org.openrewrite.java.cleanup.SimplifyBooleanExpressionVisitor Maven / Gradle / Ivy
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/*
* Copyright 2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.openrewrite.java.cleanup;
import org.jspecify.annotations.Nullable;
import org.openrewrite.ExecutionContext;
import org.openrewrite.Tree;
import org.openrewrite.java.JavaVisitor;
import org.openrewrite.java.MethodMatcher;
import org.openrewrite.java.search.SemanticallyEqual;
import org.openrewrite.java.tree.*;
import org.openrewrite.marker.Markers;
import java.util.Collections;
public class SimplifyBooleanExpressionVisitor extends JavaVisitor {
@Override
public J visitBinary(J.Binary binary, ExecutionContext ctx) {
J j = super.visitBinary(binary, ctx);
J.Binary asBinary = (J.Binary) j;
if (asBinary.getOperator() == J.Binary.Type.And) {
if (isLiteralFalse(asBinary.getLeft())) {
j = asBinary.getLeft();
} else if (isLiteralFalse(asBinary.getRight())) {
j = asBinary.getRight().withPrefix(asBinary.getRight().getPrefix().withWhitespace(""));
} else if (isLiteralTrue(asBinary.getLeft())) {
j = asBinary.getRight();
} else if (isLiteralTrue(asBinary.getRight())) {
j = asBinary.getLeft().withPrefix(asBinary.getLeft().getPrefix().withWhitespace(""));
} else if (!(asBinary.getLeft() instanceof MethodCall) &&
SemanticallyEqual.areEqual(asBinary.getLeft(), asBinary.getRight())) {
j = asBinary.getLeft();
}
} else if (asBinary.getOperator() == J.Binary.Type.Or) {
if (isLiteralTrue(asBinary.getLeft())) {
j = asBinary.getLeft();
} else if (isLiteralTrue(asBinary.getRight())) {
j = asBinary.getRight().withPrefix(asBinary.getRight().getPrefix().withWhitespace(""));
} else if (isLiteralFalse(asBinary.getLeft())) {
j = asBinary.getRight();
} else if (isLiteralFalse(asBinary.getRight())) {
j = asBinary.getLeft().withPrefix(asBinary.getLeft().getPrefix().withWhitespace(""));
} else if (!(asBinary.getLeft() instanceof MethodCall) &&
SemanticallyEqual.areEqual(asBinary.getLeft(), asBinary.getRight())) {
j = asBinary.getLeft();
}
} else if (asBinary.getOperator() == J.Binary.Type.Equal) {
if (isLiteralTrue(asBinary.getLeft())) {
if (shouldSimplifyEqualsOn(asBinary.getRight())) {
j = asBinary.getRight().withPrefix(asBinary.getRight().getPrefix().withWhitespace(""));
}
} else if (isLiteralTrue(asBinary.getRight())) {
if (shouldSimplifyEqualsOn(asBinary.getLeft())) {
j = asBinary.getLeft().withPrefix(asBinary.getLeft().getPrefix().withWhitespace(" "));
}
} else if (isLiteralFalse(asBinary.getLeft())) {
if (shouldSimplifyEqualsOn(asBinary.getRight())) {
j = not(asBinary.getRight());
}
} else if (isLiteralFalse(asBinary.getRight())) {
if (shouldSimplifyEqualsOn(asBinary.getLeft())) {
j = not(asBinary.getLeft());
}
} else {
j = maybeReplaceCompareWithNull(asBinary, true);
}
} else if (asBinary.getOperator() == J.Binary.Type.NotEqual) {
if (isLiteralFalse(asBinary.getLeft())) {
if (shouldSimplifyEqualsOn(asBinary.getRight())) {
j = asBinary.getRight().withPrefix(asBinary.getRight().getPrefix().withWhitespace(""));
}
} else if (isLiteralFalse(asBinary.getRight())) {
if (shouldSimplifyEqualsOn(asBinary.getLeft())) {
j = asBinary.getLeft().withPrefix(asBinary.getLeft().getPrefix().withWhitespace(" "));
}
} else if (isLiteralTrue(asBinary.getLeft())) {
if (shouldSimplifyEqualsOn(asBinary.getRight())) {
j = not(asBinary.getRight());
}
} else if (isLiteralTrue(asBinary.getRight())) {
if (shouldSimplifyEqualsOn(asBinary.getLeft())) {
j = not(asBinary.getLeft());
}
} else {
