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Merged
merged 5 commits into from
Jul 31, 2025
Merged

PreferIncrementOperator - more coverage - compound assignment operators #680

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0cca614
Support for compound assignment operators
greg-at-moderne Jul 31, 2025
5ec4712
Support for non-literals too
greg-at-moderne Jul 31, 2025
9767fd3
Suprressing warnings
greg-at-moderne Jul 31, 2025
d1542a6
Shorter description
greg-at-moderne Jul 31, 2025
51be89e
Removed unused import
greg-at-moderne Jul 31, 2025
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61 changes: 37 additions & 24 deletions src/main/java/org/openrewrite/staticanalysis/PreferIncrementOperator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
import org.openrewrite.TreeVisitor;
import org.openrewrite.internal.ListUtils;
import org.openrewrite.java.JavaIsoVisitor;
import org.openrewrite.java.search.SemanticallyEqual;
import org.openrewrite.java.tree.*;
import org.openrewrite.marker.Markers;

Expand All @@ -33,12 +34,12 @@ public class PreferIncrementOperator extends Recipe {

@Override
public String getDisplayName() {
return "Prefer increment and decrement operators";
return "Prefer increment/decrement and compound assignment operators";
}

@Override
public String getDescription() {
return "Prefer the use of increment and decrement operators (`++` and `--`) over their more verbose equivalents.";
return "Prefer the use of increment and decrement operators (`++`, `--`, `+=`, `-=`) over their more verbose equivalents.";
}

@Override
Expand All @@ -62,33 +63,45 @@ public J.Block visitBlock(J.Block block, ExecutionContext ctx) {
if (statement instanceof J.Assignment) {
J.Assignment assignment = (J.Assignment) statement;

if (assignment.getVariable() instanceof J.Identifier && assignment.getAssignment() instanceof J.Binary) {
J.Identifier variable = (J.Identifier) assignment.getVariable();
if (assignment.getAssignment() instanceof J.Binary) {
Expression variable = assignment.getVariable();
J.Binary binary = (J.Binary) assignment.getAssignment();

if (binary.getOperator() == J.Binary.Type.Addition || binary.getOperator() == J.Binary.Type.Subtraction) {
if (binary.getLeft() instanceof J.Identifier) {
J.Identifier binaryLeft = (J.Identifier) binary.getLeft();
if (variable.getSimpleName().equals(binaryLeft.getSimpleName()) &&
TypeUtils.isOfType(variable.getType(), binaryLeft.getType())) {

if (binary.getRight() instanceof J.Literal) {
J.Literal literal = (J.Literal) binary.getRight();
if (literal.getValue() instanceof Integer && (Integer) literal.getValue() == 1) {
J.Unary.Type unaryType = binary.getOperator() == J.Binary.Type.Addition ?
J.Unary.Type.PostIncrement : J.Unary.Type.PostDecrement;

return new J.Unary(
Tree.randomId(),
assignment.getPrefix(),
assignment.getMarkers(),
new JLeftPadded<>(Space.EMPTY, unaryType, Markers.EMPTY),
variable.withPrefix(Space.EMPTY),
assignment.getType()
);
}
Expression binaryLeft = binary.getLeft();

if (SemanticallyEqual.areEqual(variable, binaryLeft)) {
Expression right = binary.getRight();

if (right instanceof J.Literal) {
J.Literal literal = (J.Literal) right;
if (literal.getValue() instanceof Integer && (Integer) literal.getValue() == 1) {
J.Unary.Type unaryType = binary.getOperator() == J.Binary.Type.Addition ?
J.Unary.Type.PostIncrement : J.Unary.Type.PostDecrement;

return new J.Unary(
Tree.randomId(),
assignment.getPrefix(),
assignment.getMarkers(),
new JLeftPadded<>(Space.EMPTY, unaryType, Markers.EMPTY),
variable.withPrefix(Space.EMPTY),
assignment.getType()
);
}
}

