@Test
@Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/423")
void addFirstFromMethodInvocation() {
rewriteRun(
//language=java
java(
"""
import java.util.*;
class Foo {
List<String> collection() {
return new ArrayList<>();
}
void bar() {
collection().add(0, "first");
}
}
""",
"""
import java.util.*;
class Foo {
List<String> collection() {
return new ArrayList<>();
}
void bar() {
collection().addFirst("first");
}
}
"""
)
);
}

@Test
void removeFirst() {
rewriteRun(
Expand All @@ -117,6 +187,42 @@ String bar(List<String> collection) {
)
);
}

@Test
@Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/423")
void removeFirstFromMethodInvocation() {
rewriteRun(
//language=java
java(
"""
import java.util.*;
class Foo {
List<String> collection() {
return new ArrayList<>();
}
String bar() {
return collection().remove(0);
}
}
""",
"""
import java.util.*;
class Foo {
List<String> collection() {
return new ArrayList<>();
}
String bar() {
return collection().removeFirst();
}
}
"""
)
);
}
}

@Nested
Expand Down

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