j = maybeReplaceCompareWithNull(asBinary, false);
}
}
if (asBinary != j) {
j = j.withPrefix(asBinary.getPrefix());
}
return j;
}
@Override
public J visitParentheses(J.Parentheses parens, ExecutionContext ctx) {
J j = super.visitParentheses(parens, ctx);
if (j != parens && j instanceof J.Parentheses) {
j = new UnnecessaryParenthesesVisitor<>().visit(j, ctx, getCursor().getParentOrThrow());
}
return j;
}
@Override
public J visitUnary(J.Unary unary, ExecutionContext ctx) {
J j = super.visitUnary(unary, ctx);
if (j instanceof J.Unary) {
J.Unary asUnary = (J.Unary) j;
if (asUnary.getOperator() == J.Unary.Type.Not) {
j = unpackExpression(asUnary.getExpression(), asUnary);
}
if (asUnary != j) {
j = j.withPrefix(asUnary.getPrefix());
}
}
return j;
}
@Override
public J visitTernary(J.Ternary ternary, ExecutionContext executionContext) {
J j = super.visitTernary(ternary, executionContext);
if (j instanceof J.Ternary) {
J.Ternary asTernary = (J.Ternary) j;
if (asTernary.getCondition() instanceof J.Unary) {
Expression negated = maybeNegate(asTernary.getCondition());
if (negated != asTernary.getCondition()) {
j = asTernary
.withCondition(negated)
.withTruePart(asTernary.getFalsePart())
.withFalsePart(asTernary.getTruePart());
}
}
}
return j;
}
private Expression unpackExpression(Expression expr, Expression j) {
if (isLiteralTrue(expr)) {
j = ((J.Literal) expr).withValue(false).withValueSource("false");
} else if (isLiteralFalse(expr)) {
j = ((J.Literal) expr).withValue(true).withValueSource("true");
} else if (expr instanceof J.Unary && ((J.Unary) expr).getOperator() == J.Unary.Type.Not) {
j = ((J.Unary) expr).getExpression();
} else if (expr instanceof J.Parentheses) {
J parenthesized = ((J.Parentheses) expr).getTree();
if (parenthesized instanceof J.Binary) {
J.Binary binary = (J.Binary) parenthesized;
J.Binary.Type negated = maybeNegate(binary.getOperator());
if (negated != binary.getOperator()) {
j = binary.withOperator(negated).withPrefix(j.getPrefix());
}
} else if (parenthesized instanceof J.Unary) {
J.Unary unary1 = (J.Unary) parenthesized;
J.Unary.Type operator = unary1.getOperator();
if (operator == J.Unary.Type.Not) {
j = unary1.getExpression().withPrefix(j.getPrefix());
}
} else if (parenthesized instanceof J.Ternary) {
J.Ternary ternary = (J.Ternary) parenthesized;
j = ternary
.withCondition(maybeNegate(ternary.getCondition()))
.withTruePart(ternary.getFalsePart())
.withFalsePart(ternary.getTruePart())
.withPrefix(j.getPrefix());
} else if (parenthesized instanceof Expression) {
j = unpackExpression((Expression) parenthesized, j);
}
}
return j;
}
private Expression maybeNegate(Expression expr) {
if (expr instanceof J.Binary) {
J.Binary.Type negated = maybeNegate(((J.Binary) expr).getOperator());
if (negated != ((J.Binary) expr).getOperator()) {
expr = ((J.Binary) expr).withOperator(negated).withPrefix(expr.getPrefix());
}
} else if (expr instanceof J.Unary && ((J.Unary) expr).getOperator() == J.Unary.Type.Not) {
expr = ((J.Unary) expr).getExpression().withPrefix(expr.getPrefix());
} else if (expr instanceof J.Ternary) {
J.Ternary ternary = (J.Ternary) expr;
Expression negatedCondition = maybeNegate(ternary.getCondition());
if (negatedCondition != ternary.getCondition()) {
expr = ternary
.withCondition(negatedCondition)
.withTruePart(ternary.getFalsePart())
.withFalsePart(ternary.getTruePart())
.withPrefix(expr.getPrefix());
}
}
return expr;
}
private J.Binary.Type maybeNegate(J.Binary.Type operator) {
switch (operator) {
case LessThan:
return J.Binary.Type.GreaterThanOrEqual;
