com.google.errorprone.refaster.UIf Maven / Gradle / Ivy
/*
* Copyright 2013 The Error Prone 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
*
* http://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 com.google.errorprone.refaster;
import com.google.auto.value.AutoValue;
import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.collect.Iterables;
import com.google.errorprone.refaster.ControlFlowVisitor.Result;
import com.sun.source.tree.IfTree;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.TreeVisitor;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.util.List;
import javax.annotation.Nullable;
/**
* {@link UTree} representation of an {@link IfTree}.
*
* @author [email protected] (Louis Wasserman)
*/
@AutoValue
abstract class UIf implements UStatement, IfTree {
public static UIf create(
UExpression condition, UStatement thenStatement, UStatement elseStatement) {
return new AutoValue_UIf(condition, thenStatement, elseStatement);
}
@Override
public abstract UExpression getCondition();
@Override
public abstract UStatement getThenStatement();
@Override
@Nullable
public abstract UStatement getElseStatement();
@Override
public R accept(TreeVisitor visitor, D data) {
return visitor.visitIf(this, data);
}
@Override
public Kind getKind() {
return Kind.IF;
}
private static Function> unifyUStatementWithSingleStatement(
@Nullable final UStatement toUnify, @Nullable final StatementTree target) {
return (Unifier unifier) -> {
if (toUnify == null) {
return (target == null) ? Choice.of(unifier) : Choice.none();
}
List list = (target == null) ? List.nil() : List.of(target);
return toUnify
.apply(UnifierWithUnconsumedStatements.create(unifier, list))
.condition(s -> s.unconsumedStatements().isEmpty())
.transform(UnifierWithUnconsumedStatements::unifier);
};
}
@Override
@Nullable
public Choice apply(UnifierWithUnconsumedStatements state) {
java.util.List unconsumedStatements = state.unconsumedStatements();
if (unconsumedStatements.isEmpty()) {
return Choice.none();
}
final java.util.List unconsumedStatementsTail =
unconsumedStatements.subList(1, unconsumedStatements.size());
StatementTree firstStatement = unconsumedStatements.get(0);
if (firstStatement.getKind() != Kind.IF) {
return Choice.none();
}
final IfTree ifTree = (IfTree) firstStatement;
Unifier unifier = state.unifier();
Choice forwardMatch =
getCondition()
.unify(ifTree.getCondition(), unifier.fork())
.thenChoose(
unifyUStatementWithSingleStatement(getThenStatement(), ifTree.getThenStatement()))
.thenChoose(
unifierAfterThen -> {
if (getElseStatement() != null
&& ifTree.getElseStatement() == null
&& ControlFlowVisitor.INSTANCE.visitStatement(ifTree.getThenStatement())
== Result.ALWAYS_RETURNS) {
Choice result =
getElseStatement()
.apply(
UnifierWithUnconsumedStatements.create(
unifierAfterThen.fork(), unconsumedStatementsTail));
if (getElseStatement() instanceof UBlock) {
Choice alternative =
Choice.of(
UnifierWithUnconsumedStatements.create(
unifierAfterThen.fork(), unconsumedStatementsTail));
for (UStatement stmt : ((UBlock) getElseStatement()).getStatements()) {
alternative = alternative.thenChoose(stmt);
}
result = result.or(alternative);
}
return result;
} else {
return unifyUStatementWithSingleStatement(
getElseStatement(), ifTree.getElseStatement())
.apply(unifierAfterThen)
.transform(
unifierAfterElse ->
UnifierWithUnconsumedStatements.create(
unifierAfterElse, unconsumedStatementsTail));
}
});
Choice backwardMatch =
getCondition()
.negate()
.unify(ifTree.getCondition(), unifier.fork())
.thenChoose(
unifierAfterCond -> {
if (getElseStatement() == null) {
return Choice.none();
}
return getElseStatement()
.apply(
UnifierWithUnconsumedStatements.create(
unifierAfterCond, List.of(ifTree.getThenStatement())))
.thenOption(
(UnifierWithUnconsumedStatements stateAfterThen) ->
stateAfterThen.unconsumedStatements().isEmpty()
? Optional.of(stateAfterThen.unifier())
: Optional.absent());
})
.thenChoose(
unifierAfterThen -> {
if (ifTree.getElseStatement() == null
&& ControlFlowVisitor.INSTANCE.visitStatement(ifTree.getThenStatement())
== Result.ALWAYS_RETURNS) {
Choice result =
getThenStatement()
.apply(
UnifierWithUnconsumedStatements.create(
unifierAfterThen.fork(), unconsumedStatementsTail));
if (getThenStatement() instanceof UBlock) {
Choice alternative =
Choice.of(
UnifierWithUnconsumedStatements.create(
unifierAfterThen.fork(), unconsumedStatementsTail));
for (UStatement stmt : ((UBlock) getThenStatement()).getStatements()) {
alternative = alternative.thenChoose(stmt);
}
result = result.or(alternative);
}
return result;
} else {
return unifyUStatementWithSingleStatement(
getThenStatement(), ifTree.getElseStatement())
.apply(unifierAfterThen)
.transform(
unifierAfterElse ->
UnifierWithUnconsumedStatements.create(
unifierAfterElse, unconsumedStatementsTail));
}
});
return forwardMatch.or(backwardMatch);
}
@Override
public List inlineStatements(Inliner inliner) throws CouldNotResolveImportException {
return List.of(
inliner
.maker()
.If(
getCondition().inline(inliner),
Iterables.getOnlyElement(getThenStatement().inlineStatements(inliner)),
(getElseStatement() == null)
? null
: Iterables.getOnlyElement(getElseStatement().inlineStatements(inliner))));
}
}