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Transform collection.size() < 1 to isEmpty() #184

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Merged
timtebeek merged 1 commit into from
Oct 3, 2023
Merged

Transform collection.size() < 1 to isEmpty() #184

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29 changes: 28 additions & 1 deletion src/main/java/org/openrewrite/staticanalysis/IsEmptyCallOnCollections.java
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Original file line number Diff line number Diff line change
Expand Up @@ -68,10 +68,10 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
public J visitBinary(J.Binary binary, ExecutionContext ctx) {
if (isZero(binary.getLeft()) || isZero(binary.getRight())) {
boolean zeroRight = isZero(binary.getRight());
J maybeSizeCall = zeroRight ? binary.getLeft() : binary.getRight();
if (binary.getOperator() == J.Binary.Type.Equal || binary.getOperator() == J.Binary.Type.NotEqual
|| zeroRight && binary.getOperator() == J.Binary.Type.GreaterThan
|| !zeroRight && binary.getOperator() == J.Binary.Type.LessThan) {
J maybeSizeCall = zeroRight ? binary.getLeft() : binary.getRight();
if (maybeSizeCall instanceof J.MethodInvocation) {
J.MethodInvocation maybeSizeCallMethod = (J.MethodInvocation) maybeSizeCall;
if (COLLECTION_SIZE.matches(maybeSizeCallMethod)) {
Expand All @@ -84,6 +84,28 @@ public J visitBinary(J.Binary binary, ExecutionContext ctx) {
}
}
}
if (isOne(binary.getLeft()) || isOne(binary.getRight())) {
boolean oneRight = isOne(binary.getRight());
if ((oneRight && binary.getOperator() == J.Binary.Type.LessThan)
|| (!oneRight && binary.getOperator() == J.Binary.Type.GreaterThan)
|| (oneRight && binary.getOperator() == J.Binary.Type.GreaterThanOrEqual)
|| (!oneRight && binary.getOperator() == J.Binary.Type.LessThanOrEqual)) {
J maybeSizeCall = oneRight ? binary.getLeft() : binary.getRight();
if (maybeSizeCall instanceof J.MethodInvocation) {
J.MethodInvocation maybeSizeCallMethod = (J.MethodInvocation) maybeSizeCall;
if (COLLECTION_SIZE.matches(maybeSizeCallMethod)) {
String op = "";
if (binary.getOperator() == J.Binary.Type.GreaterThanOrEqual || binary.getOperator() == J.Binary.Type.LessThanOrEqual) {
op = "!";
}
return (maybeSizeCallMethod.getSelect() == null ?
isEmptyNoReceiver.apply(getCursor(), binary.getCoordinates().replace(), op) :
isEmpty.apply(getCursor(), binary.getCoordinates().replace(), op, maybeSizeCallMethod.getSelect())
).withPrefix(binary.getPrefix());
}
}
}
}
return super.visitBinary(binary, ctx);
}
});
Expand All @@ -92,4 +114,9 @@ public J visitBinary(J.Binary binary, ExecutionContext ctx) {
private static boolean isZero(Expression expression) {
return expression instanceof J.Literal && Integer.valueOf(0).equals(((J.Literal) expression).getValue());
}

private static boolean isOne(Expression expression) {
return expression instanceof J.Literal && Integer.valueOf(1).equals(((J.Literal) expression).getValue());
}

}
47 changes: 45 additions & 2 deletions src/test/java/org/openrewrite/staticanalysis/IsEmptyCallOnCollectionsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ boolean test() {
}

@Test
void isEmptyCallOnCollections() {
void comparisonWithZero() {
rewriteRun(
//language=java
java(
Expand All @@ -84,7 +84,7 @@ void isEmptyCallOnCollections() {

class Test {
static void method(List<String> l) {
if (l.isEmpty() || 0 == l.size()) {
if (l.size() == 0 || 0 == l.size()) {
// empty body
} else if (l.size() != 0 || 0 != l.size()) {
// empty body
Expand Down Expand Up @@ -117,6 +117,49 @@ static void method(List<String> l) {
);
}

@Test
void comparisonWithOne() {
rewriteRun(
//language=java
java(
"""
import java.util.List;

class Test {
static void method(List<String> l) {
if (l.size() < 1 || 1 > l.size()) {
// empty body
} else if (l.size() > 1 || 1 < l.size()) {
// empty body
} else if (l.size() >= 1 || 1 <= l.size()) {
// empty body
} else if (l.size() <= 1 || 1 >= l.size()) {
// empty body
}
}
}
""",
"""
import java.util.List;

class Test {
static void method(List<String> l) {
if (l.isEmpty() || l.isEmpty()) {
// empty body
} else if (l.size() > 1 || 1 < l.size()) {
// empty body
} else if (!l.isEmpty() || !l.isEmpty()) {
// empty body
} else if (l.size() <= 1 || 1 >= l.size()) {
// empty body
}
}
}
"""
)
);
}

@Issue("https://github.com/openrewrite/rewrite/issues/1112")
@Test
void formatting() {
Expand Down