J.AssignmentOperation.Type opType = binary.getOperator() == J.Binary.Type.Addition ?
J.AssignmentOperation.Type.Addition : J.AssignmentOperation.Type.Subtraction;

return new J.AssignmentOperation(
Tree.randomId(),
assignment.getPrefix(),
assignment.getMarkers(),
variable.withPrefix(Space.EMPTY),
new JLeftPadded<>(Space.SINGLE_SPACE, opType, Markers.EMPTY),
right.withPrefix(Space.SINGLE_SPACE),
assignment.getType()
);
}
}
}
Expand Down
101 changes: 65 additions & 36 deletions src/test/java/org/openrewrite/staticanalysis/PreferIncrementOperatorTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,14 +16,13 @@
package org.openrewrite.staticanalysis;

import org.junit.jupiter.api.Test;
import org.junitpioneer.jupiter.ExpectedToFail;
import org.openrewrite.DocumentExample;
import org.openrewrite.test.RecipeSpec;
import org.openrewrite.test.RewriteTest;

import static org.openrewrite.java.Assertions.java;

@SuppressWarnings("ConstantConditions")
@SuppressWarnings({"ConstantConditions", "UnusedAssignment"})
class PreferIncrementOperatorTest implements RewriteTest {

@Override
Expand Down Expand Up @@ -105,22 +104,20 @@ void test() {
}

@Test
void multipleIncrements() {
void incrementByTwo() {
rewriteRun(
java(
"""
class Test {
void test(int i, int j) {
i = i + 1;
j = j - 1;
void test(int i) {
i = i + 2;
}
}
""",
"""
class Test {
void test(int i, int j) {
i++;
j--;
void test(int i) {
i += 2;
}
}
"""
Expand All @@ -129,13 +126,14 @@ void test(int i, int j) {
}

@Test
void doNotChangeNonLiteralOne() {
void doNotChangeDifferentVariable() {
rewriteRun(
java(
"""
class Test {
void test(int i) {
i = i + 2;
int i, j = 0;
Test() {
i = j + 1;
}
}
"""
Expand All @@ -144,13 +142,14 @@ void test(int i) {
}

@Test
void doNotChangeDifferentVariable() {
void doNotChangeIfOrderIsReversed() {
// No strong feelings here, just documenting the current behavior of not applying the change here.
rewriteRun(
java(
"""
class Test {
void test(int i, int j) {
i = j + 1;
void test(int i) {
i = 1 + i;
}
}
"""
Expand All @@ -159,13 +158,28 @@ void test(int i, int j) {
}

@Test
void doNotChangeIfOrderIsReversed() {
void compoundAssignmentForVariousValues() {
rewriteRun(
java(
"""
class Test {
void test(int i) {
i = 1 + i;
void test(int i, int j, long l, long n) {
i = i + 1;
j = j + 5;
i = i + 100;
l = l + 2L;
n = n - 2;
}
}
""",
"""
class Test {
void test(int i, int j, long l, long n) {
i++;
j += 5;
i += 100;
l += 2L;
n -= 2;
}
}
"""
Expand All @@ -174,47 +188,62 @@ void test(int i) {
}

@Test
void longType() {
void doNotChangeAssignmentInIfCondition() {
// No strong feelings here, just documenting the current behavior of not applying the change here.
rewriteRun(
java(
"""
class Test {
void test(long l) {
l = l + 1;
}
}
""",
"""
class Test {
void test(long l) {
l++;
void test(int i) {
if ((i = i + 1) > 10) {
System.out.println(i);
}
}
}
"""
)
);
}

@ExpectedToFail("Not implemented yet")
@Test
void fieldIncrement() {
void compoundAssignmentWithNonLiterals() {
rewriteRun(
java(
"""
class Test {
int count;
int field = 4;
int[] arr = new int[10];
Test other;

void test() {
this.count = this.count + 1;
void test(int i, int j, int k, int size) {
i = i + j;
k = k - size;
i = i + "alef".length();
j = j - (k * 2);
field = field + 4;
this.field = this.field + 3;
this.field = field + 6; // This is not changed as the logic to detect "this.field" is equivalent to "field" in this case is not implemented.
arr/*comment*/[0] = arr/*other comment*/[0] + 1;
other.field = other.field + 2;
}
}
""",
"""
class Test {
int count;
int field = 4;
int[] arr = new int[10];
Test other;

void test() {
this.count++;
void test(int i, int j, int k, int size) {
i += j;
k -= size;
i += "alef".length();
j -= (k * 2);
field += 4;
this.field += 3;
this.field = field + 6; // This is not changed as the logic to detect "this.field" is equivalent to "field" in this case is not implemented.
arr/*comment*/[0]++;
other.field += 2;
}
}
"""
Expand Down