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/*
* Copyright 2014 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.Functions;
import com.google.common.base.MoreObjects;
import com.google.common.base.Optional;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.errorprone.refaster.PlaceholderUnificationVisitor.State;
import com.google.errorprone.refaster.UPlaceholderExpression.UncheckedCouldNotResolveImportException;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.TreeVisitor;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.util.List;
/**
* A representation of a block placeholder.
*
* @author [email protected] (Louis Wasserman)
*/
@AutoValue
abstract class UPlaceholderStatement implements UStatement {
static UPlaceholderStatement create(
PlaceholderMethod placeholder,
Iterable arguments,
ControlFlowVisitor.Result implementationFlow) {
ImmutableList placeholderParams = placeholder.parameters().asList();
ImmutableList argumentsList = ImmutableList.copyOf(arguments);
ImmutableMap.Builder builder = ImmutableMap.builder();
for (int i = 0; i < placeholderParams.size(); i++) {
builder.put(placeholderParams.get(i), argumentsList.get(i));
}
return new AutoValue_UPlaceholderStatement(
placeholder, builder.buildOrThrow(), implementationFlow);
}
abstract PlaceholderMethod placeholder();
abstract ImmutableMap arguments();
abstract ControlFlowVisitor.Result implementationFlow();
@Override
public Kind getKind() {
return Kind.OTHER;
}
@Override
public R accept(TreeVisitor visitor, D data) {
return visitor.visitOther(this, data);
}
@AutoValue
abstract static class ConsumptionState {
static ConsumptionState empty() {
return new AutoValue_UPlaceholderStatement_ConsumptionState(0, List.nil());
}
abstract int consumedStatements();
abstract List placeholderImplInReverseOrder();
ConsumptionState consume(JCStatement impl) {
return new AutoValue_UPlaceholderStatement_ConsumptionState(
consumedStatements() + 1, placeholderImplInReverseOrder().prepend(impl));
}
}
public boolean reverify(Unifier unifier) {
return MoreObjects.firstNonNull(
new PlaceholderVerificationVisitor(
Collections2.transform(
placeholder().requiredParameters(), Functions.forMap(arguments())),
arguments().values())
.scan(unifier.getBinding(placeholder().blockKey()), unifier),
true);
}
@Override
public Choice apply(UnifierWithUnconsumedStatements initState) {
PlaceholderUnificationVisitor visitor =
PlaceholderUnificationVisitor.create(
TreeMaker.instance(initState.unifier().getContext()), arguments());
PlaceholderVerificationVisitor verification =
new PlaceholderVerificationVisitor(
Collections2.transform(
placeholder().requiredParameters(), Functions.forMap(arguments())),
arguments().values());
// The choices where we might conceivably have a completed placeholder match.
Choice> realOptions = Choice.none();
// The choice of consumption states to this point in the block.
Choice> choiceToHere =
Choice.of(
State.create(List.nil(), initState.unifier(), ConsumptionState.empty()));
if (verification.allRequiredMatched()) {
realOptions = choiceToHere.or(realOptions);
}
for (StatementTree targetStatement : initState.unconsumedStatements()) {
if (!verification.scan(targetStatement, initState.unifier())) {
break; // we saw a variable that's not allowed to be referenced
}
// Consume another statement, or if that fails, fall back to the previous choices...
choiceToHere =
choiceToHere.thenChoose(
(State consumptionState) ->
visitor
.unifyStatement(targetStatement, consumptionState)
.transform(
(State stmtState) ->
stmtState.withResult(
consumptionState.result().consume(stmtState.result()))));
if (verification.allRequiredMatched()) {
realOptions = choiceToHere.or(realOptions);
}
}
return realOptions.thenOption(
(State consumptionState) -> {
if (ImmutableSet.copyOf(consumptionState.seenParameters())
.containsAll(placeholder().requiredParameters())) {
Unifier resultUnifier = consumptionState.unifier().fork();
int nConsumedStatements = consumptionState.result().consumedStatements();
ImmutableList remainingStatements =
initState
.unconsumedStatements()
.subList(nConsumedStatements, initState.unconsumedStatements().size());
UnifierWithUnconsumedStatements result =
UnifierWithUnconsumedStatements.create(resultUnifier, remainingStatements);
List impl =
consumptionState.result().placeholderImplInReverseOrder().reverse();
ControlFlowVisitor.Result implFlow = ControlFlowVisitor.INSTANCE.visitStatements(impl);
if (implFlow == implementationFlow()) {
List prevBinding = resultUnifier.getBinding(placeholder().blockKey());
if (prevBinding != null && prevBinding.toString().equals(impl.toString())) {
return Optional.of(result);
} else if (prevBinding == null) {
resultUnifier.putBinding(placeholder().blockKey(), impl);
return Optional.of(result);
}
}
}
return Optional.absent();
});
}
@Override
public List inlineStatements(Inliner inliner) throws CouldNotResolveImportException {
try {
Optional> binding = inliner.getOptionalBinding(placeholder().blockKey());
// If a placeholder was used as an expression binding in the @BeforeTemplate,
// and as a bare statement or as a return in the @AfterTemplate, we may need to convert.
Optional exprBinding = inliner.getOptionalBinding(placeholder().exprKey());
binding =
binding.or(
exprBinding.transform(
(JCExpression expr) -> {
switch (implementationFlow()) {
case NEVER_EXITS:
return List.of(inliner.maker().Exec(expr));
case ALWAYS_RETURNS:
return List.of(inliner.maker().Return(expr));
default:
throw new AssertionError();
}
}));
return UPlaceholderExpression.copier(arguments(), inliner).copy(binding.get(), inliner);
} catch (UncheckedCouldNotResolveImportException e) {
throw e.getCause();
}
}
}
