/*
* Copyright 2013 Google Inc. All rights reserved.
*
* 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 lowasser@google.com (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, D> R accept(TreeVisitor<R, D> visitor, D data) {
return visitor.visitIf(this, data);
}
@Override
public Kind getKind() {
return Kind.IF;
}
private static Function<Unifier, Choice<Unifier>> unifyUStatementWithSingleStatement(
@Nullable final UStatement toUnify, @Nullable final StatementTree target) {
return new Function<Unifier, Choice<Unifier>>() {
@Override
public Choice<Unifier> apply(Unifier unifier) {
if (toUnify == null) {
return (target == null) ? Choice.of(unifier) : Choice.<Unifier>none();
}
List<StatementTree> list = (target == null) ? List.<StatementTree>nil() : List.of(target);
return toUnify
.apply(UnifierWithUnconsumedStatements.create(unifier, list))
.thenOption(
new Function<UnifierWithUnconsumedStatements, Optional<Unifier>>() {
@Override
public Optional<Unifier> apply(UnifierWithUnconsumedStatements state) {
return state.unconsumedStatements().isEmpty()
? Optional.of(state.unifier())
: Optional.<Unifier>absent();
}
});
}
};
}
@Override
@Nullable
public Choice<UnifierWithUnconsumedStatements> apply(UnifierWithUnconsumedStatements state) {
java.util.List<? extends StatementTree> unconsumedStatements = state.unconsumedStatements();
if (unconsumedStatements.isEmpty()) {
return Choice.none();
}
final java.util.List<? extends StatementTree> 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<UnifierWithUnconsumedStatements> forwardMatch =
getCondition()
.unify(ifTree.getCondition(), unifier.fork())
.thenChoose(
unifyUStatementWithSingleStatement(getThenStatement(), ifTree.getThenStatement()))
.thenChoose(
new Function<Unifier, Choice<UnifierWithUnconsumedStatements>>() {
@Override
public Choice<UnifierWithUnconsumedStatements> apply(Unifier unifier) {
if (getElseStatement() != null
&& ifTree.getElseStatement() == null
&& ControlFlowVisitor.INSTANCE.visitStatement(ifTree.getThenStatement())
== Result.ALWAYS_RETURNS) {
Choice<UnifierWithUnconsumedStatements> result =
getElseStatement()
.apply(
UnifierWithUnconsumedStatements.create(
unifier.fork(), unconsumedStatementsTail));
if (getElseStatement() instanceof UBlock) {
Choice<UnifierWithUnconsumedStatements> alternative =
Choice.of(
UnifierWithUnconsumedStatements.create(
unifier.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(unifier)
.transform(
new Function<Unifier, UnifierWithUnconsumedStatements>() {
@Override
public UnifierWithUnconsumedStatements apply(Unifier unifier) {
return UnifierWithUnconsumedStatements.create(
unifier, unconsumedStatementsTail);
}
});
}
}
});
Choice<UnifierWithUnconsumedStatements> backwardMatch =
getCondition()
.negate()
.unify(ifTree.getCondition(), unifier.fork())
.thenChoose(
new Function<Unifier, Choice<Unifier>>() {
@Override
public Choice<Unifier> apply(Unifier unifier) {
if (getElseStatement() == null) {
return Choice.none();
}
return getElseStatement()
.apply(
UnifierWithUnconsumedStatements.create(
unifier, List.of(ifTree.getThenStatement())))
.thenOption(
new Function<UnifierWithUnconsumedStatements, Optional<Unifier>>() {
@Override
public Optional<Unifier> apply(
UnifierWithUnconsumedStatements state) {
return state.unconsumedStatements().isEmpty()
? Optional.of(state.unifier())
: Optional.<Unifier>absent();
}
});
}
})
.thenChoose(
new Function<Unifier, Choice<UnifierWithUnconsumedStatements>>() {
@Override
public Choice<UnifierWithUnconsumedStatements> apply(Unifier unifier) {
if (ifTree.getElseStatement() == null
&& ControlFlowVisitor.INSTANCE.visitStatement(ifTree.getThenStatement())
== Result.ALWAYS_RETURNS) {
Choice<UnifierWithUnconsumedStatements> result =
getThenStatement()
.apply(
UnifierWithUnconsumedStatements.create(
unifier.fork(), unconsumedStatementsTail));
if (getThenStatement() instanceof UBlock) {
Choice<UnifierWithUnconsumedStatements> alternative =
Choice.of(
UnifierWithUnconsumedStatements.create(
unifier.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(unifier)
.transform(
new Function<Unifier, UnifierWithUnconsumedStatements>() {
@Override
public UnifierWithUnconsumedStatements apply(Unifier unifier) {
return UnifierWithUnconsumedStatements.create(
unifier, unconsumedStatementsTail);
}
});
}
}
});
return forwardMatch.or(backwardMatch);
}
@Override
public List<JCStatement> inlineStatements(Inliner inliner) throws CouldNotResolveImportException {
return List.<JCStatement>of(
inliner
.maker()
.If(
getCondition().inline(inliner),
Iterables.getOnlyElement(getThenStatement().inlineStatements(inliner)),
(getElseStatement() == null)
? null
: Iterables.getOnlyElement(getElseStatement().inlineStatements(inliner))));
}
}