case GreaterThan:
return J.Binary.Type.LessThanOrEqual;
case LessThanOrEqual:
return J.Binary.Type.GreaterThan;
case GreaterThanOrEqual:
return J.Binary.Type.LessThan;
case Equal:
return J.Binary.Type.NotEqual;
case NotEqual:
return J.Binary.Type.Equal;
default:
return operator;
}
}
private final MethodMatcher isEmpty = new MethodMatcher("java.lang.String isEmpty()");
@Override
public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext executionContext) {
J j = super.visitMethodInvocation(method, executionContext);
J.MethodInvocation asMethod = (J.MethodInvocation) j;
Expression select = asMethod.getSelect();
if (isEmpty.matches(asMethod)
&& select instanceof J.Literal
&& select.getType() == JavaType.Primitive.String) {
return booleanLiteral(method, J.Literal.isLiteralValue(select, ""));
}
return j;
}
private boolean isLiteralTrue(@Nullable Expression expression) {
return expression instanceof J.Literal && ((J.Literal) expression).getValue() == Boolean.valueOf(true);
}
private boolean isLiteralFalse(@Nullable Expression expression) {
return expression instanceof J.Literal && ((J.Literal) expression).getValue() == Boolean.valueOf(false);
}
private boolean isNullLiteral(Expression expression) {
return expression instanceof J.Literal && ((J.Literal) expression).getType() == JavaType.Primitive.Null;
}
private boolean isNonNullLiteral(Expression expression) {
return expression instanceof J.Literal && ((J.Literal) expression).getType() != JavaType.Primitive.Null;
}
private J maybeReplaceCompareWithNull(J.Binary asBinary, boolean valueIfEqual) {
Expression left = asBinary.getLeft();
Expression right = asBinary.getRight();
boolean leftIsNull = isNullLiteral(left);
boolean rightIsNull = isNullLiteral(right);
if (leftIsNull && rightIsNull) {
return booleanLiteral(asBinary, valueIfEqual);
}
boolean leftIsNonNullLiteral = isNonNullLiteral(left);
boolean rightIsNonNullLiteral = isNonNullLiteral(right);
if ((leftIsNull && rightIsNonNullLiteral) || (rightIsNull && leftIsNonNullLiteral)) {
return booleanLiteral(asBinary, !valueIfEqual);
}
return asBinary;
}
private static J.Literal booleanLiteral(J j, boolean value) {
return new J.Literal(Tree.randomId(),
j.getPrefix(),
j.getMarkers(),
value,
String.valueOf(value),
Collections.emptyList(),
JavaType.Primitive.Boolean);
}
private static J.Unary not(Expression sideRetained) {
if (!(sideRetained instanceof J.FieldAccess) &&
!(sideRetained instanceof J.Identifier) &&
!(sideRetained instanceof J.Literal) &&
!(sideRetained instanceof J.MethodInvocation) &&
!(sideRetained instanceof J.Parentheses) &&
!(sideRetained instanceof J.Unary)) {
sideRetained = new J.Parentheses<>(Tree.randomId(),
Space.EMPTY,
Markers.EMPTY,
JRightPadded.build(sideRetained));
}
return new J.Unary(Tree.randomId(),
sideRetained.getPrefix(),
sideRetained.getMarkers(),
JLeftPadded.build(J.Unary.Type.Not),
sideRetained
.withPrefix(Space.EMPTY)
.withMarkers(Markers.EMPTY),
JavaType.Primitive.Boolean);
}
/**
* Override this method to disable simplification of equals expressions,
* specifically for Kotlin while that is not yet part of the OpenRewrite/rewrite.
*
* Comparing Kotlin nullable type `?` with tree/false can not be simplified,
* e.g. `X?.fun() == true` is not equivalent to `X?.fun()`
*
* Subclasses will want to check if the `org.openrewrite.kotlin.marker.IsNullSafe`
* marker is present.
*
* @param j the expression to simplify
* @return true by default, unless overridden
*/
protected boolean shouldSimplifyEqualsOn(J j) {
return true;
}
}