com.google.errorprone.refaster.UBlank.java Source code

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Here is the source code for com.google.errorprone.refaster.UBlank.java

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/*
 * Copyright 2014 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 static com.google.common.base.MoreObjects.firstNonNull;

import com.google.auto.value.AutoValue;
import com.google.common.base.Function;
import com.google.common.collect.ContiguousSet;
import com.google.common.collect.DiscreteDomain;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Range;
import com.google.errorprone.refaster.UStatement.UnifierWithUnconsumedStatements;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.TreeVisitor;
import com.sun.source.util.TreeScanner;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.util.ListBuffer;
import java.util.Collection;
import java.util.List;
import java.util.UUID;

/**
 * Equivalent to a no-arg block placeholder invocation.
 */
@AutoValue
abstract class UBlank implements UStatement {
    static UBlank create() {
        return new AutoValue_UBlank(UUID.randomUUID());
    }

    abstract UUID unique();

    Key key() {
        return new Key(unique());
    }

    static class Key extends Bindings.Key<List<? extends StatementTree>> {
        Key(UUID k) {
            super(k.toString());
        }
    }

    private static final TreeScanner<Boolean, Unifier> FORBIDDEN_REFERENCE_SCANNER = new TreeScanner<Boolean, Unifier>() {
        @Override
        public Boolean reduce(Boolean l, Boolean r) {
            return firstNonNull(l, false) || firstNonNull(r, false);
        }

        @Override
        public Boolean scan(Tree t, Unifier unifier) {
            if (t != null) {
                Boolean forbidden = t.accept(PlaceholderUnificationVisitor.FORBIDDEN_REFERENCE_VISITOR, unifier);
                return firstNonNull(forbidden, false) || firstNonNull(super.scan(t, unifier), false);
            }
            return false;
        }
    };

    @Override
    public Tree.Kind getKind() {
        return Kind.OTHER;
    }

    @Override
    public <R, D> R accept(TreeVisitor<R, D> visitor, D data) {
        return visitor.visitOther(this, data);
    }

    @Override
    public Choice<UnifierWithUnconsumedStatements> apply(final UnifierWithUnconsumedStatements state) {
        int goodIndex = 0;
        while (goodIndex < state.unconsumedStatements().size()) {
            StatementTree stmt = state.unconsumedStatements().get(goodIndex);
            if (firstNonNull(FORBIDDEN_REFERENCE_SCANNER.scan(stmt, state.unifier()), false)
                    && ControlFlowVisitor.INSTANCE.visitStatement(stmt) == ControlFlowVisitor.Result.NEVER_EXITS) {
                break;
            } else {
                goodIndex++;
            }
        }
        Collection<Integer> breakPoints = ContiguousSet.create(Range.closed(0, goodIndex),
                DiscreteDomain.integers());
        return Choice.from(breakPoints).transform(new Function<Integer, UnifierWithUnconsumedStatements>() {
            @Override
            public UnifierWithUnconsumedStatements apply(Integer k) {
                Unifier unifier = state.unifier().fork();
                unifier.putBinding(key(), state.unconsumedStatements().subList(0, k));
                List<? extends StatementTree> remaining = state.unconsumedStatements().subList(k,
                        state.unconsumedStatements().size());
                return UnifierWithUnconsumedStatements.create(unifier, remaining);
            }
        });
    }

    @Override
    public com.sun.tools.javac.util.List<JCStatement> inlineStatements(Inliner inliner) {
        ListBuffer<JCStatement> buffer = new ListBuffer<>();
        for (StatementTree stmt : inliner.getOptionalBinding(key()).or(ImmutableList.<StatementTree>of())) {
            buffer.add((JCStatement) stmt);
        }
        return buffer.toList();
    }
}